串行级联脉冲位置调制码辅助的时隙同步技术

针对深空光脉冲位置调制(PPM)通信，基于最大期望(EM)定时误差估计原理，研究了一种基于串行级联脉冲位置调制(SCPPM)码辅助的光PPM时隙同步的解决方案。由于标准的SCPPM译码方法无法获得EM估计时所需的期望值，因此提出一种将SCPPM译码输出的软信息转换为PPM各时隙期望值的方法。由SCPPM译码输出先进行硬判决，再通过累加模块获得累加器状态；根据该状态选择下一个PPM映射方式，进而获得各PPM时隙的概率及期望；最后利用EM算法预测时钟偏差值从而获得最佳采样点。仿真结果表明，对于2倍PPM时隙频率的异步采样信号，当时钟误差在-0.5～0.5个PPM时隙范围内时，此方法能有效实现PPM时隙同步。

Abstract

Aiming at deep space optical pulse position modulation (PPM) communications, based on the principle of expectation-maximization (EM) timing error estimation, a new solution of optical PPM slot synchronization based on serial concatenated pulse position modulation (SCPPM) code is studied. Due to that the expected value of EM estimation can not be got by the standard SCPPM decoding method, a method to convert the soft information output from SCPPM decoder to the expected value of each PPM slot is proposed. Firstly, the hard decision of output from the SCPPM decoder is made, and the accumulator state through accumulation module is got. Then, a mapping method according to the former accumulator state is chosen, and the probability and expectation of each PPM slot is obtained. Finally, EM algorithm is used to predict the clock offset and then to obtain the best sampling point. According to the simulation results, for the asynchronous sampling signal with two times PPM slot frequency, the proposed method can effectively achieve the PPM slot synchronization under the condition of the clock error among －0.5~0.5 PPM slots.

参考文献

[1] 任鑫, 李洪祚, 王岩, 等. 脉冲位置调制对脉冲式光纤激光器调制速率的影响[J]. 光学学报, 2014, 34(7): 0706002.

Ren Xin, Li Hongzuo, Wang Yan, et al. Effect for modulation rate of pulsed fiber laser on pulse position modulation[J]. Acta Optica Sinica, 2014, 34(7): 0706002.

[2] 刘宏展, 廖仁波, 孙建锋, 等. 无线光通信新型组合脉冲调制性能分析[J]. 光学学报, 2015, 35(7): 0706004.

Liu Hongzhan, Liao Renbo, Sun Jianfeng, et al. Performance analysis of new hybrid pulse modulation scheme in optical wireless system[J]. Acta Optica Sinica, 2015, 35(7): 0706004.

[3] Rouissat M, Borsali R A, Chikh-Bled M E. AH-MPPM a new modulation scheme for free space optical communication systems[C]. 8th International Conference on High-Capacity Optical Networks and Emerging Technologies, 2013, 35(2): 188-192.

[4] Moision B, Hamkins J. Coded modulation for the deep-space optical channel: serially concatenated pulse-position modulation[R]. The Interplanetary Network Progress Report 42-161, 2005: 1-26.

[5] Noels N, Lottici V, Dejonghe A, et al. A theoretical framework for soft-information-based synchronization in iterative (Turbo) receivers[J]. EURASIP Journal on Wireless Communications and Networking, 2005: 117-129.

[6] Man X, Zhai H T, Yang J, et al. Improved code-aided symbol timing recovery with large estimation range for LDPC-coded systems[J]. IEEE Communications Letters, 2013, 17(5): 1008-1011.

[7] 周相超, 赵旦峰, 薛睿. 深空通信系统中高阶LDPC码的软定时同步算法[J]. 哈尔滨工业大学学报, 2014, 46(3): 110-114.

Zhou Xiangchao, Zhao Danfeng, Xue Rui. Soft timing synchronization algorithm for LDPC codes on GF(q) in deep space communication[J]. Journal of Harbin Institute of Technology, 2014, 46(3): 110-114.

[8] 赵旦峰, 周相超, 钱晋希, 等. 残留频偏下LDPC-MSK系统码辅助载波同步算法[J]. 系统工程与电子技术, 2012, 34(9): 1900-1905.

Zhao Danfeng, Zhou Xiangchao, Qian Jinxi, et al. Code-aided carrier synchronization for LDPC-MSK systems in presence of residual frequency offset[J]. Systems Engineering and Electronics, 2012, 34(9): 1900-1905.

[9] 史治平, 唐发建, 晏辉, 等. 极低信噪比下的导频联合编码辅助载波同步算法[J]. 电子与信息学报, 2011, 33(10): 2506-2510.

Shi Zhiping, Tang Fajian, Yan Hui, et al. Joint assisted carrier synchronization algorithm by pilot and code at extremely low SNR[J]. Journal of Electronies & Information Technology, 2011, 33(10): 2506-2510.

[10] Quirk K J, Srinivasan M. Optical PPM demodulation form slot-sampled photon counting detectors[C]. IEEE Military Communications Conference, 2013: 1634-1638.

[11] 刘磊, 肖江南, 唐进, 等. 相干光差分正交相移键控系统中改进的Gardner定时恢复方法实验研究[J]. 光学学报, 2013, 33(4): 0406002.

Liu Lei, Xiao Jiangnan, Tang Jin, et al. Experimental research on timing recovery of a differential quadrature phase shift keying coherent optical transmission system based on an improved Gardner algorithm[J]. Acta Optica Sinica, 2013, 33(4): 0406002.

[12] 张鼎臣, 周小林, 杜建红. 自由空间光通信中的PPM迭代软解调算法[J]. 计算机工程, 2013, 39(4): 1-4.

Zhang Dingchen, Zhou Xiaolin, Du Jianhong. PPM iterative soft demodulation algorithm in free-space optical communication[J]. Computer Engineering, 2013, 39(4): 1-4.

[13] 胡昊, 王红星, 徐建武, 等. 无线光通信中一种迭代解调的比特交织乘积编码脉冲位置调制[J]. 光学学报, 2011, 31(8): 0806004.

Hu Hao, Wang Hongxing, Xu Jianwu, et al. Bit interleaved product coded pulse position modulation with iterative demodulation for free-space optical communication[J]. Acta Optica Sinica, 2011, 31(8): 0806004.

向劲松, 吴涛, 黄胜, 刘焕淋. 串行级联脉冲位置调制码辅助的时隙同步技术[J]. 光学学报, 2016, 36(8): 0806006. Xiang Jingsong, Wu Tao, Huang Sheng, Liu Huanlin. Slot Synchronization Aided by Serial Concatenated Pulse Position Modulation Code System[J]. Acta Optica Sinica, 2016, 36(8): 0806006.

串行级联脉冲位置调制码辅助的时隙同步技术

关于本站 Cookie 的使用提示

全站搜索

串行级联脉冲位置调制码辅助的时隙同步技术

相关论文

相关资讯

关于本站 Cookie 的使用提示

全站搜索