码率兼容QC-LDPC码在水声通信中的应用
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摘要
针对水声信道复杂多变、强多途和大起伏干扰等特点,提出采用码率兼容QC-LDPC码的自适应信道编码技术,以提高水声数据传输的可靠性和水声信道的信道吞吐率。建立了码率兼容QC-LDPC码在水声信道中的仿真模型,构造码率为1/2、2/3…5/6等一系列QC-LDPC码,在三种典型的水声信道中对其性能进行仿真。结果表明所设计的码率兼容QC-LDPC码在三种不同信道下可行有效,能较大地提高水声通信系统的性能。由于信道时延越长、信噪比越低,满足通信指标的码率就越低;并给出码率兼容QC-LDPC码在浅海水声信道中不同信噪比下满足通信性能指标的编码码率的查找表。码率兼容QC-LDPC码提高了水声通信的信道利用率,具有灵活的编译码性能,在水声自适应通信中具有很好的应用前景。
The underwater acoustic(UWA) channel is characterized as a complex variable, strong multipath and fluctuation interference channel. Adaptive channel coding techniques which use rate-compatible QC-LDPC(RC QC-LDPC) codes are proposed to enhance the reliability of UWA data transmission and channel throughput. A system simulation model including RC QC-LDPC codes for the UWA channels is built. With constructing a series code-rates(such as 1/2, 2/3, …, 5/6) of QC-LDPC codes, the performance of the system is simulated over three different kinds of UWA channels. The simulation results show that the designed RC QC-LDPC codes are feasible and effective, can dramatically improve the performance of UWA communication system, have good applicability in UWA channels. In the case that the worse the channel, due to longer channel delay and lower signal-to-noise ratio, the lower the code-rate is taken to meet system communication indicators. The lookup table(LUT) of the rate compatible QC-LDPC codes, which meet the communication indicators of the shallow water acoustic communication system under different signal-to-noise ratios, is given. The RC QC-LDPC codes with flexible encoding and decoding performances can improve the utilization of UWA communication channel and have good application prospects.
The underwater acoustic(UWA) channel is characterized as a complex variable, strong multipath and fluctuation interference channel. Adaptive channel coding techniques which use rate-compatible QC-LDPC(RC QC-LDPC) codes are proposed to enhance the reliability of UWA data transmission and channel throughput. A system simulation model including RC QC-LDPC codes for the UWA channels is built. With constructing a series code-rates(such as 1/2, 2/3, …, 5/6) of QC-LDPC codes, the performance of the system is simulated over three different kinds of UWA channels. The simulation results show that the designed RC QC-LDPC codes are feasible and effective, can dramatically improve the performance of UWA communication system, have good applicability in UWA channels. In the case that the worse the channel, due to longer channel delay and lower signal-to-noise ratio, the lower the code-rate is taken to meet system communication indicators. The lookup table(LUT) of the rate compatible QC-LDPC codes, which meet the communication indicators of the shallow water acoustic communication system under different signal-to-noise ratios, is given. The RC QC-LDPC codes with flexible encoding and decoding performances can improve the utilization of UWA communication channel and have good application prospects.
引文
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[3]白栎旸.LDPC码及其在浅海OFDM水声通信系统中的应用研究和DSP实现[D].厦门:厦门大学,2011.BAI Liyang.The research and DSP implementation of LDPC codes in OFDM underwater acoustic communication system[D].Xiamen:Xiamen University,2011.
[4]CHEN Y,XU X,ZHANG L,et al.Design and Application of dynamic coding in shallow water acoustic communications[C]//OCEANS,2012-Yeosu.IEEE,2012:1-6.
[5]李宗臣.码率兼容QC-LDPC码的设计和实现[D].西安:西安电子科技大学,2011.LI Zongcheng.Design and implementation of rate-compatable QC-LDPC codes[D].Xi’an:Xidian University,2011.
[6]Vajapeyam M,Vedantam S,Mitra U,et al.Distributed space–time cooperative schemes for underwater acoustic communications[J].IEEE Journal of Oceanic Engineering,2008,33(4):489-501.
[7]艾宇慧,高静.水声信道相关均衡器仿真研究[J].声学学报,1999,24(6):589-597.AI Yuhui,GAO Jing.A simulation study on correlation equalization of underwater acoustic channels[J].Acta Acustica,1999,24(6):589-597.
[8]陈海兰,胡晓毅,许茹,等.LMS算法和RLS算法在水声信道通信系统中应用的比较[J].无线通信,2007,242(3):18-19.CHEN Hailan,HU Xiaoyi,XU Ru,et al.Comparison of LMS algorithm and RLS algorithm using in the underwater acoustic communication system[J].Modern Electronics Technique,2007,242(3),18-19.