Coded Quadrature Amplitude Modulations For XOR Physical Layer Network Coding With Precoding

This paper proposes novel coded quadrature amplitude modulations for XOR physical layer network coding (XOR-PLNC) with lattice reduction-aided precoding in multiple-input-multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) bi-directional relay systems. The proposed XOR-PLNC introduces a new type of coded modulations for the relays to decode the signals after XOR encoding of the two transmit signals. To implement the decoding with little additional complexity at the relays, the proposed network coding applies a new lattice reduction-aided precoding with adaptive power loading. The performance of the proposed XOR-PLNC is evaluated by computer simulation in a two hop MIMO-OFDM bi-directional relay system. The proposed decoding attains a gain of more than 4dB at the relays.