Low complexity semi-blind maximum-likelihood multiuser receiver for MC-CDMA systems

We present a novel joint multiuser detection method based on sphere packing lattice decoding and semi-blind channel estimation for multicarrier code-division multiple-access (MC-CDMA) systems. After modelling MC-CDMA as a sphere packing lattice, a low-complexity maximum-likelihood (ML) detection, sphere decoding algorithm, is applied to jointly detect all users. The impacts of channel estimation errors are studied by incorporating a semi-blind subspace based channel estimation in the receiver. The selection of search radius and the complexity of the receiver are also investigated. Another promising detection technique, genetic algorithm (GA) based multiuser detector (MLJD) is also studied. Simulation results demonstrate the superior performance of the semi-blind receiver compared to the conventional receivers for MC-CDMA and its robustness to channel estimation errors.