Sphere decoder with dichotomic search

Sphere Decoder (SD) is a widely used and studied decoder for MIMO systems. As the number of antenna grows, SD becomes computationally intensive. To overcome this disadvantage, this paper proposes an improvement of SD consisting in an efficient radius update strategy using dichotomy. With no performance loss, the resulting algorithm allows a considerable complexity saving compared to conventional SD, up to 90% in some scenarios. This gain is due to the decrease in the number of visited lattice points in the spherical region shown to be logarithmic as a function of the SNR. We provide simulation results and a theoretical proof of the expected complexity reduction.