WO2001017306A1 - Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system - Google Patents

Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system Download PDF

Info

Publication number
WO2001017306A1
WO2001017306A1 PCT/EP2000/007911 EP0007911W WO0117306A1 WO 2001017306 A1 WO2001017306 A1 WO 2001017306A1 EP 0007911 W EP0007911 W EP 0007911W WO 0117306 A1 WO0117306 A1 WO 0117306A1
Authority
WO
WIPO (PCT)
Prior art keywords
network
handover
subscriber station
power
measurement
Prior art date
Application number
PCT/EP2000/007911
Other languages
French (fr)
Inventor
Justus Petersson
Original Assignee
Telefonaktiebolaget Lm Ericsson (Publ)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget Lm Ericsson (Publ) filed Critical Telefonaktiebolaget Lm Ericsson (Publ)
Priority to DE60033406T priority Critical patent/DE60033406T2/en
Priority to AU64418/00A priority patent/AU764548B2/en
Priority to EP00951507A priority patent/EP1208711B1/en
Publication of WO2001017306A1 publication Critical patent/WO2001017306A1/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/06—Reselecting a communication resource in the serving access point
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/06—TPC algorithms
    • H04W52/12—Outer and inner loops
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/0085—Hand-off measurements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/24—Reselection being triggered by specific parameters
    • H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
    • H04W36/304—Reselection being triggered by specific parameters by measured or perceived connection quality data due to measured or perceived resources with higher communication quality
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00837—Determination of triggering parameters for hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/12—Reselecting a serving backbone network switching or routing node
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/24—TPC being performed according to specific parameters using SIR [Signal to Interference Ratio] or other wireless path parameters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/30—TPC using constraints in the total amount of available transmission power
    • H04W52/36—TPC using constraints in the total amount of available transmission power with a discrete range or set of values, e.g. step size, ramping or offsets
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/38—TPC being performed in particular situations
    • H04W52/40—TPC being performed in particular situations during macro-diversity or soft handoff
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/38—TPC being performed in particular situations
    • H04W52/44—TPC being performed in particular situations in connection with interruption of transmission

Definitions

  • the invention relates to a subscriber station, a network control means and a method for triggering inter-frequency measurements in a mobile communication system.
  • the invention also relates to a mobile communication system in which such a subscriber station, such a network control means and such a method are employed.
  • an inter-frequency measurement trigger signal is generated to indicate the need for an inter-frequency or inter-system handover and to initiate inter-frequency measurements on a different frequency than currently used.
  • inter-frequency measurements are carried-out on one or more different frequencies and * if a suitable new frequency has been found the actual an inter-frequency or inter-system handover takes place.
  • CD cn CO tn CO ⁇ -3 p H- H3 0 iQ 3 s: ⁇ ffi CO s; H3 Hi rr tl rt 3 ⁇ - 0 tl tl rr ⁇ - ⁇ O s; ⁇ JD rt J rt t H- 1 O H- 1 0 CD ro ⁇ - > CD ⁇ - rr rro 0 0 o CD 3 o o CD H tl 0 rt rrrr
  • Fig. 1 only shows two mobile communication systems Tl, T2 as an example where both such handover procedures may take place.
  • Fig. 1 shows as an example for the first mobile communication system Tl a WCDMA (Wideband Code Division Multiple Access) or CDMA (Code Division Multiple Access) communication system comprising a network control means RNC (Radio Network Controller), at least one base transceiver station RBS, RBS' (in WCDMA called radio base station) , at least one subscriber station MS (Mobile Station) as well as a number of (possibly) overlapping cells SI, S2 , S3, SI', S3'.
  • RNC Radio Network Controller
  • the second mobile communication system T2 is a communication system according to the GSM (Global System for Mobile Communications) , PDC (Personal Digital Cellular) and D-AMPS (Digital-Advanced Mobile Personal Service) standards.
  • GSM Global System for Mobile Communications
  • PDC Personal Digital Cellular
  • D-AMPS Digital-Advanced Mobile Personal Service
  • Fig. 1 an example of a GSM system is shown for the second mobile communication system T2.
  • the GSM system shown in Fig. 1 comprises the conventional units of a base station controller BSC, at least one mobile switching center MSC as well as a gateway mobile switching center GMSC .
  • the mobile stations MS are served by a plurality of base transceiver stations BTS within the cells C1-C6 in which the mobile station MS can move around .
  • the network control means RNC of the WCDMA system in Fig. 1 is connected via a UMSC unit to the gateway mobile switching center GMSC of the GSM system.
  • the cells SI, S2 , S3, SI', S3' of the first mobile communication system Tl may also completely or partially overlap with the cells C1-C6 of the second mobile communication system T2.
  • the mobile station MS is to carry out an inter-system handover - then the mobile station MS will be able to operate according to the specifications of the first and the second mobile communication system.
  • One reason for performing inter- frequency or inter-system handovers in the telecommunication system TELE in Fig. 1 may be due to coverage reasons. This is due to the fact that neither the first communication system nor any other system has a complete coverage in all geographical areas, e.g. hot spots in UMTS. Furthermore, some cells within the mobile communication system may operate on frequencies which are not applicable in adjacent cells. Therefore, by letting the mobile station MS or the network control means RNC perform either an inter-frequency handover of an inter-system handover, the mobile station MS can be used in a larger area without interruptions in the communication.
  • Another reason for the handover may be capacity reasons. Either the mobile communication system or other mobile communication systems may become heavily loaded at times, so that an inter-system handover may be required.
  • the mobile station MS may have established a connection on a particular frequency and it may be necessary that another frequency is to be used. This other frequency may be present within the same cell or in another cell and both are generally termed inter-frequency handover.
  • the inter-frequency measurements (necessary for an inter-frequency handover/or an inter-system handover) is always carried-out by an inter- frequency measurement means IFMM situated in a mobile station MS.
  • the network control means RNC comprises a paging flag sending means PFSM for sending a paging flag to the mobile station MS Pi rt cn JD rr H H cn H 3 H 3 rt ⁇ £, ro TJ 3 3 ⁇ ⁇ o ⁇ ⁇ Hh rt CO t cn o n CO tl ro ro rr ⁇ - Pi JD p ⁇ ⁇ - 4 CD H J CD rr Hi rr X CD CD CD CD CD 0 0 ⁇ - 0 O rr rt o rt TJ c s; ro CO rr tn ro iQ ⁇ ts ⁇ -3 ( Q JD JD ro ⁇ - D TJ Hi JD JD 3 3 rt IQ m Hi CD JD ts JD CD cr ⁇ - rt rt CD ⁇ - p JD i o O a t
  • CD 0 (D ⁇ CD iQ 0 Hi rt 0 ⁇ ts 0 ⁇ - H
  • step STll each can initiate a handover according to the triggering conditions which are respectively monitored.
  • the four basic criteria during the monitoring in step STll in the prior art are the "base station traffic load exceeded” condition, the “distance limits exceeded” condition, the “pilot strength below a predetermined threshold” condition and the “power level exceeded” condition as will be explained below and as is described in the aforementioned reference [1] .
  • the network handover means HORM determines the necessity for a handover by monitoring loads at all base stations BS in the mobile communicaton system Tl and outputs the IF measurement signal IFTS in order to balance loads between all base stations, in order to achieve a higher traffic efficiency. For example, the network handover means HORM outputs the trigger signal in step ST13 whenever the load at a base station exceeds a predetermined load threshold.
  • the subscriber handover means and/or the network handover menas HOM are adapted to determine the necessity for the handover on the basis of a supervision of the distance between a base station BS and the subscriber station MS.
  • the distance between the relevant base station and the subscriber station can be determined in a synchronized system. Therefore, the trigger signal IFTS is output in step ST13 whenever the measured distance exceeds a predetermined distance .
  • the subscriber handover means and/or the network handover means are adapted to determine the necessity for a handover on the basis of a supervision of a measured pilot signal strength falling below a predetermined power threshold.
  • a data transmission between a base transceiver station RBS and a subscriber station MS is carried-out by transmitting data frames FR and the transmission frames FR consist of a control portion CP and a data portion DP. This is true for CDMA frames (Fig. 3-1) and TDMA frames in GSM (Fig. 4-1) .
  • the control portion CP consists at least of pilot symbols PS and preferably also of other control symbols CS .
  • each base station BS may transmit a pilot signal PS of constant power on the same frequency.
  • the subscriber station MS can monitor the received power level of the received pilot signal and can thus estimate the power loss on the connection between the base station BS and the subscriber station MS.
  • the subscriber handover means HORM uses the pilot signal strength for estimating the path loss, the subscriber handover means HORM outputs the trigger signal IFTS in step ST13 if the path loss is greater than a predetermined path loss threshold.
  • the subscriber handover means and/or the network handover means are adapted to determine the necessity for a handover on the basis of a supervision that in response to a power increase command by a base station BS a subscriber power adjustment module PAM (shown in Fig. 1 in the mobile station MS) is unable to further increase its power on the up-link of the communication connection CC .
  • PAM subscriber power adjustment module
  • Fig. 5a-d show such a conventional adjustment of the transmission power when exchanging frames FR consisting of a number of time slots TSl ... TS15 between a base transceiver station (generally called node “B") RBS and a subscriber station MS.
  • a power adjustment module PAM in the base transceiver station (node "B") RBS presets an upper threshold PUP, a lower threshold PDWN and an offset value POFF for the power.
  • the power offset value POFF is used in connection with a slow power control and the upper and lower threshold values PUP, PDWN are used in connection with a fast power control in the node B .
  • Steps PI, P2 relate to the slow power control (the outer control loop) carried out on the RNC-side or the MS-side.
  • the frame error rate FER (or the block error rate BLER) is measured and in step P2 the measured FER (or the BLER) is compared with a FER target value (or a BLER target value) .
  • a new signal interference ratio target value SIR-target is obtained.
  • a known (simulated) relationship between a delta_SIR_target value (dB) and the logarithm of the measured FER value exists.
  • SIR_target SIR_target + delta_SIR_target *
  • the outer loop or slow power control will generate in step P8 new SIR-target values whenever steps Pi, P2 are executed.
  • the new SIR-target value is then used in the fast power control (inner loop) carried out on the node B-side or the MS-side, respectively.
  • the slow power control and the fast power control result in a stepwise adjustment of the power P ou t on the downlink DL . Since the slow power control performs steps Pi, P2 for calculating the frame error rate FER (or block error rate BLER) for every frame (or block) a new SIR-target value is obtained less frequently than the fast power control carried out with steps P5 , P4 , P6 , P7 for each slot.
  • steps Pi for calculating the frame error rate FER (or block error rate BLER) for every frame (or block) a new SIR-target value is obtained less frequently than the fast power control carried out with steps P5 , P4 , P6 , P7 for each slot.
  • the offset value P Q ff and the upper and lower threshold values P up , d n are also used in the power adjustment. For example, when the output power P ou t exceeds the upper threshold P up then the offset value P Q ff is slightly increased and when the power is lower than the lower threshold P ⁇ n the offset value P Q ff is slightly decreased.
  • the stepwise adjustment of the power is always performed within the power range between P ⁇ bn ano ⁇ p up • Since the values P 0 ff, P U p and P ⁇ wn are only used for the triggering of a soft-handover , they are not of any further relevance for the present invention and any further descriptions thereof are therefore omitted.
  • the network handover means HORM may request a measurement by issuing the IF trigger signal.
  • reference [1] relates to the IS-95 standard and describes a synchronized CDMA system
  • 3GPP third generation partnership project
  • TSG technical specification group
  • condition 3 "pilot strength below a predetermined threshold" the subscriber station MS must perform measurements for triggering IF measurements and thus for triggering a handover.
  • These continuous measurements of the pilot signal strength may drastically reduce the lifetime of the battery of the subscribers station, since the subscriber station MS must perform an average filtering of the pilot channel during a predetermined measurement time.
  • the decrease of the lifetime of the battery is to be avoided in all circumstances, since there are already a lot of measurements that must be performed by the subscriber station, e.g. the IF measurements on other frequencies when the IF measurement trigger signal IFTS has been issued.
  • the subscriber station MS has to report the pilot signal strength cn 3 ⁇ - ft
  • the data communication is performed by exchanging data frames FR consisting of a plurality of time slots TS1..TS15.
  • Each time slot comprises a control portion CP and a data portion DP.
  • a compressed mode also called slotted mode
  • the network control means RNC comprises a compressed mode setting means CMSM in which the data contained in the data portion DP is compressed, i.e. concentrated to a smaller part of the frame, resulting in an idle time portion ITP.
  • the subscriber station MS comprises a compressed mode determining means CMDM which determines i.e. realizes - being informed about the compressed mode of transmission via signalling or some information sent from the compressed mode setting means CMSM of the network control means RNC - the compressed mode of operation. If such a compressed mode of operation is detected, the subscriber station MS enters a compressed mode of operation and performs the IF measurements in the idle time IT in step ST21'' in Fig. 3-2.
  • CMDM compressed mode determining means CMDM which determines i.e. realizes - being informed about the compressed mode of transmission via signalling or some information sent from the compressed mode setting means CMSM of the network control means RNC - the compressed mode of operation. If such a compressed mode of operation is detected, the subscriber station MS enters a compressed mode of operation and performs the IF measurements in the idle time IT in step ST21'' in Fig. 3-2.
  • Fig. 4-1 and steps SC21''' and ST21'''' show another possibility of how a time interval can be provided in which the field measurements can be carried out.
  • a specific time slot FMS of a frame consisting of a plurality of TDMA time slots TS1...TS-M is specified and the field measurements are carried-out in the portion FMP . That is, in a GSM system a predetermined field measurement slot is provided in which no data is sent from the network control means or the base station transmitter to the subscriber station MS.
  • the network control means RNC triggers the mobile station and step ST13 to perform the IF measurements and it will also indicate to the subscriber statin MS on which frequency belonging to a different cell or a different system said IF measurements are to be carried-out.
  • the subscriber station SS will report the IF measurements back to the network control means RNC within a predetermined time.
  • the network control means RNC will determine whether a handover to the selected frequency (cell or different system) is possible. If it is not possible, because for example a too high interference is
  • the WCDMA procedure of carrying-out field measurements in connection with the compressed mode of operation has the following disadvantages, in particular for the system. If the spreading factor SF in the down link DL is reduced to provide the idle time interval IT in which the subscriber station MS is to perform the field measurements on other systems, the available channelization codes are reduced. That is, the hard capacity for the CDMA system is decreased.
  • the subscriber station MS has to increase its output power when measurements are performed due to the compressed mode operation, since the same data information is transmitted during a smaller time period, i.e. in the compressed data period. If the output power of the subscriber station MS and/or base transceiver station RBS would not be increased, the performance will be decreased. However, this requirement to increase the peak power of the subscriber station MS may imply a distance limitation if the subscriber station MS is already transmitting at its maximum output power. Furthermore, there is a higher risk to lose information, since the data field is not protected to the same extent when the coding rate is reduced.
  • the procedure to use a PN sequence transmission as shown in Fig. 6 has the following disadvantages.
  • all other existing mobile communication systems have to be equipped with an apparatus which transmits a PN sequence which can be detected by the subscriber station MS. This will imply high costs for the operators (and thus for the end users) .
  • the PN sequence used in the other mobile communication systems will interfere with the CDMA systems and will reduce the capacity as well as the quality of data transmission.
  • the last mentioned method of increasing the power before and after the measurement time interval has the disadvantage that there is a high risk that a loss of frames due to the measurement time interval will deteriorate the speech quality in situations where speech quality is already very low, when it is likely that the subscriber station MS wants to do an inter-frequency handover close to a cell border or when the cell (sector) exhibits a high load.
  • the above mentioned first to fourth conditions for triggering inter-frequency measurements in a mobile communication system are not generally applicable to all systems, i.e. to synchronized or non-synchronized systems. Furthermore, the lifetime of the battery is reduced. In addition, the interference level on the up-link as well as the overall signaling load in the network may be increased. The present invention aims at avoiding these disadvantages .
  • the object of the present invention is to provide a subscriber station, a network control means, a method and a mobile communication system in which the inter- frequency measurements carried out by the subscriber station can be triggered without a reduction of a battery consumption in the subscriber station and without increasing the signaling load in the network and the interference on the uplink connection.
  • a subscriber station (claim 1) of a mobile communication system, which comprises at least one base transceiver station and a network control means for establishing at least one communication connection with said subscriber station, including an inter-frequency IF measurement means adapted to perform IF measurements, characterized by said IF measurement means being adapted to perform said IF measurements in response to a network IF measurement trigger signal transmitted and generated by an IF handover means of said network control means in response to a quality measurement means determining that the transmission quality on the down-link of said communication connection drops under a predetermined quality measure.
  • a method for triggering inter-frequency IF measurements in a subscriber station of a mobile communication system which comprises at least one base transceiver station and a network control means for establishing at least one communication connection with said subscriber station, including an inter-frequency IF measurement means adapted to perform said IF measurements, characterized by the steps of monitoring in said network control means the transmission quality on the down-link of said communication connection; generating a network IF measurement trigger signal when said transmission quality drops under a predetermined quality measure and sending said generated network IF measurement trigger signal to said subscriber station; and performing said IF measurements by said IF measurement means in said subscriber station in response to said network IF measurement trigger signal.
  • a mobile communication system comprising at least one subscriber station inclduing an inter-frequency IF measurement means adapted to perform said IF measurements and at least one base transceiver station and a network control means for establishing at least one communication connection with said subscriber station, characterized by said network control means comprising a quality measurement means adapted to monitor the transmission quality on the down-link of said communication connection and a network IF handover means adapted to generate a network IF measurement trigger signal when said transmission quality drops under a predetermined quality measure and to send said generated network IF measurement trigger signal to said subscriber station, wherein said IF measurement means is adapted to perform said IF measurements in said subscriber station in response to said network IF measurement trigger signal.
  • a network control means (claim 48) of a mobile communication system comprising at least one subscriber station including an inter-frequency measurement means adapted to perform said IF measurements and at least one base transceiver station for establishing at least one communication connection with said subscriber station, characterized by said network control means comprising a quality measurement means adapted to monitor the transmission quality on the down-link of said communication connection and a network IF handover means adapted to generate a network IF measurement trigger signal when said transmission quality drops under a predetermined quality measure and to send said generated network IF measurement trigger signal to said subscriber station, wherein and said IF measurement means is adapted to perform said IF measurements in said subscriber station in response to said network IF measurement trigger signal .
  • the IF measurements carried out by an IF measurement means in the subscriber station are started in response to a network IF measurement trigger signal transmitted and generated from the network control means in response to a quality measurement means in the network determining that the transmission quality on the down-link of the communication connection drops under a predetermined quality measure.
  • a power measurement means PWM in the network control means measures a tranmitted output power on down-link and the IF measurement trigger signal is generated, when the transmitted output power on the down-link exceeds a predetermined power of said value.
  • PWM in the network control means measures a tranmitted output power on down-link and the IF measurement trigger signal is generated, when the transmitted output power on the down-link exceeds a predetermined power of said value.
  • advantageously also other parameters can be evaluated to detect a degradation of the transmission quality on the down-link.
  • the IF measurement trigger signal is generated by the network control means only if the transmitted output power measured on the down-link by the power measurement means exceeds said predetermined power of said value longer than a predetermined time interval.
  • the power measurement on the down- link is carried out within the slow and fast power control carried out between the network control means and the subscriber station when adjusting the transmission power.
  • the network IF measurement trigger signal is generated when the quality measurement means determines that the transmission quality on all downlinks DL of all said communication connections drops under a respective predetermined quality measure.
  • the measure can be the measurement of power on the down-link.
  • a subscriber IF handover means transmits a suibscriber IF measurement trigger signal or some measurements in some form over the air- interface to the network control means and the network handover means will only generate and transmit the network IF measurement signal, when the measurements in the subscriber IF measurement signal indicate the necessity for a handover and said quality measurement means determines that the transmission quality on the down-link of the communication connection has dropped under said predetermined quality meaure . That is, based on the down-link quality measurement performed by the network and other measurements from the subscriber station, the network can trigger the subscriber station to perform said IF measurements.
  • the network control means performs down-link quality measurements on the down-link and receives additional information, for example the total up-link interference level from the network and the network control means only issues the network interfrequency trigger signal if all measurements and conditions indicate the need for IF measurements .
  • the outputting of the network IF measurement signal can additionally be made dependent on the conditions "base station traffic load exceeded”, “distance limits exceeded”, “pilot strength below a predetermined threshold” and “power level exceeded” in addition to being dependent on the down-link quality measurements .
  • the subscriber station does not need to perform measurements for triggering an interfrequency or inter-system handover. That is, all this is carried out autonomously in the network control means by monitoring the down-link quality on the down-link of the communication connection. Therefore, there will be no signaling over the air-interface and the subscriber station has no need to report any measurements to the network control means, which thus increases the lifetime of the battery.
  • Fig. 1 shows a principal overview of a telecommunication system TELE comprising at least two different mobile communications systems Tl , T2 according to the prior art
  • Fig. 2 shows a flow chart for performing an inter- frequency and/or inter-system handover in the telecommunication system TELE shown in Fig. 1;
  • Fig. 3-1 shows the constitution of data frames and time slots when a compressed mode of operation is used
  • Fig. 3-2 shows a flow chart similar to Fig. 2 when a compressed mode of operation is used as shown in Fig. 3-1;
  • Fig. 4-1 shows the provision of a field measurement time slot in a conventional TDMA mobile communication system such as GSM;
  • Fig. 4-2 shows a flow chart similar as in Fig. 3-2 for the case when IF measurements are carried out in a specific IF measurement time slot as shown in Fig. 4-1;
  • Fig. 5a shows a diagram illustrating a power adjustment procedure between a subsriber station MS and a node B (base transceiver station RBS) according to the prior art
  • Fig. 5b shows the stepwise adjustment of the output power on the downlink DL
  • Fig. 5c shows a slow power control and a fast power control resulting in the stepwise change of the output power in Fig. 5b;
  • Fig. 5d shows the mapping of a measured frame error rate
  • Fig. 6 shows a diagram for illustrating a handover procedure in connection with the transmission of PN sequences from a PN sequence generator PNG for inter-system handovers ;
  • Fig. 7 shows a principle block diagram of a subscriber station MS and a network control means RNC according to the invention
  • Fig. 8 shows a flow chart similar to Fig. 2, however incorporating a step ST111, ST121, ST131 according to the invention.
  • Fig. 9 shows a diagram similar to Fig. 5b where a power limit value P ⁇ m it i used according to the invention.
  • triggering of IF measurements in connection with handover procedures are carried in general in both cases when a communication connection CC is set up or when merely a signaling connection has been set up with the mobile station MS in a non-active mode of operation. That is, the need for a cell update may exist when the mobile station MS is merely registered in the network and does not initiate a call (or when no call is pending for the mobile station MS at the network control means) .
  • Fig. 7 shows a principle block diagram of a mobile communication system Tl according to the invention.
  • the network control means RNC comprises a quality measurement means QMM adapted to monitor the transmission quality on the down-link of the communication connection, a power measurement means PMM for measuring the transmitted output power on the downlink, a power control means PAM which generates the power offset value P D ff the upper threshold P up , the lower threshold PDWN n ⁇ ⁇ a ti e interval signal TINT indicating a predetermined measurement interval and a power limit value Piimit* ⁇ ⁇ e P ower control means PAM may cooperate with a calibration means CAL for calibrating the values P 0 ff, PuP' P DWN-
  • the network control means RNC contains a time interval determining means TIDM.
  • the principal idea of the invention is that in said STlll the quality measurement means QMM monitors the transmission quality on the down-link DL of the communication connection CC and the network IF handover means receives a quality signal QS from the quality measurement means QMM.
  • This quality signal QS indicates to the network IF handover means HORM whether the determined transmission quality on the down-link is lower than a predetermined quality measure QoS-MS which is also supplied to the quality measurement means QMM (see fig. 7) .
  • step ST121 it is determined by the quality measurement means QMM that the detected down-link quality is under the threshold quality QoS-MS, than the quality signal QS will indicate this condition to the handover means HORM such that in step ST132 the handover means HORM outputs the network IF trigger signal IFTS.
  • the IF measurement means IFM in the subscriber station MS receives this trigger signal NIFTS, it will start performing IF measurements in said IF measurement means IFMM in step ST21 as alredy discussed with respect to Fig. 2 above.
  • the other steps in Fig. 8 are the same as in Fig. 2.
  • the network control means RNC the quality measurement means QMM
  • the use of the subscriber station battery will be reduced and there is no additional interference in the up-link and the signaling load in the network is not increased since the subscriber station does not need to report the received signals strength to the network in order to trigger an inter-frequency or inter- system handover. That is, due to the inventive procedure for triggering the IF measurements, there will be no additional signaling over the air-interface.
  • the quality of the down-link connection (which can be measured even from the network control side) can be used since the transmission conditions, even when they are measured on the network side, are a reflection of the current transmission conditions between the subscriber station MS and the network control means RNC.
  • this can be done completely autonomously by the network control means RNC.
  • the quality measurement comprises the measuring of the transmitted output power P Q ut on the down-link DL from the network control means to the subscriber station.
  • the power measurement means PMM measures the transmitted output power P ou t on the down-link in step STlll and the network IF measurement trigger signal NIFTS is generated in step ST131 by the network IF handover means HORM when the measured transmitted output power on the down-link preset by the power adjustment module.
  • the power measurement means PMM outputs a transmission power signal TP DL exceeds a predetermined power limit value P ⁇ i m it which is indicating the measured output power P D ut o the quality measurement means QMM and the predetermined power limit value Pl mit can ⁇ or example be constituted by the quality measurement signal QoS-MS or it can be supplied to the quality measurement means QMM by the power adjustment module PAM as was explained above with reference to Fig. 5.
  • Fig. 9 shows a diagram similar to Fig. 5b where this power limit value Plimit i s shown to be set preferably between P G ff and p up •
  • the network IF measuement trigger signal NIFTS is only generated by the IF handover means if the measured transmitted output power on the down-link DL exceeds the predetemined power limit value P]_imit ( e -9- contained in the QoS-MS signal) longer than a predetermined measurement interval TINT (this interval is also called the Time-To- Trigger interval) .
  • a predetermined measurement interval can be indicated to the quality measurement means QMM from the power adjustment module PAM or from the power measurement means PMM.
  • the predetermined measurement interval TINT is a number of frames, for example in a CDMA system the predetermined measurement interval may be 10 to 100 frames.
  • a predetermined measurement interval may be as long as 28 to 120 frames.
  • the predetermined measurement interval TINT may be 10 to 20 frames.
  • the aforementioned quality measurement procedure or power transmission measurement on the down-link can be performed for each of several communication connctions between one or several base stations BS and the subscriber station MS.
  • the network IF measurement trigger signal NIFTS is generated by said network IF handover means HORM when the quality measurement QMM determines that the transmission quality on all downlinks DL of all said communication connections CC drop under a predetermined quality measure.
  • the network IF measurement trigger signal NIFTS is generated when the transmitted output power on all down-links exceeds a predetermined threshold power or exceeds the power limit value P]_imit ° r a predetermined measurement interval. It is also possible to set different power limit values ⁇ mit and different predetermined measurement intervals TINT for the different communication connections .
  • a predetermined power limit value Piimi c n be used against which the determined transmitted output power on the down-link DL is compared.
  • a power limit value P ⁇ i m it can ⁇ > e the threshold value P Q ff used in connection with a slow and fast power control as explained above with reference to Fig. 5.
  • the power offset value P 0 ff can be dependent on a slow power control and said upper and lower power thresholds P up; Pdwn can be variable dependent on a fast power control respectively carried out by said power adjustment means PAM of said network control means RNC. Therefore, the offset power as well as the output power interval can be changed due to new conditions in the system.
  • the aforementioned power values are set for the down-link and present - when compared with the transmitted power - a measure of the transmission conditions on the down-link.
  • the power values are used in a slow and fast power control on the down-link, the power values are not exclusively dependent on the network side, but also incorporate effects on the subscriber station SS.
  • the power adjustment means PAM may cooperate with a calibration means CAL for adjusting the power values.
  • the calibration means CAL calibrates each power step within the range determined by the upper and lower power thresholds P U p, P wn an ⁇ ⁇ said variable power offset values to predetermined (beforehand known) values .
  • down-link quality measurements e.g. the transmitted power from the node B are performed by the network control means in order to output the network IF measurement trigger signal NIFTF .
  • the network handover means HORM outputs the trigger signal NIFTS also on the basis of some measurements performed in the subscriber station MS.
  • the subscriber handover means HORM independently performs measurements regarding the need for handover and the IF measurement means IFMM only starts the IF measurements when the network trigger signal NIFTS as well the subscriber trigger signal SIFTS are generated.
  • the subscriber IF handover means HORM transmits the subscriber IF measurement trigger signal SIFTS to said network control means RNC. That is, the subscriber station SS transmits in the subscriber IF measurement trigger signal SIFTS measurements which have been performed on the side of the subscriber station.
  • the network control means RNC also processes the subscriber trigger signal SIFTS (as shown in Fig. 7 with the input of SIFTS to the handover means HORM) and generates and transmits the network IF measurement signal NIFTS only when the measurements in the subscriber trigger signal SIFTS indicate the necessity for a handover and the quality measurement means determine that the transmission quality on the down link of said communication connection has dropped under said predetermined quality measure as discussed above.
  • the network control means triggers the subscriber station MS to perform inter-frequency/inter-system measurements on the basis on the down link quality measurements performed by the network control means and other measurements performed in the subscriber station MS. This eventually results in a more acuarate generation of the trigger signal, although the measurements will have to be reported to the network control means on the up link UL and therefore the interference level on the up link UL is increased.
  • the network control means RNC already bases a part of the trigger signal generation on the down link quality and therefore only a small amount of additional information (subscriber measurements) need to be transmitted from the subscriber station to the network control means RNC. Therefore, the additional interference on the up link and the increase of the overall load in the communication system will be small.
  • Typical measurements which can be carried out by the subscriber station MS are those described above with respect to the conventional four trigger conditions .
  • the network control means RNC generates the network IF measurement trigger signal NIFTS if the measurements reported in the subscriber IF measurement trigger signal SIFTS from the subscriber station MS indicate the need for a handover (as in the second embodiment) if said quality measurement means QMM determines that the transmission quality on the down link DL of said communication connection has dropped under said predetermined quality threshold (as in the first and second embodiments) and if in addition additional system information IL; TDLP provided in the network control means RNC also indicate handover .
  • the network trigger signal NIFTS is generated based on the down link quality measurements performed by the quality measurement means QMM, additional system information as well as other measurements from the subscriber station.
  • additional system information can be the total up link interference level IL of the communication connection CC between the subscriber station SS and the network control means RNC or the base transceiver station RBS and/or the total down link output power TDLP (in Fig. 7 these parameters are shown as input to the handover means HORM) .
  • the network control means RNC triggers the subscriber station MS to perform inter-frequency/inter-system measurements .
  • the quality of the transmission conditions on the down link is used as a measure for triggering the subscriber station to perform IF measurements.
  • a quality measure is constituted by the transmitted output power on the down link.
  • additional information is used for generating the trigger signal in the network control means.
  • the additional information provided in the network control means RNC may be the total up link interference level IL of the communication connection CC and/or the total down link output power TDLP.
  • the measurements carried out in the subscriber station MS can be an average filtering of a pilot channel during a predetermined time.
  • the additional information provided in the network controls means RNC may relate to the "base station traffic load" referred to as first condition above. That is, the network IF handover means HORM may determine the necessity for handover also on the basis of a supervision of the loads at all base stations RBS in the network.
  • the subscriber handover means HORM and/or the network handover means HORM can determine the necessity for handover additionally also on the basis of a supervision of the distance D between a base station RBS and the subscriber station MS which has been referred to above as the second condition "a distance limits exceeded" .
  • the network trigger signal NIFTS can also be generated additionally on the basis of the third condition "pilot strength below a predetermined threshold" .
  • the trigger signal NIFTS is generated, when the subscriber IF handover means HORM and/or said network IF handover means HORM determine the necessity for a handover on the basis of a supervision of a measured pilot signal strength PLT (as shown as input to the network handover means HORM in Fig. 7) .
  • the trigger signal is only generated, when the quality on the down link drops below a predetermined measure and if the measured pilot signal strength falls below a predetermined power threshold.
  • the subscriber handover means HORM and/or the network handover means HORM determine the necessity for a handover on the basis of an output by a network supervision means PAM that in response to a power increase command by a base station BS a subscriber station power adjustment module PAM is unable to further increase the power on the up link of said communication connection CC .
  • This additional condition has been referred to as the fourth condition "power level exceeded" above.
  • Such additional decision criteria determined in the subscriber station and/or the network control means RNC can be used in connection with the principle of the invention and in connection with the first, second and third embodiments.
  • the IF measurement means IFMM in the mobile station MS carries out the field measurements in step ST21 in O n H
  • time interval in which the measurements are carried out will start a little later than the receipt of the trigger signals .
  • the subscriber station MS If only a signalling communication exists between the subscriber station MS and the network control means RNC then it is also possible to monitor the transmission of a paging flag in the subscriber station MS. If no paging flag is transmitted then the subscriber station MS judges that the network is not about to perform a data transmission. Therefore, at each time point where the signalling communication is monitored and no paging flag is detected, the subscriber station sets a predetermined number of time slots or data frames as the predetermined time interval.
  • the IF measurements carried out in the subscriber station are not only carried out in the predetermined time interval, but also in a idle time interval IT of a data frame FR when the transmission between the network and the subscriber station MS is carried out in a compressed mode of operation.
  • the predetermined time interval used for the IF measurements corresponds to a number of data slots or frames where no data transmission takes place (as determined by the data transmission determining means DTDM) and a number of idle time portions of data frames or slots where data transmission is carried in a compressed mode.
  • the time interval is determined by the subscriber station after receiving the trigger signal from the network, it is also possible that the network control means ifself transmits an indication to the subscriber station about the time interval which should be used for the IF measurements .
  • the network IF measurement trigger signal NIFTS or a further control signal from the network control means RNC can indicate the time interval in which said subscriber station is to carry out said IF measurements. Since the trigger signal needs to be sent to the subscriber station MS in order to trigger the subscriber station MS, it is advantageous to contain the indication of the time interval in the trigger signal such that the subscriber station MS is immediately informed - together with the triggering - about the time interval which should be used for the IF measurements .
  • the network control means RNC can autonomously determine the time interval to be used for the IF measurements as a time interval in which a temporary degradation of the transmission conditions between the subscriber station MS and the base transceiver station RBS is determined as acceptable. Such a temporary reduction of the quality of service may be determined because of a deletion of data during a delay- sensitive data transmission between the subscriber station MS and the base transceiver station RBS. If such a deletion is necessary, then the subscriber MS and the network control means RNC will respectively increase a transmission power on the down link DL and the up link UL on the communication connection before the beginning of said predetermined time interval and/or after the end of said predetermined time interval .
  • the first embodiment of the present invention already monitors the transmitted power on the down link in order to generate the trigger signal, this can be advantageously coupled with the determination of the time interval on the basis of a temporary reduction of the quality of transmission, since the network control means RNC can combine the measurement of the transmitted power for generating the trigger signal with the determination of the time interval.
  • the generation of the trigger signal according to the present invention can be applied to any mobile communication system comprising at least one communication network, independent of the transmission standard used. Therefore, the present invention can be used in the context of GSM, PDS, TACS or D-AMPS systems or combinations of two or more of the systems.
  • GSM Global System for Mobile communications
  • PDS Packet Data Service
  • TACS Transmission Control Protocol
  • D-AMPS D-AMPS systems or combinations of two or more of the systems.
  • the subscriber station MS as described above will be able to operate according to both standards (e.g. dual-mode- operation) .

Abstract

A quality measurement means (QMM) provided in a network control means (RNC) of a communication system (T1) monitors the transmission quality on the down link (DL) of a communication connection (CC) between the base transceiver station (RBS) and the subscriber station (MS). A network inter-frequency (IF) handover means generates a network IF measurement trigger signal (NIFTS) when the transmission quality drops under a predetermined quality measure (QoS-MS). The generated network (IF) measurement trigger signal (NIFTS) is sent to the subscriber station (MS) and an IF measurement means (IFMM) in the subscriber station (MS) starts the IF measurements in response to a receipt of the network IF measurement trigger signal (NIFTS). One example of evaluating the quality on the down link of the communication connection (CC) is to monitor the transmitted output power on the down link. Thus, the network control means (RNC) can independently generate the trigger signal without the need of measurement from the subscriber station (MS) and without an additional interference on the up link due to a transmission of such measurements and without an unnecessary reduction of the lifetime of the battery of the subscriber station (MS).

Description

SUBSCRIBER STATION, NETWORK CONTROL MEANS AND METHOD FOR TRIGGERING INTER-FREQUENCY MEASUREMENTS IN A MOBILE
COMMUNICATION SYSTEM
FIELD OF THE INVENTION
The invention relates to a subscriber station, a network control means and a method for triggering inter-frequency measurements in a mobile communication system. The invention also relates to a mobile communication system in which such a subscriber station, such a network control means and such a method are employed.
As will be explained with more details below, in a mobile communication system transmission conditions on a connection (communication connection or signaling connection) between a subscriber station and a base transmitter station are monitored and the need for an inter-frequency or inter-system handover is detected, e.g. when the transmission conditions deteriorate. When the need for an inter-frequency or inter- system handover is detected, an inter-frequency measurement trigger signal is generated to indicate the need for an inter-frequency or inter-system handover and to initiate inter-frequency measurements on a different frequency than currently used. In response to the trigger signal inter- frequency measurements are carried-out on one or more different frequencies and* if a suitable new frequency has been found the actual an inter-frequency or inter-system handover takes place. Hereinafter, the term "handover" is used to designate an inter-frequency handover or an inter- system handover, even if not explicitly stated. CD cn CO tn CO ι-3 p) H- H3 0 iQ 3 s: ω ffi CO s; H3 Hi rr tl rt 3 μ- 0 tl tl rr μ- Ω O s; β JD rt J rt t H-1 O H-1 0 CD ro μ- > CD μ- rr rr ro 0 0 o CD 3 o o CD H tl 0 rt rr
3 JD .. JD . ., 3 r. P) rt o tl iQ μ- ro CO s: rt JD TJ 3 rt JD tl JD ro j rr CD rr rt o o TJ CD O rr « ro ø o TJ CD CD μ- CO o 3 pi ≤ Hi JD tι rr ti
CD H- JD H- -3 TJ H3 Hi Hi c Ω μ- JD rr TJ 0 P tl Hi £ JD 0 Hi tl CD μ- g CO O H 0 H- cr ro t H- P) Hi Hi *> r3 tJ ro μ- H| rt tl rt Hi μ- Ω 0 JD
* ■ ts i H rt CD Hi . cn CD ro o J o ro O Hi rt rt CD JD μ- JD O JD rt tl cn rr PJ CD 3 n Hi Hh o CO CD - rr μ- 3 tl o Ω μ- Ω
H rt g o s H- 0 cr > ω 0 CD T 2 rt O P CD JD JD CD rt JD μ- 3 0 r O JD O
0) rr ro n H-1 O 3 TJ <! P CD Q CD Hi P., P rt JD rr rt tl rt co C tl μ- ts tl ts h- ' g 1 CD ro CO PJ CD rt Ω H μ- rt 0 -1 ro rt JD CD n < Pi tι co 3 O o ro Hi p: rt HJ CO rt O rt rt s: rt CO Pi rt rt rt ro μ- ro rr o JD cn JD JD J H- cr *. μ- Hi μ- μ- rt JD rr rt rt TJ Hi rr 1 o rt Ω
JD O h{ j H n cr HJ O H-1 μ- μ- rt ø μ- o P rr ro rr CD P. JD 3 ro 3 rr rt
TJ t rr n CD CD 3 0 ►3 rt CQ 3 < CD CO ro μ- n JD tl C o ro ro μ-
TJ JD TJ ϋ 3 CD rt Hi 3 g CD iQ CO CD μ- ua rt rt O ω n P. cn O
Pj ts ro C 0 3 rr H- cn 0) PJ Hi CD P μ- n tι μ- (Q CD 3 rt o ro rt ω P
H- t CD < 0 H- ro cr rt 0 1 Hi cn rt tl JD rt tι CD μ- μ- tι JD c n cr H- Hi CD cr P CD Hh 3 n H Hi μ- rr μ- rt H( CD rt H| o 0 r n ts 0 cr cr μ-
JD CD 3 o r H- Hi Hi rt o o 2 μ a o o CD Hi H| (D tl rt JD ro Hi H-1 cn cn cr rr H O JD rt H- ≤ 0) cr P 2 ro iQ tl Hi μ- 1 H CO s; CD Hi n μ- Ω o p CD 3 H{ CD rr Hi n o μ- < W .Q 1 CD Hh 1 μ- rr rt Pi Hi rt 0 CO Hi ro
CD 0 HJ PJ 0 CD ω rt rt CD 2 f.; cn Pi μ- H i Hi Hh iQ ro rr - μ- TJ t μ- tn D rr 1 JD H- f- o rt P> P CD CD P 4 CD C tι μ ro Hi P tl ro 0 CD CD cr rr O Ml D n H Hi HJ Q ω rt H- ft H P n cr ro o tP ro JD CO O o Hi Pi CD JD o OJ Hi PJ g CD 3 H- Hi CD n μ- O o rr CD T Λ C c £) h-1 JD o μ- JD Hi cr
H( cn H- CD [3 n o o Hi O o 0 2 > P) c rt ro c tl o tl rt JD rt s: H-1 rr rr p Hi Oi C- 0 cr p ro O g tJ μ- c CD ts CD CO Pi tι n ts μ- μ- cn μ- ft rr ro rr ro H- P £S H- Hi g § J s: tι cn rt tl μ- n tl rr 0 CD μ- Pi o rt rt o H I-! 0) 3 CD £S Hi H- a, H^ ro § C μ- rt CD μ- O tl o 0 rr CD tl tl rr JD rr
H- rt Hi rt Hi o CD CD ø c P H-1 ro Pi n " c o o 0 rt rt ~ rt CD
IQ rr 1 CD JD 3 . rt p μ- 3 Hi C rt 3 s; r rt CD rr rt μ- Pi . IQ rr (D Hi ϊf Hi rt 0 O CQ μ- o CD 1 rt h-1 3 rr CD 3 i μ- IX H| CD rt rr 0
(D rr U Hi JD CD H- cr o 3 o PJ rr cr Hh o JD CD ro JD ro rt 0 CD 1 rr CD ts cr
M CD i ro 0 2 o H- g 0 PJ rt rr D H| H| O JD cr rr tl Hi Hh CO ro ro
H- O .b Pi r V § P> cr rt μ- o CD iQ CO n cn CD ro £ Hi £ H| CO rt
2 •0 £ O CD C μ- μ- O Pi P> >P CD JD t: c Hi C ≤ μ- CD cr CD ^ c ro s: iQ H| CD CD < o CO ø 3 h-1 0 tl cr C ø Hj cr ro Hi (Q μ- μ- CO KQ cn cr < CD J CD M V CD CD n H- 0 ro 2 Hh cr ro CD Pi CD cn 3 CD ro tι h-1 CD c o JD CO CD CD
JD cn n Hi ω 0 o cr cn O Hi V H| Hi 3 n CD 3 tl rt H-1 ro Hi Ω ts 3 - 2 CD rr *< \-> rt 3 P) H- n cn K Hi CD n JD ro CD h tl CD ro CD cn tl μ- s: H|
3 0 n cn (D § rt H-1 0 CO rt O 0 μ- ft tl H| Hi cr 0 n cr JD μ- μ- rt
H- rr -\ rr Hi 3 c H- CD O rt rt μ- CD CO rt cr cn rt JD 1 ro 3 ^ CD cr Hi rr tl Hi JD H- CO P o g rt CD Hi P) 3 CD ro cn rt Hi ro Hi cn ro ro rr P- HJ P rr H1 H3 H- ^ tn C CD 3 μ- rt CD rt cn rt H| rt • ro μ 3 h o ro ø 0 ro » H> 0 rt P 3 iQ CD JD rr Hi rr Pi CD 0 0 ro cn CD ts rr
3 0 h - P> n P) μ- iQ Pi cn CD rt μ- O ro H a CO Hh D rt X CO JD
1 CD H- CO rt »< rt O H3 ^ CD C rr tQ rt 3 rr cr c rt tn JD μ- rt ; CO
Hi P rr CD JD DO H3 H- cn H- CD a μ- Hi £ rt CD iQ JD O ^ CD • rt c rt co JD ro
H rr t-f Hi ~ to 0 rt 0 rt \r> iQ μ- μ- CD Hi CD rt ro CO ts rr H| μ- rt rt JD
CD H- CD r 0 ro 3 μ- M • tl rt 3 μ- TJ Hi μ- rr rt o CD CD 0 CO μ- rt o s; r O rt 3 o cQ rr ro IQ Hi 0 < o rr tl 3 s O cn Hj
P o H- CD > rr cn S P μ* ø iQ 0 O tι CD c ro 0 CD ω tl μ- JD ro rr rt - ro ^ H3 O rr H = rt CD cr μ- CO rt tl JD 0 iQ 2 tl H- rr rr 3 cn M - CO μ- CO ^ H CO Hi H1 iQ μ- . tl rr rt tl 3 cr ts cn n CO CD H- 0 O 3 rt - n rr 1 ^ CD tl V JD ro D cn CD CD JD Ω
^ H. 0 cr H> o CD 3 ω rr 0 = 3 JD cr rt Hi μ- ro
H- - cr 3 3 rr rt s: ro ro S rt Pi tl μ- μ- rt H- P) H- CD cn ^ 0 rr rr JD i ts < rr CD H-1 o 3 H| CD ro rt iQ CD ro CD rr O fu π tι JD μ,
handover within the same system and/or an inter-system handover and Fig. 1 only shows two mobile communication systems Tl, T2 as an example where both such handover procedures may take place.
Fig. 1 shows as an example for the first mobile communication system Tl a WCDMA (Wideband Code Division Multiple Access) or CDMA (Code Division Multiple Access) communication system comprising a network control means RNC (Radio Network Controller), at least one base transceiver station RBS, RBS' (in WCDMA called radio base station) , at least one subscriber station MS (Mobile Station) as well as a number of (possibly) overlapping cells SI, S2 , S3, SI', S3'.
An example for the second mobile communication system T2 is a communication system according to the GSM (Global System for Mobile Communications) , PDC (Personal Digital Cellular) and D-AMPS (Digital-Advanced Mobile Personal Service) standards.
In Fig. 1 an example of a GSM system is shown for the second mobile communication system T2. However, it should be noted that the invention can in principle be applied to any type of digital mobile telephone system and is as such not restricted to the aforementioned systems. The GSM system shown in Fig. 1 comprises the conventional units of a base station controller BSC, at least one mobile switching center MSC as well as a gateway mobile switching center GMSC . The mobile stations MS are served by a plurality of base transceiver stations BTS within the cells C1-C6 in which the mobile station MS can move around .
The network control means RNC of the WCDMA system in Fig. 1 is connected via a UMSC unit to the gateway mobile switching center GMSC of the GSM system.
Depending on the geographical layout of the first and second mobile communication systems Tl , T2 the cells SI, S2 , S3, SI', S3' of the first mobile communication system Tl may also completely or partially overlap with the cells C1-C6 of the second mobile communication system T2. Of course, if the mobile station MS is to carry out an inter-system handover - then the mobile station MS will be able to operate according to the specifications of the first and the second mobile communication system.
One reason for performing inter- frequency or inter-system handovers in the telecommunication system TELE in Fig. 1 may be due to coverage reasons. This is due to the fact that neither the first communication system nor any other system has a complete coverage in all geographical areas, e.g. hot spots in UMTS. Furthermore, some cells within the mobile communication system may operate on frequencies which are not applicable in adjacent cells. Therefore, by letting the mobile station MS or the network control means RNC perform either an inter-frequency handover of an inter-system handover, the mobile station MS can be used in a larger area without interruptions in the communication.
Another reason for the handover may be capacity reasons. Either the mobile communication system or other mobile communication systems may become heavily loaded at times, so that an inter-system handover may be required. Analogously, the mobile station MS may have established a connection on a particular frequency and it may be necessary that another frequency is to be used. This other frequency may be present within the same cell or in another cell and both are generally termed inter-frequency handover. As indicated in Fig. 1, the inter-frequency measurements (necessary for an inter-frequency handover/or an inter-system handover) is always carried-out by an inter- frequency measurement means IFMM situated in a mobile station MS.
The network control means RNC comprises a paging flag sending means PFSM for sending a paging flag to the mobile station MS Pi rt cn JD rr H H cn H 3 H 3 rt Ω £, ro TJ 3 3 Ω Ω o ^ Ω Hh rt CO t cn o n CO tl ro ro rr μ- Pi JD p ^ μ- 4 CD HJ CD rr Hi rr X CD CD CD 0 0 μ- 0 O rr rt o rt TJ c s; ro CO rr tn ro iQ < ts ι-3 (Q JD JD ro μ- D TJ Hi JD JD 3 3 rt IQ m Hi CD JD ts JD CD cr μ- rt rt CD μ- p JD i o O a ts 3 CO rt rt H-i Hh rs i § 3 • tl rt 1 rt Hi ω rt s; JD rs iQ 3 JD s 0 Hj JD cn ro c 3 CD rr JD O tn CO c c JD CD rt n μ- JD μ- JD Ω Ω o cr
J_S o rt μ- H-1 Ω JD Hi 0 Hi CD μ- Hi ts tl tl to Ω rr CD 0 Ω 0 rt Hi rr Hi JD
CD cr JD CD CD s JD a O CD cr μ- H| tι 3 w ffi μ- μ- rt ro rt ts rt n μ- μ- ro μ-
Pi μ- H iQ Hi Hj H u o c 3 μ- JD ro JD _3 o Ω Ω μ- cn μ- s: μ- 0 cr Pi • ω CO
^ CD CO ^ 0 Hi ro μ- Pi ts o M JD JD t rr O cn o S < μ- tl CD rr μ- rt CD 1-3 0 s; rt rt ^ cr g CD n CD P. n Ω g rt rt rt o tι Hi to CD n • Hi o ^ CD IQ
Hi to c rr 0 ro to CD • 3 rt D JD CD o μ- μ- CD s; cr X tl o Pi P μ- CO CO CD TJ ro cn O rt J cr H| -—* 0 0 Hi cn μ- CO μ- 3 cn cn H| JD iQ rt μ- tl TJ 0 rt ts rt CD Hi 0 H ffi π rs 1 tn Ω Ω co O C rt JD cr H-1
C JD ø rt CD co Hi H cn rt μ- JD Hi μ- < CD rt JD Hi JD Hi o Pi Ω cn JD n CD CD
CD rt o rt Hi μ- tl rt 3 n CD IQ rr ts Ω CO rt μ- n μ- CD rr rt rt Pi X rt μ-
Hj μ- CD rr Hh μ1 JD IQ μ- rt μ- μ- Ω • JD CD i o ro (Q 0 cr rr t JD μ- JD z ts
0 μ- TJ ro 0 > iQ n Hi cn 0 ts μ- Hi o n CO £1 CD CD H| < 0 JD tl 0 rr 3 ro iQ
TJ tl rt HJ Hi Hi . tl CD Pi μ- rt tl CD TJ H Pi 3 < t rt C ts cr H| 0 0 Hh & tl JD TJ ro
Hj rr o ro 3 ro H| μ- iQ CD Pi H-1 ts μ- o CD ro CD CD CD CD W tl cr cn ts Ω
0 £ ro rt CD Ω iQ TJ μ- CD ø cr ) Ω 3 ts H| CO CD O o μ- CD 0
Ω to Hj μ- μ- JD . Pi JD CD co μ- CO iQ μ- rt Ω JD tn rt 3 Pi TJ tι co cr ^ rt |3
CD pi o o rt HJ O tι JD rt 3 μ- s: ^ CD JD CD CD 1 0 CD rr 3 rt CD Hh Hi cr CD H rt CD rt CD ro o rr rt rt JD cr H| JD TJ μ- CD s: CD C
C O rr rt JD K Pi O H> Hi to rr TJ rr JD ts CD O Hi μ- tl ^ JD Ω CD ts ts rr tl
H{ Hh CD rt rr tn 1 μ- KX> μ- rt JD CD CO n tι Hi O cn rt rt Hi CD tn μ- ro rr ro rt CD JD μ- iQ . iQ CD i CO rt CO μ- 0 TJ n Hi μ- μ- JD JD Hi n c Ω
Ω ts ro < ts ts (Q TJ i •^ Ω JD -^ tn JD μ- s- 2 ro 0 < rt ro cr JD o ro tι JD JD 3 JD £ CD o JD rt tι rt to z. Ω ts CD μ- Hi (Q rt cn ft rt C rt o CD tl o HJ H o Hi to < to TJ μ- cn O cn rt Ω 0 to n ro 0 CD μ- rr Ω μ- rr Hi s; c ro Pi c cr μ- Hi CD >-3 ro JD o μ- CD μ- CD rr - μ- rt 3 ts (Q CO ro Hi 0
CD CO o rt Pi JD μ- |Q H CD i H-1 H rt Ω ts rt rt iQ Hi JD rt JD < rr o μ- rt μ- tι
Hi CD Hi TJ Hi rt H-1 ^ H1 rr μ- C
^ rs 1 Hi rr ts tl μ- ro Pi 3 co CD 3 cr ro £ Hh ro CD CD TJ rt μ- CD rt g JD C JD O rt CD Pi JD tι CD CD rt Hi 0 CD H-1 rt o Pi 1 H1 to JD 0 cn to rt TJ ^ 3 iQ 0 JD CD ro cr Hi μ- μ- μ- Ω rt Hi μ- 1 CD - Hi H rr ^ CD • μ- cn o CO s; CD TJ O tl Pi μ- rι ω tι 0 μ- JD rr ; μ- rt TJ Hi tl JD Ω 3 i n rt Hh c rr rt ro Hi cn CD CO tl ts cn cr JD JD rt cn μ- CD CD tι O o H iQ CD cr ro * rr Hi Pi μ- CD ft 3 tι o rt iQ C H-1 P H-1 rr Ω Hi CO Ω Pi <! n μ- tl 3 JD CO n ro JD 0 to ts JD rr
0 Hi Hi Ω CD £ ro O Hh 0 CD 0 CD μ- rs Ω Ω rt TJ O JD cn rt JD rt i 0 o rr o JD C 0 cn <! H| rt CO o rr 3 Hi JD rr TJ μ- CD g ts rt rt μ- cn
CD Hh μ- < rt H rt JD Hi . — . O CD JD O rt rt n JD CD μ- CD JD 0 H| pi rr JD O
JD Hi JD tι ro CD ^ TJ Hi 3 - JD Hi IQ h ty CD ts n r cr o IQ ts JD rr CD rt tl JD
3 JD rt Hi Pi 1 C H-' Hi CD ω CD TJ ro rr CD 0 μ- rt 0 ts μ- H cn rt CD rr CD 1 3 rt μ- = 3 Ω 0 0 H| 3 JD tl 0 μ- M 0 tι O g Hj μ- o JD Hi JD Hi rt rr CD "• ts CD JD rt n to rt < Pi § iQ Hh 0 i t ro tι to CD ts tl CD tl 1 H| JD JD cr rt μ- JD JD tn rr CD ^ μ- ro cn Ω ts CO 1 rt JD iQ TJ O Pi Hi μ- ts CO μ- CD tι Ω n TJ CD rt μ> 0 Hi Hh rt t JD Hi rt JD
Hi μ- 0 Hj (Q i c tι H| Ω cn CD s: > tl 0 JD μ- H-1 rr rt Ω z £ JD Pi o to ts
5 1 CO ^
CD 0 (D < CD iQ 0 Hi rt 0 Ω ts 0 μ- H| rt Ω CD H rr ft H{ P-I
<! 3 cr D CD
£ < CD rr tn Hh rt Hi t rt CD H( JD 0 n μ- JD iQ t ro μ- rr rr μ- Hi CD cr
O h-1 3 ro rt Hi CD Pi o CO rt X Hi Ω 0 rt μ- tn JD rt CD
Hi Pi CD - CD Hi CD CD CD TJ μ- 2 £ rr JD JD tl μ- cn H c tn CO CD CO rr CD μ- CD JD 3 tn t rr TJ n s JD 0 Ω JD JD H| O H
■g cr C d ft CD t iQ tJ rt μ- Ω μ- r rt JD CO (Q CO Hi 0 tι 3 Hi S D TJ ω Ω cr 3 rr cr iQ JD Pi h rt iQ Hi cn rs to CD i X ts P. 0 to CD Hh Ω
\ rr O 0 CD ro
CD μ- n μ- i ^ tl μ> rt CD rt 0 cr μ- ts H| Hi Ω Pi CD
Hi $ 0 iQ μ- (D iQ 3 0 h-1 Ω to 0 Ω H| < μ- tι Pi 0 μ- JD H{ ro p μ- CD Hi iQ cn (Q CD < ) ~— μ- 0 CD (Q μ- 3 cr μ-
2 CD CD JD CD ^ rt Pi H| CD 1 D CD
H| H| t Hi JD cr 0
(Q h-1 μ- rr CD (Q i-i Hi
1 tι CO tl CD cn Hi
Figure imgf000007_0001
comprise a handover HORM each can initiate a handover according to the triggering conditions which are respectively monitored. The four basic criteria during the monitoring in step STll in the prior art are the "base station traffic load exceeded" condition, the "distance limits exceeded" condition, the "pilot strength below a predetermined threshold" condition and the "power level exceeded" condition as will be explained below and as is described in the aforementioned reference [1] .
Firstly, regarding the condition "base station traffic load exceeded" , the network handover means HORM determines the necessity for a handover by monitoring loads at all base stations BS in the mobile communicaton system Tl and outputs the IF measurement signal IFTS in order to balance loads between all base stations, in order to achieve a higher traffic efficiency. For example, the network handover means HORM outputs the trigger signal in step ST13 whenever the load at a base station exceeds a predetermined load threshold.
Secondly, regarding the condition "distance limits exceeded" the subscriber handover means and/or the network handover menas HOM are adapted to determine the necessity for the handover on the basis of a supervision of the distance between a base station BS and the subscriber station MS. The distance between the relevant base station and the subscriber station can be determined in a synchronized system. Therefore, the trigger signal IFTS is output in step ST13 whenever the measured distance exceeds a predetermined distance .
Thirdly, regarding the condition "pilot strength below a predetermined threshold" , the subscriber handover means and/or the network handover means are adapted to determine the necessity for a handover on the basis of a supervision of a measured pilot signal strength falling below a predetermined power threshold. As is illustrated in Fig. 3-1 and in Fig. 4-1, in modern mobile communication systems a data transmission between a base transceiver station RBS and a subscriber station MS is carried-out by transmitting data frames FR and the transmission frames FR consist of a control portion CP and a data portion DP. This is true for CDMA frames (Fig. 3-1) and TDMA frames in GSM (Fig. 4-1) . The control portion CP consists at least of pilot symbols PS and preferably also of other control symbols CS . For example, each base station BS may transmit a pilot signal PS of constant power on the same frequency. The subscriber station MS can monitor the received power level of the received pilot signal and can thus estimate the power loss on the connection between the base station BS and the subscriber station MS. Using the pilot signal strength for estimating the path loss, the subscriber handover means HORM outputs the trigger signal IFTS in step ST13 if the path loss is greater than a predetermined path loss threshold.
Fourthly, regarding the condition "power level exceeded" the subscriber handover means and/or the network handover means are adapted to determine the necessity for a handover on the basis of a supervision that in response to a power increase command by a base station BS a subscriber power adjustment module PAM (shown in Fig. 1 in the mobile station MS) is unable to further increase its power on the up-link of the communication connection CC .
Fig. 5a-d show such a conventional adjustment of the transmission power when exchanging frames FR consisting of a number of time slots TSl ... TS15 between a base transceiver station (generally called node "B") RBS and a subscriber station MS. A power adjustment module PAM in the base transceiver station (node "B") RBS presets an upper threshold PUP, a lower threshold PDWN and an offset value POFF for the power. The power offset value POFF is used in connection with a slow power control and the upper and lower threshold values PUP, PDWN are used in connection with a fast power control in the node B .
The slower power control and the fast power control as illustrated in Fig. 5b is carried out according to the flow chart in Fig. 5c. Steps PI, P2 relate to the slow power control (the outer control loop) carried out on the RNC-side or the MS-side. In step Pi the frame error rate FER (or the block error rate BLER) is measured and in step P2 the measured FER (or the BLER) is compared with a FER target value (or a BLER target value) . In step P8 a new signal interference ratio target value SIR-target is obtained. As shown in Fig. 5d, a known (simulated) relationship between a delta_SIR_target value (dB) and the logarithm of the measured FER value exists. Between two threshold values UL_delta_SIR_2 and UL_delta_SIR_l a predetermined "working area" exists. This relationship is known, i.e. simulated beforehand. As indicated in Fig. 5d, depending on the measured value log (measured FER) a value delta_SIR_target* is read out. A new SIR_target value SIR_target is calculated according to the following equation:
SIR_target=SIR_target + delta_SIR_target*
Thus, the outer loop or slow power control will generate in step P8 new SIR-target values whenever steps Pi, P2 are executed. The new SIR-target value is then used in the fast power control (inner loop) carried out on the node B-side or the MS-side, respectively.
In step P5 the SIR ( Signal-to-Interference ratio) per slot is measured and in step P4 the measured SIR value is compared with the (current) SIR-target value as obtained in step P8. If the measured SIR value is greater than the current SIR- target value, then a decrease command is sent to the mobile station MS/network, i.e. the transmission power control parameter TPC is set to TPC = "00" in step P7. When the measured SIR value is smaller then the (current) SIR-target value in step P4 , then an increase command is sent to the mobile station MS/network in step P6 by setting the transmission power control parameter TPC to TPC = "11".
As illustrated in Fig. 5b, the slow power control and the fast power control result in a stepwise adjustment of the power Pout on the downlink DL . Since the slow power control performs steps Pi, P2 for calculating the frame error rate FER (or block error rate BLER) for every frame (or block) a new SIR-target value is obtained less frequently than the fast power control carried out with steps P5 , P4 , P6 , P7 for each slot.
The offset value PQff and the upper and lower threshold values Pup, d n are also used in the power adjustment. For example, when the output power Pout exceeds the upper threshold Pup then the offset value PQff is slightly increased and when the power is lower than the lower threshold P^ n the offset value PQff is slightly decreased. The stepwise adjustment of the power is always performed within the power range between P^bn ano^ pup • Since the values P0ff, PUp and P^wn are only used for the triggering of a soft-handover , they are not of any further relevance for the present invention and any further descriptions thereof are therefore omitted.
As explained above, in the fourth condition "power level exceeded" the node B (the base station BS) commands the subscriber station MS to increase its power and if the power adjustment module PAM in the node B notices that there is no further increase of power in response to a power increase command TCP, the network handover means HORM may request a measurement by issuing the IF trigger signal.
Regarding the above described four different conditions, there are a number of significant disadvantages and some of the four described conditions can not even be implemented in future wideband code division multiple access systems (WCDMA) .
Whilst reference [1] relates to the IS-95 standard and describes a synchronized CDMA system, reference [2]: TS 25.201 V2.1.0 , a third generation partnership project (3GPP); technical specification group (TSG) ; radio access network
(RAN; working group 1 (WG1); physical layer-general description, dated June 1999, describes a non-synchronized WCDMA system, in particular the multiple access used therein. In a synchronized system like the one described in reference [1] either the base station BS or the subscriber station MS can still estimate the distance between them (second trigger condition) . This is possible since the chip rate on the pilot channel and all channels are synchronized (locked) to a precise system clock. This is in reference [1] accomplished by using a global positioning system (GPS) . However, due to multipath propagation delay and shadowing between the base station BS and the subscriber station MS, the estimated distance may be erroneous. Therefore, the second condition
"distance limits exceeded" may not be very accurate.
In condition 3 "pilot strength below a predetermined threshold" the subscriber station MS must perform measurements for triggering IF measurements and thus for triggering a handover. These continuous measurements of the pilot signal strength may drastically reduce the lifetime of the battery of the subscribers station, since the subscriber station MS must perform an average filtering of the pilot channel during a predetermined measurement time. The decrease of the lifetime of the battery is to be avoided in all circumstances, since there are already a lot of measurements that must be performed by the subscriber station, e.g. the IF measurements on other frequencies when the IF measurement trigger signal IFTS has been issued. Furthermore, the subscriber station MS has to report the pilot signal strength cn 3 μ- ft
CD ts rr tn (D Hh CD rt tn 0
CD c Hj CO
3 Hj 3 c
CO CD JD cr
3 ft O μ- CD μ- Ω t rs o Hj rt tl μ-
0 cr
Hj rt o D
Pi μ- P Hj
CD 3
Hj CD ft n rr rt ft rr ro JD
0 JD rt
CO Ω μ-
JD O c o
H-1 rt Hi tι
0 Hj 0 0 CD 3 O s: cr P to ro ft μ- μ- tι Ω Hi CO rt Hi Hi
CD ro CD ts
Hj JD 0
1 rt
Hh CD ■9 Hi
CD g
Hi p. rs JD
CD Ω
£1 μ- K
C n
CD JD 3 rs cn n cr
Ω 0 P. c
^ 3 CO
CD rt
3 rr
CD £ c Hi
JD JD tn CD
CO Ω c tn CD
Hi μ- 0 μ-
CD n 3 <
3 CD μ-
CD O ts rs c iQ ft Ω cn rr
Figure imgf000013_0001
without a drastic loss of data. Conventional methods for determining a time interval in which field measurements are carried out will be described below as reference to Fig. 3-1, 3-2, Fig. 4-1, 4-2 and Fig.6.
As already discussed above with reference to Fig. 3-1, in a CDMA communication system the data communication is performed by exchanging data frames FR consisting of a plurality of time slots TS1..TS15. Each time slot comprises a control portion CP and a data portion DP. As described in the aforementioned reference [2] and as also indicated with step ST21' in Fig. 3-2 and in Fig. 3-1, it also possible to carry out the data transmission in a compressed mode (also called slotted mode) in order to create some time for the IF measurement. For this purpose the network control means RNC comprises a compressed mode setting means CMSM in which the data contained in the data portion DP is compressed, i.e. concentrated to a smaller part of the frame, resulting in an idle time portion ITP. The subscriber station MS comprises a compressed mode determining means CMDM which determines i.e. realizes - being informed about the compressed mode of transmission via signalling or some information sent from the compressed mode setting means CMSM of the network control means RNC - the compressed mode of operation. If such a compressed mode of operation is detected, the subscriber station MS enters a compressed mode of operation and performs the IF measurements in the idle time IT in step ST21'' in Fig. 3-2.
In a CDMA system such a concentration of information is achieved by reducing the processing gain G = chips /information bits = 1/SF, e.g. by decreasing the spreading factor SF . Another possibility how the concentration of information can be achieved is by changing the channel coding scheme, e.g. from r = 1/3 to r = 1/2. Due to the compressed mode of operation a time interval IT is generated in which the IF measurements can be carried out by the IF measurement means IFMM in the subscribed station MS.
Fig. 4-1 and steps SC21''' and ST21'''' show another possibility of how a time interval can be provided in which the field measurements can be carried out. In a GSM system, a specific time slot FMS of a frame consisting of a plurality of TDMA time slots TS1...TS-M is specified and the field measurements are carried-out in the portion FMP . That is, in a GSM system a predetermined field measurement slot is provided in which no data is sent from the network control means or the base station transmitter to the subscriber station MS.
A further approach how an idle time interval can be provided is described in reference [1] for the case when an inter- system handover should be carried-out. In this case, as illustrated in Fig. 6, the subscriber station MS does not perform any measurements on another system and instead the other system transmits a pseudo-noise PN sequence which is received by the subscriber station MS on the same frequency on which the subscriber station MS already communicates . When the power of this PN sequence exceeds a predetermined threshold during a predetermined time, compared to other PN sequences, an inter-system handover is carried-out.
As shown in Fig. 2 and in Fig. 3-1, 4-1, the network control means RNC triggers the mobile station and step ST13 to perform the IF measurements and it will also indicate to the subscriber statin MS on which frequency belonging to a different cell or a different system said IF measurements are to be carried-out. The subscriber station SS will report the IF measurements back to the network control means RNC within a predetermined time. Then, in step ST22, the network control means RNC will determine whether a handover to the selected frequency (cell or different system) is possible. If it is not possible, because for example a too high interference is
Figure imgf000016_0001
frames by increasing the power before and after the determined measurement time interval. Therefore, on the side of the subscriber station MS and on the side of the network control means RNC the quality of the received is increased. However, the above described procedures (which are generally used in CDMA 2000 and IS '95) for providing a given time interval in which the mobile station MS is to carry-out field mesurements in step ST21, the PN sequence transmission and the compensation for erased frames by increasing the power, still exhibit some major drawbacks when implemented in the system as explained below.
In addition, the WCDMA procedure of carrying-out field measurements in connection with the compressed mode of operation has the following disadvantages, in particular for the system. If the spreading factor SF in the down link DL is reduced to provide the idle time interval IT in which the subscriber station MS is to perform the field measurements on other systems, the available channelization codes are reduced. That is, the hard capacity for the CDMA system is decreased.
On the other hand, if the channel coding rate is increased for a certain time period, a complicated code-rate apparatus must be implemented in the network control means RNC, since a CDMA system can carry services with different coding schemes and different interleaving depths on the same radio link.
Furthermore, the subscriber station MS has to increase its output power when measurements are performed due to the compressed mode operation, since the same data information is transmitted during a smaller time period, i.e. in the compressed data period. If the output power of the subscriber station MS and/or base transceiver station RBS would not be increased, the performance will be decreased. However, this requirement to increase the peak power of the subscriber station MS may imply a distance limitation if the subscriber station MS is already transmitting at its maximum output power. Furthermore, there is a higher risk to lose information, since the data field is not protected to the same extent when the coding rate is reduced.
The procedure to use a PN sequence transmission as shown in Fig. 6 has the following disadvantages. In this case, all other existing mobile communication systems have to be equipped with an apparatus which transmits a PN sequence which can be detected by the subscriber station MS. This will imply high costs for the operators (and thus for the end users) . Moreover, the PN sequence used in the other mobile communication systems will interfere with the CDMA systems and will reduce the capacity as well as the quality of data transmission.
The last mentioned method of increasing the power before and after the measurement time interval has the disadvantage that there is a high risk that a loss of frames due to the measurement time interval will deteriorate the speech quality in situations where speech quality is already very low, when it is likely that the subscriber station MS wants to do an inter-frequency handover close to a cell border or when the cell (sector) exhibits a high load.
Summarizing the above disadvantages of providing a time interval for IF measurements according to the afore described prior art, such provisions of the measurement time interval will result in a decreased quality of service (e.g. due to loss of frames), require a complicated system modification (due to the incorporation of PN sequence generators), and will shorten the lifetime of the battery in the subscriber station MS (if the power is increased before and after the time interval) . SUMMARY OF THE INVENTION
As explained above, the above mentioned first to fourth conditions for triggering inter-frequency measurements in a mobile communication system are not generally applicable to all systems, i.e. to synchronized or non-synchronized systems. Furthermore, the lifetime of the battery is reduced. In addition, the interference level on the up-link as well as the overall signaling load in the network may be increased. The present invention aims at avoiding these disadvantages .
In particular, the object of the present invention is to provide a subscriber station, a network control means, a method and a mobile communication system in which the inter- frequency measurements carried out by the subscriber station can be triggered without a reduction of a battery consumption in the subscriber station and without increasing the signaling load in the network and the interference on the uplink connection.
This object is solved by a subscriber station (claim 1) of a mobile communication system, which comprises at least one base transceiver station and a network control means for establishing at least one communication connection with said subscriber station, including an inter-frequency IF measurement means adapted to perform IF measurements, characterized by said IF measurement means being adapted to perform said IF measurements in response to a network IF measurement trigger signal transmitted and generated by an IF handover means of said network control means in response to a quality measurement means determining that the transmission quality on the down-link of said communication connection drops under a predetermined quality measure.
This object is also solved by a method (claim 21) for triggering inter-frequency IF measurements in a subscriber station of a mobile communication system, which comprises at least one base transceiver station and a network control means for establishing at least one communication connection with said subscriber station, including an inter-frequency IF measurement means adapted to perform said IF measurements, characterized by the steps of monitoring in said network control means the transmission quality on the down-link of said communication connection; generating a network IF measurement trigger signal when said transmission quality drops under a predetermined quality measure and sending said generated network IF measurement trigger signal to said subscriber station; and performing said IF measurements by said IF measurement means in said subscriber station in response to said network IF measurement trigger signal.
This object is also solved by a mobile communication system (claim 37) comprising at least one subscriber station inclduing an inter-frequency IF measurement means adapted to perform said IF measurements and at least one base transceiver station and a network control means for establishing at least one communication connection with said subscriber station, characterized by said network control means comprising a quality measurement means adapted to monitor the transmission quality on the down-link of said communication connection and a network IF handover means adapted to generate a network IF measurement trigger signal when said transmission quality drops under a predetermined quality measure and to send said generated network IF measurement trigger signal to said subscriber station, wherein said IF measurement means is adapted to perform said IF measurements in said subscriber station in response to said network IF measurement trigger signal.
This object is also solved by a network control means (claim 48) of a mobile communication system comprising at least one subscriber station including an inter-frequency measurement means adapted to perform said IF measurements and at least one base transceiver station for establishing at least one communication connection with said subscriber station, characterized by said network control means comprising a quality measurement means adapted to monitor the transmission quality on the down-link of said communication connection and a network IF handover means adapted to generate a network IF measurement trigger signal when said transmission quality drops under a predetermined quality measure and to send said generated network IF measurement trigger signal to said subscriber station, wherein and said IF measurement means is adapted to perform said IF measurements in said subscriber station in response to said network IF measurement trigger signal .
According to a first aspect of the invention the IF measurements carried out by an IF measurement means in the subscriber station are started in response to a network IF measurement trigger signal transmitted and generated from the network control means in response to a quality measurement means in the network determining that the transmission quality on the down-link of the communication connection drops under a predetermined quality measure.
According to a second aspect of the invention a power measurement means PWM in the network control means measures a tranmitted output power on down-link and the IF measurement trigger signal is generated, when the transmitted output power on the down-link exceeds a predetermined power of said value. However, advantageously also other parameters can be evaluated to detect a degradation of the transmission quality on the down-link.
According to a third aspect of the invention, the IF measurement trigger signal is generated by the network control means only if the transmitted output power measured on the down-link by the power measurement means exceeds said predetermined power of said value longer than a predetermined time interval. Preferably, the power measurement on the down- link is carried out within the slow and fast power control carried out between the network control means and the subscriber station when adjusting the transmission power.
According to a fourth aspect of the invention, if several communication connections are established between the network and the subscriber station, the network IF measurement trigger signal is generated when the quality measurement means determines that the transmission quality on all downlinks DL of all said communication connections drops under a respective predetermined quality measure. As before the measure can be the measurement of power on the down-link.
According to a fifth aspect of the invention a subscriber IF handover means transmits a suibscriber IF measurement trigger signal or some measurements in some form over the air- interface to the network control means and the network handover means will only generate and transmit the network IF measurement signal, when the measurements in the subscriber IF measurement signal indicate the necessity for a handover and said quality measurement means determines that the transmission quality on the down-link of the communication connection has dropped under said predetermined quality meaure . That is, based on the down-link quality measurement performed by the network and other measurements from the subscriber station, the network can trigger the subscriber station to perform said IF measurements.
According to a sixth aspect of the invention the network control means performs down-link quality measurements on the down-link and receives additional information, for example the total up-link interference level from the network and the network control means only issues the network interfrequency trigger signal if all measurements and conditions indicate the need for IF measurements . According to a seventh aspect of the invention the outputting of the network IF measurement signal can additionally be made dependent on the conditions "base station traffic load exceeded", "distance limits exceeded", "pilot strength below a predetermined threshold" and "power level exceeded" in addition to being dependent on the down-link quality measurements .
In all aforementioned aspects the subscriber station does not need to perform measurements for triggering an interfrequency or inter-system handover. That is, all this is carried out autonomously in the network control means by monitoring the down-link quality on the down-link of the communication connection. Therefore, there will be no signaling over the air-interface and the subscriber station has no need to report any measurements to the network control means, which thus increases the lifetime of the battery.
Further advantageous embodiments and improvements of the invention may be taken from the dependent claims. Furthermore, the invention can comprise embodiments resulting from a combination of aspects and features which have been separately described and/or claimed in the description and/or the attached claims.
Hereinafter, embodiments of the invention will be described with reference to the attached drawings .
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a principal overview of a telecommunication system TELE comprising at least two different mobile communications systems Tl , T2 according to the prior art; Fig . 2 shows a flow chart for performing an inter- frequency and/or inter-system handover in the telecommunication system TELE shown in Fig. 1;
Fig. 3-1 shows the constitution of data frames and time slots when a compressed mode of operation is used;
Fig. 3-2 shows a flow chart similar to Fig. 2 when a compressed mode of operation is used as shown in Fig. 3-1;
Fig. 4-1 shows the provision of a field measurement time slot in a conventional TDMA mobile communication system such as GSM;
Fig. 4-2 shows a flow chart similar as in Fig. 3-2 for the case when IF measurements are carried out in a specific IF measurement time slot as shown in Fig. 4-1;
Fig. 5a shows a diagram illustrating a power adjustment procedure between a subsriber station MS and a node B (base transceiver station RBS) according to the prior art;
Fig. 5b shows the stepwise adjustment of the output power on the downlink DL;
Fig. 5c shows a slow power control and a fast power control resulting in the stepwise change of the output power in Fig. 5b; and
Fig. 5d shows the mapping of a measured frame error rate
FER or block error rate BLER to a delta_SIR__target value ; Fig. 6 shows a diagram for illustrating a handover procedure in connection with the transmission of PN sequences from a PN sequence generator PNG for inter-system handovers ;
Fig. 7 shows a principle block diagram of a subscriber station MS and a network control means RNC according to the invention;
Fig. 8 shows a flow chart similar to Fig. 2, however incorporating a step ST111, ST121, ST131 according to the invention; and
Fig. 9 shows a diagram similar to Fig. 5b where a power limit value Pϋmit i used according to the invention.
It should be noted that throughout the drawings the same or similar reference numerals designate the same or similar steps and features. In particular, the units described for a conventional subscriber station MS and a conventional network control means RNC in Fig. 2 are also present in the embodiments of the invention. Furthermore, it should be noted that the invention is not restricted to the specific CDMA, WCDMA, D-AMPS or GSM systems decribed above. That is, the invention can be applied to any telecommunications system where a handover needs to be performed between frequencies, cells and different systems.
PRINCIPLE OF THE INVENTION
It should be noted that the triggering of IF measurements in connection with handover procedures are carried in general in both cases when a communication connection CC is set up or when merely a signaling connection has been set up with the mobile station MS in a non-active mode of operation. That is, the need for a cell update may exist when the mobile station MS is merely registered in the network and does not initiate a call (or when no call is pending for the mobile station MS at the network control means) .
Although hereinafter the quality measurement will be described with reference to the quality on a down-link of a communication conenction, it may be noted that a similar procedure can be used fot determining the quality on the down-link of a signalling communication, for example by monitoring the strength of a paging flag sent by the paging flag sending means PFM of the network control means. However, since one of the core aspects is that only the network control means carries out decisions regarding the triggering of the IF measurements, hereinafter it will be assumed that a communication connection has already been set up between the mobile station MS and the network control means RNC (radio network controller) .
Fig. 7 shows a principle block diagram of a mobile communication system Tl according to the invention. In addition to the units already described in Fig. 1 according to the prior art, the network control means RNC comprises a quality measurement means QMM adapted to monitor the transmission quality on the down-link of the communication connection, a power measurement means PMM for measuring the transmitted output power on the downlink, a power control means PAM which generates the power offset value PDff the upper threshold Pup, the lower threshold PDWN n<^ a ti e interval signal TINT indicating a predetermined measurement interval and a power limit value Piimit* τ^e Power control means PAM may cooperate with a calibration means CAL for calibrating the values P0ff, PuP' PDWN- Optionally, the network control means RNC contains a time interval determining means TIDM.
A shown in Fig. 8, the principal idea of the invention is that in said STlll the quality measurement means QMM monitors the transmission quality on the down-link DL of the communication connection CC and the network IF handover means receives a quality signal QS from the quality measurement means QMM. This quality signal QS indicates to the network IF handover means HORM whether the determined transmission quality on the down-link is lower than a predetermined quality measure QoS-MS which is also supplied to the quality measurement means QMM (see fig. 7) .
If in step ST121 it is determined by the quality measurement means QMM that the detected down-link quality is under the threshold quality QoS-MS, than the quality signal QS will indicate this condition to the handover means HORM such that in step ST132 the handover means HORM outputs the network IF trigger signal IFTS. When the IF measurement means IFM in the subscriber station MS receives this trigger signal NIFTS, it will start performing IF measurements in said IF measurement means IFMM in step ST21 as alredy discussed with respect to Fig. 2 above. The other steps in Fig. 8 are the same as in Fig. 2.
As explained above, since only the network control means RNC (the quality measurement means QMM) must perform quality measurements on the down-link, the use of the subscriber station battery will be reduced and there is no additional interference in the up-link and the signaling load in the network is not increased since the subscriber station does not need to report the received signals strength to the network in order to trigger an inter-frequency or inter- system handover. That is, due to the inventive procedure for triggering the IF measurements, there will be no additional signaling over the air-interface.
Of course, according to the prior art, it is always easy to monitor the transmission quality in the subscriber station, i.e. by monitoring the strength of a pilot signal contained in a control portion of the transmission frame. However, in this case, as explained before, the subscriber station must report such measurements to the network control means RNC which thus increases the interference on the up-link of the communication connection CC and the overall load in the network. On the other hand, according to the principle of the invention, it was realized by the inventors, that in a typical WCDMA, CDMA, TDMA communication systems the quality of the down-link connection (which can be measured even from the network control side) can be used since the transmission conditions, even when they are measured on the network side, are a reflection of the current transmission conditions between the subscriber station MS and the network control means RNC. However, as explained before, this can be done completely autonomously by the network control means RNC.
Hereinafter several embodiments of the invention will be described with reference to the aspects how the quality can be measured on the down-link of the communication connection in order to output the network IF measurement signal NIFTS to the subscriber station MS.
FIRST EMBODIMENT OF THE INVENTION
According to a first aspect of the first embodiment of the invention the quality measurement comprises the measuring of the transmitted output power PQut on the down-link DL from the network control means to the subscriber station. For example, the power measurement means PMM measures the transmitted output power Pout on the down-link in step STlll and the network IF measurement trigger signal NIFTS is generated in step ST131 by the network IF handover means HORM when the measured transmitted output power on the down-link preset by the power adjustment module. Therefore, the power measurement means PMM outputs a transmission power signal TP DL exceeds a predetermined power limit value Pχimit which is indicating the measured output power PDut o the quality measurement means QMM and the predetermined power limit value Pl mit can ^or example be constituted by the quality measurement signal QoS-MS or it can be supplied to the quality measurement means QMM by the power adjustment module PAM as was explained above with reference to Fig. 5. Fig. 9 shows a diagram similar to Fig. 5b where this power limit value Plimit is shown to be set preferably between PGff and pup •
According to another aspect of the first embodiment of the invention, the network IF measuement trigger signal NIFTS is only generated by the IF handover means if the measured transmitted output power on the down-link DL exceeds the predetemined power limit value P]_imit (e-9- contained in the QoS-MS signal) longer than a predetermined measurement interval TINT (this interval is also called the Time-To- Trigger interval) . Such a predetermined measurement interval can be indicated to the quality measurement means QMM from the power adjustment module PAM or from the power measurement means PMM.
Typically the predetermined measurement interval TINT is a number of frames, for example in a CDMA system the predetermined measurement interval may be 10 to 100 frames. On the other hand, in a TDMA-system (e.g. a GSM-system) a predetermined measurement interval may be as long as 28 to 120 frames. In a WCDMA system the predetermined measurement interval TINT may be 10 to 20 frames.
It may also be noted that the aforementioned quality measurement procedure or power transmission measurement on the down-link can be performed for each of several communication connctions between one or several base stations BS and the subscriber station MS. In this case, the network IF measurement trigger signal NIFTS is generated by said network IF handover means HORM when the quality measurement QMM determines that the transmission quality on all downlinks DL of all said communication connections CC drop under a predetermined quality measure. For example, the network IF measurement trigger signal NIFTS is generated when the transmitted output power on all down-links exceeds a predetermined threshold power or exceeds the power limit value P]_imit °r a predetermined measurement interval. It is also possible to set different power limit values ϋmit and different predetermined measurement intervals TINT for the different communication connections .
As explained above, for the case of one or several communication links between the base transceiver station RBS and the subscriber station MS a predetermined power limit value Piimi c n be used against which the determined transmitted output power on the down-link DL is compared. Such a power limit value Pχimit can ^>e the threshold value PQff used in connection with a slow and fast power control as explained above with reference to Fig. 5.
As explained above, the power offset value P0ff can be dependent on a slow power control and said upper and lower power thresholds Pup; Pdwn can be variable dependent on a fast power control respectively carried out by said power adjustment means PAM of said network control means RNC. Therefore, the offset power as well as the output power interval can be changed due to new conditions in the system. It should be noted, that the aforementioned power values are set for the down-link and present - when compared with the transmitted power - a measure of the transmission conditions on the down-link. However, since the power values are used in a slow and fast power control on the down-link, the power values are not exclusively dependent on the network side, but also incorporate effects on the subscriber station SS.
As shown in Fig. 7, the power adjustment means PAM may cooperate with a calibration means CAL for adjusting the power values. In particular, the calibration means CAL calibrates each power step within the range determined by the upper and lower power thresholds PUp, P wn an<^ said variable power offset values to predetermined (beforehand known) values .
SECOND EMBODIMENT OF THE INVENTION
As explained above, according to the first embodiment of the invention, down-link quality measurements (e.g. the transmitted power from the node B are performed by the network control means in order to output the network IF measurement trigger signal NIFTF . However, it is possible that the network handover means HORM outputs the trigger signal NIFTS also on the basis of some measurements performed in the subscriber station MS.
In this case, it is possible that the subscriber handover means HORM independently performs measurements regarding the need for handover and the IF measurement means IFMM only starts the IF measurements when the network trigger signal NIFTS as well the subscriber trigger signal SIFTS are generated.
On the other hand, it is also possible that the subscriber IF handover means HORM transmits the subscriber IF measurement trigger signal SIFTS to said network control means RNC. That is, the subscriber station SS transmits in the subscriber IF measurement trigger signal SIFTS measurements which have been performed on the side of the subscriber station. In this case, the network control means RNC also processes the subscriber trigger signal SIFTS (as shown in Fig. 7 with the input of SIFTS to the handover means HORM) and generates and transmits the network IF measurement signal NIFTS only when the measurements in the subscriber trigger signal SIFTS indicate the necessity for a handover and the quality measurement means determine that the transmission quality on the down link of said communication connection has dropped under said predetermined quality measure as discussed above. Therefore, according to the second embodiment of the invention the network control means triggers the subscriber station MS to perform inter-frequency/inter-system measurements on the basis on the down link quality measurements performed by the network control means and other measurements performed in the subscriber station MS. This eventually results in a more acuarate generation of the trigger signal, although the measurements will have to be reported to the network control means on the up link UL and therefore the interference level on the up link UL is increased.
On the other hand, the network control means RNC already bases a part of the trigger signal generation on the down link quality and therefore only a small amount of additional information (subscriber measurements) need to be transmitted from the subscriber station to the network control means RNC. Therefore, the additional interference on the up link and the increase of the overall load in the communication system will be small. Typical measurements which can be carried out by the subscriber station MS are those described above with respect to the conventional four trigger conditions .
THIRD EMBODIMENT OF THE INVENTION
According to a third embodiment of the invention, the network control means RNC generates the network IF measurement trigger signal NIFTS if the measurements reported in the subscriber IF measurement trigger signal SIFTS from the subscriber station MS indicate the need for a handover (as in the second embodiment) if said quality measurement means QMM determines that the transmission quality on the down link DL of said communication connection has dropped under said predetermined quality threshold (as in the first and second embodiments) and if in addition additional system information IL; TDLP provided in the network control means RNC also indicate handover .
That is, according to the third embodiment the network trigger signal NIFTS is generated based on the down link quality measurements performed by the quality measurement means QMM, additional system information as well as other measurements from the subscriber station. Preferably, such additional system information can be the total up link interference level IL of the communication connection CC between the subscriber station SS and the network control means RNC or the base transceiver station RBS and/or the total down link output power TDLP (in Fig. 7 these parameters are shown as input to the handover means HORM) . If the quality measurements, the additional system information and the subscriber station measurements indicate the need for a handover, the network control means RNC according to the third embodiment of the invention triggers the subscriber station MS to perform inter-frequency/inter-system measurements .
FOURTH EMBODIMENT OF THE INVENTION
As explained above, according to the principle of the invention the quality of the transmission conditions on the down link is used as a measure for triggering the subscriber station to perform IF measurements. According to the first embodiment of the invention such a quality measure is constituted by the transmitted output power on the down link.
According to the second and third embodiments of the invention additional information is used for generating the trigger signal in the network control means. The additional information provided in the network control means RNC may be the total up link interference level IL of the communication connection CC and/or the total down link output power TDLP. In the simplest case, the measurements carried out in the subscriber station MS can be an average filtering of a pilot channel during a predetermined time.
However, other conventional criteria as explained above with reference to Figs. 1 - 5 may be used in the embodiments of the invention.
For example, the additional information provided in the network controls means RNC may relate to the "base station traffic load" referred to as first condition above. That is, the network IF handover means HORM may determine the necessity for handover also on the basis of a supervision of the loads at all base stations RBS in the network.
Furthermore, regarding the measurements in the subscriber station and the additional system information, the subscriber handover means HORM and/or the network handover means HORM can determine the necessity for handover additionally also on the basis of a supervision of the distance D between a base station RBS and the subscriber station MS which has been referred to above as the second condition "a distance limits exceeded" .
Furthermore, the network trigger signal NIFTS can also be generated additionally on the basis of the third condition "pilot strength below a predetermined threshold" . In this case, in addition to the determining of the down link quality, the trigger signal NIFTS is generated, when the subscriber IF handover means HORM and/or said network IF handover means HORM determine the necessity for a handover on the basis of a supervision of a measured pilot signal strength PLT (as shown as input to the network handover means HORM in Fig. 7) . The trigger signal is only generated, when the quality on the down link drops below a predetermined measure and if the measured pilot signal strength falls below a predetermined power threshold. Furthermore, it is also possible that the subscriber handover means HORM and/or the network handover means HORM determine the necessity for a handover on the basis of an output by a network supervision means PAM that in response to a power increase command by a base station BS a subscriber station power adjustment module PAM is unable to further increase the power on the up link of said communication connection CC . This additional condition has been referred to as the fourth condition "power level exceeded" above.
Such additional decision criteria determined in the subscriber station and/or the network control means RNC can be used in connection with the principle of the invention and in connection with the first, second and third embodiments.
Furthermore, it should be noted that a skilled person can devise other criteria for determining the down link quality and that the determination of the down link on the basis of the evaluation of the down link transmitted power is only one of the methods how the quality on the down link can be determined. Other measures like the bit error rate or the interference level on the down link may also be used. The common aspect amongst all these quality measurement procedures is that they can be carried out autonomously in the network control means without needing additional information from the subscriber station. That is, all information in addition to the down link quality measurement (such as network internal information or measurements transmitted from the subscriber station) are only used additionally to make the trigger signal generation even more accurate .
ADDITIONAL EMBODIMENTS OF THE INVENTION
As explained above with reference to Fig. 2, after having been triggered the IF measurement means IFMM in the mobile station MS carries out the field measurements in step ST21 in O n H
1 3 —
Figure imgf000036_0001
J b
time interval in which the measurements are carried out will start a little later than the receipt of the trigger signals .
If only a signalling communication exists between the subscriber station MS and the network control means RNC then it is also possible to monitor the transmission of a paging flag in the subscriber station MS. If no paging flag is transmitted then the subscriber station MS judges that the network is not about to perform a data transmission. Therefore, at each time point where the signalling communication is monitored and no paging flag is detected, the subscriber station sets a predetermined number of time slots or data frames as the predetermined time interval.
In this case, it is also possible that the IF measurements carried out in the subscriber station are not only carried out in the predetermined time interval, but also in a idle time interval IT of a data frame FR when the transmission between the network and the subscriber station MS is carried out in a compressed mode of operation. In this case, carrying out data transmission in said compressed mode after receiving the network trigger signal, the predetermined time interval used for the IF measurements corresponds to a number of data slots or frames where no data transmission takes place (as determined by the data transmission determining means DTDM) and a number of idle time portions of data frames or slots where data transmission is carried in a compressed mode.
Whilst in the aforementioned examples the time interval is determined by the subscriber station after receiving the trigger signal from the network, it is also possible that the network control means ifself transmits an indication to the subscriber station about the time interval which should be used for the IF measurements .
In particular, the network IF measurement trigger signal NIFTS or a further control signal from the network control means RNC can indicate the time interval in which said subscriber station is to carry out said IF measurements. Since the trigger signal needs to be sent to the subscriber station MS in order to trigger the subscriber station MS, it is advantageous to contain the indication of the time interval in the trigger signal such that the subscriber station MS is immediately informed - together with the triggering - about the time interval which should be used for the IF measurements .
The network control means RNC can autonomously determine the time interval to be used for the IF measurements as a time interval in which a temporary degradation of the transmission conditions between the subscriber station MS and the base transceiver station RBS is determined as acceptable. Such a temporary reduction of the quality of service may be determined because of a deletion of data during a delay- sensitive data transmission between the subscriber station MS and the base transceiver station RBS. If such a deletion is necessary, then the subscriber MS and the network control means RNC will respectively increase a transmission power on the down link DL and the up link UL on the communication connection before the beginning of said predetermined time interval and/or after the end of said predetermined time interval .
Since the first embodiment of the present invention already monitors the transmitted power on the down link in order to generate the trigger signal, this can be advantageously coupled with the determination of the time interval on the basis of a temporary reduction of the quality of transmission, since the network control means RNC can combine the measurement of the transmitted power for generating the trigger signal with the determination of the time interval. INDUSTRIAL APPLICABILITY
As explained above, the generation of the trigger signal according to the present invention can be applied to any mobile communication system comprising at least one communication network, independent of the transmission standard used. Therefore, the present invention can be used in the context of GSM, PDS, TACS or D-AMPS systems or combinations of two or more of the systems. Of course, if a handover to a system with a different standard is required, the subscriber station MS as described above will be able to operate according to both standards (e.g. dual-mode- operation) .
Furthermore, it should be noted that what has been described above is what the inventors currently perceive as the best mode of the invention. However, of course further modifications and variations of the invention are possible on the basis of the teaching herein and the presented disclosure. As explained above, the invention may comprise embodiments which result from a combination of features which have been separately described in the description and claimed in the claims.
Reference numerals in the claims only serve clarification purposes and do not limit the scope of protection.

Claims

1. Subscriber station (MS) of a mobile communication system (GSM; WCDMA) , which comprises at least one base transceiver station (RBS) and a network control means (RNC) for establishing at least one communication connection (CC) with said subscriber station (MS) , including an inter-frequency (IF) measurement means (IFMM) adapted to perform IF measurements, characterized by said IF measurement means (IFMM) being adapted to perform said IF measurements in response to a network IF measurement trigger signal (NIFTS) transmitted and generated by an IF handover means (HORM) of said network control means (RNC) in response to a quality measurement means (QMM) determining (NEHO) that the transmission quality on the down-link (DL) of said communication connection (CC) drops under a predetermined quality measure (QoS-MS) .
2. Subscriber station (MS) according to claim 1, characterized in that said network IF measurement trigger signal (NIFTS) indicates that a transmitted output power measured on the down-link (DL) by a power measurement means (PMM) exceeds a predetermined power limit value (Plimit) .
3. Subscriber station (MS) according to claim 2, characterized in that said network IF measurement trigger signal (NIFTS) indicates that said transmitted output power measured on the down-link (DL) b^ said power measurement means (PMM) exceeds said predetermined power limit value (Plimit) at least for a predetermined measurement interval (TINT) .
4. Subscriber station (MS) according to claim 2 or 3 , characterized in that a power adjustment means (PAM) presets for the donwlink
(DL) a predetermined power offset value (Poff ) as well as an upper and lower threshold value (PUP; PWN) within which said measured down-link power is allowed to vary.
Subscriber station (MS) according to claim 2 or 3 , characterized in that said power offset value (POFF) is variable dependent on a slow power control, and said upper and lower threshold values (PUP; PDWN) are variable dependent on a fast power control, respectively carried out by said network control means (RNC) , wherein a calibration means (CAL) is adapted to calibrate each power step within the range determined by the upper and lower thresholds (PUP; PDWN) and said variable power offset values (POFF) to predetermined values .
Subscriber station (MS) according to claim 1, characterized in that at least two communication connections (CC) are established between several base station transceivers (RBS) and said subscriber station (MS) , wherein said network IF measurement trigger signal (NIFTS) is generated by said network handover means (HORM) when said quality measurement means (QMM) determines that the transmission quality on all down-links (DL) of all said communication connection (CC) drops under a respective predetermined quality measure (QoS-MS) .
Subscriber station (MS) according to claim 1, characterized by a subscriber handover means (HORM) for performing measurements for generating a subscriber IF measurement trigger signal (SIFTS) , wherein said IF measurement means (IFMM) is adapted to start said IF measurements only when said network trigger signal (NIFTS) and said subscriber trigger signal (SIFTS) are generated.
8. Subscriber station (MS) according to claim 7, characterized by said subscriber handover means (HORM) transmitting to said network control means (RNC) said subscriber IF measurement trigger signal (SIFTS) indicating said measurements, wherein said network handover means (HORM) generates and transmits said network IF measurement signal (NIFTS) only when said measurements in said subscriber IF measurement trigger signal (SIFTS) indicate the necessity for a handover and said quality measurement means (QMM) determines (NEHO) that the transmission quality on the down-link (DL) of said communication connection (CC) has dropped under said predetermined quality threshold (QoS-TH) .
9. Subscriber station (MS) according to claim 8, characterized by said network IF measurement trigger signal (NIFTS) is generated only if said measurements reported in said subscriber IF measurement trigger signal (SIFTS) from said subscriber station (MS) indicate a handover, said quality measurement means (QMM) determines (NEHO) that the transmission quality on the down-link (DL) of said communication connection (CC) has dropped under said predetermined quality threshold (QoS-TH) , and additional system information provided in the network control means (RNC) also indicate a handover.
10. Subscriber station (MS) according to claim 7-9, characterized in that said subscriber handover means (HORM) is adpated to perform measurements by an average filtering of a pilot channel during a predetermined time .
11. Subscriber station (MS) according to claim 9, characterized in that said additional information is a total uplink (UL) interference level (SIR) of the communication connection and/or the total down-link output power.
12. Subscriber station (MS) according to claim 7-9, characterized in that said network handover means (HORM) is adapted to determine the necessity for a handover on the basis of a supervision of the loads at all base stations (BS) in the network (Base station Traffic load) .
13. Subscriber station (MS) according to claim 7-9, characterized in that said subscriber handover means (HORM) and/or said network handover means (HORM) are adapted to determine the necessity for a handover on the basis of a supervision of the distance between a base station (BS) and the subscriber station (MS) (Distance limits exceeded) .
14. Subscriber station (MS) according to claim 7-9, characterized in that said subscriber handover means (HORM) and/or said network handover means (HORM) are adapted to determine the necessity for a handover on the basis of a supervision of a measured pilot signal strength falling below a predetermined power threshold (Pilot strength below a predefined Threshold) .
15. Subscriber station (MS) according to claim 7-9, characterized in that said subscriber handover means (HORM) and/or said network handover means (HORM) are adapted to determine the necessity for a handover on the basis of a supervision that in response to a power increase command by a base station (BS) , a subscriber station power adjustment module (PAM) is unable to further increase its power on the uplink of said communication connetion (CC) (Power level exceeded) .
16. Subscriber station (MS) according to claim 1, characterized by a data transmission determining means (DTDM) adapted to determine a predetermined time interval in which a base transceiver station (RBS) will not direct to said subscriber station (MS) a data transmission, wherein said IF measurement means (IFMM) is adapted to perform said IF measurements in said predetermined time interval after said network IF measurement trigger signal is received.
17. Subscriber station (MS) according to claim 16, characterized in that a transmission of data is carried out on said communication connection (CC) via said transmission frames (FR) consisting of a control portion (CP) and a data portion (DP) , wherein said data transmission determining means (DTDM) is adapted to determine the power ratio of the information contained in the data portion (DP) to the information contained in the control portion (CP) and comprises power estimation means adapted to determine that no data transmission will take place in a time interval corresponding to a predetermined number of data slots following the output of said IF measurement trigger signal, if said power ratio is below a predefined power ratio.
18. Subscriber station (MS) according to claim 16, characterized by a non-active mode operation means (SOM) adapted to hold the subscriber station (MS) in a non-active operation mode in which at least a signalling communication is established between said subscriber station (MS) and said base transceiver station (RBS) , and a paging flag monitoring means (PFMM) adapted to monitor the transmission of a paging flag (PF) from said base transceiver station (RBS) to said subscriber station (MS) , wherein, when said paging flag monitoring means (PFMM) determines no transmission of said paging flag (PF) , said data transmission determining means (DTDM) determines that a data transmission will not take place in a time interval corresponding to a predetermined number of data slots after detecting said paging flag (PF) .
19. Subscriber station (MS) according to claim 1, characterized in that said data transmission between said subscriber station (MS) and said base transceiver station (RBS) is carried out in a compressed mode by compression of transmission data in said data portion (DP) in at least one time slot such that an idle time interval is provided in said time slot where no data transmission occurs, wherein said subscriber station (MS) contains a compression-mode detection means (CMDM) for detecting data transmission in said compressed mode and wherein said predetermined time interval corresponds to a number of data slots where no data transmission takes place and a number of idle time portions of data slots where data transmission is carried in a compressed mode.
20. Subscriber station (MS) according to claim 1, characterized in that said network IF measurement trigger signal (NIFTS) or a further control signal from the network control means (RNC) indicates a time interval in which said subscriber station is to carry out said IF measurments .
21. Method for triggering inter-frequency (IF) measurements
(ST21, ST21', ST21''; ST21'''; ST21'''') in a subscriber station (MS) of a mobile communication system (GSM; WCDMA) , which comprises at least one base transceiver station (RBS) and a network control means (RNC) for establishing at least one communication connection (CC) with said subscriber station (MS) , including an inter- frequency (IF) measurement means (IFMM) adapted to perform said IF measurements, characterized by the steps of monitoring (STlll) in said network control means (RNC) the transmission quality on the down-link (DL) of said communication connection (CC) ; generating (STlll) a network IF measurement trigger signal (NIFTS) when said transmission quality drops (ST121) under a predetermined quality measure (QoS-MS) and sending (ST131) said generated network IF measurement trigger signal (NIFTS) to said subscriber station (MS); and performing (ST21) said IF measurements by said IF measurement means (IFMM) in said subscriber station (MS) in response to said network IF measurement trigger signal (NIFTS) .
22. Method according to claim 21, characterized in that a transmitted output power (TP) on the down-link (DL) is measured (STlll) on the down-link (DL) by a power measurement means (PMM) and said network IF measurement trigger signal (NIFTS) is generated (ST131) when said transmitted output power on the down-link (DL) exceeds a predetermined power limit value (Plimit) .
23. Method according to claim 22, characterized in that said network IF measurement trigger signal (NIFTS) is generated (ST131) if said transmitted output power measured on the down-link (DL) by said power measurement means (PMM) exceeds said predetermined power offset value (POFF) longer than a predetermined measurement interval (TINT) .
24. Method according to claim 22 or 23, characterized in that said quality measurement means (QMM) presets for the donwlink (DL) a predetermined power offset value (Plimit) as well as an upper and lower threshold values (PUP; PDWN) within which said measured down-link power is allowed to vary.
25. Method according to claim 22 or 23, characterized in that said power offset value (POFF) is variable dependent on a slow power control (PCTL) , and said upper and lower power thresholds (PUP; PDWN) are variable dependent on a fast power control (PCTL) , respectively carried out by a power adjustment means (PAM) of said network control means (RNC) , wherein a calibration means (CAL) calibrates each power step within the range determined by the upper and lower power thresholds (PUP; PDWN) and said variable power offset value (POFF) to predetermined values .
26. Method according to claim 21, characterized in that several communication connections (CC) are established between several base stations (BS) and said subscriber station (MS) , wherein said network IF measurement trigger signal (NIFTS) is generated (ST131) by said network handover means (HORM) when said quality measurement means (QMM) determines that the transmission quality on all down-links (DL) of all said communication connection (CC) drop under a respective predetermined quality threshold (QoS-TH) .
27. Method according to claim 21, characterized in that measurements for generating a subscriber IF measurement trigger signal (SIFTS) are performed in said subscriber station, wherein said IF measurement means (IFMM) is adapted to start said IF measurements only when said network trigger signal (NIFTS) and said subscriber trigger signal (SIFTS) are generated.
28. Method according to claim 27, characterized in that transmitting said subscriber IF measurement trigger signal (SIFTS) to said network control means (RNC) indicating said mesasurements , wherein said network handover means (HORM) generates and transmits said network IF measurement signal (NIFTS) only when said measurements in said subscriber IF measurement trigger signal (SIFTS) indicate the necessity for a handover and said quality measurement means (QMM) determines (NEHO) that the transmission quality on the down-link (DL) of said communication connection (CC) has dropped under said predetermined quality measure (QoS-MS) .
29. Method according to claim 28, characterized by said network IF measurement trigger signal (NIFTS) is generated only if said measurements reported in said subscriber IF measurement trigger signal (SIFTS) from said subscriber station (MS) indicate a handover, said quality measurement means (QMM) determines (NEHO) that the transmission quality on the down-link (DL) of said communication connection (CC) has dropped under said predetermined quality measure (QoS-MS) , and additional system information (IL; TDLP) provided in the network control means (RNC) also indicate a handover.
30. Method according to Claim 27-29, characterized in that said subscriber handover means (HORM) performs measurements by an average filtering of a pilot channel during a predetermined time.
31. Method according to claim 29, characterized in that said additional information is a total uplink (UL) interference level (IL) of the communication connection (CC) and/or the total down-link output power (TDLP) .
32. Method according to claim 27-29, characterized in that said network handover means (HORM) is adapted to determine the necessity for a handover on the basis of a supervision of the loads (LOAD) at all base stations (BS) in the network (Base station Traffic load) .
33. Method according to claim 27-29, characterized in that said subscriber handover means (HORM) and/or said network handover means (HORM) determine the necessity for a handover on the basis of a supervision of the distance (D) between a base station (BS) and the subscriber station (MS) (Distance limits exceeded) .
34. Method according to claim 27-29, characterized in that said subscriber handover means (HORM) and/or said network handover means (HORM) determine the necessity for a handover on the basis of a supervision of a measured pilot signal strength (PLT) falling below a predetermined power threshold (Pilot strength below a predefined Threshold) .
35. Method according to claim 27-29, characterized in that said subscriber handover means (HORM) and/or said network handover means (HORM) determine the necessity for a handover on the basis of a supervision (PSV) that in response to a power increase command by a base station (BS) , a subscriber station power adjustment module (PAM) is unable to further increase its power on the uplink of said communication connetion (CC) (Power level exceeded) .
36. Method according to claim 21, characterized in that said network IF measurement trigger signal (NIFTS) or a further control signal from the network control means (RNC) indicates a time interval in which said subscriber station is to carry out said IF measurments .
37. Mobile communication system (GSM; WCDMA) comprising at least one subscriber station (MS) inclduing an inter- frequency (IF) measurement means (IFMM) adapted to perform said IF measurements and at least one base transceiver station (RBS) and a network control means (RNC) for establishing at least one communication connection (CC) with said subscriber station (MS) , characterized by said network control means comprising a quality measurement means (QMM) adapted to monitor
(STlll) the transmission quality on the down-link (DL) of said communication connection (CC) and a network IF handover means (HORM) adapted to generate (STlll) a network IF measurement trigger signal (NIFTS) when said transmission quality drops (ST121) under a predetermined quality measure (QoS-MS) and to send (ST131) said generated network IF measurement trigger signal (NIFTS) to said subscriber station (MS) , wherein said IF measurement means (IMM) is adapted to perform (ST21) said IF measurements in said subscriber station (MS) in response to said network IF measurement trigger signal
(NIFTS) .
38. System according to claim 37, characterized by a subscriber IF handover means (HORM) adapted to perform measurements for generating a subscriber IF measurement trigger signal (SIFTS) in said subscriber station, WO 01/17306 c n PCT/EPOO/07911
50
wherein said IF measurement means (IFMM) is adapted to start said IF measurements only when said network trigger signal (NIFTS) and said subscriber trigger signal (SIFTS) are generated.
39. System according to claim 38, characterized in that said subscriber IF handover means (HORM) is adapted to transmit said subscriber IF measurement trigger signal (SIFTS) to said network control means (RNC) indicating said mesasurements, wherein said network handover means (HORM) generates and transmits said network IF measurement signal (NIFTS) only when said measurements in said subscriber IF measurement trigger signal (SIFTS) indicate the necessity for a handover and said quality measurement means (QMM) determines (NEHO) that the transmission quality on the down-link (DL) of said communication connection (CC) has dropped under said predetermined quality measure (QoS-MS) .
40. System according to claim 39, characterized by said network IF measurement trigger signal (NIFTS) is generated by said network IF handover request means (HORM) if said measurements reported in said subscriber IF measurement trigger signal (SIFTS) from said subscriber station (MS) indicate a handover, said quality measurement means (QMM) determines (NEHO) that the transmission quality on the down-link (DL) of said communication connection (CC) has dropped under said predetermined quality measure (QoS-MS) , and additional system information (IL; TDLP) provided in the network control means (RNC) also indicate a handover.
41. System according to claim 38-40, characterized in that said subscriber handover means (HORM) performs measurements by an average filtering of a pilot channel during a predetermined time.
42. System according to claim 38, characterized in that said additional information is a total uplink (UL) interference level (IL) of the communication connection (CC) and/or the total down-link output power (TDLP) .
43. System according to claim 38-40, characterized in that said network IF handover means (HORM) is adapted to determine the necessity for a handover on the basis of a supervision of the loads (LOAD) at all base stations (BS) in the network (Base station Traffic load) .
44. System according to claim 38-40, characterized in that said subscriber handover-request means (HORM) and/or said network handover means (HORM) determine the necessity for a handover on the basis of a supervision of the distance (D) between a base station (BS) and the subscriber station (MS) (Distance limits exceeded) .
45. System according to claim 38-40, characterized in that said subscriber IF handover means (HORM) and/or said network IF handover means (HORM) determine the necessity for a handover on the basis of a supervision of a measured pilot signal strength (PLT) falling below a predetermined power threshold (Pilot strength below a predefined Threshold) .
46. System according to claim 38-40, characterized in that said subscriber handover means (HORM) and/or said network handover means (HORM) determine the necessity for a handover on the basis of an output by a network power supervision means (PAM) that in response to a power increase command by a base station (BS) , a subscriber station power adjustment module (PAM) is unable to further increase its power on the uplink of said communication connection (CC) (Power level exceeded) .
47. System according to claim 37, characterized in that said network IF measurement trigger signal (NIFTS) or a further control signal from the network control means (RNC) indicates a time interval in which said subscriber station is to carry out said IF measurments .
48. Network control means (RNC) of a mobile communication system (GSM; WCDMA) comprising at least one subscriber station (MS) including an inter-frequency (IF) measurement means (IFMM) adapted to perform said IF measurements and at least one base transceiver station
(RBS) for establishing at least one communication connection (CC) with said subscriber station (MS) , characterized by said network control means comprising a quality measurement means (QMM) adapted to monitor
(STlll) the transmission quality on the down-link (DL) of said communication connection (CC) and a network IF handover means (HORM) adapted to generate (STlll) a network IF measurement trigger signal (NIFTS) when said transmission quality drops (ST121) under a predetermined quality measure (QoS-MS) and to send (ST131) said generated network IF measurement trigger signal (NIFTS) to said subscriber station (MS) , wherein and said IF measurement means (IMM) is adapted to perform (ST21) said IF measurements in said subscriber station (MS) in response to said network IF measurement trigger signal (NIFTS) .
49. Network control means (RNC) according to claim 48, characterized in that a transmitted output power (TP) on the down-link (DL) is measured (STlll) by a power measurement means (PMM) and said network IF measurement trigger signal (NIFTS) is generated (ST131) by said network IF handover means (HORM) when said transmitted output power on the downlink (DL) exceeds a predetermined power limit value (Plimit) .
50. Network control means (RNC) according to claim 49, characterized in that said network IF measurement trigger signal (NIFTS) is generated (ST131) by said IF handover means (HORM) if said transmitted output power measured on the down-link (DL) by said power measurement means (PMM) exceeds said predetermined power limit value (Plimit) longer than a predetermined measurement interval (TINT) .
51. Network control means (RNC) according to claim 49 or 50, characterized in that said quality measurement means (QMM) presets for the donwlink (DL) a predetermined power offset value (POFF) as well as an upper and lower threshold values (PUP; PDWN) within which said measured down-link power is allowed to vary.
52. Network control means (RNC) according to claim 49 or 50, characterized in that said power offset value (POFF) is variable dependent on a slow power control (PCTL) , and said upper and lower power thresholds (PUP; PDWN) are variable dependent on a fast power control (PCTL) , respectively carried out by a power control means (PCTL) of said network control means WO 01/17306 c . PCT/EPOO/07911
D 4
(RNC) , wherein a calibration means (CAL) calibrates each power step within the range determined by the upper and lower power thresholds (PUP; PDWN) and said variable power offset values (POFF) to predetermined values.
53. Network control means (RNC) according to claim 48 characterized in that several communication connections (CC) are established between several base stations (BS) and said subscriber station (MS) , wherein said network IF measurement trigger signal (NIFTS) is generated (ST131) by said network IF handover means (HORM) when said quality measurement means (QMM) determines that the transmission quality on all down-links (DL) of all said communication connections (CC) drops under a respective predetermined quality measure (QoS-MS) .
PCT/EP2000/007911 1999-08-31 2000-08-14 Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system WO2001017306A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
DE60033406T DE60033406T2 (en) 1999-08-31 2000-08-14 SUBSCRIBER, NETWORK CONTROL DEVICE AND METHOD FOR TRIGGERING INTERFACE MEASUREMENTS IN A MOBILE COMMUNICATION SYSTEM
AU64418/00A AU764548B2 (en) 1999-08-31 2000-08-14 Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system
EP00951507A EP1208711B1 (en) 1999-08-31 2000-08-14 Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP99117127.3 1999-08-31
EP99117127A EP1081977A1 (en) 1999-08-31 1999-08-31 Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system

Publications (1)

Publication Number Publication Date
WO2001017306A1 true WO2001017306A1 (en) 2001-03-08

Family

ID=8238900

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2000/007911 WO2001017306A1 (en) 1999-08-31 2000-08-14 Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system

Country Status (11)

Country Link
US (1) US6567670B1 (en)
EP (2) EP1081977A1 (en)
KR (1) KR100729020B1 (en)
CN (1) CN1185901C (en)
AR (1) AR025473A1 (en)
AT (1) ATE354265T1 (en)
AU (1) AU764548B2 (en)
DE (1) DE60033406T2 (en)
ES (1) ES2279765T3 (en)
TW (1) TW477126B (en)
WO (1) WO2001017306A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007110746A3 (en) * 2006-03-27 2008-01-10 Nokia Corp Apparatus, method and computer program product providing 3.9g mobile-assisted cell change
CN100568825C (en) * 2002-07-22 2009-12-09 意大利电信股份公司 Monitor service method for quality, system and assembly and computer product in the telecommunications network

Families Citing this family (79)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6560461B1 (en) 1997-08-04 2003-05-06 Mundi Fomukong Authorized location reporting paging system
US6222832B1 (en) 1998-06-01 2001-04-24 Tantivy Communications, Inc. Fast Acquisition of traffic channels for a highly variable data rate reverse link of a CDMA wireless communication system
US9525923B2 (en) 1997-12-17 2016-12-20 Intel Corporation Multi-detection of heartbeat to reduce error probability
US7936728B2 (en) 1997-12-17 2011-05-03 Tantivy Communications, Inc. System and method for maintaining timing of synchronization messages over a reverse link of a CDMA wireless communication system
US7394791B2 (en) 1997-12-17 2008-07-01 Interdigital Technology Corporation Multi-detection of heartbeat to reduce error probability
US7773566B2 (en) 1998-06-01 2010-08-10 Tantivy Communications, Inc. System and method for maintaining timing of synchronization messages over a reverse link of a CDMA wireless communication system
US8134980B2 (en) 1998-06-01 2012-03-13 Ipr Licensing, Inc. Transmittal of heartbeat signal at a lower level than heartbeat request
US7221664B2 (en) * 1998-06-01 2007-05-22 Interdigital Technology Corporation Transmittal of heartbeat signal at a lower level than heartbeat request
WO2001026396A1 (en) * 1999-09-30 2001-04-12 Fujitsu Limited Mobile communication system
FI111120B (en) 1999-10-25 2003-05-30 Nokia Corp Timing Method and Arrangement for Performing Preliminary Measurements of Inter-frequency Link Transfer
GB9929794D0 (en) * 1999-12-16 2000-02-09 Nokia Networks Oy Data transmission apparatus
EP1117268A1 (en) 2000-01-14 2001-07-18 Telefonaktiebolaget L M Ericsson (Publ) Subscriber station, network control means and method for carrying out inter-frequency measurements in a mobile communication system
WO2001058044A2 (en) 2000-02-07 2001-08-09 Tantivy Communications, Inc. Minimal maintenance link to support synchronization
DE10010958A1 (en) * 2000-03-06 2001-09-20 Siemens Ag Intersystem relaying method enabling efficient and reliable relaying - involves initiating transmission quality measurement for transmission to base station in second communications system if threshold not reached in first system
US6996081B1 (en) * 2000-10-05 2006-02-07 Telefonaktiebolaget Lm Ericsson (Publ) Resource capacity reporting to control node of radio access network
JP3543759B2 (en) * 2000-11-15 2004-07-21 日本電気株式会社 Transmission power control method, transmitting / receiving apparatus, base station and mobile station
JP2002152844A (en) * 2000-11-15 2002-05-24 Sony Corp Communication system and its method, and communication terminal
US8155096B1 (en) 2000-12-01 2012-04-10 Ipr Licensing Inc. Antenna control system and method
EP2490489A3 (en) * 2000-12-26 2012-10-31 Fujitsu Limited Error rate control apparatus
US7551663B1 (en) 2001-02-01 2009-06-23 Ipr Licensing, Inc. Use of correlation combination to achieve channel detection
US6954448B2 (en) 2001-02-01 2005-10-11 Ipr Licensing, Inc. Alternate channel for carrying selected message types
US6836471B2 (en) * 2001-02-02 2004-12-28 Nokia Mobile Phones Ltd. Method and system for inter-operator handover between WCDMA and GSM
US8605686B2 (en) * 2001-02-12 2013-12-10 Qualcomm Incorporated Method and apparatus for power control in a wireless communication system
DE60132564T2 (en) * 2001-05-25 2009-01-29 Lucent Technologies Inc. Transmission power control for the downlink
US6615044B2 (en) * 2001-06-06 2003-09-02 Nokia Mobile Phones, Ltd. Method of WCDMA coverage based handover triggering
SG185139A1 (en) * 2001-06-13 2012-11-29 Ipr Licensing Inc Transmittal of heartbeat signal at a lower level than heartbeat request
US6983166B2 (en) * 2001-08-20 2006-01-03 Qualcomm, Incorporated Power control for a channel with multiple formats in a communication system
US20030072279A1 (en) * 2001-10-15 2003-04-17 Nokia Corpration Power control during compressed mode
RU2287902C2 (en) * 2001-11-16 2006-11-20 Эл Джи Электроникс Инк. Power control data transfer method for shared high-speed control channel in mobile communication system
KR100811043B1 (en) 2001-11-16 2008-03-06 엘지전자 주식회사 method for controlling transmission power of SCH and HI in mobile communication
FR2838279B1 (en) * 2002-04-05 2004-09-24 Nortel Networks Ltd METHOD OF CONTROL OF RADIO RESOURCES ASSIGNED TO A COMMUNICATION BETWEEN A MOBILE TERMINAL AND A CELLULAR INFRASTRUCTURE, AND EQUIPMENT FOR IMPLEMENTING THIS PROCESS
US6717927B2 (en) * 2002-04-05 2004-04-06 Interdigital Technology Corporation System for efficient recovery of node B buffered data following serving high speed downlink shared channel cell change
TW200420163A (en) * 2002-04-05 2004-10-01 Interdigital Tech Corp Node B and RNC actions during a serving HSDPA cell change
TW201002122A (en) * 2002-04-12 2010-01-01 Interdigital Tech Corp Access burst detector correlator pool
KR100721787B1 (en) * 2002-05-09 2007-05-25 노키아 코포레이션 HSDPA CQI, ACK, NACK power offset known in node B and in SRNC
KR100891816B1 (en) * 2002-05-11 2009-04-07 삼성전자주식회사 Method for transmitting information of power offset of high speed physical downlink shared channel for high speed downlink packet access in wcdma communication system
US6850771B2 (en) 2002-06-24 2005-02-01 Qualcomm Incorporated Uplink power control
US7706405B2 (en) * 2002-09-12 2010-04-27 Interdigital Technology Corporation System for efficient recovery of Node-B buffered data following MAC layer reset
US7423976B2 (en) * 2002-09-24 2008-09-09 Interdigital Technology Corporation Block error rate estimate reporting for target signal to interference ratio adjustment
US7215929B2 (en) * 2002-10-08 2007-05-08 Nokia Corporation Method and apparatus for maintaining desired link quality when no data is transmitted on transport channels having quality targets
JP2004207840A (en) * 2002-12-24 2004-07-22 Nec Corp Method of managing radio resource, managing apparatus used therefor, base station and terminal
US7010329B2 (en) * 2003-03-11 2006-03-07 Interdigital Technology Corp. System and method for battery conservation with assistance from the network and radio resource management
JP4197266B2 (en) * 2003-04-10 2008-12-17 株式会社エヌ・ティ・ティ・ドコモ Radio control apparatus and handover control method
US6879829B2 (en) * 2003-05-16 2005-04-12 Mobile Satellite Ventures, Lp Systems and methods for handover between space based and terrestrial radioterminal communications, and for monitoring terrestrially reused satellite frequencies at a radioterminal to reduce potential interference
US7392055B2 (en) * 2003-06-23 2008-06-24 Lucent Technologies Inc. Method for allocating resources in a wireless data system based on system loading
KR20140072137A (en) * 2003-07-17 2014-06-12 인터디지탈 테크날러지 코포레이션 Signaling method for wlan network control
JP4175510B2 (en) * 2003-08-29 2008-11-05 ソニー・エリクソン・モバイルコミュニケーションズ株式会社 Mobile terminal, wireless relay device, mobile communication system
KR100560845B1 (en) * 2003-10-09 2006-03-13 에스케이 텔레콤주식회사 Method for Modem Switching for use with MM-MB Terminal
FI20040865A0 (en) * 2004-06-21 2004-06-21 Nokia Corp Communication in a telecommunication system
US20070183388A1 (en) * 2005-04-25 2007-08-09 Volker Breuer Method for performing measurements by a mobile station of a radio-communication system, corresponding mobile station, and unit for a radio-communication system
US8200230B2 (en) * 2005-06-15 2012-06-12 Telefonaktiebolaget Lm Ericsson (Publ) Method and means for reducing interference peaks during soft handover
JP4593396B2 (en) * 2005-08-02 2010-12-08 株式会社日立製作所 Mobile communication system
US7826837B1 (en) * 2005-08-05 2010-11-02 Verizon Services Corp. Systems and methods for tracking signal strength in wireless networks
US7738903B2 (en) * 2005-08-16 2010-06-15 Telefonaktiebolaget Lm Ericsson (Publ) Transmit power initialization for secondary reverse link carriers in a wireless communication network
JP4761890B2 (en) * 2005-08-23 2011-08-31 株式会社エヌ・ティ・ティ・ドコモ Transmission rate control method, radio base station, and radio network controller
EP1781056A1 (en) * 2005-10-25 2007-05-02 Siemens Aktiengesellschaft Intra-frequency and inter-frequency measurements in a radio communication system
WO2007130746A2 (en) * 2006-03-28 2007-11-15 The Board Of Governors For Higher Education, State Of Rhode Island And Providence Plantations Systems and methods for distance estimation between electronic devices
GB2437343B (en) * 2006-04-21 2008-04-23 Motorola Inc Handover between radio networks
KR101221908B1 (en) * 2006-09-04 2013-01-15 엘지전자 주식회사 Method of executing hand-over and Mobile Station implementing the same
JP4860381B2 (en) * 2006-07-10 2012-01-25 日本電気通信システム株式会社 Wireless communication system, system control apparatus, wireless base station, wireless communication terminal, communication control method, and communication control program
GB2440577B (en) * 2006-07-28 2011-06-29 Nec Technologies Trigger of inter-frequency measurements within mobile radio communications device
US9072009B1 (en) 2006-09-15 2015-06-30 Sprint Spectrum L.P. Carrier selection based on probable mobility of packet flow
WO2008063109A1 (en) * 2006-11-20 2008-05-29 Telefonaktiebolaget Lm Ericsson (Publ) Scenario based measurement type selection
US8503403B2 (en) * 2006-12-21 2013-08-06 Sony Corporation Network control of uplink transmit timing for compressed mode
WO2008117203A2 (en) * 2007-03-28 2008-10-02 Nxp B.V. Wireless transmission power control method and system
JP5145852B2 (en) * 2007-10-15 2013-02-20 日本電気株式会社 Coefficient determination device, radio communication system, coefficient determination method, and coefficient determination program
EP2321994B1 (en) * 2008-03-13 2016-02-24 Telefonaktiebolaget LM Ericsson (publ) Quality based handover procedure between co-located cells
US8412252B2 (en) * 2009-12-31 2013-04-02 Samsung Electronics Co., Ltd. System and method using rate split scheme based on cooperation between receivers
JP2011199498A (en) * 2010-03-18 2011-10-06 Fujitsu Ltd Base station device and communication method
US8917700B2 (en) 2010-09-17 2014-12-23 Qualcomm Incorporated Method and apparatus for interference mitigation in wireless networks
US8521168B1 (en) * 2011-04-13 2013-08-27 Sprint Spectrum L.P. Resource allocation based on wireless device motion specified in connection request
JP5726717B2 (en) * 2011-12-09 2015-06-03 株式会社Ｎｔｔドコモ Radio base station and radio system transition control method
EP2897425B1 (en) * 2012-09-13 2016-11-23 Fujitsu Limited Wireless base station device, and communication method for controlling downlink power when a victim terminal is detected
US9625497B2 (en) 2013-04-26 2017-04-18 Telefonaktiebolaget Lm Ericsson (Publ) Predicting a network performance measurement from historic and recent data
US9414301B2 (en) * 2013-04-26 2016-08-09 Telefonaktiebolaget Lm Ericsson (Publ) Network access selection between access networks
KR20150012705A (en) * 2013-07-26 2015-02-04 주식회사 팬택 Apparatus and method for saving current in terminal
US9629055B2 (en) * 2014-11-09 2017-04-18 Comsats Institute Of Information Technology System and method for uninterrupted communication across black spots for multi interface mobile nodes
CN110545547B (en) * 2018-05-29 2020-11-27 中国移动通信有限公司研究院 Measuring method, device, terminal, network side equipment and storage medium
US20230156545A1 (en) * 2021-11-15 2023-05-18 Motorola Solutions, Inc. System and method for dynamic optimization of radio access network site

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999043178A1 (en) * 1998-02-17 1999-08-26 Nokia Networks Oy Measurement reporting in a telecommunication system

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5526404A (en) * 1991-10-10 1996-06-11 Space Systems/Loral, Inc. Worldwide satellite telephone system and a network coordinating gateway for allocating satellite and terrestrial gateway resources
US5594718A (en) * 1995-03-30 1997-01-14 Qualcomm Incorporated Method and apparatus for providing mobile unit assisted hard handoff from a CDMA communication system to an alternative access communication system
DE69626294T2 (en) * 1995-10-17 2003-11-13 Ericsson Telefon Ab L M METHOD FOR CONNECTING AND NETWORK CHANGING IN A RADIO TRANSMISSION ENVIRONMENT
US5940762A (en) * 1996-05-01 1999-08-17 Lee; Kuo-Chun Inter-system calling supporting inter-system soft handoff
US5828661A (en) * 1996-05-22 1998-10-27 Qualcomm Incorporated Method and apparatus for providing a cone of silence in a cellular communication system
US5848063A (en) * 1996-05-23 1998-12-08 Qualcomm Incorporated Method and apparatus for hard handoff in a CDMA system
US6069880A (en) * 1997-05-19 2000-05-30 Qualcomm Incorporated Method and apparatus for scanning other frequency pilot signals in a code division multiple access communication system
US6128506A (en) * 1997-09-24 2000-10-03 Telefonaktiebolaget Lm Ericsson Integrated power control and congestion control in a communication system
GB2337413A (en) * 1998-05-15 1999-11-17 Nokia Mobile Phones Ltd alternative Channel Measurement in a Radio Communication system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999043178A1 (en) * 1998-02-17 1999-08-26 Nokia Networks Oy Measurement reporting in a telecommunication system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100568825C (en) * 2002-07-22 2009-12-09 意大利电信股份公司 Monitor service method for quality, system and assembly and computer product in the telecommunications network
WO2007110746A3 (en) * 2006-03-27 2008-01-10 Nokia Corp Apparatus, method and computer program product providing 3.9g mobile-assisted cell change
US8000707B2 (en) 2006-03-27 2011-08-16 Nokia Corporation Apparatus, method and computer program product providing 3.9G mobile-assisted cell change

Also Published As

Publication number Publication date
DE60033406D1 (en) 2007-03-29
CN1185901C (en) 2005-01-19
AU764548B2 (en) 2003-08-21
US6567670B1 (en) 2003-05-20
AU6441800A (en) 2001-03-26
EP1208711A1 (en) 2002-05-29
ES2279765T3 (en) 2007-09-01
KR100729020B1 (en) 2007-06-14
ATE354265T1 (en) 2007-03-15
TW477126B (en) 2002-02-21
KR20020030799A (en) 2002-04-25
AR025473A1 (en) 2002-11-27
CN1371586A (en) 2002-09-25
EP1208711B1 (en) 2007-02-14
EP1081977A1 (en) 2001-03-07
DE60033406T2 (en) 2007-11-29

Similar Documents

Publication Publication Date Title
WO2001017306A1 (en) Subscriber station, network control means and method for triggering inter-frequency measurements in a mobile communication system
AU766725B2 (en) Subscriber station, network control means and method for carrying out inter-frequency measurements in a mobile communication system
KR100691555B1 (en) Downlink power control with limit to dynamic range using detection of downlink transmit power
US6490461B1 (en) Power control based on combined quality estimates
KR101046321B1 (en) Outer loop power control method in wireless communication system
EP1072162B1 (en) Method and apparatus for power control in a mobile telecommunication system
EP1206891B1 (en) Subscriber station and method for carrying out inter-frequency measurements in a mobile communication system
MXPA02011087A (en) Power control in radio system.
US20060229025A1 (en) Method for extracting optimal reverse link capacity by scaling reverse link Eb/No setpoint based on aggregate channel load and condition
US20030156554A1 (en) Method for regulating transmission power in a radiocommunications system
CA2387167C (en) Method and arrangement for controlling transmission power and a network element
EP1261145B1 (en) Downlink transmission power control
EP1134911A1 (en) Operating a cellular telecommunication system

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AL AM AT AU AZ BA BB BG BR BY CA CH CN CR CU CZ DE DK DM EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
WWE Wipo information: entry into national phase

Ref document number: 2000951507

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 64418/00

Country of ref document: AU

Ref document number: 008122539

Country of ref document: CN

Ref document number: 1020027002777

Country of ref document: KR

WWP Wipo information: published in national office

Ref document number: 1020027002777

Country of ref document: KR

WWP Wipo information: published in national office

Ref document number: 2000951507

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWG Wipo information: grant in national office

Ref document number: 64418/00

Country of ref document: AU

NENP Non-entry into the national phase

Ref country code: JP

WWG Wipo information: grant in national office

Ref document number: 2000951507

Country of ref document: EP