A cognitive spatial multiplexing scheme for MIMO-CDMA networks

The existing cognitive schemes have not considered cognitive spatial multiplexing (CSM) for MIMO-CDMA network, there are three vital problems to hinder CSM's application: spatial channels' estimation for mobile stations(MSs), space-time coding and decoding for base station (BS) and MSs, the implementation complexity of BS and MSs. To solve the problems, a simplified cognitive spatial multiplexing scheme is proposed, including BS and MS systems, where MIMO BS in a cell has two antennas and each MS of lower moving speed has one antenna only. To ensure communication quality of the network, the scheme applies LDPC as the channel coding instead of space-time coding for BSs and MSs. BS assigns the same CDMA channels for MSs to have larger space interval. Simulations show that good spatial multiplexing capacity and BER performance have been achieved by the proposed scheme.