Network Coded Cooperation Receiver with Analog XOR Mapping for Enhanced BER

Abstract

In this paper, we propose a novel physical layer decoding technique for Device-to-Device Network Coded Cooperation (NCC) receivers in the Two Way Relay Channel (TWRC) scenario. The proposed technique is efficiently applicable either when Channel State Information (CSI) are available at the receiver or not. It first employs XOR arithmetic analog mapping to extract a distorted version of the intended signal from the network-coded signal received from the relay. The obtained signal is then combined with the direct signal received from the source, resulting in a higher SNR version of the intended signal. Combining technique used is either Cooperative Maximum Ratio Combining (C-MRC) or Equal Gain Combining (EGC) depending on whether CSI are available or not. The proposed receiver has two advantages over the optimum Maximum Likelihood (ML) receiver. First is its applicability under CSI unavailability circumstances. Second is its lower computation complexity. The BER performance of the proposed scheme has been evaluated through exhaustive Monte-Carlo simulations. According to the obtained results, the proposed scheme is superior to the conventional Network Coding (NC) scheme in both CSI availability and unavailability scenarios. It achieves BER reduction of approximately 71.65 % and 41% in the two scenarios, respectively. Further, when CSI are available, results show that the proposed scheme achieved BER approaches that of the optimum ML (< 6% increase over ML), being noticeably superior to the conventional Cooperative Communication (CC) scheme with Maximum Ratio Combining (MRC) (achieved BER reduction ≈ 55.2%). An accurate closed form for the proposed scheme theoretical achieved BER has been derived in the CSI unavailability case, with BPSK assumed.