A Novel Joint Detection Algorithm Based on Sphere Decoder for LAS-CDMA System

A new reduced-complexity joint detection algorithm based on sphere decoder for LAS-CDMA (large area synchronous code division multiple access) system is proposed in this paper. This algorithm can approach ML performance in polynomial complexity. Special zero correlation window property of LS code can reduce complexity of this algorithm greatly. Simulation indicates it is more insensitive to the choice of initial radius. Thus, by making the choice of radius sufficiently large, the ML solution is guaranteed with low complexity, even for large constellations. We then extend this joint detection algorithm to MIMO case and compare it with MMSE, ZF multicode detectors. Numerical results show performance of this algorithm is good even at very high speed such as 160 Km/h, this give us some insights on developing high efficient practical joint detection algorithm for further LAS-CDMA system.