Research On Channel Equalization Technique In Underwater Acoustic Communication

Underwater acoustic channel has been considered as instable with many unique characters which bring huge obstacle to underwater communication such as serious multipath effect, time varying and frequency-selective. Traditional time domain equalizing technique can be hardly used in OFDM (Orthogonal frequency division multiplexing) communication system or SC (Single Carrier) communication system. The goal to get high-rate, high credibility and great capability has become the direction of modern underwater communication research. Due to the particularity of underwater acoustic channel, efficient and reliable systems are required. Combine frequent domain equalization with spatial diversity equalization, the frequency select fading and multipath effect can be restrained and the system's performance can be improved. The new method can achieve high-speed reliable underwater communication, is one of the underwater communication develop direction.In order to overcome the co-channel interference, the main content is as follows:1. OFDM underwater acoustic communication system is based on the study of basic theory. Channel estimation in OFDM has been deeply researched, including LS and MMSE. The computer simulation is used to testify the ability of the above arithmetic.2. SC underwater acoustic communication system is based on the study of basic theory. The build of UW in SC-FDE and channel estimation based on UW have been deeply researched. The study in SC-FDE channel estimation includes ZF, MMSE and improved arithmetic.3. Three combination of spatial diversity has been studied, MRC (Maximum Ratio Combining), EGC (Equal Gain Combining), SC (Selection Combining). Particular attention has been paid on the spatial diverse technique in both OFDM and SC underwater communication system.4. Through experiment in the channel pool, the feasible of the combination in OFDM system and SC-FDE system has been testified.