Efficient iterative ordering scheme based on successive interference cancelling for sphere detection in multiple input multiple output system

In this study, an efficient ordering scheme for sphere detection (SD) is presented. The proposed scheme can substantially reduce SD computation complexity which combines Vertical Bell Laboratories Layered Space-Time (V-BLAST) with gradient-based (GB) ordering and smartly modifies them based on iterative successive interference canceling (SIC), attempting to exploit the potential of both the channel matrix and the received noisy signal as full as possible, whereas offering almost the same preprocessing complexity as balanced sorted QR (BSQR) and V-BLAST ordering. The simulation results show that, in terms of the number of visited nodes, the proposed scheme can achieve a significant complexity reduction, especially for high numbers of antenna and large constellation sizes in the low signal-to-noise ratio (SNR) region. Compared with SD under BSQR decomposition and GB orderings at SNR =5 dB, the average number of visited nodes under our proposed ordering is reduced by >;30% in 4×4 16QAM system, and by almost 30 and 50% reduction in 6×6 16QAM system, respectively. For 4×4 64QAM system, >;70% reduction at SNR = 0 dB and >;40% reduction at SNR = 5 dB can be achieved, respectively.