Joint Beamforming and Power Allocation for MIMO Relay Broadcast Channel with Individual SINR Constraints

TL;DR

This paper develops joint beamforming and power allocation schemes for MIMO relay broadcast channels with individual SINR constraints, utilizing uplink-downlink duality and convex optimization to improve power efficiency.

Contribution

It introduces two novel joint beamforming and power allocation schemes based on uplink-downlink duality for MIMO relay channels with SINR constraints.

Findings

Feasible solutions exist under practical power constraints.

Sum power can be minimized efficiently with convex optimization.

Channel pairing at the relay reduces transmission power.

Abstract

In this paper, system design for the multi-input multi-output (MIMO) relay broadcast channel with individual signal-to-interference-plus-noise ratio (SINR) constraints at the mobile stations (MS) is considered. By exploring the structure of downlink (DL) uplink (UL) duality at either the base station (BS) or the relay station (RS), we propose two schemes of joint power allocation and beamforming design at the BS and the RS. The problem of existence of feasible solutions under practical power constraints at the BS and the RS with given SINR targets is considered first. Then the problem of sum power minimization is considered. Each design problem can be solved efficiently using optimal joint power allocation and beamforming under the framework of convex optimization. We also show that with subchannel pairing at the RS, the transmission power can be reduced by channel compensation at either hop. Finally, an extension to more general multi-hop applications is provided to further improve the power efficiency.