基于低密度奇偶校验码和脉冲位置调制的水下长距离光通信系统设计
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摘要
基于蒙特卡罗方法对水下激光脉冲长距离传输进行了模拟仿真。根据激光脉冲在水下的展宽情况及脉冲能量的变化规律,系统采用波长为532 nm、单脉冲能量为1 mJ的全固态脉冲激光器作为发射光源,采用口径为100 mm、接收视场角为15°的望远镜作为接收机。采用现场可编程门阵列(FPGA)进行低密度奇偶校验码(LDPC)编码和脉冲位置调制(PPM),经光电转换及采样后的接收端信号被发送到上位机进行后处理。最后,基于研制的实验系统开展了水池实验,以验证系统性能。理论与实验结果表明,在JerlovⅡ类水质条件下,误码率情况相同时LDPC编码与PPM相结合的通信系统可获得2.34 dB的编码增益。实验证明该系统可以实现水下130 m处误码率低于10~(-5)的可靠通信。
The long distance transmission of underwater laser pulse is simulated based on Monte Carlo method. According to the underwater broadening of laser pulse and the variation of pulse energy, the system uses a solid-state laser with the wavelength of 532 nm and the single pulse energy of 1 mJ as the emission source, and uses a telescope with the aperture of 100 mm and the field angle of 15° as the receiver. Low-density parity check codes(LDPC) and pulse-position modulation(PPM) are accomplished based on a field-programmable gate array(FPGA). The received signal after photoelectric conversion and sampling is transmitted to the host computer for post-processing. Finally, a pool experiment is used to verify the system performance based on the developed experimental system. The theoretical and experimental results demonstrate that the designed system with LDPC and PPM can obtain 2.34 dB coding gain at the same bit error rate(BER) under the condition of Jerlov Ⅱ water quality. Experiment shows that the system can achieve reliable underwater communication with BER of 10~(-5) and distance of 130 m.
The long distance transmission of underwater laser pulse is simulated based on Monte Carlo method. According to the underwater broadening of laser pulse and the variation of pulse energy, the system uses a solid-state laser with the wavelength of 532 nm and the single pulse energy of 1 mJ as the emission source, and uses a telescope with the aperture of 100 mm and the field angle of 15° as the receiver. Low-density parity check codes(LDPC) and pulse-position modulation(PPM) are accomplished based on a field-programmable gate array(FPGA). The received signal after photoelectric conversion and sampling is transmitted to the host computer for post-processing. Finally, a pool experiment is used to verify the system performance based on the developed experimental system. The theoretical and experimental results demonstrate that the designed system with LDPC and PPM can obtain 2.34 dB coding gain at the same bit error rate(BER) under the condition of Jerlov Ⅱ water quality. Experiment shows that the system can achieve reliable underwater communication with BER of 10~(-5) and distance of 130 m.
引文
[1] Kaushal H, Kaddoum G. Underwater optical wireless communication[J]. IEEE Access, 2016, 4: 1518-1547.
[2] Hu S Q, Mi L, Zhou T H, et al. Viterbi equalization for long-distance, high-speed underwater laser communication[J]. Optical Engineering, 2017, 56(7): 076101.
[3] Hu X H, Zhou T H, He Y, et al. Design and analysis of underwater optical communication transceiver system based on digital signal processor[J]. Chinese Journal of Lasers, 2013, 40(3): 0305003. 胡秀寒, 周田华, 贺岩, 等. 基于数字信号处理机的水下光通信收发系统设计及分析[J]. 中国激光, 2013, 40(3): 0305003.
[4] Li J W, Bi W H, Ren Y H. A method for simulating time-domain broadening of laser pulse in the underwater laser communication[J]. Optical Technique, 2012, 38(5): 569-572. 李仅伟, 毕卫红, 任炎辉. 水下激光通信中脉冲时域展宽的模拟计算方法[J]. 光学技术, 2012, 38(5): 569-572.
[5] Gabriel C, Khalighi M A, Bourennane S, et al. Investigation of suitable modulation techniques for underwater wireless optical communication[C]//2012 International Workshop on Optical Wireless Communications, October 22, 2012, Pisa, Italy. New York: IEEE, 2012: 13116994.
[6] Liang B, Chen W B. Error correction for optical PPM communication using combination of RS and trellis code modulation techniques[J]. Acta Photonica Sinica, 2008, 37(7): 1361-1364. 梁波, 陈卫标. 基于RS编码及网格编码调制的光PPM通信纠错技术[J]. 光子学报, 2008, 37(7): 1361-1364.
[7] Han Z, Feng G Z, Bian Y B. Performance comparison of short LDPC and RS codes based on BP algorithm[J]. Journal of Chongqing University of Posts and Telecommunications(Natural Science Edition), 2009, 21(1): 61-65. 韩壮, 酆广增, 卞银兵. 短LDPC码和RS码基于BP算法的性能比较[J]. 重庆邮电大学学报(自然科学版), 2009, 21(1): 61-65.
[8] Richardson T J, Urbanke R L. Efficient encoding of low-density parity-check codes[J]. IEEE Transactions on Information Theory, 2001, 47(2): 638-656.
[9] Liu M. Research on the transmission performance of LDPC and PPM in wireless laser communication system[D]. Xi′an: Xidian university, 2013. 刘敏. 无线激光通信系统中LDPC码和PPM的传输性能研究[D]. 西安: 西安电子科技大学, 2013.
[10] Gabriel C, Khalighi M A,Bourennane S, et al. Monte-Carlo-based channel characterization for underwater optical communication systems[J]. Journal of Optical Communications and Networking, 2012, 5(1): 1-12.
[11] Cochenour B, Mullen L, Muth J. Temporal response of the underwater optical channel for high-bandwidth wireless laser communications[J]. IEEE Journal of Oceanic Engineering, 2013, 38(4): 730-742.
[12] Cox Jr W C. Simulation, modeling, and design of underwater optical communication systems[M]. North Carolina State: North Carolina State University, 2012.
[13] Jerlov N G. Marine optics[M]. Amsterdam: Elsevier, 1976.
[14] Hu X H, Hu S Q, Zhou T H, et al. Rapid estimation of the maximum communication distance for an underwater laser communication system[J]. Chinese Journal of Lasers, 2015, 42(8): 0805007. 胡秀寒, 胡思奇, 周田华, 等. 水下激光通信系统最大通信距离的快速估计[J]. 中国激光, 2015, 42(8): 0805007.
[2] Hu S Q, Mi L, Zhou T H, et al. Viterbi equalization for long-distance, high-speed underwater laser communication[J]. Optical Engineering, 2017, 56(7): 076101.
[3] Hu X H, Zhou T H, He Y, et al. Design and analysis of underwater optical communication transceiver system based on digital signal processor[J]. Chinese Journal of Lasers, 2013, 40(3): 0305003. 胡秀寒, 周田华, 贺岩, 等. 基于数字信号处理机的水下光通信收发系统设计及分析[J]. 中国激光, 2013, 40(3): 0305003.
[4] Li J W, Bi W H, Ren Y H. A method for simulating time-domain broadening of laser pulse in the underwater laser communication[J]. Optical Technique, 2012, 38(5): 569-572. 李仅伟, 毕卫红, 任炎辉. 水下激光通信中脉冲时域展宽的模拟计算方法[J]. 光学技术, 2012, 38(5): 569-572.
[5] Gabriel C, Khalighi M A, Bourennane S, et al. Investigation of suitable modulation techniques for underwater wireless optical communication[C]//2012 International Workshop on Optical Wireless Communications, October 22, 2012, Pisa, Italy. New York: IEEE, 2012: 13116994.
[6] Liang B, Chen W B. Error correction for optical PPM communication using combination of RS and trellis code modulation techniques[J]. Acta Photonica Sinica, 2008, 37(7): 1361-1364. 梁波, 陈卫标. 基于RS编码及网格编码调制的光PPM通信纠错技术[J]. 光子学报, 2008, 37(7): 1361-1364.
[7] Han Z, Feng G Z, Bian Y B. Performance comparison of short LDPC and RS codes based on BP algorithm[J]. Journal of Chongqing University of Posts and Telecommunications(Natural Science Edition), 2009, 21(1): 61-65. 韩壮, 酆广增, 卞银兵. 短LDPC码和RS码基于BP算法的性能比较[J]. 重庆邮电大学学报(自然科学版), 2009, 21(1): 61-65.
[8] Richardson T J, Urbanke R L. Efficient encoding of low-density parity-check codes[J]. IEEE Transactions on Information Theory, 2001, 47(2): 638-656.
[9] Liu M. Research on the transmission performance of LDPC and PPM in wireless laser communication system[D]. Xi′an: Xidian university, 2013. 刘敏. 无线激光通信系统中LDPC码和PPM的传输性能研究[D]. 西安: 西安电子科技大学, 2013.
[10] Gabriel C, Khalighi M A,Bourennane S, et al. Monte-Carlo-based channel characterization for underwater optical communication systems[J]. Journal of Optical Communications and Networking, 2012, 5(1): 1-12.
[11] Cochenour B, Mullen L, Muth J. Temporal response of the underwater optical channel for high-bandwidth wireless laser communications[J]. IEEE Journal of Oceanic Engineering, 2013, 38(4): 730-742.
[12] Cox Jr W C. Simulation, modeling, and design of underwater optical communication systems[M]. North Carolina State: North Carolina State University, 2012.
[13] Jerlov N G. Marine optics[M]. Amsterdam: Elsevier, 1976.
[14] Hu X H, Hu S Q, Zhou T H, et al. Rapid estimation of the maximum communication distance for an underwater laser communication system[J]. Chinese Journal of Lasers, 2015, 42(8): 0805007. 胡秀寒, 胡思奇, 周田华, 等. 水下激光通信系统最大通信距离的快速估计[J]. 中国激光, 2015, 42(8): 0805007.