USRE40568E1 - Synchronization symbol structure using OFDM based transmission method - Google Patents

Synchronization symbol structure using OFDM based transmission method Download PDF

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USRE40568E1
USRE40568E1 US11/286,440 US28644005A USRE40568E US RE40568 E1 USRE40568 E1 US RE40568E1 US 28644005 A US28644005 A US 28644005A US RE40568 E USRE40568 E US RE40568E
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symbols
symbol sequence
subcarriers
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Ralf Böhnke
Thomas Dölle
Tino Puch
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Redwood Technologies LLC
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Sony Corp
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00Baseband systems
    • H04L25/02Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006Arrangements for removing intersymbol interference
    • H04L25/03343Arrangements at the transmitter end
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2602Signal structure
    • H04L27/261Details of reference signals
    • H04L27/2613Structure of the reference signals
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2614Peak power aspects
    • H04L27/262Reduction thereof by selection of pilot symbols
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00Arrangements affording multiple use of the transmission path
    • H04L5/0001Arrangements for dividing the transmission path
    • H04L5/0003Two-dimensional division
    • H04L5/0005Time-frequency
    • H04L5/0007Time-frequency the frequencies being orthogonal, e.g. OFDM(A), DMT
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00Arrangements affording multiple use of the transmission path
    • H04L5/003Arrangements for allocating sub-channels of the transmission path
    • H04L5/0042Arrangements for allocating sub-channels of the transmission path intra-user or intra-terminal allocation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2657Carrier synchronisation
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/26Systems using multi-frequency codes
    • H04L27/2601Multicarrier modulation systems
    • H04L27/2647Arrangements specific to the receiver only
    • H04L27/2655Synchronisation arrangements
    • H04L27/2662Symbol synchronisation

Definitions

  • the present invention relates to a method for generating synchronization bursts for OFDM transmission systems, a method for synchronizing wireless OFDM systems, an OFDM transmitter as well as to a mobile communications device comprising such a transmitter.
  • the present invention relates generally to the technical field of synchronizing wireless OFDM (orthogonal frequency division multiplexing) systems. Thereby it is known to use a synchronization burst constructed using especially designed OFDM symbols and time domain repetitions.
  • FIG. 6 shows the structure of the known synchronization field.
  • the synchronization field consists of so-called short symbols t 1 , t 2 , . . . t 6 and two long symbols T 1 , T 2 .
  • the short symbols t 1 , t 2 . . . t 6 are of interest.
  • FIG. 5 shows only the synchronization preamble structure as the structure of the following signal field indicating the type of baseband modulation and the coding rate as well as the structure of further following data fields are not of interest in view of the present invention. For further details reference is made to said prior art document.
  • the symbols t 1 , t 2 , t 3 , t 4 are generated by means of an OFDM modulation using selected subcarriers from the entire available subcarriers.
  • the symbols used for the OFDM modulation as well as the mapping to the selected subcarriers will now be explained with reference to FIG. 6 .
  • Each of the short OFDM symbols t 1 , . . . t 6 is generated by using 12 modulated subcarriers phase-modulated by the elements of the symbol alphabet:
  • the multiplication by a factor of ⁇ 2 is in order to normalize the average power of the resulting OFDM symbol.
  • T TSHORT1 is equal to nine 0.8 ⁇ sec periods, i.e. 7.2 ⁇ sec.
  • the way to implement the inverse Fourier transform is by an IFFT (Inverse Fast Fourier Transform) algorithm. If, for example, a 64 point IFFT is used, the coefficients 1 to 24 are mapped to same numbered IFFT inputs, while the coefficients ⁇ 24 to ⁇ 1 are copied into IFFT inputs 40 to 63. The rest of the inputs, 25 to 39 and the 0 (DC) input, are set to zero. This mapping is illustrated in FIG. 7 . After performing an IFFT the output is cyclically extended to the desired length.
  • IFFT Inverse Fast Fourier Transform
  • the resulting time domain signal consists of 4 periodically repeated short symbols t 1 , t 2 , t 3 , t 4 , and cyclically extended by a copy of t 1 , t 2 , which copy is depicted in FIG. 5 as t 5 , t 6 .
  • PAPR Peak-to-Average-Power-Ratio
  • FIGS. 8a , 8 b show the “absolute” (sqrt ⁇ In*+Quad*Quad ⁇ ) value of the resulting time domain signal waveform with the sequences proposed by Lucent Technologies. Oversampling (8*) was considered in order to ensure the peak was captured correctly using the limited 64-point IFFT.
  • FIGS. 8c , 8 d show the real and imaginary part of the resulting transmitted time domain waveform.
  • the resulting PAPR is 2.9991 dB (no oversampling) and 3.0093 dB (with 8 times oversampling).
  • a method for generating synchronization bursts for OFDM transmission systems is provided. Symbols of a predefined symbol sequence are mapped according to a predefined mapping scheme on subcarriers of the OFDM system wherein the symbols of the predefined symbol sequence represent subcarriers with nonzero amplitudes.
  • a synchronization burst is generated by inverse fast Fourier transforming the subcarriers mapped with a predefined symbol sequence.
  • the predefined symbol sequence is optimized such that the envelope fluctuation of the time domain signal (Peak-to-average-power-ratio) is minimized.
  • mapping of the symbols of the predefined symbol sequence and the Inverse Fast Fourier Transform can be set such that the resulting time domain signal of the synchronization burst represents a periodic nature.
  • mapping of the symbols of the predefined symbol sequence and the Inverse Fast Fourier Transform is set such that one burst part of the synchronization burst in the time domain is generated and the periodic nature of the synchronization burst in the time domain is achieved by copying the one burst part.
  • the number of symbols of a symbol sequence (n) can for example be 12.
  • the above equations define generally the symbol sequences according to the present invention.
  • the predefined symbol sequence can therefore be for example:
  • A is a complex value
  • A is a complex value
  • a method for synchronizing wireless OFDM systems wherein a synchronization burst is generated according to a method as set forth above and the synchronization burst is transmitted respectively before the transmission of data fields.
  • time domain signals of the synchronization burst can be precomputed and stored in a memory, such that the computation of the time domain signal of the burst is only effected once.
  • a OFDM transmitter comprising a mapping unit for mapping the symbols of a predefined symbols sequence according to a predefined mapping scheme on subcarriers of the OFDM system, wherein the symbols of a predefined symbols sequence represent the subcarriers of the OFDM system with nonzero amplitudes.
  • an inverse fast Fourier transforming unit is provided for generating a synchronization burst by inverse fast Fourier transforming the subcarriers of the OFDM mapped with said predefined symbols sequence.
  • the mapping unit thereby is designed such that the resulting time domain signal of the synchronization burst represents a periodic nature.
  • the mapping unit according to the present invention uses a predefined symbol sequence which is such that the envelope fluctuation of the time domain signal of the synchronization burst is minimized.
  • a mobile communications device such as set forth above is used.
  • FIG. 1 shows schematically a transmitter according to the present invention
  • FIG. 2 shows an alternative embodiment for a transmitter according to the present invention
  • FIG. 3 shows an alternative mapping scheme according to the present invention
  • FIGS. 4a to 4 d show the time domain signal properties achieved with the synchronization symbol structure using OFDM based transmission according to the present invention
  • FIGS. 5a to 5 d show the time domain signal properties of synchronization symbol structures according to alternative embodiments of the present invention
  • FIG. 6 shows a synchronization preamble structure known from the prior art
  • FIG. 7 shows an IFFT mapping according to the prior art
  • FIGS. 8a to 8 d show the time domain properties of the synchronization symbol structure according to the prior art
  • FIGS. 9a and 9b show the time domain properties, particularly the dynamic range of the synchronization symbol structure according to the prior art.
  • FIGS. 10a and 10b show the time domain properties of the synchronization symbol structure according to further alternative embodiments of the present invention.
  • the time domain synchronization burst structure as shown in FIG. 6 is maintained.
  • the IFFT mapping as shown in FIG. 7 can be maintained or alternatively the IFFT mapping according to FIG. 3 can be used.
  • the symbol sequences mapped to the subcarriers are optimized to sequences which result in a lower PAPR.
  • a short OFDM symbol (t 1 , . . . t 6 ) consists of 12 phase-modulated subcarriers.
  • the predefined symbol sequence therefore is chosen such that the envelope fluctuation of the time domain signal of the synchronization burst is minimized.
  • FIGS. 5a and 5b thereby show the time domain signal (magnitude) when using the optimized sequence according to the present invention in the case of no oversampling/8-times oversampling is effected.
  • PAPR in decibel is limited to 2.059 (even when using a time domain oversampling to capture the actual peak).
  • FIGS. 5c and 5d show the in-phase and quadrature-phase component, respectively, of the resulting wave form. It is clearly visible that the full symbol consists of four repetitions of a short sequence.
  • FIGS. 5a to 5 d show graphics corresponding to FIGS. 4a to 4 d for the other proposed sequences S 1 , S 2 and S 3 .
  • the PAPR is 3.01 dB and the dynamic range (defined as the ratio of the peak power to the minimum power) is 30.82 dB (see FIGS. 9 a and 9 b).
  • the PAPR is reduced to 2.06 dB, however, the dynamic range is increased as the signal power is ‘0’ at some points.
  • the symbol sequence is C 0 , C 1 , . . . C 11 and the mapping is:
  • the PAPR is reduced to 2.24 dB and the dynamic range is limited to 7.01 dB as it is shown in FIGS. 10a and 10b .
  • the sync symbol data 1 are prepared and mapped in a IFFT mapping unit 2 to the appropriate IFFT points.
  • the subcarriers of the OFDM system are transformed by a IFFT unit 3 and then the time domain signal is extended in a time extension unit 4 by copying parts of the signals (for example, t 1 , t 2 are copied to t 5 , t 6 ).
  • the time extended signal is then sent to the I/Q modulator 5 .
  • the time domain signal can be precomputed once in a computation unit 7 and then be stored in a memory 6 for the precomputed sample for the time signal. Then the time domain signal of the synchronization burst can be sent to the modulator 5 directly from the memory 6 .
  • the IFFT size is now only 16 (instead of 64 as it is the case in FIG. 7 ). Only one of the bursts t 1 , t 2 , . . . t 6 will be generated.
  • the other bursts can be generated by copying to retain the periodic nature of the synchronization time domain signal necessary for the correlation and synchronization on the receiving side. Therefore for example the time extension unit 4 can perform the copying of the 16-sample burst t 1 generated by the IFFT 16 according to FIG. 7 to the other burst t 2 , t 3 , . . . t 6 .
  • the mapping scheme according to FIG. 3 reduces the computing effort necessary for the IFFT.
  • the periodic nature of the time domain signal of the SYNCH bursts is therefore no longer achieved by the IFFT step, but by copying the burst t 1 generated with the simplified IFFT mapping scheme.
  • mapping scheme shown in FIG. 3 is also advantageous in combination with the precomputing technique shown in FIG. 2 .
  • a synchronization burst structure to be used in high speed wireless transmission systems is proposed.
  • the synchronization burst is constructed using especially designed OFDM symbols and time domain repetitions.
  • the resulting synchronization burst achieves a high timing detection and frequency offset estimation accuracy.
  • the burst is optimized to achieve a very low envelope fluctuation (Low peak-to-average-power-ratio) to reduce the complexity on the receive and to reduce time and frequency acquisition time at the receiver.
  • the synchronization performance can further be improved.
  • the envelope of the OFDM based synchronization burst in the time domain is reduced, the AGC pool-in speed at the receiver can be improved and an accurate time and frequency synchronization can be achieved.
  • the synchronization complexity on the receiver side can be reduced due to the reduced resolution requirements necessary due to reduced envelope fluctuation.

Abstract

The present invention proposes a method for generating synchronization bursts for OFDM transmission systems. The symbols of a predefined symbol sequence are mapped according to a predefined mapping scheme on subcarriers of the OFDM systems by a mapping unit (2), wherein the symbols of the predefined symbol sequence represent subcarriers of the OFDM system with nonzero amplitudes. A synchronization burst is generated by a inverse fast Fourier transforming unit (3) transforming the subcarriers of the OFDM system mapped to said predefined symbol sequence. The mapping (2) of the symbols of the predefined symbol sequence is set such that the resulting time domain signal of the synchronization burst represents a periodic nature. According to the invention the predefined symbol sequence is set such that the envelope fluctuation of the time domain signal of the synchronization burst is minimized. Therefore advantageous symbol sequences reducing said the envelope fluctuation of the time domain signal are proposed.

Description

The present invention relates to a method for generating synchronization bursts for OFDM transmission systems, a method for synchronizing wireless OFDM systems, an OFDM transmitter as well as to a mobile communications device comprising such a transmitter.
The present invention relates generally to the technical field of synchronizing wireless OFDM (orthogonal frequency division multiplexing) systems. Thereby it is known to use a synchronization burst constructed using especially designed OFDM symbols and time domain repetitions.
Particularly from the document IEEE P802.11a/d2.0 “Draft supplement to a standard for telecommunications and information exchange between systems—LAN/MAN specific requirements—part 1: wireless medium access control (MAC) and physical layer (PHY) specifications: high-speed physical layer in the 5 GHz band” a synchronization scheme for OFDM systems is proposed. This document is herewith included by reference as far as it concerns the synchronization including the proposed implementation. Said known scheme will now be explained with reference to FIG. 6 to 8 of the enclosed drawings.
FIG. 6 shows the structure of the known synchronization field. As shown in FIG. 6 the synchronization field consists of so-called short symbols t1, t2, . . . t6 and two long symbols T1, T2. In view of the present invention particularly the short symbols t1, t2 . . . t6 are of interest. Among the short symbols t1, t2, . . . t6 used for the amplifier gain control (t1, t2, t3) and the course frequency offset and timing control only the symbols t1, t2, t3 and t4 are actually generated, whereas the symbols t5, t6 are cyclic extensions (copies of the symbols t1 and t2, respectively). It is to be noted that FIG. 5 shows only the synchronization preamble structure as the structure of the following signal field indicating the type of baseband modulation and the coding rate as well as the structure of further following data fields are not of interest in view of the present invention. For further details reference is made to said prior art document.
The symbols t1, t2, t3, t4 are generated by means of an OFDM modulation using selected subcarriers from the entire available subcarriers. The symbols used for the OFDM modulation as well as the mapping to the selected subcarriers will now be explained with reference to FIG. 6.
Each of the short OFDM symbols t1, . . . t6 is generated by using 12 modulated subcarriers phase-modulated by the elements of the symbol alphabet:
S= 2(±1±j)
The full sequence used for the OFDM modulation can be written as follows:
    • S−24,24=√2*{1+j,0,0,0,1+j,0,0,0,−1−j,0,0,0,−1−j,0,0,0,1−j,0,0,0,−1−j,0,0,0,0 0,0,0,1+j,0,0,0,1+j,0,0,0,−1−j,0,0,0,1+j,0,0,0,−1+j,0,0,0,1+j}
The multiplication by a factor of √2 is in order to normalize the average power of the resulting OFDM symbol.
The signal can be written as: r SHORT ( t ) = w SHORT 1 ( t ) k = - N 2 / 2 N s / 2 S k exp ( j2π k Δ F t )
The fact that only spectral lines of S−24, 24 with indices which are a multiple of 4 have nonzero amplitude results in a periodicity of TFFT/4=0.8 μsec. The interval TTSHORT1 is equal to nine 0.8 μsec periods, i.e. 7.2 μsec.
Applying a 64-point IFFT to the vector S, where the remaining 15 values are set to zero, four short training symbols t1, t2, t3, t4 (in the time domain) can be generated. The IFFT output is cyclically extended to result in 6 short symbols t1, t2, t3, . . . t6. The mapping scheme is depicted in FIG. 7. The so called virtual subcarriers are left unmodulated.
The way to implement the inverse Fourier transform is by an IFFT (Inverse Fast Fourier Transform) algorithm. If, for example, a 64 point IFFT is used, the coefficients 1 to 24 are mapped to same numbered IFFT inputs, while the coefficients −24 to −1 are copied into IFFT inputs 40 to 63. The rest of the inputs, 25 to 39 and the 0 (DC) input, are set to zero. This mapping is illustrated in FIG. 7. After performing an IFFT the output is cyclically extended to the desired length.
With the proposed inverse fast Fourier transform (IFFT) mapping as shown in FIG. 7 the resulting time domain signal consists of 4 periodically repeated short symbols t1, t2, t3, t4, and cyclically extended by a copy of t1, t2, which copy is depicted in FIG. 5 as t5, t6. Note that in the present case only spectral lines with indices which are a multiple of 4 have nonzero amplitude. Other periodic natures can be generated by setting other multiples of the spectral lines to nonzero amplitudes.
Though the known synchronization scheme is very effective, it provides for disadvantage regarding the time domain signal properties.
For OFDM (or in general multicarrier signals) the signal envelope fluctuation (named Peak-to-Average-Power-Ratio=PAPR) is of great concern. A large PAPR results in poor transmission (due to nonlinear distortion effects of the power amplifier) and other signal limiting components in the transmission system (e.g. limited dynamic range of the AD converter).
For synchronization sequences it is even more desirable to have signals with a low PAPR in order to accelerate the receiver AGC (automatic gain control) locking and adjusting the reference signal value for the A/D converter (the whole dynamic range of the incoming signal should be covered by the A/D converter resolution without any overflow/underflow).
FIGS. 8a, 8b show the “absolute” (sqrt{In*+Quad*Quad}) value of the resulting time domain signal waveform with the sequences proposed by Lucent Technologies. Oversampling (8*) was considered in order to ensure the peak was captured correctly using the limited 64-point IFFT.
FIGS. 8c, 8d show the real and imaginary part of the resulting transmitted time domain waveform. The resulting PAPR is 2.9991 dB (no oversampling) and 3.0093 dB (with 8 times oversampling).
Therefore it is the object of the present invention to provide for a synchronization technique which bases on the known synchronization technique but which presents improved time domain signal properties to reduce the requirements for the hardware.
The above object is achieved by means of the features of the independent claims. The dependent claims develop further the central idea of the present invention.
According to the present invention therefore a method for generating synchronization bursts for OFDM transmission systems is provided. Symbols of a predefined symbol sequence are mapped according to a predefined mapping scheme on subcarriers of the OFDM system wherein the symbols of the predefined symbol sequence represent subcarriers with nonzero amplitudes. A synchronization burst is generated by inverse fast Fourier transforming the subcarriers mapped with a predefined symbol sequence. According to the present invention the predefined symbol sequence is optimized such that the envelope fluctuation of the time domain signal (Peak-to-average-power-ratio) is minimized.
The predefined symbol sequence can be chosen such that the following equations are satisfied for all symbols of the predefined symbol sequence:
n=2m,
Ci−1=±C1−i,
    • n being the number of symbols of the predefined symbol sequence,
    • m being an integer larger than one,
    • C being the symbol value, and
    • i being an integer running from 1 to m.
The mapping of the symbols of the predefined symbol sequence and the Inverse Fast Fourier Transform can be set such that the resulting time domain signal of the synchronization burst represents a periodic nature.
Alternatively the mapping of the symbols of the predefined symbol sequence and the Inverse Fast Fourier Transform is set such that one burst part of the synchronization burst in the time domain is generated and the periodic nature of the synchronization burst in the time domain is achieved by copying the one burst part.
The number of symbols of a symbol sequence (n) can for example be 12.
The above equations define generally the symbol sequences according to the present invention. The predefined symbol sequence can therefore be for example:
A A A −A −A −A −A A −A −A A −A,
wherein A is a complex value.
Alternatively the predefined symbol sequence can be:
A −A A A −A A A A A −A −A −A,
wherein A is a complex value.
Alternatively the following predefined symbol sequence can be used:
A B −A B −A −B B A −B A −B −A,
wherein A, B are complex values.
As a further alternative the following sequence can be used:
A −B −A −B −A B −B A B A B −A,
wherein A, B are complex values.
According to the present invention furthermore a method for synchronizing wireless OFDM systems is provided, wherein a synchronization burst is generated according to a method as set forth above and the synchronization burst is transmitted respectively before the transmission of data fields.
Thereby the time domain signals of the synchronization burst can be precomputed and stored in a memory, such that the computation of the time domain signal of the burst is only effected once.
According to the present invention furthermore a OFDM transmitter is provided comprising a mapping unit for mapping the symbols of a predefined symbols sequence according to a predefined mapping scheme on subcarriers of the OFDM system, wherein the symbols of a predefined symbols sequence represent the subcarriers of the OFDM system with nonzero amplitudes. Furthermore an inverse fast Fourier transforming unit is provided for generating a synchronization burst by inverse fast Fourier transforming the subcarriers of the OFDM mapped with said predefined symbols sequence. The mapping unit thereby is designed such that the resulting time domain signal of the synchronization burst represents a periodic nature. The mapping unit according to the present invention uses a predefined symbol sequence which is such that the envelope fluctuation of the time domain signal of the synchronization burst is minimized.
According to the present invention furthermore a mobile communications device such as set forth above is used.
With reference to the figures of the enclosed drawings referred embodiments of the present invention will now be explained.
FIG. 1 shows schematically a transmitter according to the present invention,
FIG. 2 shows an alternative embodiment for a transmitter according to the present invention,
FIG. 3 shows an alternative mapping scheme according to the present invention,
FIGS. 4a to 4d show the time domain signal properties achieved with the synchronization symbol structure using OFDM based transmission according to the present invention,
FIGS. 5a to 5d show the time domain signal properties of synchronization symbol structures according to alternative embodiments of the present invention,
FIG. 6 shows a synchronization preamble structure known from the prior art,
FIG. 7 shows an IFFT mapping according to the prior art, and
FIGS. 8a to 8d show the time domain properties of the synchronization symbol structure according to the prior art,
FIGS. 9a and 9b show the time domain properties, particularly the dynamic range of the synchronization symbol structure according to the prior art, and
FIGS. 10a and 10b show the time domain properties of the synchronization symbol structure according to further alternative embodiments of the present invention,
According to the present invention the time domain synchronization burst structure as shown in FIG. 6 is maintained. The IFFT mapping as shown in FIG. 7 can be maintained or alternatively the IFFT mapping according to FIG. 3 can be used. The symbol sequences mapped to the subcarriers are optimized to sequences which result in a lower PAPR.
According to the present invention a short OFDM symbol (t1, . . . t6) consists of 12 phase-modulated subcarriers.
C00 C01 C02 C03 C04 C05 C06 C07 C08 C09 C10 C11
Seq0 A  A  A −A −A −A −A A −A −A  A −A
Seq1 A −A  A  A −A  A  A A  A −A −A −A
Seq2 A  B −A  B −A −B  B A −B  A −B −A
Seq3 A −B −A −B −A  B −B A  B  A  B −A

with A = exp ( j * 2 + π * φ A ) and B = A * exp ( j π 2 ) = exp ( j2π * φ A + j π 2 ) and 0 .0 φ A < 1.0 .
Generally the predefined symbol sequence therefore is chosen such that the envelope fluctuation of the time domain signal of the synchronization burst is minimized.
Therefore generally the predefined symbol sequence is set such that the following equations are satisfied for all symbols for the predefined symbol sequence:
n=2m,
Ci−1=±Cn−i
    • wherein n is a number of symbols of the predefined symbol sequence,
    • m is an integer larger than 1,
    • c is the symbol value, and
    • i is an integer value running from 1 to m.
In the following the time domain signal properties of the new sequences according to the present invention will be shown with reference to FIGS. 4a to 4d and FIGS. 5a to 5d.
For simplicity we use in our demonstration the classical quadriphase symbol alphabet, S = 1 2 ( ± 1 ± j ) ,
(this corresponds to φA=0.125)
Symbol
 A exp ( j π 4 ) 1 2 ( + 1 + j )
-A - exp ( j π 4 ) = exp ( j 5 π 4 ) 1 2 ( - 1 - j )
 B exp ( j π 4 + j π 2 ) = exp ( j 3 π 4 ) 1 2 ( - 1 + j )
-B - exp ( j 3 π 4 ) = exp ( j 7 π 4 ) 1 2 ( + 1 - j )

Table 1: Complex symbol mapping
FIGS. 5a and 5b thereby show the time domain signal (magnitude) when using the optimized sequence according to the present invention in the case of no oversampling/8-times oversampling is effected.
PAPR (in decibel) is limited to 2.059 (even when using a time domain oversampling to capture the actual peak).
FIGS. 5c and 5d show the in-phase and quadrature-phase component, respectively, of the resulting wave form. It is clearly visible that the full symbol consists of four repetitions of a short sequence.
FIGS. 5a to 5d show graphics corresponding to FIGS. 4a to 4d for the other proposed sequences S1, S2 and S3.
Further simulations have shown that not only the PAPR can be optimized but also the dynamic range of the signal should be minimized. Therefore another four sequences, with achieve a small PAPR and at the same time a small overall dynamic range are proposed further below.
Using the sequence as proposed in the state of the art the PAPR is 3.01 dB and the dynamic range (defined as the ratio of the peak power to the minimum power) is 30.82 dB (see FIGS. 9a and 9b).
Using the sequences according to the present invention and as described above the PAPR is reduced to 2.06 dB, however, the dynamic range is increased as the signal power is ‘0’ at some points.
Therefore the following four sequences are proposed as a further embodiment of the present invention:
The symbol sequence is C0, C1, . . . C11 and the mapping is:
    • S=2*{C00, 0, 0, 0, C01, 0, 0, 0, C02, 0, 0, 0, C03, 0, 0, 0, C04, 0, 0, 0, C05, 0, 0, 0, 0, 0, 0, 0, C06, 0, 0, 0, C07, 0, 0, 0, C08, 0, 0, 0, C09, 0, 0, 0, C10, 0, 0, 0, C11}
C00 C01 C02 C03 C04 C05 C06 C07 C08 C09 C10 C11
Seq-Alt0 A  A  A  A −A −A  A −A −A  A −A A
Seq-Alt1 A −A  A −A −A  A −A −A  A  A  A A
Seq-Alt2 A  B −A −B −A −B −B −A −B −A  B A
Seq-Alt3 A −B −A  B −A  B  B −A  B −A −B A

with A=exp (i*2*π*φA) and B = A * exp ( j π 2 ) = exp ( j2π * φ A + j π 2 )
and 0.0≦φA<1.0.
Using these sequences the PAPR is reduced to 2.24 dB and the dynamic range is limited to 7.01 dB as it is shown in FIGS. 10a and 10b.
The advantages are the same as described before, however, the clipping problem is further reduced due to the very limited dynamic range of the signal.
With reference to FIG. 1 and 2 possible implementations of a transmitter according to the present invention will now be explained.
In the transmitter the sync symbol data 1 are prepared and mapped in a IFFT mapping unit 2 to the appropriate IFFT points. The subcarriers of the OFDM system are transformed by a IFFT unit 3 and then the time domain signal is extended in a time extension unit 4 by copying parts of the signals (for example, t1, t2 are copied to t5, t6). The time extended signal is then sent to the I/Q modulator 5.
As shown in FIG. 2 alternatively the time domain signal can be precomputed once in a computation unit 7 and then be stored in a memory 6 for the precomputed sample for the time signal. Then the time domain signal of the synchronization burst can be sent to the modulator 5 directly from the memory 6.
With reference to FIG. 3 a modified IFFT mapping scheme will now be explained.
According to this scheme, the principle of setting only every fourth subcarrier of the OFDM system to a non-zero amplitude (see FIG. 7) is abandoned. Therefore the time domain signal achieved according to the mapping scheme of FIG. 3 will not present a periodic nature.
The IFFT size is now only 16 (instead of 64 as it is the case in FIG. 7). Only one of the bursts t1, t2, . . . t6 will be generated. The other bursts can be generated by copying to retain the periodic nature of the synchronization time domain signal necessary for the correlation and synchronization on the receiving side. Therefore for example the time extension unit 4 can perform the copying of the 16-sample burst t1 generated by the IFFT 16 according to FIG. 7 to the other burst t2, t3, . . . t6. Obviously the mapping scheme according to FIG. 3 reduces the computing effort necessary for the IFFT. The periodic nature of the time domain signal of the SYNCH bursts is therefore no longer achieved by the IFFT step, but by copying the burst t1 generated with the simplified IFFT mapping scheme.
The mapping scheme shown in FIG. 3 is also advantageous in combination with the precomputing technique shown in FIG. 2.
According to the present invention therefore a synchronization burst structure to be used in high speed wireless transmission systems is proposed. The synchronization burst is constructed using especially designed OFDM symbols and time domain repetitions. The resulting synchronization burst achieves a high timing detection and frequency offset estimation accuracy. Furthermore the burst is optimized to achieve a very low envelope fluctuation (Low peak-to-average-power-ratio) to reduce the complexity on the receive and to reduce time and frequency acquisition time at the receiver.
Therefore the synchronization performance can further be improved. As with the scheme according to the present invention the envelope of the OFDM based synchronization burst in the time domain is reduced, the AGC pool-in speed at the receiver can be improved and an accurate time and frequency synchronization can be achieved. Furthermore the synchronization complexity on the receiver side can be reduced due to the reduced resolution requirements necessary due to reduced envelope fluctuation.
The advantages of the present invention can be set forth as following:
    • An OFDM based SYNCH symbol with a reduced Peak-to-Average-Power-Ratio (PARP) is proposed,
    • Improved synchronization performance (compared to the state of the art proposal),
    • Reduced AGC (automatic gain control) pull-in time due to reduced dynamic range of the SYNCH burst,
    • Improved AGC settlement (AGC has to adjust to a incoming signal level that later on now overflow/underflow in the AD happens. The reduced dynamic range of the SYNCH burst help to find this reference level more accurate),
    • Reduced synchronization detection complexity on the receiver (reduced resolution necessary due to reduced envelope fluctuation).

Claims (34)

1. A method for generating synchronization bursts for OFDM transmission systems, comprising the following steps:
mapping the symbols of a predefined symbol sequence according to a predefined mapping scheme on subcarriers S of the OFDM system, wherein the symbols of the predefined symbol sequence represent subcarriers of the OFDM system with non-zero-amplitude, and
generating a synchronization burst by Inverse Fourier Transforming the subcarriers S of the OFDM system mapped with the symbols of said predefined symbol sequence,
characterized in that
the predefined symbol sequence is set such that the envelope fluctuation of the time domain signal of the synchronization burst is minimized and the symbols of the predefined symbols sequence can be expressed as
A −A A −A −A A −A −A A A A A
A being a complex value.
2. A method for synchronizing wireless OFDM systems, characterized by the steps of
generating a synchronization burst according to a method according to claim 1, and
transmitting the synchronization burst.
3. A method according to claim 2, characterized in that
the time domain signal of the synchronization burst is precomputed and stored in a memory.
4. An OFDM transmitter, comprising:
a unit for mapping the symbols of a predefined symbol sequence according to a predefined mapping scheme on subcarriers of the OFDM system, wherein the symbols of the predefined symbol sequence represent subcarriers of the OFDM system with non-zero-amplitude, and
a unit for generating a synchronization burst by Inverse Fourier Transforming the subcarriers of the OFDM system mapped with the symbols of said predefined symbol sequence,
characterized in that
the mapping unit is designed to modulate the subcarriers such that the envelope fluctuation of the time domain signal of the synchronization burst is minimized by using the following predefined symbol sequence:
A −A A −A −A A −A −A A A A A
A being a complex value.
5. An OFDM transmitter according to claim 4, characterized by
a time extension unit copying the burst part to achieve a periodic nature of the time domain signal.
6. An OFDM transmitter according to claim 4, characterized by
a processing unit for precomputing the time domain signal of the synchronization burst
and a memory for storing the precomputed time domain signal of the synchronization burst.
7. A mobile communications device, comprising a transmitter according to claim 4.
8. A synchronization burst signal for synchronizing OFDM systems generated by a method according to claim 1.
9. A method for generating a synchronization signal by using a plurality of subcarriers for an OFDM transmission system, comprising the steps of:
mapping symbols of a predefined symbol sequence in accordance with a predefined mapping scheme on said plurality of subcarriers, wherein pre-selected twelve symbols of the predefined symbol sequence have non-zero values, and
generating a synchronization signal by Inverse Fourier Transforming said plurality of subcarriers mapped with the symbols of said predefined symbol sequence,
wherein the symbols of the predefined symbols sequence are expressed as
A −A A −A −A A −A −A A A A A
A being a complex value.
10. A method for generating a synchronization signal by using a plurality of subcarriers in an OFDM transmission system, comprising the steps of:
generating a predefined symbol sequence having at least twelve symbols corresponding to respective pre-selected ones of said plurality of subcarriers, and
generating said synchronization signal in time domain by performing Inverse Fourier Transforming on said preselected ones of said plurality of subcarriers,
wherein said twelve symbols are set to nonzero having complex values and others of said symbols are set to zero, such that said twelve symbols are arranged periodically in said predefined symbol sequence in the frequency domain, and
wherein said symbol sequence of said twelve symbols is A −A A −A −A A −A −A A A A A, where A is a complex value.
11. A method for generating a synchronization signal by using a plurality of subcarriers in an OFDM transmission system, comprising the steps of:
generating a predefined symbol sequence having twelve symbols each set to a non-zero value and a plurality of further symbols each set to a zero value, wherein each of said symbols is mapped respectively on a predefined subcarrier of said plurality of subcarriers, and
generating said synchronization signal in time domain by performing Inverse Fourier Transforming on said plurality of subcarriers mapped with said predefined symbol sequence,
wherein said twelve symbols of the predefined symbol sequence is expressed as
A −A A −A −A A −A −A A A A A
A being a complex value.
12. A method for transmitting OFDM data signals in an OFDM transmission system, comprising the steps of:
receiving a plurality of subcarriers on which a predefined symbol sequence is mapped, said predefined symbol sequence having twelve symbols set to non-zero values and other symbols set to zero values, and wherein said twelve symbols of said predefined symbols sequence are expressed as
A −A A −A −A A −A −A A A A A
A being a complex value,
generating a synchronization signal in time domain by performing Inverse Fourier Transforming on said plurality of subcarriers, and
transmitting said synchronization signals and said OFDM data signals.
13. A method for transmitting OFDM data signals in an OFDM transmission system, comprising the steps of:
receiving a plurality of subcarriers on which a predefined symbol sequence is mapped,
generating a synchronization signal in time domain by performing Inverse Fourier Transforming on said plurality of subcarriers, and
transmitting said synchronization signals and said OFDM data signals,
wherein said predefined symbol sequence has twelve symbols having complex value and said twelve symbols of said predefined symbols sequence can be expressed as
A −A A −A −A A −A −A A A A A
wherein twelve symbols are arranged in said predefined symbol sequence such that every fourth subcarrier among said plurality of subcarriers has non-zero amplitude.
14. A method for transmitting OFDM data signals in an OFDM transmission system, comprising the steps of:
generating synchronization signals in time domain by performing Inverse Fourier Transforming on a plurality of subcarriers on which a predefined symbol sequence is mapped in accordance with a predefined mapping scheme, and
transmitting said synchronization signals and said OFDM data signals,
wherein said predefined symbol sequence contains the following symbol sequence comprising twelve complex values:
A −A A −A −A A −A −A A A A A
wherein said twelve symbols are mapped on every fourth subcarriers of said plurality of subcarriers.
15. Apparatus for generating a synchronization signal by using a plurality of subcarriers for an OFDM transmission system, comprising:
a unit mapping symbols of a predefined symbol sequence in accordance with a predefined mapping scheme on said plurality of subcarriers, wherein pre-selected twelve symbols of the predefined symbol sequence have non-zero values, and
a unit for generating a synchronization signal by Inverse Fourier Transforming said plurality of subcarriers mapped with the symbols of said predefined symbol sequence,
wherein the symbols of the predefined symbols sequence are expressed as
A −A A −A −A A −A −A A A A A
A being a complex value.
16. Apparatus for generating a synchronization signal by using a plurality of subcarriers in an OFDM transmission system, comprising
a unit for generating a predefined symbol sequence having at least twelve symbols corresponding to respective pre-selected ones of said plurality of subcarriers, and
a unit for generating said synchronization signal in time domain by performing Inverse Fourier Transforming on said preselected ones of said plurality of subcarriers,
wherein said twelve symbols are set to nonzero having complex values and others of said symbols are set to zero, such that said twelve symbols are arranged periodically in said predefined symbol sequence in the frequency domain, and
wherein said symbol sequence of said twelve symbols is A −A A −A −A A −A −A A A A A, where A is a complex value.
17. Apparatus for generating a synchronization signal by using a plurality of subcarriers in an OFDM transmission system, comprising:
a unit for generating a predefined symbol sequence having twelve symbols each set to a non-zero value and a plurality of further symbols each set to a zero value, wherein each of said symbols is mapped respectively on a predefined subcarrier of said plurality of subcarriers, and
a unit for generating said synchronization signal in time domain by performing Inverse Fourier Transforming on said plurality of subcarriers mapped with said predefined symbol sequence,
wherein said twelve symbols of the predefined symbol sequence is expressed as
A −A A −A −A A −A −A A A A A
A being a complex value.
18. Apparatus for transmitting OFDM data signals in an OFDM transmission system, comprising:
a unit for receiving a plurality of subcarriers on which a predefined symbol sequence is mapped, said predefined symbol sequence having twelve symbols set to non-zero values and other symbols set to zero values, and wherein said twelve symbols of said predefined symbols sequence are expressed as
A −A A −A −A A −A −A A A A A
A being a complex value,
a unit for generating a synchronization signal in time domain by performing Inverse Fourier Transforming on said plurality of subcarriers, and
a transmitter for transmitting said synchronization signals and said OFDM data signals.
19. Apparatus for transmitting OFDM data signals in an OFDM transmission system, comprising:
a unit for receiving a plurality of subcarriers on which a predefined symbol sequence is mapped,
a unit for generating a synchronization signal in time domain by performing Inverse Fourier Transforming on said plurality of subcarriers, and
a transmitter for transmitting said synchronization signals and said OFDM data signals,
wherein said predefined symbol sequence has twelve symbols having complex value and said twelve symbols of said predefined symbols sequence can be expressed as
A −A A −A −A A −A −A A A A A
wherein twelve symbols are arranged in said predefined symbol sequence such that every fourth subcarrier among said plurality of subcarriers has non-zero amplitude.
20. Apparatus for transmitting OFDM data signals in an OFDM transmission system, comprising:
a unit for generating synchronization signals in time domain by performing Inverse Fourier Transforming on a plurality of subcarriers on which a predefined symbol sequence is mapped in accordance with a predefined mapping scheme, and
a transmitter for transmitting said synchronization signals and said OFDM data signals,
wherein said predefined symbol sequence contains the following symbol sequence comprising twelve complex values:
A −A A −A −A A −A −A A A A A
wherein said twelve symbols are mapped on every fourth subcarriers of said plurality of subcarriers.
21. A method for synchronizing a wireless communication device in an OFDM communication system, comprising the steps of:
receiving data signals and a synchronization signal exhibiting periodicity, the data signals and synchronization signal being transmitted from a transmitter side by using a plurality of subcarriers, said synchronization signal being based on a predefined symbol sequence having twelve complex value symbols with the symbol sequence
A −A A −A −A A −A −A A A A A
wherein A is a complex value, and
wherein said twelve symbols are mapped on every fourth subcarrier of said plurality of subcarriers so that said periodic nature of synchronization signal contains four repetitions of one synchronization signal in time domain; and
performing time and frequency synchronization in accordance with said periodicity of synchronization signal.
22. A method for synchronizing a wireless communication device in an OFDM communication system, comprising the steps of:
receiving data and synchronization signals transmitted from a transmitter side by using a plurality of subcarriers, and
performing time and frequency synchronization in accordance with said synchronization signal;
wherein said synchronization signal is generated based on a predefined symbol sequence comprising twelve symbols having complex values and a sequence of said twelve symbols is expressed as
A −A A −A −A A −A −A A A A A
wherein A is a complex value.
23. A method for synchronizing a wireless communication device in an OFDM communication system, comprising the steps of:
receiving data and synchronization signals transmitted from a transmitter side by using a plurality of subcarriers, and
performing time and frequency synchronization in accordance with said synchronization signal;
wherein said synchronization signal is generated based on a predefined symbol sequence comprising twelve nonzero symbols having complex value and other symbols being set to zero so that said twelve symbols are arranged with periodicity in said predefined symbol sequence in the frequency domain, and
wherein a sequence of said twelve symbols in the frequency domain is
A −A A −A −A A −A −A A A A A
wherein A is a complex value.
24. A method for synchronizing a wireless communication device in an OFDM communication system, comprising the steps of:
receiving data and synchronization signals transmitted from a transmitter side by using a plurality of subcarriers, and
performing time and frequency synchronization in accordance with said synchronization signal;
wherein said synchronization signal is based on a predefined symbol sequence comprised of twelve symbols having complex value, said twelve symbols being expressed as
A −A A −A −A A −A −A A A A A
wherein A is a complex value and
wherein the twelve symbols are arranged such that every fourth subcarrier among said plurality of subcarriers has non-zero amplitude.
25. A method for transmitting data signals in an OFDM transmission system, comprising the steps of:
generating a predefined symbol sequence comprised of a plurality of complex value symbols mapped on a plurality of subcarriers,
generating a synchronization signal by supplying said plurality of subcarriers having non-zero amplitude to an inverse Fourier Transform unit, such that said plurality of subcarriers mapped with said predefined symbol sequence are transformed into a time domain signal to generate only one synchronization signal,
copying said one synchronization signal to generate other synchronization signals in the time domain; and
transmitting said generated synchronization signals and said data signals.
26. The method according to claim 25,
wherein the symbols of said predefined symbol sequence are expressed by C i−1 or C n−i , wherein:
n is the number of symbols of said predefined symbol sequence,
m is a half value of n,
i is an integer running from 1 to m
wherein said symbols expressed by C i−1 are supplied to one set of inputs of said inverse Fourier transform unit, and said symbols expressed by C n−i are supplied to another set of said inputs of said inverse Fourier transform unit.
27. A method for transmitting data signals in an OFDM transmission system, comprising the steps of:
receiving a plurality of subcarriers on which a predefined symbol sequence is mapped, said predefined symbol sequence being formed of a plurality of symbols set to complex values,
transforming said plurality of subcarriers, of non-zero amplitude, mapped with said predefined symbol sequence into a time domain signal using inverse Fourier transformation, so as to generate only one synchronization signal,
copying said one synchronization signal in the time domain to provide a synchronization signal with periodicity, and
transmitting said provided synchronization signal and said data signals.
28. A method for transmitting data signals in an OFDM transmission system, comprising the steps of:
receiving a plurality of subcarriers on which a predefined symbol sequence is mapped, said predefined symbol sequence being formed of a plurality of symbols set to complex values,
transforming said plurality of subcarriers, set to non-zero amplitude, mapped with said predefined symbol sequence into a time domain signal by using Inverse Fourier Transformation, to generate only one synchronization signal,
copying said one synchronization signal to generate other synchronization signals in the time domain; and
transmitting said generated synchronization signals and said data signals.
29. A method for transmitting OFDM data signals in an OFDM transmission system, comprising the steps of:
generating one synchronization signal in the time domain by performing Inverse Fourier Transformation on a plurality of subcarriers on which a predefined symbol sequence is mapped in accordance with a predefined mapping scheme, wherein all symbols of said predefined symbol sequence are set to complex values,
generating a synchronization signal of periodicity by copying said one synchronization signal in the time domain, and
transmitting said synchronization signal of periodicity and said OFDM data signals.
30. A method for transmitting OFDM data signals in an OFDM transmission system, comprising the steps of:
generating a predefined symbol sequence having at least twelve non-zero complex value symbols, each of said twelve symbols being mapped in a periodic manner on a plurality of pre-selected subcarriers in the frequency domain,
generating a time domain signal by performing Inverse Fourier transformation on said plurality of pre-selected subcarriers mapped with said predefined symbol sequence,
said predefined symbol sequence conforming with the following equations for all symbols of said predefined symbol sequence:

n=2m,

C i−1 =±C n− i
wherein:
n is the number of symbols of said predefined symbol sequence,
m is an integer larger than one,
C is the symbol value, and
i is an integer from 1 to m.
31. A method for transmitting OFDM data signals by using a plurality of subcarriers in an OFDM transmission system, comprising the steps of:
generating a predefined symbol sequence having at least twelve symbols corresponding to respective pre-selected ones of said plurality of subcarriers,
generating a time domain signal by performing Inverse Fourier transformation on said plurality of pre-selected subcarriers corresponding to the symbols of said predefined symbol sequence,
wherein each of twelve symbols is set to a nonzero complex value and said predefined symbol sequence has a binary symbol sequence expressed by A and −A, where A is a complex value, and wherein said predefined symbol sequence satisfies the following equations for all symbols of said predefined symbol sequence:

n=2m,

C i−1 =±C n− i
wherein:
n is the number of symbols of said predefined symbol sequence,
m is an integer larger than one,
C is the symbol value, and
i is an integer from 1 to m.
32. A method for transmitting OFDM data signals by using a plurality of subcarriers in an OFDM transmission system, comprising the steps of:
generating a predefined symbol sequence having at least twelve symbols corresponding to respective pre-selected subcarriers of said plurality of subcarriers,
generating a time domain signal by performing Inverse Fourier transformation on said plurality of pre-selected subcarriers corresponding to the symbols of said predefined symbol sequence,
wherein each of said twelve symbols has a nonzero complex value expressed by A or −A, and wherein said predefined symbol sequence satisfies the following equations for all symbols of said predefined symbol sequence:

n=2m,

C i−1 =±C n− i
wherein:
n is the number of symbols of said predefined symbol sequence,
m is an integer larger than one,
C is the symbol value, and
i is an integer from 1 to m.
33. A method for transmitting OFDM data signals by using a plurality of subcarriers in an OFDM transmission system, comprising the steps of:
generating a predefined symbol sequence having predefined symbols, each of said symbols being mapped on a respective predefined subcarrier, and
generating a time domain signal by Inverse Fourier Transforming said plurality of subcarriers mapped with the symbols of said predefined symbol sequence,
wherein said predefined symbols are set to nonzero complex values and have a binary sequence of symbol values expressed by A or −A,
wherein said predefined symbol sequence satisfies the following equations for all symbols of said predefined symbol sequence:

n=2m,

C i−1 =±C n− i
wherein:
n is the number of symbols of said predefined symbol sequence,
m is an integer larger than one,
C is the symbol value, and
i is an integer from 1 to m.
34. A method for transmitting OFDM data signals in an OFDM transmission system, comprising the steps of:
mapping symbols of a predefined symbol sequence in accordance with a predefined mapping scheme on said plurality of subcarriers, wherein pre-selected symbols of the predefined symbol sequence have non-zero values, and
generating a time domain signal by Inverse Fourier Transforming said plurality of subcarriers mapped with the symbols of said predefined symbol sequence,
wherein said predefined symbol sequence satisfies the following equations for all symbols of said predefined symbol sequence:

n=2m,

C i−1 =±C n− i
wherein:
n is the number of symbols of said predefined symbol sequence,
m is an integer larger than one,
C is the symbol value, and
i is an integer from 1 to m.
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Families Citing this family (64)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1439677B9 (en) 1999-01-08 2007-11-07 Sony Deutschland GmbH Synchronisation symbol structure for an OFDM system
ATE340465T1 (en) 1999-06-16 2006-10-15 Sony Deutschland Gmbh OPTIMIZED SYNCHRONIZATION PREAMBLE STRUCTURE FOR OFDM SYSTEM
EP1170897B1 (en) * 2000-07-05 2020-01-15 Wi-Fi One Technologies International Limited Pilot pattern design for a STTD scheme in an OFDM system
US9130810B2 (en) 2000-09-13 2015-09-08 Qualcomm Incorporated OFDM communications methods and apparatus
US7295509B2 (en) 2000-09-13 2007-11-13 Qualcomm, Incorporated Signaling method in an OFDM multiple access system
US6754170B1 (en) * 2000-09-29 2004-06-22 Symbol Technologies, Inc. Timing synchronization in OFDM communications receivers
US6950475B1 (en) * 2000-12-11 2005-09-27 Cisco Technology, Inc. OFDM receiver clock synchronization system
EP1481502B1 (en) * 2002-03-07 2008-05-14 Alvarion Ltd. Hierarchical preamble constructions for ofdma based on complementary sequences
KR20040029253A (en) * 2002-09-30 2004-04-06 삼성전자주식회사 Apparatus for generating preamble sequence in communication system using orthogonal frequency division multiplexing scheme and method thereof
WO2004039026A1 (en) * 2002-10-23 2004-05-06 Samsung Electronics Co., Ltd. Apparatus and method for generating a preamble sequence in an ofdm communication system
CN1692586A (en) * 2002-11-30 2005-11-02 三星电子株式会社 Apparatus and method for generating preamble sequence in an OFDM communication system
KR100905572B1 (en) * 2002-12-03 2009-07-02 삼성전자주식회사 Apparatus and method for generating preamble sequence in a communication system using orthogonal frequency division multiplexing scheme
EP1592192B1 (en) 2004-04-28 2019-01-16 Samsung Electronics Co., Ltd. Method and apparatus for generating preamble sequence for adaptive antenna system in orthogonal frequency division multiple access communication system
US9137822B2 (en) 2004-07-21 2015-09-15 Qualcomm Incorporated Efficient signaling over access channel
US9148256B2 (en) 2004-07-21 2015-09-29 Qualcomm Incorporated Performance based rank prediction for MIMO design
US7961828B2 (en) * 2004-10-06 2011-06-14 Motorola Mobility, Inc. Sync bursts frequency offset compensation
CN1780276B (en) * 2004-11-25 2012-01-04 都科摩(北京)通信技术研究中心有限公司 Combined time synchronizing and frequency bias evaluation and evaluating device for orthogonal frequency division duplex system
US9246560B2 (en) 2005-03-10 2016-01-26 Qualcomm Incorporated Systems and methods for beamforming and rate control in a multi-input multi-output communication systems
US9154211B2 (en) 2005-03-11 2015-10-06 Qualcomm Incorporated Systems and methods for beamforming feedback in multi antenna communication systems
US8446892B2 (en) 2005-03-16 2013-05-21 Qualcomm Incorporated Channel structures for a quasi-orthogonal multiple-access communication system
US9461859B2 (en) 2005-03-17 2016-10-04 Qualcomm Incorporated Pilot signal transmission for an orthogonal frequency division wireless communication system
US9520972B2 (en) 2005-03-17 2016-12-13 Qualcomm Incorporated Pilot signal transmission for an orthogonal frequency division wireless communication system
US9143305B2 (en) 2005-03-17 2015-09-22 Qualcomm Incorporated Pilot signal transmission for an orthogonal frequency division wireless communication system
JP4429945B2 (en) 2005-03-23 2010-03-10 株式会社エヌ・ティ・ティ・ドコモ MIMO multiplex communication apparatus and signal separation method
US9184870B2 (en) 2005-04-01 2015-11-10 Qualcomm Incorporated Systems and methods for control channel signaling
US9036538B2 (en) 2005-04-19 2015-05-19 Qualcomm Incorporated Frequency hopping design for single carrier FDMA systems
US9408220B2 (en) 2005-04-19 2016-08-02 Qualcomm Incorporated Channel quality reporting for adaptive sectorization
US8879511B2 (en) 2005-10-27 2014-11-04 Qualcomm Incorporated Assignment acknowledgement for a wireless communication system
US8565194B2 (en) 2005-10-27 2013-10-22 Qualcomm Incorporated Puncturing signaling channel for a wireless communication system
US8611284B2 (en) 2005-05-31 2013-12-17 Qualcomm Incorporated Use of supplemental assignments to decrement resources
US8462859B2 (en) 2005-06-01 2013-06-11 Qualcomm Incorporated Sphere decoding apparatus
US8599945B2 (en) 2005-06-16 2013-12-03 Qualcomm Incorporated Robust rank prediction for a MIMO system
US9179319B2 (en) 2005-06-16 2015-11-03 Qualcomm Incorporated Adaptive sectorization in cellular systems
JP4563453B2 (en) * 2005-08-03 2010-10-13 国立大学法人 奈良先端科学技術大学院大学 Transmitter and receiver
US8885628B2 (en) 2005-08-08 2014-11-11 Qualcomm Incorporated Code division multiplexing in a single-carrier frequency division multiple access system
US20070041457A1 (en) 2005-08-22 2007-02-22 Tamer Kadous Method and apparatus for providing antenna diversity in a wireless communication system
US9209956B2 (en) 2005-08-22 2015-12-08 Qualcomm Incorporated Segment sensitive scheduling
US8644292B2 (en) 2005-08-24 2014-02-04 Qualcomm Incorporated Varied transmission time intervals for wireless communication system
US9136974B2 (en) 2005-08-30 2015-09-15 Qualcomm Incorporated Precoding and SDMA support
US8693405B2 (en) 2005-10-27 2014-04-08 Qualcomm Incorporated SDMA resource management
US8582509B2 (en) 2005-10-27 2013-11-12 Qualcomm Incorporated Scalable frequency band operation in wireless communication systems
US9144060B2 (en) 2005-10-27 2015-09-22 Qualcomm Incorporated Resource allocation for shared signaling channels
US8477684B2 (en) 2005-10-27 2013-07-02 Qualcomm Incorporated Acknowledgement of control messages in a wireless communication system
US9210651B2 (en) 2005-10-27 2015-12-08 Qualcomm Incorporated Method and apparatus for bootstraping information in a communication system
US9088384B2 (en) 2005-10-27 2015-07-21 Qualcomm Incorporated Pilot symbol transmission in wireless communication systems
US9172453B2 (en) 2005-10-27 2015-10-27 Qualcomm Incorporated Method and apparatus for pre-coding frequency division duplexing system
US8045512B2 (en) 2005-10-27 2011-10-25 Qualcomm Incorporated Scalable frequency band operation in wireless communication systems
US9225416B2 (en) 2005-10-27 2015-12-29 Qualcomm Incorporated Varied signaling channels for a reverse link in a wireless communication system
US9225488B2 (en) 2005-10-27 2015-12-29 Qualcomm Incorporated Shared signaling channel
US8582548B2 (en) 2005-11-18 2013-11-12 Qualcomm Incorporated Frequency division multiple access schemes for wireless communication
US8831607B2 (en) 2006-01-05 2014-09-09 Qualcomm Incorporated Reverse link other sector communication
CN1852281B (en) * 2006-01-23 2010-06-09 北京邮电大学 Synchronizing method for quadrature frequency division multiple access system
US7983143B2 (en) 2006-02-08 2011-07-19 Motorola Mobility, Inc. Method and apparatus for initial acquisition and cell search for an OFDMA system
US7911935B2 (en) * 2006-02-08 2011-03-22 Motorola Mobility, Inc. Method and apparatus for interleaving sequence elements of an OFDMA synchronization channel
JP2007259445A (en) 2006-03-20 2007-10-04 Fujitsu Ltd Transmitters and methods in ofdm communication systems
EP1838061B1 (en) * 2006-03-20 2009-03-11 Fujitsu Ltd. Symbol to subcarrier allocation in OFDM communication systems and methods
CN101022438B (en) * 2006-03-30 2011-12-14 北京新岸线移动通信技术有限公司 Compatible DAB digital broadcasting receiver carrier synchronizing method and system
PT2090050E (en) * 2007-05-02 2011-04-14 Huawei Tech Co Ltd Method and apparatus of establishing a synchronisation signal in a communication system
CN101083508B (en) * 2007-07-19 2010-06-02 清华大学 OFDM modulation system performance test method based on low peak-valley ratio sequence transmission
CN101420411B (en) * 2008-12-05 2011-02-09 航天恒星科技有限公司 Fast carrier capture method with low signal-noise ratio
CN106685876B (en) * 2016-11-14 2021-08-10 西南石油大学 Multi-dimensional PTS method for reducing peak-to-average power ratio of OFDM system
ES2895680T3 (en) * 2017-11-07 2022-02-22 Siemens Ag Procedure for the synchronization of transmitting and receiving units in a multicarrier signal transmission
CN110535795B (en) * 2018-05-24 2021-11-05 中兴通讯股份有限公司 Signal processing method and device
CN113315730B (en) * 2021-05-24 2022-12-27 扬州大学 Time-frequency synchronization method based on filter multi-carrier system

Citations (56)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5450456A (en) 1993-11-12 1995-09-12 Daimler Benz Ag Method and arrangement for measuring the carrier frequency deviation in a multi-channel transmission system
WO1998000946A2 (en) 1996-06-20 1998-01-08 The Board Of Trustees Of The Leland Stanford Junior University Timing and frequency synchronization of ofdm signals
EP0836303A2 (en) 1996-10-14 1998-04-15 Ntt Mobile Communications Network Inc. Reduction of peak to average power ratio in MCM systems
GB2320868A (en) 1996-12-03 1998-07-01 Ensigma Ltd Measuring coarse frequency offset of a multi-carrier signal
EP0869646A2 (en) 1997-04-01 1998-10-07 Lucent Technologies Inc. Complementary encoding and modulation for multicarrier transmission
EP0982905A1 (en) 1998-08-28 2000-03-01 Sony International (Europe) GmbH Universal PSK modulation apparatus and method
EP0984595A1 (en) 1998-09-03 2000-03-08 Sony International (Europe) GmbH Blind modulation detection
EP0984596A1 (en) 1998-09-03 2000-03-08 Sony International (Europe) GmbH Adpative PSK system and timing offset compensation circuit
EP0987863A1 (en) 1998-09-17 2000-03-22 Sony International (Europe) GmbH Soft decision method and apparatus for 8PSK demodulation
EP1014562A1 (en) 1997-12-18 2000-06-28 Sony International (Europe) GmbH Demodulator and method for the demodulation of modulated RF signals
CA2291847A1 (en) 1999-01-08 2000-07-08 Sony International (Europe) G.M.B.H. Synchronization symbol structure using ofdm based transmission method
EP1037481A1 (en) 1999-03-15 2000-09-20 Sony International (Europe) GmbH Simultaneous transmission of random access bursts
EP1039661A1 (en) 1999-03-03 2000-09-27 Sony International (Europe) GmbH Multicast channel for a CDMA system
US6160791A (en) 1997-08-29 2000-12-12 Sony International (Europe) Gmbh Transmission system for the transmission of power control information in an OFDM system
US6160821A (en) 1997-11-05 2000-12-12 Sony International (Europe) Gmbh Synchronization of digital communication systems
EP1065855A1 (en) 1999-06-29 2001-01-03 Sony International (Europe) GmbH Adaptation of cyclic extensions in an OFDM communication system
EP1162764A1 (en) 2000-06-05 2001-12-12 Sony International (Europe) GmbH Indoor wireless system using active reflector
EP1170916A1 (en) 2000-07-05 2002-01-09 Sony International (Europe) GmbH Channel estimator for OFDM system
EP1170917A1 (en) 2000-07-06 2002-01-09 Sony International (Europe) GmbH Method and device to provide an OFDM up-link using Time-Frequency interleaving
EP1207662A1 (en) 2000-11-20 2002-05-22 Sony International (Europe) GmbH OFDM system with antenna diversity in the transmitter and pre-equalisation
EP1207661A1 (en) 2000-11-20 2002-05-22 Sony International (Europe) GmbH Adaptive subcarrier loading
US6407846B1 (en) 2001-03-16 2002-06-18 All Optical Networks, Inc. Photonic wavelength shifting method
US6438173B1 (en) 1997-08-05 2002-08-20 Infineon Technologies Ag Multicarrier transmission system for irregular transmission of data blocks
US6452987B1 (en) 1998-11-25 2002-09-17 Lucent Technologies Inc. Fast start-up in discrete multi-tone (DMT) based communications system
US6470055B1 (en) 1998-08-10 2002-10-22 Kamilo Feher Spectrally efficient FQPSK, FGMSK, and FQAM for enhanced performance CDMA, TDMA, GSM, OFDN, and other systems
US6507733B1 (en) 1998-12-18 2003-01-14 Sony International (Europe) Gmbh Three port junction receiver
EP1276251A1 (en) 2001-07-11 2003-01-15 Sony International (Europe) GmbH Method for calculating a weighting vector for an antenna array
EP1276288A1 (en) 2001-07-10 2003-01-15 Sony International (Europe) GmbH Reference symbols for channel estimation with multicarrier transmission
US6535501B1 (en) 1997-11-07 2003-03-18 Sony International (Europe) Gmbh Transmission method and transmission apparatus for transmitting signals on the basis of a OFDM/TDMA-system in a GSM/system
US6539215B1 (en) 1999-05-27 2003-03-25 Sony Corporation Down converter and demodulator using a three port junction
US6545997B1 (en) 1998-02-22 2003-04-08 Sony International (Europe) Gmbh Transmission method and transmission apparatus for transmitting signals on the basis of a OFDM/TDMA-system with pilot symbols
US6557139B2 (en) 1998-12-10 2003-04-29 Sony International (Europe) Gmbh Encoding apparatus and encoding method for multidimensionally coding and encoding method and decoding apparatus for iterative decoding of multidimensionally coded information
US6567374B1 (en) 1998-02-18 2003-05-20 Sony International (Europe) Gmbh Data and pilot mapping in an OFDM system
US6567383B1 (en) 1998-02-18 2003-05-20 Sony International (Europe) Gmbh Header structure for TDD systems
US6609010B1 (en) 1998-11-30 2003-08-19 Sony International (Europe) Gmbh Dual frequency band transceiver
US6674732B1 (en) 1998-02-13 2004-01-06 Sony Corporation Transmitting method, receiving method, transmitter, and receiver
US6674817B1 (en) 1999-04-12 2004-01-06 Sony International (Europe) Gmbh Communication device and distinguishing method for distinguishing between different data burst types in a digital telecommunication system
EP1379026A1 (en) 2002-07-03 2004-01-07 Sony International (Europe) GmbH Dual rate wireless transmission system
US6704562B1 (en) 1999-06-16 2004-03-09 Sony International (Europe) Gmbh N-port receiver with RF/LO isolation
US6724246B2 (en) 2000-01-24 2004-04-20 Sony International (Europe) Gmbh Demodulation structure and method
US6728550B1 (en) 1999-07-09 2004-04-27 Sony International (Europe) Gmbh Coverage and cell extension in downlink power controlled wireless radio communication systems
US6731594B1 (en) 1997-09-04 2004-05-04 Sony International (Europe) Gmbh Transmission system for OFDM-signals with optimized synchronisation
US6735261B1 (en) 1999-07-08 2004-05-11 Sony International (Europe) Gmbh Calibration of a N-port receiver
US6738443B1 (en) 1999-06-16 2004-05-18 Sony International (Europe) Gmbh Optimized synchronization preamble structure
US6748203B1 (en) 1999-09-29 2004-06-08 Sony International (Europe) Gmbh Three port structure with modulated LO signal
US6917580B2 (en) 2000-08-01 2005-07-12 Sony International (Europe) Gmbh Frequency reuse scheme for OFDM system
US20060045219A1 (en) 2004-08-24 2006-03-02 Zhaocheng Wang Backscatter interrogator reception method and interrogator for a modulated backscatter system
US7012882B2 (en) 2000-08-01 2006-03-14 Sony International (Europe) Gmbh Channel estimator for OFDM system
US20060133408A1 (en) 2004-11-15 2006-06-22 Juan Nogueira-Nine Beaconless communication system
US20060148926A1 (en) 2002-01-25 2006-07-06 Bide Martin J Bifunctionalized polyester material for surface treatment and biomodification
US7106821B2 (en) 2000-03-15 2006-09-12 Sony Corporation Data modulation method, data modulation device and communication device
US20060269008A1 (en) 1999-02-24 2006-11-30 Sony Deutschland Gmbh Receiving apparatus and synchronising method for a digital telecommunication system
US7145955B1 (en) 1999-04-23 2006-12-05 Sony Deutschland Gmbh Optimized synchronization preamble structure
US20070036235A1 (en) 1999-02-24 2007-02-15 Sony Deutschland Gmbh Transmitting apparatus and method for a digital telecommunication system
US7184725B2 (en) 2004-05-11 2007-02-27 Sony Deutschland Gmbh Pole switch down converter with symmetric resonator
US20070115827A1 (en) 2003-12-19 2007-05-24 Sony Deutschland Gmbh Wireless communication network architecture

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5990176A (en) 1997-01-27 1999-11-23 Abbott Laboratories Fluoroether compositions and methods for inhibiting their degradation in the presence of a Lewis acid
KR20000000479A (en) * 1999-10-27 2000-01-15 신창우 Skin for wig

Patent Citations (70)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5450456A (en) 1993-11-12 1995-09-12 Daimler Benz Ag Method and arrangement for measuring the carrier frequency deviation in a multi-channel transmission system
WO1998000946A2 (en) 1996-06-20 1998-01-08 The Board Of Trustees Of The Leland Stanford Junior University Timing and frequency synchronization of ofdm signals
US5732113A (en) * 1996-06-20 1998-03-24 Stanford University Timing and frequency synchronization of OFDM signals
EP0836303A2 (en) 1996-10-14 1998-04-15 Ntt Mobile Communications Network Inc. Reduction of peak to average power ratio in MCM systems
GB2320868A (en) 1996-12-03 1998-07-01 Ensigma Ltd Measuring coarse frequency offset of a multi-carrier signal
EP0869646A2 (en) 1997-04-01 1998-10-07 Lucent Technologies Inc. Complementary encoding and modulation for multicarrier transmission
US6438173B1 (en) 1997-08-05 2002-08-20 Infineon Technologies Ag Multicarrier transmission system for irregular transmission of data blocks
US6160791A (en) 1997-08-29 2000-12-12 Sony International (Europe) Gmbh Transmission system for the transmission of power control information in an OFDM system
US6731594B1 (en) 1997-09-04 2004-05-04 Sony International (Europe) Gmbh Transmission system for OFDM-signals with optimized synchronisation
US6160821A (en) 1997-11-05 2000-12-12 Sony International (Europe) Gmbh Synchronization of digital communication systems
US6535501B1 (en) 1997-11-07 2003-03-18 Sony International (Europe) Gmbh Transmission method and transmission apparatus for transmitting signals on the basis of a OFDM/TDMA-system in a GSM/system
US6803814B1 (en) 1997-12-18 2004-10-12 Sony International (Europe) Gmbh Demodulator and method for the demodulation of modulated RF signals
EP1014562A1 (en) 1997-12-18 2000-06-28 Sony International (Europe) GmbH Demodulator and method for the demodulation of modulated RF signals
US6650178B1 (en) 1997-12-18 2003-11-18 Sony International (Europe) Gmbh N-port direct receiver
US6674732B1 (en) 1998-02-13 2004-01-06 Sony Corporation Transmitting method, receiving method, transmitter, and receiver
US6567374B1 (en) 1998-02-18 2003-05-20 Sony International (Europe) Gmbh Data and pilot mapping in an OFDM system
US6567383B1 (en) 1998-02-18 2003-05-20 Sony International (Europe) Gmbh Header structure for TDD systems
US6545997B1 (en) 1998-02-22 2003-04-08 Sony International (Europe) Gmbh Transmission method and transmission apparatus for transmitting signals on the basis of a OFDM/TDMA-system with pilot symbols
US6470055B1 (en) 1998-08-10 2002-10-22 Kamilo Feher Spectrally efficient FQPSK, FGMSK, and FQAM for enhanced performance CDMA, TDMA, GSM, OFDN, and other systems
EP0982905A1 (en) 1998-08-28 2000-03-01 Sony International (Europe) GmbH Universal PSK modulation apparatus and method
EP0984595A1 (en) 1998-09-03 2000-03-08 Sony International (Europe) GmbH Blind modulation detection
EP0984596A1 (en) 1998-09-03 2000-03-08 Sony International (Europe) GmbH Adpative PSK system and timing offset compensation circuit
EP0987863A1 (en) 1998-09-17 2000-03-22 Sony International (Europe) GmbH Soft decision method and apparatus for 8PSK demodulation
US6452987B1 (en) 1998-11-25 2002-09-17 Lucent Technologies Inc. Fast start-up in discrete multi-tone (DMT) based communications system
US6609010B1 (en) 1998-11-30 2003-08-19 Sony International (Europe) Gmbh Dual frequency band transceiver
US6557139B2 (en) 1998-12-10 2003-04-29 Sony International (Europe) Gmbh Encoding apparatus and encoding method for multidimensionally coding and encoding method and decoding apparatus for iterative decoding of multidimensionally coded information
US6507733B1 (en) 1998-12-18 2003-01-14 Sony International (Europe) Gmbh Three port junction receiver
JP2000209183A (en) 1999-01-08 2000-07-28 Sony Internatl Europ Gmbh Method for generating synchronization burst, synchronization method adopting radio orthogonal frequency division multiplex system, transmitter and mobile communication unit adopting orthogonal frequency division system
EP1439677A1 (en) 1999-01-08 2004-07-21 Sony International (Europe) GmbH Synchronisation symbol structure for OFDM system
EP1705852A2 (en) 1999-01-08 2006-09-27 Sony Deutschland Gmbh Synchronisation symbol structure for OFDM system
EP1530336A1 (en) 1999-01-08 2005-05-11 Sony International (Europe) GmbH Synchronization preamble structure for OFDM system
EP1722527A1 (en) 1999-01-08 2006-11-15 Sony Deutschland Gmbh Synchronisation symbol structure for OFDM system
US6654339B1 (en) 1999-01-08 2003-11-25 Sony International (Europe) Gmbh Synchronization symbol structure using OFDM based transmission method
EP1018827A1 (en) 1999-01-08 2000-07-12 Sony International (Europe) GmbH Synchronisation structure for OFDM system
CA2291847A1 (en) 1999-01-08 2000-07-08 Sony International (Europe) G.M.B.H. Synchronization symbol structure using ofdm based transmission method
KR100712865B1 (en) 1999-01-08 2007-05-03 소니 도이치란드 게엠베하 Synchronization symbol structure using OFDM based transmission method
US20060269008A1 (en) 1999-02-24 2006-11-30 Sony Deutschland Gmbh Receiving apparatus and synchronising method for a digital telecommunication system
US7154975B1 (en) 1999-02-24 2006-12-26 Sony Deutschland Gmbh Receiving apparatus and synchronizing method for a digital telecommunication system
US20070036235A1 (en) 1999-02-24 2007-02-15 Sony Deutschland Gmbh Transmitting apparatus and method for a digital telecommunication system
EP1039661A1 (en) 1999-03-03 2000-09-27 Sony International (Europe) GmbH Multicast channel for a CDMA system
EP1037481A1 (en) 1999-03-15 2000-09-20 Sony International (Europe) GmbH Simultaneous transmission of random access bursts
US6674817B1 (en) 1999-04-12 2004-01-06 Sony International (Europe) Gmbh Communication device and distinguishing method for distinguishing between different data burst types in a digital telecommunication system
US7145955B1 (en) 1999-04-23 2006-12-05 Sony Deutschland Gmbh Optimized synchronization preamble structure
US6539215B1 (en) 1999-05-27 2003-03-25 Sony Corporation Down converter and demodulator using a three port junction
US6704562B1 (en) 1999-06-16 2004-03-09 Sony International (Europe) Gmbh N-port receiver with RF/LO isolation
US20040196916A1 (en) 1999-06-16 2004-10-07 Ralf Bohnke Optimized synchronization preamble structure
US6738443B1 (en) 1999-06-16 2004-05-18 Sony International (Europe) Gmbh Optimized synchronization preamble structure
EP1065855A1 (en) 1999-06-29 2001-01-03 Sony International (Europe) GmbH Adaptation of cyclic extensions in an OFDM communication system
US6735261B1 (en) 1999-07-08 2004-05-11 Sony International (Europe) Gmbh Calibration of a N-port receiver
US6728550B1 (en) 1999-07-09 2004-04-27 Sony International (Europe) Gmbh Coverage and cell extension in downlink power controlled wireless radio communication systems
US6748203B1 (en) 1999-09-29 2004-06-08 Sony International (Europe) Gmbh Three port structure with modulated LO signal
US6724246B2 (en) 2000-01-24 2004-04-20 Sony International (Europe) Gmbh Demodulation structure and method
US7106821B2 (en) 2000-03-15 2006-09-12 Sony Corporation Data modulation method, data modulation device and communication device
EP1162764A1 (en) 2000-06-05 2001-12-12 Sony International (Europe) GmbH Indoor wireless system using active reflector
EP1170916A1 (en) 2000-07-05 2002-01-09 Sony International (Europe) GmbH Channel estimator for OFDM system
EP1170917A1 (en) 2000-07-06 2002-01-09 Sony International (Europe) GmbH Method and device to provide an OFDM up-link using Time-Frequency interleaving
US7012882B2 (en) 2000-08-01 2006-03-14 Sony International (Europe) Gmbh Channel estimator for OFDM system
US6917580B2 (en) 2000-08-01 2005-07-12 Sony International (Europe) Gmbh Frequency reuse scheme for OFDM system
EP1207662A1 (en) 2000-11-20 2002-05-22 Sony International (Europe) GmbH OFDM system with antenna diversity in the transmitter and pre-equalisation
EP1207661A1 (en) 2000-11-20 2002-05-22 Sony International (Europe) GmbH Adaptive subcarrier loading
US6407846B1 (en) 2001-03-16 2002-06-18 All Optical Networks, Inc. Photonic wavelength shifting method
EP1276288A1 (en) 2001-07-10 2003-01-15 Sony International (Europe) GmbH Reference symbols for channel estimation with multicarrier transmission
EP1276251A1 (en) 2001-07-11 2003-01-15 Sony International (Europe) GmbH Method for calculating a weighting vector for an antenna array
EP1667341A1 (en) 2001-07-11 2006-06-07 Sony Deutschland GmbH Method for calculating a weighting vector for an antenna array
US20060148926A1 (en) 2002-01-25 2006-07-06 Bide Martin J Bifunctionalized polyester material for surface treatment and biomodification
EP1379026A1 (en) 2002-07-03 2004-01-07 Sony International (Europe) GmbH Dual rate wireless transmission system
US20070115827A1 (en) 2003-12-19 2007-05-24 Sony Deutschland Gmbh Wireless communication network architecture
US7184725B2 (en) 2004-05-11 2007-02-27 Sony Deutschland Gmbh Pole switch down converter with symmetric resonator
US20060045219A1 (en) 2004-08-24 2006-03-02 Zhaocheng Wang Backscatter interrogator reception method and interrogator for a modulated backscatter system
US20060133408A1 (en) 2004-11-15 2006-06-22 Juan Nogueira-Nine Beaconless communication system

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
Bauml R W et al: "Reducing The Peak-To-Average Power Ratio of Multicarrier Modulationby Selected Mapping" Electronics Letters, vol. 32, No. 22, Oct. 24, 1996 (Oct. 24, 1996), pp. 2056-2057, XP000643915.
Dinis R et al: "Carrier Synchronization with CEPB-OFDM" 1997 IEEE 47<SUP>th</SUP>Vehicular Technology Conference, Phoenix, May 4-7, 1997, vol. 3, No. Conf. 47, May 4, 1997 (May 4, 1997), pp. 1370-1374, XP000738586 Institute of Electrical and Electronics Engineers.
Mizoguchi et al, A Fast Burst Synchronization Scheme for OFDM, IEEE, pp. 125-129, 1998. *
Schmidl et al, Low-Overhead, Low-complexity [Burst] Synchronization for OFDM, IEEE, pp. 1301-1306, 1996. *
Schmidl T M et Al: "Low-Overhead, Low-Complexity Burst Synchronization For OFDM" 1996 IEEE International Conference On Communications (ICC), Converging Technologies For Tommorrow's Applications Dallas, Jun. 23-27, 1996, vol. 3, Jun. 23, 1996 (Jun. 23, 1996), pp. 1301-1306, XP000625022 Institute of Electrical & Electronics Engineers ISBN: 0-7803-3251-2.

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