On the Degrees of Freedom Achievable Through Interference Alignment in a MIMO Interference Channel
Abstract
Consider a K-user flat fading MIMO interference channel where the k-th transmitter (or receiver) is equipped with M_k (respectively N_k) antennas. If a large number of statistically independent channel extensions are allowed either across time or frequency, the recent work [1] suggests that the total achievable degrees of freedom (DoF) can be maximized via interference alignment, resulting in a total DoF that grows linearly with K even if M_k and N_k are bounded. In this work we consider the case where no channel extension is allowed, and establish a general condition that must be satisfied by any degrees of freedom tuple (d_1, d2, ..., d_K) achievable through linear interference alignment. For a symmetric system with M_k = M, N_k = N, d_k = d for all k, this condition implies that the total achievable DoF cannot grow linearly with K, and is in fact no more than K(M + N)=(K + 1). We also show that this bound is tight when the number of antennas at each transceiver is divisible by the number of data streams.
Cite
@article{arxiv.1104.0992,
title = {On the Degrees of Freedom Achievable Through Interference Alignment in a MIMO Interference Channel},
author = {Meisam Razaviyayn and Gennady Lyubeznik and Zhi-Quan Luo},
journal= {arXiv preprint arXiv:1104.0992},
year = {2015}
}