MIMO-OFDM水声通信系统中峰均功率比抑制技术研究

发布时间：2018-04-29 21:28

本文选题：多输入多输出正交频分复用 + 峰均功率比抑制　；参考：《哈尔滨工程大学》2014年硕士论文

【摘要】：浅海水声信道载波频率较低、多径干扰较强及高背景噪声的特性使其成为迄今为止通信最为困难的无线信道,并且水声通信中可利用的带宽资源非常有限。因此,寻找在提升信道容量的同时具有抗多径干扰能力的通信方式,是水声通信研究者们关注的重点。多输入多输出(MIMO)技术能够成倍提升通信系统容量及频带利用率,而无需增加系统的带宽,正交频分复用(OFDM)技术的抗码间干扰能力出众,在水声通信中将二者结合的方案成为近年来水声通信的新热点。MIMO-OFDM系统由于采用多载波调制方式,存在着峰均功率比(PAPR)较高的缺陷,这不但限制了系统对于发射功率的充分利用,而且提高了对功率放大器动态范围的要求,增加了系统成本,限制了MIMO-OFDM水声通信系统的进一步发展。因此,在信号进入放大器前抑制其峰均功率比显得至关重要。本文在回顾了 MIMO-OFDM系统中现有不同种类的峰均比抑制技术的基础上,深入研究了选择性映射(SLM)技术,论文主要的研究工作如下:1.仿真分析比较了不同种类的峰均比抑制技术,对其应用于水声通信中的可行性与优缺点进行了分析,为后文改进算法的提出奠定基础。2.针对SLM峰均比抑制技术需要传递边带信息、且冗余量较大的缺点,结合浅海水声信道的稀疏性,提出了两种基于信道检测的无边带信息改进SLM算法,设计了基于时域内插和压缩感知的两种相位序列检测器。改进SLM算法采用的相位序列检测器的核心思想是通过对信道特征的分析提取,实现对所选加扰相位序列的自主识别。仿真实验表明,上述两种改进SLM算法与接收端边带信息已知时的SLM算法在系统的误比特率(BER)性能上不相上下;经水池实验验证,改进算法可在信道状态信息及边带信息均未知的情况下完成相位序列序号的准确检测,保证了通信系统的可靠性与实时性。3.提出了基于判决反馈的无边带信息改进SLM算法,利用判决反馈思想与卷积码维特比译码的误差传递特性,通过对接收信号的对比检测得到所选加扰序列序号。通过计算机仿真给出了改进SLM算法与传统SLM算法的性能对比分析,不论是在高斯白噪声还是突发噪声环境中,改进SLM算法的边带信息正确率均高于传统SLM算法,有效地降低了 SLM算法中存在的边带信息解读风险,同时提高了系统的通信效率和频带利用率,适合通信带宽资源紧缺的水声通信。水池实验中良好的通信效果为仿真分析的结果提供了有力佐证。
[Abstract]:The characteristics of low carrier frequency, strong multipath interference and high background noise in shallow water acoustic channel make it the most difficult wireless channel to communicate, and the bandwidth available in underwater acoustic communication is very limited. Therefore, it is the focus of underwater acoustic communication researchers to find a communication mode that can resist multipath interference while increasing channel capacity. Multiple-Input-Multiple-Output (Mimo) technology can greatly improve the capacity and frequency band efficiency of communication system without increasing the bandwidth of the system. The OFDM (orthogonal Frequency Division Multiplexing) technology has excellent anti-inter-symbol interference (ISI) capability. In recent years, the scheme of combining the two in underwater acoustic communication has become a new hotspot in underwater acoustic communication. MIMO-OFDM system has the defect of high peak-to-average power ratio (PAPR) because of adopting multicarrier modulation, which not only limits the full utilization of transmission power in the system. Moreover, the requirement of dynamic range of power amplifier is increased, the system cost is increased, and the further development of MIMO-OFDM underwater acoustic communication system is restricted. Therefore, it is very important to suppress the PAPR before the signal enters the amplifier. On the basis of reviewing the existing PAPR suppression techniques in MIMO-OFDM systems, the selective mapping technique is studied in this paper. The main work of this paper is as follows: 1. The feasibility, advantages and disadvantages of different PAPR suppression techniques in underwater acoustic communication are analyzed by simulation, which lays a foundation for the later improved algorithms. 2. Aiming at the disadvantage of SLM peak-to-average ratio (PAPR) suppression technology which needs to transmit sideband information and has a large amount of redundancy, combining with the sparsity of shallow water acoustic channel, two improved SLM algorithms based on channel detection are proposed. Two phase sequence detectors based on time domain interpolation and compression sensing are designed. The core idea of the phase sequence detector used in the improved SLM algorithm is to realize the autonomous recognition of the selected scrambling phase sequences by analyzing and extracting the channel features. The simulation results show that the performance of the two improved SLM algorithms is comparable to that of the SLM algorithm when the sideband information of the receiver is known. The improved algorithm can accurately detect the sequence number of phase sequences when both channel state information and sideband information are unknown, which ensures the reliability and real-time performance of the communication system. An improved SLM algorithm based on decision feedback is proposed in this paper. By using the idea of decision feedback and the error transfer characteristic of convolutional code Viterbi decoding, the sequence number of scrambled sequence is obtained by comparing and detecting the received signal. The performance of the improved SLM algorithm and the traditional SLM algorithm is compared with that of the traditional SLM algorithm by computer simulation. In the environment of Gao Si white noise or burst noise, the improved SLM algorithm has a higher sideband information accuracy than the traditional SLM algorithm. It can effectively reduce the risk of sideband information interpretation in SLM algorithm, improve the communication efficiency and frequency band efficiency of the system, and is suitable for underwater acoustic communication with scarce communication bandwidth. The good communication effect in the tank experiment provides strong evidence for the result of simulation analysis.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.3

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