A Study On High-Speed Underwater Acoustic Communications

With the increasing of ocean exploitation, underwater acoustic (UWA) communications have received much attention and being one of the most challenging subjects in the research of underwater acoustics.Due to severe signal degradation caused by multipath propagation and high temporal and spatial variability of the channel conditions, UWA communication is difficult. In order to achieve high data rates on the severely band-limited UWA channels, band-width efficient phase-coherent modulation techniques must be employed, together with the equalization processing, to compensate for intersymbol interference and carrier phase fluctuation. In order to control error-rate, error-correction coding is made with permission of data rates.Designing high-speed UWA communication system is selected as major research issue. The main content in this paper are as follows:1. It is put forward that pseudo-noise(PN) code is select as synchronization signal. PN code has good pertinence and it can be made training code, so data rate is advanced.2. Error-correction technology, especially Reed-Solomon code is introduced. And its performances are compared by simulation3. The linear and nonlinear adaptive equalization arithmetic is studied elaborately. The realization of phase-coherent modulation is studied, especially the carrier recovery. In order to improve the system performance, we consider a receiver witch performs optimal phase synchronization and channel equalization jointly.