Reduced Complexity Sphere Decoder for Spatial Modulation Detection Receivers

In this paper a novel detection algorithm for spatial modulation (SM) based on sphere decoder (SD) tree search idea is proposed. The aim is to reduce the receiver complexity of the existing optimal decoder while maintaining an optimum performance. The algorithm performs a maximum likelihood (ML) search, only over those points that lie inside a sphere, centered at the received signal, of given radius. It is shown with the aid of analytical derivations, that for a SNR (signal-to-noise ratio) between 2~dB and 18~dB at least 45% and up to 85% reduction in the number of complex operations can be achieved with a close to optimal bit-error-ratio (BER) performance.