A fast sphere decoding framework for space-frequency block codes

In order to make the multi-antenna OFDM systems an attractive choice for practical applications, implementation issues such as decoding complexity must be addressed successfully. In this paper, we propose a computationally efficient decoding algorithm for space-frequency block codes. The central part of the algorithm is a complex-domain, modulation-independent sphere decoding framework. The simulation results demonstrate that the proposed algorithm can significantly reduce the decoding complexity. For the 64 QAM modulation, we observe up to about 73% reduction in the required FLOP count per code block compared to the previously proposed methods without noticeable performance degradation.