Sphere Decoding Algorithm for Joint Decoding in CDMA System
Yao Wen-yuan · Journal of Changchun Post and Telecommunication Institute · 2005
Complexity of ML(Maximum Likelihood) joint detection using exhaust search increases exponentially as input length.Sphere decoding becomes a hot spot because it can achieve ML performance in complexity of polynomial. We propose in a new reduced complexity decoder for CDMA(Code Division Multiple Access) system based on LS code. Compared to the original algorithm, this algorithm has lower computation complexity and is more insensitive to the choice of initial radius. Simulation indicates the complexity can reduce to half of that of original one. Thus, by making the choice of radius sufficiently large, the ML solution is guaranteed with low complexity, even for large constellations, this algorithm is optimal for LAS-CDMA system in the sense of ML.