64-QAM 4×4 MIMO decoders based on Successive Projection Algorithm

This paper presents two algorithms to extend the MIMO-decoding capability of successive projection algorithm (SPA). The algorithms, called Flag-SPA and Relaxed-SPA, are based on different methods to avoid repeating the selected path in each iteration of the algorithm, the first by using a flag matrix, the second by assigning a high weight to a selected path. Equivalences with K-best algorithm in terms of average BER for a SNR range from 25 to 30 dB have been found and it is shown that for low SNR the proposed SPA-based algorithms exhibit lower computational load than their equivalent K-best algorithm.