Reduced complexity sphere decoding using a geometrical approach

In this paper we propose an algorithm with reduced complexity for the sphere detection (SD) which is used in multiple input multiple output (MIMO) detection algorithms without any performance degradation. The trade-off between the complexity and the bit error rate is a main challenge in wireless MIMO systems. The maximum likelihood (ML) detector considered as the optimum detector in the literatures. Since the complexity of the naive ML detectors is significantly high, the SD algorithms are proposed to lower the complexity. In this paper, we use the result of the geometrical decoder (GD) proposed in [8] which performs as the ML detector and has lower complexity than SD algorithm. We propose a method to further reduce the complexity of this SD algorithm. We show that the complexity is further reduced by almost 60%, i.e, the number of nodes visited by the proposed SD method is in average 60% less than that of the original one.