SINR Enhancement Techniques for an IS-95 Downlink SIC Receiver

Due to near-far effects and multiple-access interference, several types of multiuser detectors have been developed in recent years to reliably demodulate user signals in a code-division multiple-access (CDMA) system. The downlink of Interim Standard 95 (IS-95) is particularly well suited to one such detector known as the successive interference canceler (SIC). In order to keep the receiver complexity low, entire base station signals are typically canceled in the receiver in a sequential manner. However, for the SIC to operate effectively, a base station signal that is being canceled must be reconstructed with enough accuracy such that sufficient interference power is removed for the subsequent base station to be reliably detected. If this is not possible, it may be necessary to employ techniques, specific to the signal format specified in the IS-95 downlink, which enhance the received signal-to-interference-plus-noise ratio (SINR). In this paper, we explore the performance gains achieved with several SINR enhancement techniques, and present computer simulations to demonstrate this improvement for example cochannel signal scenarios.