【作者】 王利平；

【导师】 孙大军；

【作者基本信息】 哈尔滨工程大学 ， 水声工程， 2010， 硕士

【摘要】 由于时变性和频率选择性衰落,水声信道是目前已知的最为复杂的信道。水声信道的这些特性阻碍了水下高可靠性、高速率通信系统的发展。传统的SC-TDE水声通信采用自适应判决反馈均衡的结构和相位跟踪的方法,随着通信速率的提高,符号持续时间变短,信道的时延扩展导致均衡器的复杂度升高,阻碍了其在高速水声通信中的进一步应用。OFDM因频谱利用率高、数据传输速率快、抗多径衰落能力强和实现简单成为近年来高速水声通信中的研究重点和热点之一,但其峰均比过高的弱点已逐渐成为系统实现和性能提高的瓶颈。SC-FDE技术,不仅可以有效对抗信道的频率选择性衰落,实现高速率、大容量的数据传输,而且能够避免SC-TDE系统复杂度过大和OFDM技术峰均比太高的不足,成为未来高速水声通信中的一项重要技术。本论文主要针对水声通信中SC-FDE的关键技术与应用进行了研究,所做的主要工作有:1.详细分析了SC-FDE系统中三种帧结构的优劣,重点研究了SC-FDE系统中参数帧周期的选取问题。2.SC-FDE水声通信系统中的多普勒估计与补偿。研究了三种多普勒估计算法,分别是块估计、CW脉冲测频估计和脉冲对估计,分析比较了不同算法的优缺点,在此基础上,论文提出了两种组合多普勒估计算法,并通过仿真验证了算法的性能。3.信道估计与均衡。分析比较了不同种类的信道估计与均衡算法并指出了如何选择SC-FDE系统的训练序列。另外,利用LS算法进行信道估计时,需要对其降噪,论文中提出采用变换域的方法对导频降噪。4.从系统原理、误码性能和峰均比等八个方面分析比较了水声SC-FDE和OFDM系统的性能。5.进行了水池实验,论证了基于SC-FDE水声通信的可行性和比较了SC-FDE和OFDM系统的性能。更多还原

【Abstract】 Underwater acoustic channel is the most challenging channel in the world for its time varying and frequency-selective characters. These facts obstacle the development of high-speed and reliable underwater data transmission. In the traditional SC-TDE underwater acoustic communication, the adaptive decision feedback equalizer coupled with phase tracking methods is adopted. As the communication rate is increasing, symbol duration is becoming shorter, and the equalizer is more complex with the channel delay spread, the application of traditional methods is hampered in the high-speed underwater acoustic communication. In recent years, OFDM becomes one of the researchful priorities and hotspots in the high-speed underwater acoustic communication due to its high spectral efficiency, high data rate, robustness against multi-path delay and simple implementation, but the high PAPR becomes one bottleneck gradually when the system is implemented and the performance is improved. SC-FDE allows an advantageous of high-speed data transmission in the frequency-selective fading channel, it avoids the complexity of SC-TDE and the high PAPR of OFDM. SC-FDE will become significant technology in the future underwater acoustic communication.In this thesis, key technologies and applications of SC-FDE are researched mainly for the underwater acoustic communication. The works done as follows:1. The advantages and disadvantages of three frame structures as well as the principles of how to choose the frame size are analyzed and studied detailedly.2. Doppler estimation and compensation in the SC-FDE underwater acoustic communication system. Three algorithms are studied and compared which are block doppler estimation and frequency measurement method based on CW pulse and pulse pairing doppler estimation. Based on the performance of different algorithms, two new kinds of combinatorial doppler estimation algorithms are proposed and the algorithm performances are validated through simulation. 3. Channel estimation and equalization. Analysis and comparison of the different types of channel estimation and equalization techniques are made out, and the principles of how to choose the training sequence are pointed out. In addition, noise reduction is a compulsory task in the channel estimation based on LS algorithm, Pilot noise reduction which is adopted in the transform domain is pointed out in this thesis.4. Analysis and comparison of mechanism, error probability, PAPR, and so on for SC-FDE and OFDM over underwater acoustic channel are done in this thesis.5. Through the trial in the tank, the feasibility of SC-FDE for the underwater acoustic communication is demonstrated, and the performance of SC-FDE and OFDM system is compared.更多还原