Physical layer network coding with multiple antennas

TL;DR

This paper introduces MIMO PNC, a novel physical layer network coding scheme for multi-antenna two-way relay channels, which improves throughput and robustness over existing MIMO network coding methods.

Contribution

The paper proposes MIMO PNC, a new scheme that extracts sum and difference signals for network coding, reducing complexity and removing phase synchronization constraints.

Findings

MIMO PNC outperforms traditional MIMO NC in simulations.

MIMO PNC is linear in complexity with respect to constellation size.

Simulation results show significant throughput gains under Rayleigh fading.

Abstract

The two-phase MIMO NC (network coding) scheme can be used to boost the throughput in a two-way relay channel in which nodes are equipped with multiple antennas. The obvious strategy is for the relay node to extract the individual packets from the two end nodes and mix the two packets to form a network-coded packet. In this paper, we propose a new scheme called MIMO PNC (physical network coding), in which the relay extracts the summation and difference of the two end packets and then converts them to the network-coded form. MIMO PNC is a natural combination of the single-antenna PNC scheme and the linear MIMO detection scheme. The advantages of MIMO PNC are many. First, it removes the stringent carrier-phase requirement in single-antenna PNC. Second, it is linear in complexity with respect to the constellation size and the number of simultaneous data streams in MIMO. Simulation shows that MIMO PNC outperforms the straightforward MIMO NC significantly under random Rayleigh fading channel. Based on our analysis, we further conjecture that MIMO PNC outperforms MIMO NC under all possible realizations of the channel.