Relay-Aided MIMO Cellular Networks Using Opposite Directional Interference Alignment

TL;DR

This paper introduces a relay-assisted interference alignment scheme for MIMO cellular networks that simplifies implementation by requiring only relay-side CSI and no user beamforming, applicable to uplink, downlink, and full-duplex scenarios.

Contribution

It proposes a novel relay-aided IA scheme with minimal CSI requirements, extending its applicability to various network configurations and demonstrating its advantages over traditional methods.

Findings

The scheme achieves feasible interference alignment with only relay CSI.

It extends to downlink and full-duplex networks maintaining similar benefits.

The scheme improves degrees-of-freedom performance in MIMO cellular networks.

Abstract

In this paper, we first propose interference alignment (IA) scheme for uplink transmission of multiple-input-mulitple-output (MIMO) cellular network with a help of relay which operates in halfduplex mode. The proposed scheme only requires global channel state information (CSI) knowledge at relay and no transmitter beamforming and time extension is required at user equipment (UE), which differs from the conventional IA schemes for cellular network. We derive the feasibility condition of the proposed scheme for the general network configuration and analyze the degrees-of-freedom (DoF) performance of the proposed IA scheme. Extension of proposed scheme for downlink and full-duplex network are further described in this paper. It is also shown that the same advantage as the uplink case can be obtained for downlink case through relay induced interfering multiple access channel (IMAC) and interfering broadcast channel (IBC) duality. Furthermore, full-duplex network is shown to have same advantages with half-duplex cases.