Interference neutralization using lattice codes

Deterministic approach of models the interaction between the bits that are received at the same signal level by the modulo 2 sum of the bits where the carry-overs that would happen with real addition are ignored. By this model in a multi-user setting, the receiver can distinguish most significant bits (MSBs) of the stronger user without any noise. A faithful implementation of the deterministic model requires one to “neutralize interference” from previous carry over digits. This paper proposes a new implementation of “interference neutralization” [2] using structured lattice codes. We first present our implementation strategy and then, as an application, apply this strategy to a symmetric half-duplex Gaussian butterfly network. In this network, two transmitters communicate their information to two destinations via a half-duplex relay. For duplexing factor 0.5 and under certain conditions, we show that our proposed scheme based on superposition of nested lattice codes can achieve the capacity region in high SNR. Also, regardless of all channel parameters, the gap between its achievable rate region and the outer bound is at most 0.293 bits/sec/Hz.