Linear Precoding and Equalization for Network MIMO with Partial Cooperation

TL;DR

This paper investigates linear precoding and equalization strategies for network MIMO systems with partial cooperation, optimizing sum-rate and mean square error under power and stream constraints, and compares various schemes through simulations.

Contribution

It introduces novel designs for minimizing weighted sum mean square error in partial cooperation MIMO systems and extends existing sum-rate maximization techniques to this context.

Findings

Proposed new WSMSE minimization techniques for partial cooperation MIMO.

Demonstrated the effectiveness of schemes through extensive simulations.

Showed the equivalence of the system to a MIMO interference channel with constraints.

Abstract

A cellular multiple-input multiple-output (MIMO) downlink system is studied in which each base station (BS) transmits to some of the users, so that each user receives its intended signal from a subset of the BSs. This scenario is referred to as network MIMO with partial cooperation, since only a subset of the BSs are able to coordinate their transmission towards any user. The focus of this paper is on the optimization of linear beamforming strategies at the BSs and at the users for network MIMO with partial cooperation. Individual power constraints at the BSs are enforced, along with constraints on the number of streams per user. It is first shown that the system is equivalent to a MIMO interference channel with generalized linear constraints (MIMO-IFC-GC). The problems of maximizing the sum-rate(SR) and minimizing the weighted sum mean square error (WSMSE) of the data estimates are non-convex, and suboptimal solutions with reasonable complexity need to be devised. Based on this, suboptimal techniques that aim at maximizing the sum-rate for the MIMO-IFC-GC are reviewed from recent literature and extended to the MIMO-IFC-GC where necessary. Novel designs that aim at minimizing the WSMSE are then proposed. Extensive numerical simulations are provided to compare the performance of the considered schemes for realistic cellular systems.