A Study Of Blind Equalizer Based On Cyclostationarity Second-Order Statistics

Blind equalization technology is a new adaptive technology without resorting to a training sequence, which only utilizes the prior information of transmitted signals to equalize the channel character, and makes sure that the output sequence approximates the transmitted signals as accurate as possible, which can compensate channel's non-idealized characteristic effectively and remove inter-symbol interference (ISI) in digital communication, In the communications field has an extremely important value. Cyclostationanty signal as a special kind of non-stationary signals, has a broad application prospects. Cyclostationanty signal exist in every corner of daily life, especially in communications, radar, sonar, and other fields.Blind equalization algorithm based on cyclostationarity was presented and developed in the middle of 90's. Among them, blind equalization technology based on SOS (second order statistics) is most popular. SOS convey not only amplitude but also complete phase information, so system can be equalized only by using output signal. The major contribution of this paper is summarized as follow:(1)This paper introduces the development tendency of blind equalization technology, expatiates the basic concept of Cyclostationarity signal, elaborats the first-order cyclic signal and the second-order cyclic signal, summarizes several kinds of algorithms based on Cyclostationarity second order statistics.(2)This paper sets up SIMO (Single-input Multiple-output) model, researches blind equalization algorithm of CMA (Constant Modulus Algorithm) and space algorithm combining, has carried on the computer simulation, analysis the performance of the algorithm.(3)According to the ZF (Zero-Forcing) criterion and the MMSE (Minimum Mean Square Error) criterion, this paper designs the ZF blind equalizer and the MMSE blind equalizer in predecessor's foundation. Then the simulation results are provided to show higher convergence speed and accuracy of the proposed algorithms compared with the existing blind equalizer. The comparisons with ZF blind equalizer of this paper improved, MMSE blind equalizer of this paper improved and CM equalizer.(4) This paper unifies the design concept of the MMSE blind equalizer, carries on the optimization to the equalizer delay, theoretically has carried on the inferential reasoning to the best equalizer, obtains the best dealy scope through the computer simulation.