【作者】 刘云涛；

【导师】 杨莘元；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2004， 博士

【摘要】 水声通信技术是解决水下信息传送和处理的关键技术，它广泛应用于水下自治机器人(AUV)、水下通讯网路，遥控，和目标检测等领域。在水下通信的初期，扩频和多进制频率调制(MFSK)是主要的调制方式，很适合几比特每秒和几百比特每秒的低、中速中远距离水下通信。当进行高速水下通信时，由于水下信道的频带有限，扩频和MFSK调制方式无法解决高速率信息传输和可利用信道频带窄的矛盾。因此，从上世纪九十年代开始，频谱利用率高的多进制相位调制(MPSK)便成为了高速水下通信的研究热点。 针对水下信道存在随机时变衰落、多径干扰严重、带宽受限等特点，本文对相位相干水下高速无线通信中的关键技术进行了研究，这些技术的应用目的是在满足一定误码率要求的情况下，使水下通信的作用距离与信息速率的乘积达到最大。 本文的主要工作和贡献如下： 第一，对相位调制水下高速通信中的关键技术，包括信道仿真、信道编码、自适应均衡技术、分集技术、Doppler补偿算法进行了研究。阐述了这些算法的基本原理和作用，并根据高速水下通信(High Speed Underwater Communication HSUWC)的系统要求，分别给出这些算法在水下信道的仿真性能分析。 第二，在系统发送端的发射机波形设计中，本文提出了一种能够抑制多径干扰的基带波形设计方法。该方法是通过保持传输信息速率不变，在成形滤波器第二个零点叠加信号来实现的。以QPSK方式采用这种波形结构进行了仿真实验和湖水试验，获得了比传统的波形结构更低的误码率。试验结果表明该波形设计方法能够提高水下通信系统的性能。 第三，在系统接收端的处理算法中，本文提出角度分集的算法。该算法的实现方式是采用预置多波束算法形成若干路不相关的波束信号，然后进行哈尔滨工程大学博士学位论文自适应空时判决反馈均衡处理。在无信道编码的实际的水下QPsK调制高速无线通信系统中把这种算法与空间分集算法进行了相同条件下的湖水试验，试验结果表明该算法在水下无线通信系统中是可行的并获得了比空间分集算法低十倍的误码率，文中给出了角度分集算法与空间分集算法的试验对比结果。 第四，在对这些算法性能仿真的基础上，搭建和实现了一套QPsK水下高速无线通信软硬件系统，并使用该系统进行了三次湖试，对实现的HSUWC关键技术算法进行了试验测试和验证，并对试验结果进行了分析。关键词:高速水下通信;相干解调;分集接收;自适应均衡更多还原

【Abstract】 Underwater acoustic communication technology is the key for solving the transmission and processing of underwater information, and it’s widely used in the fields of AUV, underwater communication network, telemetry, and target detection. Spread spectrum and MFSK modulation is primary modulation modes in beginning of underwater communication. They suit underwater communication of middle-long distance with transmission rate of several bps and several hundred bps. Because of limited frequency band of channel, spread spectrum and MFSK modulations can not resolve that high speed transmission is in contradiction with limited frequency band. So, MPSK become research hot point of high speed underwater communication, because MPSK has higher frequency validity since 1990’s.According to characters of underwater channel and the development of communication technology, the key technologies of phase coherent underwater high speed communication are researched in this paper. These technologies are used to overcome characters of underwater channel, including stochastic time fading, serious multipath interference, limited frequency band. Every technology need to be meticulously researched in underwater high speed communication system, in order to maximum the product of transmission distance and information transmission rate on condition that error code rate is satisfactory.The main content and contributions in this paper are as follows:Firstly, key technologies of phase coherent underwater high speed communication are discussed in this paper. The key technologies include channel code, adaptive equalizing, diversity technology, compensation algorithm of Doppler. Theory and emulation results in different hydrologic condition of thesetechnologies are provided.Secondly, this paper proposed a method of waveform design that can restrain multipath interference. This method is implemented by folding signal at second zero point, keeping invariant information rate. Emulate experiments and lake experiment obtained lower error code rate than traditional waveform design method using this waveform structure with MPSK. The results of experiment show that the method of waveform design can improve performance of underwater communication system.Thirdly, Based on space diversity technology, this paper proposed a receive algorithm, that is angle diversity combined with spatio-temporal decision feedback equalizer. This paper also introduced implement method of the algorithm. Experiment results of space diversity and angle diversity are compared, and lower error code rate is obtained by using angle diversity algorithm.Fourthly, Based on emulation and implement of these technologies, a QPSK underwater high speed communication system is implemented. We completed three times lake experiments using this system, which validated the feasibility and validity of these algorithms. In the end, experiment results were analysed.更多还原