Soft Decision Approaches for Blind Adaptive Decision Feedback Equalizer

• Main Authors: Sheng-Hui Liao, 廖盛惠
• Other Authors: Fu-Sheng Lu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/60781162149955816270

碩士 === 國立臺灣海洋大學 === 電機工程學系 === 93 === Because of multi-path and Doppler effect, the development of the underwater acoustic communication system is a challenging task. The optimum equalization and appropriate signal processing technique are needed to improve the quality of communications. In this thesis, the implementation algorithms based on the blind adaptive decision feedback equalization (BADFE), whose function can be automatically adjusted according to variations of channel, are investigated. The soft decision is combined with the BADFE to get a modified equalization scheme. The proposed method combines decision feedback, blind adaptive scheme, and the soft decision method at the same time. Therefore it can combat the distortion occurred in underwater communication channels without the need of the training sequence. The bit error rates and the transmission efficiency are improved. Computer simulation results indicate that the performances of the proposed method always has better convergence speed and lower bit error rate even in the bad channel and low SNR.