Precoded Spatial Modulation-Aided Cooperative NOMA

In this letter, a precoded spatial modulation-aided cooperative nonorthogonal multiple access (NOMA), referred to as PC-NOMA, has been proposed for multiple-input and multiple-output (MIMO) downlink scenario. In PC-NOMA scheme, the base station (BS) broadcasts three users' information over two time slots: in the first slot, the two near users receive data through direct links and in the second slot, the third user (far) receives data indirectly from the near users. The precoded direct links' signal has been superposed with indirect link's signal in broadcast phase at the BS. The indirect link's signal has been decoded and forwarded at the direct link's user using the successive-interference cancellation (SIC) method in cooperative phase. The symbol error rate (SER) and mutual information (MI) under inter-users interference (IUI) have been derived for the proposed PC-NOMA. The impact of various system parameters, such as the number of transmitting and receiving antennas, have been analyzed for the proposed PC-NOMA.