Performance of multiuser receivers for asynchronous CDMA with multiple symbol differential detection and pilot symbol-aided coherent detection

Multiple-symbol differential detection (MSDD) and pilot symbol-aided detection (PSAD) are two detection schemes that have been proposed for detecting data transmitted over fast fading channels. When the parameters of these detectors are chosen properly, they can provide an error performance that is close to ideal coherent detection. In this paper, we apply these two detection methods to a multiuser receiver for direct sequence CDMA. The multi-user receiver is implemented in the form of a multi-channel linear equalizer (LE), followed by either a bank of MSDD or a bank of PSAD. With this receiver structure, the front end equalizer is not required to perform any channel estimation. Fading gain estimation and compensation are done by the MSDD or the PSAD. It was found that both MSDD and PSAD perform substantially better than conventional differential detection when the signal-to-noise ratio (SNR) is large (greater than 20 dB) and/or when the fade rate is high (greater than 1 percent the symbol rate)