Selective multistage detection algorithm in flat Rayleigh fading channel

Abstract

Selective multistage detection algorithm applied in AWGN channel is first proposed in [1]. It is shown that the BER performance of this detector is slightly better than conventional multistage detector if the threshold level is properly selected. At the same time, the number of computations performed by the receiver is greatly reduced since MAI cancellation is only applied to those decision variables whose magnitudes are less than a threshold value. In this thesis, we will investigate the performance of selective multistage detection algorithm for the frequency nonselective Rayleigh fading channel which is more common in the wireless communications. The performance will be determined by computer simulation. First, we will consider the performance of selective multistage detection and nonselective multistage detection when the receiver perfectly estimates the channel gains of all of the users. Then we will employ pilots based estimation with optimum interpolator to estimate the channel gains. Receiver will make use of the estimated channel gain to detect the data of every user. Finally we will compare the performances of selective and nonselective multistage detectors under the imperfect channel estimation case. We also propose a modified selective multistage algorithm in order to improve the performance of selective multistage detector further without a large increase in the amount of computation. It applies partial MAI cancellation, instead of full cancellation, to those decision variables whose magnitudes are less than a threshold value. By employing the modified selective multistage algorithm, we will achieve the performance that is close to that of conventional multistage with perfect channel estimation.