Precoder Design for Communication-Efficient Distributed MIMO Receivers With Controlled Peak-Average Power Ratio

We consider the problem of communicating over a relay-assisted multiple-input multiple-output (MIMO) channel with additive noise, in which physically separated relays forward quantized information to a central decoder where the transmitted message is to be decoded. We assume that channel state information is available in the transmitter and show that the design of a rational-forcing precoder - a precoder which is matched to the quantizers used in the relays - is beneficial for reducing the symbol error probability. It turns out that for such rational-forcing precoder based systems, there is natural tradeoff between the peak to average power ratio in the transmitter and the rate of communication between the relays and the central decoder. The precoder design problem is formulated mathematically, and several algorithms are developed for realizing this tradeoff. Optimality of the decoder communication rate is shown based on a result in distributed function computation. Numerical and simulation results show that a useful tradeoff can be obtained between the excess decoder communication rate and the peak-average power ratio in the transmitter.

I. Introduction

We consider a point-to-point, multiple-input multiple-output (MIMO), relay assisted communication problem in which spatially distributed relays are deployed between the transmitter and the receiver. Each relay node (RN) forwards quantized information to a central receiver node (CN) over a noiseless link. The message is decoded by the CN. The combination of RNs and the CN will be referred to as the receiver. The communication system is illustrated in Fig. 1. Fig. 1.

System Diagram. represents the quantizer in the -th RN.