波束形成技术及其在水声通信中的应用研究

发布时间：2018-10-05 14:48

【摘要】：多径哀落、频带有限和共信道干扰是影响宽带水声通信性能和容量的主要因素。OFDM技术具有较高的频谱利用率和良好的抗多径干扰能力,被广泛地用于解决宽带水声通信中频带有限和多径哀落对系统性能影响的问题。波束形成技术被认为是解决共信道干扰的重要途径,其主要功能是使接收系统形成空间指向性,进行空域滤波,抑制干扰或噪声,提高接收端信噪比,增加系统容量。将波束形成技术应用于OFDM水声通信中,在不需要额外的发射功率或频带的条件下,可以进一步增加OFDM水声通信系统的信道容量,提高系统通信距离。波束形成算法决定了波束形成器的性能。MVDR波束形成算法在干扰抑制和方位分辨力方面都具有明显优势,然而,MVDR是一种窄带信号处理方法,对于OFDM水声通信系统中的已调宽带信号并不适用,因此需要将窄带MVDR算法扩展到宽带,基于此本文重点研究了适用于OFDM水声通信的宽带MVDR波束形成算法,包括宽带非相干MVDR算法和STMV算法,在此基础上提出一种CBF和STMV级联式的改进算法,解决了STMV算法感兴趣方位波束谱背景变高的问题,并有效地降低了STMV算法的运算量,改进算法综合了CBF和STMV算法优点,具有算法稳健、分辨力高和抗干扰性能强等特点。在宽带MVDR波束形成算法研究的基础上,本文提出并设计了基于CBF、STMV以及改进STMV算法的OFDM水声通信系统,仿真结果表明采用波束形成技术的OFDM系统较传统的单水听器OFDM系统的通信性能得到了大幅提升,验证了波束形成技术在OFDM水声通信中应用的可行性和有效性,为进一步提高OFDM水声通信系统信道容量,改善通信性能,实现远程、高速水声通信探寻了新的技术途径。
[Abstract]:Multi-path fading, limited frequency band and co-channel interference are the main factors affecting the performance and capacity of broadband underwater acoustic communication. OFDM technology has high spectral efficiency and good anti-multipath interference capability. It is widely used to solve the problem of the influence of limited frequency band and multi-path lull on the system performance in broadband underwater acoustic communication. Beamforming technology is considered to be an important way to solve the co-channel interference. Its main function is to make the receiving system spatial directivity, spatial filtering, suppress interference or noise, improve the signal-to-noise ratio of the receiver, and increase the system capacity. Applying beamforming technology to OFDM underwater acoustic communication, the channel capacity and communication distance of OFDM underwater acoustic communication system can be further increased without additional transmitting power or frequency band. Beamforming algorithm determines the performance of beamformer. MVDR beamforming algorithm has obvious advantages in interference suppression and azimuth resolution. However, MVDR is a narrow band signal processing method. It is not applicable to the modulated wideband signal in the OFDM underwater acoustic communication system, so it is necessary to extend the narrowband MVDR algorithm to the wideband band. Based on this, this paper focuses on the broadband MVDR beamforming algorithm for OFDM underwater acoustic communication. It includes wideband incoherent MVDR algorithm and STMV algorithm. On this basis, an improved CBF and STMV cascade algorithm is proposed, which solves the problem that the STMV algorithm is interested in high background of azimuth beam spectrum, and effectively reduces the computational complexity of STMV algorithm. The improved algorithm combines the advantages of CBF and STMV algorithms, and has the advantages of robust algorithm, high resolution and strong anti-jamming performance. Based on the research of wideband MVDR beamforming algorithm, a OFDM underwater acoustic communication system based on CBF,STMV and improved STMV algorithm is proposed and designed in this paper. The simulation results show that the communication performance of the OFDM system using beamforming technology is greatly improved than that of the traditional single hydrophone OFDM system. The feasibility and effectiveness of the application of beamforming technology in OFDM underwater acoustic communication are verified. In order to further improve the channel capacity of OFDM underwater acoustic communication system, improve the communication performance, realize remote and high-speed underwater acoustic communication, a new technical approach has been explored.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.3

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