Intersymbol Interference Distortion Cancellation Using a Modified Maximal Ratio Combiner in Mobile Wireless Communication

Abstract

This paper presents a modified maximum Ratio Combiner (MRC) for correcting inter symbol interference (ISI) distortion in mobile wireless channel. Mobile wireless system produces fast frequency selective fading channel which is due to the variation of the channel in such a way that the coherent time will be less than the symbol period of the modulation schemes considered and the delay be greater than the symbol period. This causes overlapping of successful symbols and resulted in intersymbol interference (ISI). The modified MRC performance investigated uses a single Radio Frequency (RF) chain and a single Matched Filter (MF). The two paths were considered and combined using MRC at the RF stage. Then the received signal was evaluated in term of Bit Error Rate (BER) and the results were compared with the conventional MRC which used many RF chains and MF depending on the number of paths. The results obtained showed that the modified MRC gave approximately the same BER performance when compared with the conventional MRC receiver indicating the same performance over this ISI distortion channel. Also, the modified MRC receiver at the RF stage gave relatively lower processing time which is an indication of a lower complexity. Therefore, the modified MRC receiver has been shown to be capable of reducing the hardware complexity and the implementation cost of the system over the ISI channel.

Keywords: Maximum Ratio Combining, Matched Filter, RF chain, Multipath fading, GMSK