Nonlinear precoding GMD based for MIMO-MC-CDMA downlink systems

Considering the error propagation effect and high complexity of spatial multiplexing based vertical vell labs layered space time(VBLAST), a novel nonlinear module algebra precoding algorithm based on geometric mean decomposition for VBLAST is proposed in multiple input multiple output multi-carrier code division multiple access (MIMO-MC-CDMA) downlink systems, geometric mean decomposition is used for precoding matrix which have the same equivalent noise gain among each sub-channel, the nonlinear module algebra Tomlinson-Harashima precoding (THP) is used between sub-carrier channels of MC-CDMA to eliminate interference from other signals at the transmitter, and can eliminate the error propagation effect of layered space-time codes effectively, At the receiver, zero forcing and minimum mean square error criterion are used, and the complexity of the downlink receiver can be reduced. Simulation results show that the proposed algorithm is better than the traditional algorithms.