Broadcast cognitive radio with dirty paper coding over Nakagami-m fading channel

The symbol error rate (SER) performance analysis of a broadcast underlay cognitive radio (CR) network, under Nakagami-m fading channels is studied in this paper. Particularly, the underlay CR network is studied as a closed loop multiple antenna system, presented with dirty paper coding (DPC) approach with the aim to allowing the secondary user (SU) transmission to utilize the spectrum resources efficiently and avoid interference to the primary user (PU) receiver. The proposed approach is capable of achieving the same performance as that of the zero-forcing (ZF) algorithm over Nakagami-m fading channels at the SU receiver. We further show with the simulation results that the SER and bit error rate (BER) performances of the PU under Nakagami-m and Rician fading channels are significantly improved for the proposed study. Finally, we optimize the power allocation of the PU transmitter and approximately achieve 3 dB performance gain over Nakagami-m fading for the SU receiver.