Improved linear group detection for combined spatial multiplexing/STBC systems

Wireless architectures combining the use of spatial division multiplexing (SDM) and space-time block coding (STBC) have begun to appear in the latest communications standards. In recent years, different detection strategies for these schemes have been proposed which can be broadly categorised as group-based or direct-detection techniques. While the former class aims at separating the different STBC streams and then apply conventional simple Alamouti decoding, the latter type directly estimates the transmitted symbols without fully exploiting the Alamouti structure. Previous publications have shown that direct-detection outperform group-based detectors with the penalty of a higher computational complexity. This letter presents a unified view of the detection strategies for hybrid SDM/STBC systems and presents two new families of group-based detectors. It is shown that linear group detection, when properly implemented, attains the same performance as linear direct detectors at a significant lower complexity.