Research On Fractionally Spaced Blind Algorithm For Underwater Acoustic Channel

Blind equalization techniques can overcome multipath fading caused by inter-symbol interference (ISI), has become a hot research topic in underwater acoustic communication.Fractionally spaced equalizer oversampling the channel output for channel equalization to provide sufficient diversity, access to more and more detailed channel information, equalizer convergence performance was significantly better than the baud spaced.fractionally spaced blind equalization Principles and algorithms for underwater acoustic channel in-depth study, the main contents are as follows:(1) The theoretical analysis of the convergence performance of the T/2fractionally spaced constant modulus algorithm analysis of different factors on theconvergence performance of the simulation ofunderwater acoustic channel.(2) For the shortcomings of the traditional constant modulus and the modified constant modulus algorithm for steady-state mean square error is higher, on the basis of the stop-and-go algorithm, a new blind equalization of stop-and-go constant modulus and the modified constant modulus is proposed (SAGCMA and SAGMCMA). The theoretical analysis and simulation have proved that the improved algorithms are altered the error function, the effects of error equalization are reduced, and the steady-state mean square error is lessened, so the improved algorithm is suitable for higher accuracy of the occasion. In addition, the drawback of slow convergence of the above two methods in eye closure can overcome by the Run-and-go algorithm. The run-and-go algorithm contains statistical and instantaneous information of the transmission code, and adaptive control area, so the algorithm can speed up the convergence rate, at the same time can get a lower steady-state mean square error.(3) Research on different tap interval value on the convergence performances. On the basis of the analysis of the T/P fractionally spaced system, the T/P fractionally spaced is divided into two cases which P to take a power of2and non-power of2studied. T/4、T/8and T/3fractionally spaced multi-channel system models are derived respectively. The study found that P to take two power fractionally spaced subchannels with the following laws:All the subchannels of T/(2P) fractionally spaced can be obtained by the subchannels of T/P fractionally spaced, and all the subchannel to comply with certain laws of arrangement. Finally, the underwater acoustic channel model, a simulation analysis of the proposed T/P fractionally spaced blind equalization algorithm.