Soft-output sphere decoding algorithms for MIMO systems

Sphere decoding (SD) algorithms for MIMO receivers can achieve similar performance to maximum-likelihood detection (MLD) algorithm with lower computational complexity. In general, channel decoding methods can achieve better performance if they are combined with soft-output SD rather than hard-output one. Unfortunately, not all soft-output values can be obtained in SD. Although several constants could be substituted for these unavailable values, it needs trial and error. Thus, in this paper, we propose novel algorithms to solve such a problem. Based on the simulation results, it can be concluded that the proposed scheme has good performance and lower complexity, as compared to other reference approaches.