A Low Complexity MMSE Detector for Multiuser Layered Space-Time Coded MIMO Systems

Merging layered space-time (LST) coding, which provides high data rate transmission, with space-time block coding (STBC) provides a tradeoff between transmit diversity and bandwidth efficiency in multiple-input multiple-output (MIMO) systems. This architecture is known as multilayered space time coding (MLSTC). In this paper, we propose a reduced complexity MMSE detector based on the Sorted QR decomposition, intended for MLSTC systems. The proposed decoder has reduced computational complexity in comparison to the group interference cancellation scheme. Our proposed decoder allows for the number of receive antennas to be less than the number of transmit antennas. Since we are dealing with a multiuser system, we wish all users to benefit from the same performance. We therefore use power allocation techniques to amplify users to the highest level of performance available and thus improving the performance.