Research On Iterative Equalization And Channel Tracking Of SC-FDE System

Single carrier frequency domain equalization (SC-FDE) is a broadband wireless communication technology which developed on the basis of the traditional single-carrier and orthogonal frequency division multiplexing (OFDM).It builds on the OFDM system in the frequency domain data processing advantages, but also to overcome the large peak to average power ratio (PAPR) and sensitive to the frequency offset other shortcomings of OFDM systems. SC-FDMA as the SC-FDE multiple access version of 4G mobile communication standards has been one of the senior long-term evolution (LTE Advanced) as uplink transmission scheme.In the aspect of frequency domain equalization, the paper begins by describing the single-carrier frequency domain equalization mathematical principles, and describes several existing iterative frequency-domain equalization algorithm. For the iterative system, its costs are often relatively large iterations, especially when the iteration has been convergence, the iteration will continue to cause unnecessary decoding delay, which will reduce the system in real time. In the use of BER transfer chart analysis of frequency-domain equalization iteration gain, this paper presents a new stopping iteration criteria——SNRe q gain criterion which using the equivalent SNR gain as a criterion to stop, compared with the traditional iteration stopping criteria, new criteria for the environment in the low signal to noise ratio significantly reduces iteration overhead.With such high-speed railway, moving vehicles and other modern tools to the growing popularity of high-speed traffic, people in fast fading scenarios for wireless communications have become increasingly frequent. In fast fading channel, it needs to eliminate the time-varying channel characteristics of the interference into the frequency domain equalization, and then apply iterative equalization algorithm in order to obtain better performance. By studying the performance impact of the channel estimation accuracy for the next iteration of the fast fading frequency domain equalization, it is necessary to introduce aspects of channel filtering to obtain a more accurate tracking of the CSI in order to better iterative frequency-domain equalization. Accurate system modeling is the key to the use of filter channel tracking algorithm. if there is a deviation of system modeling it will likely result in performance degradation or even filter divergence. In order to enhance the channel tracking algorithm accuracy, the paper designs a Kalman filter algorithm with a simple variable forgetting factor, simulations show that, compared with the standard Kalman filter, the variable forgetting factor Kalman filter channel tracking has better performance,combined of iterative frequency domain which based on ICI interference cancellation can be good against fast fading influence.