WO2006064411A2 - Power control method and apparatus for p2p communication - Google Patents
Power control method and apparatus for p2p communication Download PDFInfo
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- WO2006064411A2 WO2006064411A2 PCT/IB2005/054092 IB2005054092W WO2006064411A2 WO 2006064411 A2 WO2006064411 A2 WO 2006064411A2 IB 2005054092 W IB2005054092 W IB 2005054092W WO 2006064411 A2 WO2006064411 A2 WO 2006064411A2
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- 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
- H04W52/32—TPC of broadcast or control channels
- H04W52/325—Power control of control or pilot channels
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- 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
- H04W52/383—TPC being performed in particular situations power control in peer-to-peer links
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Abstract
A power control method for P2P communication to be executed by a UE is provided, comprising the steps of: (a) receiving P2P signals transmitted via P2P direct link from another UE and control signals transmitted via control downlink from a network system; (b) determining the UE's transmission power according to the TPC command included in the P2P signals and the TPC command included in the control signals.
Description
POWER CONTROL METHOD AND APPARATUS FOR P2P COMMUNICATION
FIELD OF THE INVENTION
The present invention relates generally to P2P communication in wireless communication, and more particularly, to a power control method and apparatus for use in
P2P communication.
BACKGROUND OF THE INVENTION
In a CDMA system, UEs (User Equipments) transmit signals with their respective spreading code assigned, occupying the same bandwidth and frequency. Due to continuous change of the mobile user's location and the existence of deep fading, user's signals with high power will suppress those with lower power, which is the so-called near-far effect, thus causing the system performance deteriorated seriously.
Power control approach is very effective in solving near-far effect. Power control generally consists of open-loop power control and closed-loop power control, wherein closed-loop power control usually includes two aspects. On the one hand, one party of a communication can determine a TPC (Transmission power Control) command according to the strength of the received radio signals from the other party of the communication, and feeds the TPC command back to the other party, so that the other party adjusts its transmission power based on the TPC command; on the other hand, the party of the communication can adjust its own transmission power according to the received TPC command from the other party of the communication.
In a conventional TD-SCDMA system as shown in Fig.l, UEl and UE2 communicate with each other through UTRAN (Universal Terrestrial Radio Access Network) consisting of a base station transceiver (Node B) and a RNC (radio network controller). According to the strength of the traffic signals transmitted over the traffic link between UTRAN and UEl and that between UTRAN and UE2, closed-loop power control can be performed between UTRAN and UEl and between UTRAN and UE2 respectively, wherein the position of the TPC command in a timeslot (i.e. traffic burst) can be referred to Fig.2.
However, in the case where UEl and UE2 are very close to each other and adopt P2P communication mode (P2P communication is a peer-to-peer direct communication where
signals are not forwarded through base stations) as shown in Fig.3, since there no longer exists traffic link between the UE and UTRAN, transmission power can't be adjusted according to conventional closed-loop power control mode when UTRAN and each UE respectively transmit control messages through the control link as represented by the dashed line.
By overhearing the channel impulse response of the midamble on the bi-directional direct link between two UEs, i.e. the P2P traffic link as represented by the solid line in Fig.3, UTRAN can send power control information to UEl and UE2 via the corresponding downlink control link respectively so that each UE adjusts its transmission power for sending signals to the base station according to the received power control information.
However, it still remains a problem to be solved as how the base station adjusts the power for transmitting control signals, that is, how the UE feeds back to the UTRAN the power control information for the base station to adjust transmission power, in the case where there is no traffic link between UTRAN and a UE. Further, as to the traffic link between UEl and UE2, one party of the communication such as UEl, can determine the TPC command according to the strength of the P2P traffic signals sent over the traffic link and transmit it to the other party of the communication (like UE2) in the P2P timeslot via the traffic link so that the other party (like UE2) can adjust its transmission power timely. However, when the traffic data transmission breaks, for example, one party of the communication keeps in data reception state without sending data, then, the other party of communication can't determine the TPC command due to failing to receive the traffic data of its peer if traffic signals are transmitted in encapsulated packets. In conventional communication mode, when the traffic data transmission between one party of the UEs and the base station breaks, the other party can determine TPC command with help of the CIR (Channel Impulse Response) of BCH (Broadcast Channel); while in P2P communication mode, since there is no BCH between UEl and UE2, TPC command can't be determined as in conventional mode when the traffic data transmission of P2P communication breaks.
Moreover, in a subframe, it's very likely that a UE in P2P communication mode receives the power control information from UTRAN in one receiving timeslot and receives the power control information from its peer UE of P2P communication in another receiving timeslot (a subframe includes 7 timeslots in TD-SCDMA system). When the UE transmits P2P traffic data to its peer UE of P2P communication and control signals to the
base station respectively, it should adopt the corresponding transmission power to transmit signals in the timeslot for sending P2P traffic data and that for sending control signals respectively according to the power control information from UTRAN and that from its peer UE of P2P communication. However, if the UE transmits control signals and P2P traffic data in the same subframe, since the timeslot interval is very short, it would be very difficult for the UE to adjust transmission power correspondingly in such a short time. Furthermore, even if transmission power can be shifted fast, sudden change of the UE's transmission power within a short time should be avoided as much as possible.
Based on the above analysis, it's necessary to put forward a complete P2P power control scheme for the P2P communication performance to satisfy the QoS (Quality of
Service) requirement, so as to guarantee that the UE can receive desirable P2P signals and control signals from the base station and interference to the system won't be brought either.
OBJECT AND SUMMARY OF THE INVENTION An object of the present invention is to provide a P2P power control method and apparatus, with which a UE can get an improved power control scheme.
To fulfill the above objects, it's provided in the present invention with a power control method for P2P communication to be executed by a UE, comprising the steps of: receiving P2P signals transmitted via P2P direct link from another UE and control signals transmitted via control downlink from a network system; determining the UE's transmission power according to the TPC command included in the P2P signals and the TPC command included in the control signals.
It's provided in the present invention with a power control method for P2P communication to be executed by a network system, comprising the steps of: transmitting a common control message to a UE in P2P communication via the control downlink; detecting whether it can receive within a predefined time period a response message sent from the UE after the common control message is received; increasing the transmission power for sending signals to the UE if the response message is not received within the predefined time period.
It's provided in the present invention with a UE, comprising: a receiving unit, for receiving P2P signals transmitted via P2P direct link from another UE and control signals
transmitted via control downlink from a network system; an adjusting unit, for determining the UE' s transmission power according to the TPC command included in the P2P signals and the TPC command included in the control signals.
It's provided in the present invention with a network system, comprising: a transmitting unit, for sending a common control message to a UE in P2P communication via a control downlink; a detecting unit, for detecting whether it can receive within a predefined time period a response message sent from the UE after the common control message is received; an adjusting unit, for increasing the transmission power for sending signals to the UE if the response message is not received within the predefined time period. Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS The invention is explained in further detail, and by way of example, with reference to the accompanying drawings wherein:
Fig.l illustrates a diagram of a TD-SCDMA system adopting conventional communication mode;
Fig.2 illustrates the structure of the timeslot for transmitting TPC command in TD- SCDMA system in conventional communication mode;
Fig.3 illustrates a diagram of a TD-SCDMA system adopting P2P communication mode;
Fig.4 illustrates a diagram of the power control method for P2P direct link and control link in accordance with an embodiment of the present invention; Fig.5 illustrates the flowchart of the power control for P2P direct link during traffic data transfer;
Fig.6 illustrates the flowchart of the power control for P2P direct link during traffic data interruption in accordance with an embodiment of the present invention;
Fig.7 illustrates the flowchart of the P2P power control for control downlink between UTRAN and UE in accordance with an embodiment of the present invention;
Fig.8 illustrates the structure of the traffic timeslot in accordance with an embodiment of the present invention;
Fig.9 illustrates the flowchart of the procedure for P2P power adjustment to be executed by a UE in P2P communication in accordance with an embodiment of the present invention;
Fig.10 illustrates the architectures of the UE and network system for performing the power control method in the present invention.
Throughout the drawings, the same reference numerals indicate similar or corresponding features or functions.
DETAILED DESCRIPTION OF THE INVENTION According to the power control method in P2P communication mode as provided in the present invention, when a UE in P2P communication receives the TPC command transmitted over P2P direct link from its peer UE in the P2P communication, if at the same time the UE also receives the TPC command transmitted over control downlink from the network side, it will give full considerations to the performance requirements of the two communication links and determine its transmission power according to the TPC command from its peer UE and that from the network side.
As shown in Fig.4, the power control procedure in P2P communication mode can be classified into two power control procedures for P2P direct link and for control link, wherein the power control procedure for P2P direct link has two cases during traffic data transfer and traffic data interruption, and the power control procedure for control link has two cases for control uplink and downlink.
In the following section, descriptions are given first to how to determine the TPC command in the power control procedure for P2P direct link in conjunction with accompanying drawings, then to the power control procedures for control uplink and downlink with reference to specific embodiments, and in the last to the P2P power control procedure when the UE gives full considerations to the TPC command sent from its peer UE and that from the network side respectively.
Power control for P2P direct link Referring to the P2P communication mode in Fig.4, traffic data is transmitted over the P2P direct link established between UEl and UE2. The dedicated channel formed between UEl and UE2 is also called P2P-DCH (P2P-Dedicated Channel).
Fig.5 illustrates the power control procedure for P2P direct link. As shown in Fig.5, during traffic data transmission, UEl sends traffic data to UE2 via P2P direct link (step SI lO), wherein the information about the transmission power used by UEl is also encapsulated into the traffic data transmitted. After receiving the traffic data sent by UEl, UE2 detects the receiving power of the traffic data and extracts the transmission power used by UEl from the received traffic data. Then, based on the detected receiving power and the extracted transmission power, UE2 computes actual SIR SIRUE1 Actual in dB (step
S120). Then, UE2 reads target SIR (Signal-to-Interference Ratio) SIRUE1 τ∞%et transmitted via control link from the base station in advance, wherein SIRUE1 Tmget is set by UTRAN according to the current operation condition of the network or the distance between UEl and UE2 (step S130), and compares SIRUE1 Actual with SIRUE1 Tw%et to determine the TPC command for adjusting UEl 's transmission power. Specifically, if
SIRuEi Actual < ^^uEi Tmgef TPC = 1, and it indicates UEl to increase the transmission power by a step, wherein TPC is for adjusting UEl 's transmission power; otherwise TPC = -1, and it indicates UEl to decrease the transmission power by a step (step S 140).
Afterwards, UE2 inserts the determined TPC command into the traffic burst shown in
Fig.2 and sends it to UEl along with the traffic data (step S 150).
During traffic data transmission, UEl and UE2 in P2P communication mode repeat steps SI lO to Sl 50, to indicate the peer UE to adjust its transmission power. Descriptions as how to realize P2P power control method on the direct link for P2P communication are disclosed in the PCT patent application filed by KONINKLIJKE PHILIPS
ELECTRONICS N.V. on February 24, 2004, Publication No. WO 04/080103 (Philips internal reference No. PHCN030003WO), and incorporated herein as reference.
However, when traffic data transmission breaks, traffic data can't be received, so the UE can't determine the TPC command for power control according to the detected signal strength of the traffic data. At this time, power control for P2P link can't be implemented using the power control method as shown in Fig.5.
It is, therefore, provided in the present invention with another power control method to determine TPC command during P2P traffic data interruption through detecting the channel impulse response of the midamble, that is, replacing the receiving power of the traffic data with the receiving power of the detected midamble, which can be referred to
Fig.6.
As shown in Fig.6, before P2P direct link is established between UEl and UE2, UTRAN first allocates midamble to the P2P direct link, i.e. UE1→UE2 and UEl <— UE2 (step S210). After a P2P direct link is established between UEl and UE2, UEl and UE2 still keep transmitting midamble to their peer UE over the P2P direct link even during traffic data interruption (step S220), wherein the transmission power used for transmitting midamble is also encapsulated in the timeslot structure transmitted. For example, when UEl is during traffic data interruption, UE2 detects the strength of the channel impulse response generated from the midamble sent by UEl via UE1 —UE2 link, to get the midamble's total receiving power Itotaι and extract the transmission power PUEl_>UE2 Mid with which UEl transmits the midamble from the received timeslot structure (step S230).
Since the midamble experiences the same channel as the traffic data, the midamble experiences the same path loss too, thus the receiving power of the received midamble is equal to that of the traffic data. The actual SIR SIRUEl Actual (in dB) of the received signals during traffic data interruption can be computed according to the following equation (step S240):
C TD P UE1->UE2 _Mid — T * CZ7 /i \
^1KUE\_ Actual = ~ -T^ ^TT ^ (1J
* total \ "ι UEl->UE2_Mid ^) where in equation (1), PUEl_>UE2 Mid (m dBm) is the transmission power with which
UEl transmits midamble, L (in dBm) is the path-loss of the midamble received by UE2, Itotal (in dBm) is the total receiving power of the midamble detected by UE2, and SF is Spread Factor.
Next, after SIRum Actual is computed, UE2 reads the target SIR SIRUEl rarge, transmitted via control link from the base station in advance (step S250) and compares SlRUEl_Actuaι with SIRUE1_Tmget . If SlRUEl_Actual < SIRUE1_Tmget , TPC = 1, indicating UEl to increase the transmission power by a step; otherwise TPC = -1, indicating UEl to decrease the transmission power by a step (step S140). Afterwards, UE2 inserts the determined TPC command into the timeslot structure and sends it to UEl (step S260).
In determination of the TPC command as shown in Fig.6, since traffic data can't be transmitted during traffic data interruption, the target SIR set by UTRAN can be lower than the target SIR during traffic data transmission. Performing power control during
traffic data interruption is beneficial to adjusting the UE's transmission power to a suitable value quickly when traffic data transmission is resumed.
According to the methods as shown in Fig.5 and Fig.6, the UE can determine the
TPC command according to the SIR of the received signals and inserts it into the timeslot structure to send it to the peer UE for indicating the peer UE to adjust transmission power whether during traffic data interruption or during traffic data transmission, thus the performance of P2P communication can be guaranteed.
Power control of control link By overhearing the channel impulse response of the midamble on the bi-directional direct link between UEl and UE2, UTRAN can send control information to UEl and UE2 respectively via the corresponding control downlink such as paging control channel, so that UEl and UE2 each can adjust its power to send control signals to the base station according to the received power control information. When failing to overhear the channel impulse response of the midamble on the direct link from UEl and/or UE2, UTRAN sends a TPC command to UEl and/or UE2 via paging control channel to indicate UEl and/or UE2 to increase transmission power.
As to the P2P power control method for control uplink in P2P communication, full descriptions are given in the PCT patent application filed by KONINKLIJKE PHILIPS ELECTRONICS N. V. on March 1 , 2004, Publication No. WO 04/077919 (Philips internal reference No. PHCN030004WO), and incorporated herein as reference.
But in P2P communication, the transmission power of UTRAN needs timely adjustment according to the movements of UEl and UE2 to ensure that UEl and UE2 can receive the control signals including power control information sent from UTRAN via control downlink, so it's provided in the present invention with a power control method for use in control downlink.
Since PICH (Paging Indicator Channel) and PCH (paging channel) are common control channels and are usually within P-CCPCH (Primary-Common Control Physical Channel) and S-CCPCH (Secondary-Common Control Physical Channel), a UE in a P2P- enabled TD-SCDMA communication system can perform power control for UTRAN-UE downlink by using the common control information read from PICH and/or PCH.
Fig.7 illustrates the power control procedure for UTRAN-UE downlink as provided in the present invention. As shown in Fig.7, first, UTRAN resets a built-in timer therein
(step S405). Then, UTRAN broadcasts information periodically to UEs in the cell over PICH or PCH (step S406). According to the predefined time interval, a UE reads the information transmitted via CCPCH (step S410) and determines whether the information of PICH or PCH is included in the information transmitted via the CCPCH (step S420). If there is no information of PICH or PCH, it means that the UE can't receive the information of the channel, so the UE keeps reading information over CCPCH. If information of PICH or PCH is included, the UE sends a response message to UTRAN (step S430).
Here, the UE can send the response message via P2P direct link, but the response message must be set in a position, data field 1 as shown in Fig.8 for example, which is different from that of the TPC command sent by the UE to the peer UE, so that the response message can be detected by UTRAN who keeps overhearing the P2P direct link. The UE can also send the response message in the P2P communication timeslot via P2P direct link like sending midamble so that the response message can be detected by UTRAN who keeps overhearing the P2P direct link. Alternatively, the UE can send the response message in the uplink timeslot to UTRAN via control uplink.
UTRAN detects the information sent by the UE, for example, overhears information on the P2P direct link (step S470) and determines whether the response message from the UE can be received within a predefined time period (step S480). If the UTRAN fails to receive the response message from the UE, it increases the timer by l(step S485) and checks whether the timer expires (step S490). If the timer doesn't expire, UTRAN assumes that the response message is not received due to fluctuations in radio signals, thus the transmission power needs no adjustment and UTRAN keeps broadcasting information over PICH or PCH. If the timer expires, UTRAN increases the transmission power by a step (step S495), and then keeps sending signals to the UE over PICH or PCH with the increased transmission power after the timer is reset.
With reference to the procedure as shown in Fig.8, UTRAN adjusts its transmission power so as to ensure that the UE can receive control signals from UTRAN.
Power control based on traffic link and control link
Descriptions are given above to the power control procedures for P2P direct link and control uplink and downlink in TD-SCDMA system after P2P communication mode is introduced.
According to the above power control procedure, if a UE like UEl receives the TPC command transmitted via P2P direct link from UE2 and the TPC command transmitted via control downlink from UTRAN and the two TPC commands happen to be used respectively for adjusting the power for sending P2P signals to UE2 and that for sending control signals to UTRAN in the same subframe, it will take the two TPC commands into full considerations to determine the power for transmitting signals.
Fig.9 illustrates the power adjustment procedure to be executed by UEl performing P2P communication. As shown in Fig.9, after initialization (step S500), UEl and UE2 establish P2P communication (step S510). Then, UEl will receive the TPC command transmitted via P2P direct link from UE2 and the TPC command transmitted via control link from UTRAN respectively (step S520), wherein the TPC command sent from UE2 can be determined by UE2 according to the receiving power of the traffic data from UEl with the method as shown in Fig.5 during traffic data transmission, or according to the receiving power of the midamble from UEl with the method as shown in Fig.6 during traffic data interruption.
If the TPC command from UE2 indicates transmission power increase while the TPC command from UTRAN indicates transmission power decrease or the TPC command from UE2 indicates transmission power decrease while the TPC command from UTRAN indicates transmission power increase or the two TPC commands both indicate transmission power increase, UEl will use the increased transmission power to transmit traffic data and control signals respectively in the corresponding timeslot in the subframe to ensure that P2P direct link and control link can both satisfy the QoS requirements.
Only when the two TPC commands both indicate transmission power decrease, UEl decreases the transmission power by a step, and uses the decreased transmission power to transmit traffic data and control signals respectively in the corresponding timeslot in the subframe (step S530).
According to the power control procedure as shown in Fig.9, the UE's power consumption won't increase and its interference to other UEs won't come, because the UE performs closed-loop power control on both P2P direct link and control uplink and the frequency at which the UE transmits P2P signals is much more higher than that for transmitting control signals (for example, the transmission cycle for traffic data is usually 5ms while that for control signals can be set to 3000ms). Therefore, even if a UE camping on the border of a cell transmits the traffic data with a higher transmission power in a
subframe according to the TPC command from UTRAN, UEl can still decrease the transmission power to a suitable value for P2P communication quickly according to the TPC command from UE2 in the subsequent subframe, thus it won't produce interference to other communicating UEs in the cell and won't consume much power either.
As to the above power control method for P2P communication as provided in the present invention, it can be implemented in software or hardware, or in combination of both.
Fig.10 illustrates the configurations of the network system and UE according to an embodiment of the present invention when the above power control method for P2P communication is implemented in hardware, wherein the components same as those in conventional network system and UE are not given herein.
As shown in Fig.10, for a UE like UEl in P2P communication mode, when receiving unit 10 receives P2P signals transmitted via P2P direct link from another UE like UE2 and control signals transmitted via control downlink from a network system like UTRAN, adjusting unit 20 determines the UE' s transmission power according to the TPC command included in the P2P signals and the TPC command included in the control signals.
Specifically, if the TPC command from UE2 indicates transmission power increase while the TPC command from UTRAN indicates transmission power decrease or the TPC command from UE2 indicates transmission power decrease while the TPC command from
UTRAN indicates transmission power increase or the two TPC commands both indicate transmission power increase, UEl will use the increased transmission power to transmit traffic data and control signals respectively, so as to ensure that P2P direct link and control link can both satisfy the QoS requirements.
Only when the two TPC commands both indicate transmission power decrease, UEl decreases the transmission power by a step, and uses the decreased transmission power to transmit traffic data and control signals respectively.
The UE further comprises a detecting unit 30, for detecting the power of the midamble from another UE when the P2P signals transmission from said another UE breaks; a computing unit 40, for computing the SIR of the midamble according to the detected power; a generating unit 50, for generating the TPC command to control the
transmission power of said another UE according to the computed SIR and a target SIR; and a transmitting unit 60, for transmitting the generated TPC command to said another UE.
The detecting unit 30 in the UE is also used for detecting whether the common control information transmitted via control downlink from the network system is received, and transmitting a response message to the network system through transmitting unit 60 over any one of control uplink and P2P direct link when detecting the common control information, so that the network system can determine whether to adjust its transmission power or not. Wherein, if the UE transmits the response message over P2P direct link, the response message is set at the position for identifying the power control information of the network system in the traffic burst sent from the UE to another UE, for example the corresponding position in data field 1 as shown in Fig.8, so as to differ from the TPC command for adjusting the transmission power of said another UE sent from the UE to said another UE. The network system 100 in Fig.10 comprises a transmitting unit 110, for sending common control messages to a UE in P2P communication via a control downlink such as paging channel or paging control channel; a detecting unit 120, for detecting whether it can receive a response message sent from the UE within a predefined time period; an adjusting unit 130, for increasing the transmission power for transmitting signals to the UE when the response message is not received within the predefined time period.
Beneficial Use of the Invention
With reference to the detailed descriptions to the present invention taken in conjunction with accompanying drawings, it can be seen that the present invention gives full considerations to the QoS requirements for two communication links of P2P direct link and control link and determines the UE' s transmission power according to the TPC command from the peer UE and that from the network side. Consequently, according to the power control method of the present invention, the P2P communication between two UEs and the communication on conventional control link between each UE and UTRAN can both satisfy the QoS requirements.
Moreover, according to the method for determining TPC command through detecting the strength of the midamble over P2P direct link during P2P traffic data interruption as
provided in the present invention, the UE' s transmission power can still be kept within a rational range during traffic data interruption, thus the UE can adjust the transmission power to a suitable value when the traffic data transmission resumes.
Further, according to the method for UTRAN to adjust its transmission power through detecting the response message from the UE as provided in the present invention, the performance of the UTRAN-UE downlink can be guaranteed.
Those skilled in the art will appreciate that various change and modification can be made on the proposed P2P power control method and apparatus in light of foregoing description while remaining within the scope of the appended claims. The remarks made herein before demonstrate that the detailed description with reference to the drawings, illustrate rather than limit the invention. There are numerous alternatives, which fall within the scope of the appended claims. The word "comprising" does not exclude the presence of other elements or steps than those listed in a claim. The word "a" or "an" preceding an element or step does not exclude the presence of a plurality of such elements or steps.
Claims
1. A power control method for P2P communication to be executed by a user equipment, comprising the steps of: (a) receiving P2P signals transmitted via P2P direct link from another user equipment and control signals transmitted via control downlink from a network system; (b) determining user equipment's transmission power according to transmission power control command included in the P2P signals and the transmission power control command included in the control signals.
2. The power control method according to claim 1, wherein said step (b) comprises: increasing the user equipment' s transmission power if at least one of the transmission power control command included in said P2P signals and the transmission power control command included in said control signals is an indication for increasing transmission power.
3. The power control method according to claim 2, wherein said step (b) comprises: decreasing the user equipment's transmission power if the transmission power control command included in said P2P signals and the transmission power control command included in said control signals are both indications for decreasing transmission power.
4. The power control method according to any one of claims 1 to 3, wherein if said P2P signal transmission from said another user equipment breaks, the method further comprises: detecting power of a midamble from said another user equipment; computing SIR of said midamble according to the detected power; generating the transmission power control command for controlling the transmission power of said another user equipment according to the computed SIR and a target SIR; transmitting the generated transmission power control command to said another user equipment.
5. The power control method according to claim 4, wherein said target SIR during said P2P signal transmission interruption is allowed to be lower than the target SIR during said P2P signal transmission.
6. The power control method according to claim 4, further comprising: detecting whether the information transmitted via said control downlink from said network system is received; transmitting a response message to said network system if the information is detected, so that said network system determines whether to adjust its transmission power or not.
7. The power control method according to claim 6, wherein said user equipment can transmit said response message through any one of said control uplink and said P2P direct link.
8. The power control method according to claim 7, wherein if said user equipment transmits said response message through said P2P direct link, said response message is set at a position for indicating the power control message of the network system in a traffic burst sent from the user equipment to said another user equipment.
9. The power control method according to claim 7, wherein if said user equipment transmits said response message through said P2P direct link, said user equipment transmits said response message when transmitting midamble to said another user equipment.
10. A power control method for P2P communication to be executed by a network system, comprising the steps of:
(a) sending a control message to a user equipment in P2P communication via the control downlink;
(b) detecting whether it can receive a response message, which is sent by the user equipment after the control message is received, within a predefined time period; (c) increasing transmission power of sending signals to the user equipment if the response message is not received within the predefined time period.
11. The power control method according to claim 10, wherein said response message from said user equipment can be transmitted to said network system through any one of said control uplink and P2P direct link.
12. The power control method according to claim 11, wherein if said response message is transmitted via said P2P direct link, said step (b) comprises: overhearing a traffic burst sent from said user equipment to said another user equipment via said P2P direct link; detecting whether said response message is included in the traffic burst within said predefined time period; wherein said response message is set at a position for indicating the power control information of the network system.
13. The power control method according to claim 11, wherein if said response message is transmitted via said P2P direct link, said step (b) comprises: overhearing midamble sent from said user equipment to said another user equipment via said P2P direct link; detecting whether said response message is sent together with said midamble within said predefined time period.
14. The power control method according to claim 10, wherein said control downlink is any one of paging channel and paging control channel.
15. A user equipment, comprising: a receiving unit, for receiving P2P signals transmitted via P2P direct link from another user equipment and control signals transmitted via control downlink from a network system; an adjusting unit, for determining user equipment's transmission power according to transmission power control command included in the P2P signals and the transmission power control command included in the control signals.
16. The user equipment according to claim 15, wherein said adjusting unit increases the user equipment's transmission power if at least one of the transmission power control command included in said P2P signals and the transmission power control command included in said control signals is an indication for increasing transmission power.
17. The user equipment according to claim 16, wherein said adjusting unit decreases the user equipment's transmission power if the transmission power control command included in said P2P signals and the transmission power control command included in said control signals are both indications for decreasing transmission power.
18. The user equipment according to any one of claims 15 to 17, further comprising: a detecting unit, for detecting the power of a midamble from said another user equipment when P2P signal transmission from said another user equipment breaks; a computing unit, for computing SIR of said midamble according to the detected power; a generating unit, for generating a transmission power control command for controlling the transmission power of said another user equipment according to the computed SIR and a target SIR; a transmitting unit, for transmitting the generated transmission power control command to said another user equipment.
19. The user equipment according to claim 18, wherein: said detecting unit detects whether the information transmitted via said control downlink from said network system is received; said transmitting unit transmits a response message to said network system when said detecting unit detects the information, so that said network system determines whether to adjust its transmission power or not.
20. The user equipment according to claim 19, wherein said user equipment can transmit said response message through any one of said control uplink and said P2P direct link.
21. The user equipment according to claim 20, wherein if said user equipment transmits said response message through said P2P direct link, said response message is set at a position for indicating the power control message of the network system in a traffic burst sent from the user equipment to another user equipment.
22. A network system, comprising: a transmitting unit, for sending a control message to a user equipment in P2P communication via a control downlink; a detecting unit, for detecting whether it can receive a response message, which is sent by the user equipment after the control message is received, within a predefined time period; an adjusting unit, for increasing transmission power for sending signals to the user equipment if the response message is not received within the predefined time period.
23. The network system according to claim 21, wherein said response message from said user equipment can be transmitted to said network system through any one of said control uplink and said P2P direct link.
24. The network system according to claim 22, wherein said control downlink is any one of paging channel and paging control channel.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200410082034.6 | 2004-12-17 | ||
| CN200410082034 | 2004-12-17 |
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| Publication Number | Publication Date |
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| WO2006064411A2 true WO2006064411A2 (en) | 2006-06-22 |
| WO2006064411A3 WO2006064411A3 (en) | 2006-11-02 |
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| Application Number | Title | Priority Date | Filing Date |
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| PCT/IB2005/054092 WO2006064411A2 (en) | 2004-12-17 | 2005-12-07 | Power control method and apparatus for p2p communication |
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