Journal of Jilin University(Engineering and Technology Edition) ›› 2022, Vol. 52 ›› Issue (11): 2728-2734.doi: 10.13229/j.cnki.jdxbgxb20210352

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A new algorithm for OFDM timing synchronization and hardware implementation optimization

Lei PAN1,2,3(),Lan CHEN1,Sheng-li ZHU4,Wen-yan TONG5   

  1. 1.Institute of Microelectronics，Chinese Academy of Sciences，Beijing 100029，China
    2.University of the Chinese Academy of Sciences，Beijing 100039，China
    3.Beijing Key Laboratory of Three Dimensional and Nanometer Integrated Circuit Design Automation Technology，Beijing 100029，China
    4.Beijing Ikingtec Intelligent Technology Co. ，Ltd. ，Beijing 100007，China
    5.Liaoning Industry and Trade School，Shenyang 110122，China
  • Received:2021-04-22 Online:2022-11-01 Published:2022-11-16

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Abstract:

This article introduces an algorithm for orthogonal frequency divisition multiplexing（OFDM） timing synchronization—correlated peak slope detection algorithm. In a multipath channel environment， due to multipath reflection， the front part of the cyclic prefix that OFDM complies with will be affected by Inter Symbol Interference（ISI）. This paper innovatively proposes a time-domain timing synchronization algorithm. The algorithm determines the arrival position of the last path by detecting the slope of the correlation peak， and estimates the dispersion length of the multipath channel， so that the subsequent fast Fourier transform（FFT） window position avoids the ISI， and provides a reference value for the selection of filter coefficients for channel estimation. This algorithm is also very suitable for application in multipath channels with equal strength and two paths. Finally， the algorithm was simulated with MATLAB and compared with the classic algorithm， which proved that the algorithm can better avoid ISI in the case of low signal-to-noise ratio. In addition， for a low-cost IoT communication system similar to NB-IOT that uses OFDM technology， this article simplifies the algorithm， which can reduce the cost of implementing the baseband chip of the IoT terminal and reduce the cost of the terminal.

Key words: orthogonal frequency divisition multiplexing（OFDM）, timing synchronization, correlated peak slope, digital IC design optimization, base band ASIC

CLC Number: 

  • TN929.5

Fig.1

Influence of multipath channel on OFDM symbol on time axis"

Fig.2

Beacon composed of PN sequence"

Fig.3

Ideal correlation peak under the condition of equal-strength two-path channel with no noise and no Doppler frequency offset"

Fig.4

Transmission data structure for simulation"

Table 1

TU channel model"

路径序号时延/μs增益/dB
10-3
20.20
30.5-2
41.6-6
52.3-8
65.0-10

Fig.5

Comparison of timing probability statistics under TU channel"

Table 1

CT-8 channel model"

路径序号时延/μs增益/dB
10-18
21.80
32.0-20
43.6-20
57.5-10
631.80

Fig.6

Comparison of timing probability statistics under CT-8 channel"

Table 3

Random channel model constraints"

随机信道条件数值
信噪比（SNR）/dB10
多径数/径1~10
延时的随机范围/μs0~30
增益的随机范围/dB0~-20

Fig.7

Random channel timing position statistics"

Table 4

Non-last path timing windowing energy loss statistics under random channel model"

早于最后一径的采样点数损失能量百分比/%
32.3915
273.1014
1041.7351

Fig.8

Random channel timing position statistics of S.C.A algorithm"

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[1] XU Wei-yang, ZHOU Jie, WANG Yu-qing, WU Yu-cheng. OFDM timing synchronization algorithm based on channel estimation [J]. 吉林大学学报(工学版), 2016, 46(1): 290-295.
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