Precoding for Multiuser MIMO Systems with Single-Fed Parasitic Antenna Arrays

TL;DR

This paper explores the use of single-fed parasitic antenna arrays at transmitters in multiuser MIMO systems, proposing a precoding methodology that maintains cooperation gains while reducing hardware complexity.

Contribution

It introduces a novel precoding design for ESPAR antenna arrays in multiuser MIMO, enabling transmitter cooperation with fewer RF chains.

Findings

Precoding techniques for ESPAR arrays are effective in multiuser MIMO.

Performance gains are achievable with single-fed parasitic arrays.

The proposed method reduces hardware complexity without sacrificing cooperation benefits.

Abstract

Transmitter (TX) cooperation at various levels has been shown to increase the sum throughput of multiuser multiple-input multiple-output (MIMO) systems. In this paper we consider a K-user MIMO system where TXs have only global channel state knowledge. It has been theoretically shown that interference alignment (IA) achieves the K/2 degrees of freedom of this K-user MIMO interference channel. However, results on IA and all proposed transceiver techniques for this channel up to date, assume conventional antenna arrays at the transceivers with multiple radio-frequency (RF) chains, each connected to a different antenna element. To reduce the consequent hardware burden and power dissipation imposed by such arrays, we propose in this paper the utilization of compact single-RF electronically steerable parasitic (passive) array radiators (ESPARs) at the cooperating TXs. A signal model capable of capturing the characteristics of the considered antenna arrays is first described and then a general precoding design methodology for the tunable parasitic loads at the TXs' ESPARs is introduced. Specific precoding techniques and an indicative ESPAR design are presented for a 3-user 2x2 MIMO system with one ESPAR TX, and the obtained performance evaluation results show that the gains of TX cooperation are still feasible.