Interferences Suppression For Frequency Domain Equalization System Over Fast Time Varying Fading Environment

The mobile broadband wireless communication system typically needs to address the interference caused by doubly selective of time-varying fading channel with the limited spectrum. Thus, equalization algorithm for interference suppression of doubly selective channel with the limited spectrum is significant. Although multi-carrier transmission such as Orthogonal Frequency Division Multiplexing (OFDM) in compensation for the double-selective channel has its special advantages and mature research results, but the high peak to average power ratio (PAPR) and sensitivity to phase noise make it not conducive to practical use. Single-carrier frequency domain equalization (SC-FDE) scheme got lots of attentions in the broadband wireless communications in decades, due to the low PAPR and similar anti-multipath performance compare with OFDM. However, the time domain modulation/demodulation bits stream of single carrier makes the interferences suppression study different from OFDM systems in the fast time varying fading environment. In view of this, the text carried out SC-FDE system interference suppression research over the fast time-varying fading environments. The main purpose of this study is to research and design shortening impulse response filter (SIRF) for inhibition of interference of SC-FDE system with insufficient cyclic prefix (CP) to reduce bit errors rate (BER) of the system and retain spectrum efficiency. Proposed the MSSNR-SIRF algorithm through reasonable inference theory formulas and the best performance parameters obtained for interference suppression over fast time-varying fading environment are the main work of this paper. While using the equivalent noise approximation, improved the optimum SIRF minimum mean square errors (MMSE) frequency domain equalizer, to a certain extent, suppresses noise interference.The main structure of the text divided into four parts. Firstly, analysing the fading fast time-varying characteristics of wireless channel focus on the doubly selection, combining a variety of frame structures elaborated on the basic principles of SC-FDE. Through analysing interference problems over fast time-varying fading environment based on the SC-FDE system mathematical model, the expression of interferences drived. Secondly, with describing the max shortening signal to noise ratio (MSSNR) SERF design algorithm, a proposed algorithm to overcome the shortcomings of limited filter length and high complexity of the MSSNR is given. Then, theoretical optimal parameters of application SIRF obtained in uncode SCFDE system through residual interference temporal expressions, while equivalent noise estimation of the MMSE frequency domain equalization algorithm is calculated. Finally, Matlab simulation results to confirm the theory of study are displayed, verifing the performance of linear equalization of uncode CP limited SC-FDE system combined with SIRF designed by the best parameter in suppressing the interferences over fast time varying fading environment.