Optimized Antenna Selection and Adaptive Power Allocation for Physical Layer Network Coding With Selective Soft-Message-Forward Cooperation

To improve the systematic bit error rate (BER) performance and power efficiency, an optimized antenna selection and adaptive power allocation scheme is proposed for physical layer network coding (PNC) with selective soft-message-forward (SSMF) cooperation. In this scheme, two adaptive power allocation (APA) schemes are proposed for the multiple access (MA) and broadcast (BC) stages, respectively. In the MA stage, the APA scheme aims to maximize the Euclidean distance of network coding symbols received by relay node. In the second BC stage, the relay node takes the maximization of the minimum mutual information of two source nodes as objective function. Then it uses the narrow range method (NRM) to select the optimal antenna set and equally allocates power to them. To further reduce the systematic complexity, an antenna set pre-selection is proposed. It minimizes the antenna number in the initial antenna set of the NRM based on the deletion standard which does not reduce the mutual information in the BC stage. Simulation results indicate that our APA schemes surpass the existing equal power allocation (EPA) scheme with a binary phase-shift keying modulation. Compared with current EPA scheme, the proposed APA schemes for the BC, MA and global stages obtain about 1 dB, 2 dB and 3.5 dB performance gains at BER of 10
^-3
with two antennas in the relay node, respectively.