Optimal Low-Complexity Detection for Space Division Multiple Access Wireless Systems

A symbol detector for wireless systems using Space Division Multiple Access (SDMA) and Orthogonal Frequency Division Multiplexing (OFDM) is derived. The detector uses a Sphere Decoder (SD) and has much less computational complexity than the naive Maximum Likelihood (ML) detector. The authors also show how to detect non-constant modulus signals with Constrained Least Squares (CLS) receiver, which is designed for constant modulus (unitary) signals. The new detector outperforms existing suboptimal detectors for both uncoded and coded systems.