Complexity-Improved Sphere Decoder for MIMO Systems Using PSK Modulations

It has been shown in recent years that the iterative decoding techniques, improve performance (e.g., bit error rate) of various digital communication systems. Techniques of Multiple-Input Multiple-Output (MIMO) are a key technology to promote and achieve high-speed wireless communications. They demand only a low complexity system for detection since a high CPU processing involves more energy consumption and therefore less flexibility in mobility terms. The sphere decoding (SD) technique has been proposed as an effcient algorithm to solve this problem. SD is known to be an algorithm of polynomial complexity that has become a powerful tool to achieve a high performance close to that given by the maximum likelihood (ML) (which is considered ideal), but with less complexity. This paper proposes a modification to the SD technique in order to reduce its complexity named: improved Less Complexity SD (iLSD).