一种基于APPA的码辅助载波同步算法

徐俊辉; 刘朝生; 张忠培

doi:10.3724/SP.J.1146.2008.01565

一种基于APPA的码辅助载波同步算法

doi: 10.3724/SP.J.1146.2008.01565

基金项目:

国家自然科学基金(60602008)和国家863计划项目(2006AA01Z269，2007AA01Z299)资助课题

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出版历程
- 收稿日期: 2008-11-26
- 修回日期: 2009-06-15
- 刊出日期: 2009-12-19

A Code-Aided Carrier Synchronization Algorithm Based on APPA

摘要

摘要: 在低信噪比环境下，小的频偏和相偏的存在会使Turbo编码系统的译码性能恶化，所以必须结合迭代译码系统，对信号的残留频偏和相差进行估计。该文提出一种改进的残留频偏载波相位估计算法后验概率辅助(APPA)相位估计，该算法将译码器输出的外信息用于辅助迭代的相位估计。环路滤波器将相位误差信号转换成控制信号，控制数控振荡器的输出，这样可以得到待估计的相位误差。仿真表明，在极低信噪比下(比如，SNR-7.8 dB)该算法在同时存在频偏和相偏的时候能正常工作，其性能非常接近理想同步条件下的性能。
- 后验概率辅助;Turbo码;载波同步
Abstract: The residual frequency and phase offset will make obvious degradations on the Turbo decoding performance under low SNR conditions, and it must introduce some coded-aided carrier synchronization algorithm for the phase estimation. In this paper, an improved residual carrier frequency offset estimation algorithm based on APPA(A Priori Probability Aided)phase estimation is proposed. It uses the extrinsic information obtained from the turbo decoder to aid an iterative phase estimation process. And the loop filter converts the phase error signal to a control word that is used to bias the numerically controlled oscillator. The simulation results show that the algorithm performs successfully with small frequency offset and phase offset at very low SNR(for example, SNR-7.8 dB) and its performance is very close to the optimally synchronized system.

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参考文献(1)

Gallager R G. Low density parity check codes [J]. IRETransations on Information Technology, 1962, 8(3): 208-220.[2]Berrou C, Blavieux A, and Thitimajshima P. Near Shannonlimit error-correcting coding and decoding: Turbo-codes[C].Proceedings of 1993 IEEE International Conference onCommunications, Geneva: ICC, 1993: 1064-1070.[3]Kenneth, Andrews S, Dolinar S, and Jones R, et al.. Thedevelopment of turbo and LDPC codes for deep-spaceapplications [J].Proceedings of the IEEE.2007, 95(11):2142-2156[4]Nele N and Heidi S. Performance analysis of ML-basedfeedback carrier phase synchronizers for coded Signal[J].IEEE Transactions on Signal Processing.2007, 55(3):1129-1136[5]Noels N, Herzet C, and Dejonghe A. Turbo synchronization:an EM algorithm interpretation [J]. IEEE InternationalConference on Communications, Alaska, 2003, 4(11-15):2933-2937.[6]Kim Pansoo, Choi Kwonhue, and Song Yun-Jeong. Jointcarrier recovery and Turbo decoding method for TDMAburst MODEM under very low SNRs[C]. VehicularTechnology Conference, VTC 2006 -Spring, Piscataway, 2006,Vol.5: 2198-2200.[7]Pan Xiao-hui, Liu Ai-jun, and Zhang Bang-ning, et al..Code-aided iterative carrier estimation in presence of residualfrequency offset [J]. Journal of System Simulation, 2008,20(2): 404-409.[8]Oh Wangrok and Cheun Kyungwhoon. Joint decoding andcarrier phase recovery algorithm for Turbo codes [J]. IEEECommunications Letters, 2001, 5(9): 375-377.[9]Rahamim Y, Freedman A, and Reichman A, et al.. MLiterative soft-decision-directed (ML-ISDD): A carriersynchronization system for short packet turbo codedcommunication [J]. IEEE Transactions on Signal Processing,2008, 56(7): 1169-1177.[10]Valles E, Jones C, and Villasenor J, et al.. Carrier and timingsynchronization of BPSK via LDPC code feedback [C]. Proc.IEEE. Asilomar Conference on Signal System and Computers,Asilomar, 2006: 2177-2181.[11]Zhang Li and Burr A G. Iterative carrier phase recoverysuited to Turbo-coded systems [J].IEEE Transactions onWireless Communications.2004, 3(6):2267-2276

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