TIMING SYNCHRONIZATION APPARATUS AND METHOD FOR MULTI-CARRIER MODULATION SIGNALS

• US 20150117576A1
• Filed: 10/27/2014
• Published: 04/30/2015
• Est. Priority Date: 10/31/2013
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: YAN, Weizhen, LI, Lei, TAO, Zhenning
• Granted Patent: US 9,258,166 B2
• Time in Patent Office: Days
• US Class Current: 375/348
• CPC Class Codes: H04L 25/03821 Inter-carrier interference cancellation [ICI]
• CPC Class Codes: H04L 27/2662 Symbol synchronisation
• CPC Class Codes: H04L 27/2665 Fine synchronisation, e.g. by positioning the FFT window
• CPC Class Codes: H04L 27/2672 Frequency domain
• CPC Class Codes: H04L 27/2675 Pilot or known symbols
• CPC Class Codes: H04L 7/0041 Delay of data signal

Abstract

Embodiments of the present invention provide a timing synchronization apparatus and method for multi-carrier modulation signals. Wherein the apparatus includes: a predicting unit configured to denoise delay of symbols received before a currently received symbol, and to predict delay of the currently received symbol or of a symbol received after the currently received symbol according to the denoised symbol delay and a sampling clock frequency offset; and a timing synchronization unit configured to perform timing synchronization according to a predicted value of the delay of the currently received symbol or of the symbol received after the currently received symbol. With the apparatus and method, a signal to noise ratio of multi-carrier modulation signals may be effectively improved, and an effect of a timing error on a communication system may be lowered, thereby improving performance of the communication system.

Claims

1. A timing synchronization apparatus for multi-carrier modulation signals, comprising:

a predicting unit configured to denoise delay of symbols received before a currently received symbol, and to predict a predicted delay of the one of the currently received symbol and a symbol received after the currently received symbol according to a denoised symbol delay and a sampling clock frequency offset; and

a timing synchronization unit configured to perform timing synchronization according to a predicted value of the predicted delay of one of the currently received symbol and the symbol received after the currently received symbol.

2. The apparatus according to claim 1, wherein the timing synchronization unit comprises:

a remaining symbol delay correcting unit configured to correct remaining symbol delay according to the one of the predicted value of the predicted delay of the currently received symbol and the symbol received after the currently received symbol;

wherein the predicting unit obtains delay of the symbols received before the currently received symbol before the remaining symbol delay correcting unit corrects the remaining symbol delay.

3. The apparatus according to claim 1, wherein the predicting unit comprises:

a denoising unit configured to denoise delay of the symbols received before the currently received symbol; and

a calculating unit configured to predict the predicted delay of the one of the currently received symbol and the symbol received after the currently received symbol according to the denoised symbol delay and the sampling clock frequency offset;

wherein the denoising unit comprises one of;

an average value calculator configured to calculate average delay of the symbols received before the currently received symbol; and

an infinite impulse response filter configured to perform infinite impulse response filtering to the delay of the symbols received before the currently received symbol.

4. The apparatus according to claim 3, wherein,

the calculating unit calculates the predicted value of the predicted delay of the one of the currently received symbol and the symbol received after the currently received symbol according to the average delay and a delay offset caused by the sampling clock frequency offset, and the infinite impulse response filtered delay and a delay offset caused by the sampling clock frequency offset.

5. The apparatus according to claim 4, wherein the calculating unit calculates the predicted value of the predicted delay of the one of the currently received symbol and of the symbol received after the currently received symbol according to formula (1) below:

{circumflex over (τ

)}_P,j={circumflex over (τ

)}_middle−

(M+j)(2N_SC+N_CP)Δ

f_s/f_s² 

 

(1)

where, M>

0, and j is a positive integer;

when j=1, {circumflex over (τ

)}_P,j denotes the delay of the currently received symbol, and when j>

1, {circumflex over (τ

)}_P,j denotes the delay of a j-th symbol received after the currently received symbol;

{circumflex over (τ

)}_middle denotes one of the average delay and the infinite impulse response filtered delay;

N_SC denotes a number of subcarriers;

N_CP denotes a number of cyclic prefixes;

f_s denotes a sampling clock frequency; and

Δ

f_s denotes the sampling clock frequency offset.

6. A receiver, comprising the apparatus as claimed in claim 1.

7. A timing synchronization method for multi-carrier modulation signals, comprising:

denoising delay of symbols received before a currently received symbol, and predicting delay of one of the currently received symbol and a symbol received after the currently received symbol according to a denoised symbol delay and a sampling clock frequency offset; and

performing timing synchronization according to a predicted value of predicted delay of one of the currently received symbol and of the symbol received after the currently received symbol.

8. The method according to claim 7, wherein the performing timing synchronization according to a predicted value of the delay of the currently received symbol or of the symbol received after the currently received symbol comprises:

correcting remaining symbol delay according to the predicted value of the one of the predicted delay of the currently received symbol and the symbol received after the currently received symbol;

wherein delay of the symbols received before the currently received symbol is obtained before correcting the remaining symbol delay.

9. The method according to claim 7, wherein the denoising delay of symbols received before a currently received symbol comprises one of:

calculating average delay of symbols received before the currently received symbol; and

performing infinite impulse response filtering to the delay of the symbols received before the currently received symbol.

10. The method according to claim 9, wherein,

predicting delay of the one of the currently received symbol and a symbol received after the currently received symbol according to the denoised symbol delay and a sampling clock frequency offset comprises:

calculating the predicted value of the predicted delay of the one of the currently received symbol and the symbol received after the currently received symbol according to the average delay and a delay offset caused by the sampling clock frequency offset, and the infinite impulse response filtered delays and a delay offset caused by the sampling clock frequency offset.