A fast generalized complex sphere decoder for MIMO systems

A fast generalized complex sphere decoder (GCSD) is proposed in this paper. This GCSD can be used to solve the under-determined MIMO systems. Moreover, it can handle not only the QAM and PSK constellations, but also the arbitrary complex constellations. The basic idea is to partition the transmitted signal vector into two sub-vectors. After some transformations, we can use a search scheme which is similar to sphere decoding and a conventional complex sphere decoder to solve these two sub-vectors respectively. Simulation results show that the complexity of our GSCD is significantly lower than the exhaustive search scheme on the under-determined part of the transmitted signal vectors.