A Fixed-Point Implementation of Successive Interference Canceller for WCDMA

Multiuser detectors (MUD) can significantly increase the spectral efficiency of Code Division Multiple Access (CDMA) systems. In this paper, we present a symbol-level fixed-point Successive Interference Canceller (SIC) that is feasible to implement in Rapid Single Flux Quantum (RSFQ) superconducting electronics. A design procedure for finding the precision of the fixed-point SIC is introduced. A set of quantizers is found out with this procedure. By applying those quantizers, the simulation results show that a fixed-point multistage SIC performs the same as a floating-point decorrelator, which increases system capacity by a factor of four for the uplink model used in this paper.