Spatial Precoder Design for Space-Time Coded MIMO Systems: Based on Fixed Parameters of MIMO Channels

TL;DR

This paper proposes linear spatial precoding schemes for MIMO systems that utilize fixed antenna placement parameters to enhance performance without requiring channel feedback, applicable to both coherent and non-coherent space-time coding.

Contribution

It introduces novel precoding schemes based on fixed antenna parameters, providing closed-form solutions for up to three receiver antennas and a generalized method for more.

Findings

Significant performance improvements at low SNRs for small antenna sizes.

Precoding schemes do not require channel state feedback.

Effective for both coherent and non-coherent space-time codes.

Abstract

In this paper, we introduce the novel use of linear spatial precoding based on fixed and known parameters of multiple-input multiple-output (MIMO) channels to improve the performance of space-time coded MIMO systems. We derive linear spatial precoding schemes for both coherent (channel is known at the receiver) and non-coherent (channel is un-known at the receiver) space-time coded MIMO systems. Antenna spacing and antenna placement (geometry) are considered as fixed parameters of MIMO channels, which are readily known at the transmitter. These precoding schemes exploit the antenna placement information at both ends of the MIMO channel to ameliorate the effect of non-ideal antenna placement on the performance of space-time coded systems. In these schemes, the precoder is fixed for given transmit and receive antenna configurations and transmitter does not require any feedback of channel state information (partial or full) from the receiver. Closed form solutions for both precoding schemes are presented for systems with up to three receiver antennas. A generalized method is proposed for more than three receiver antennas. We use the coherent space-time block codes (STBC) and differential space-time block codes to analyze the performance of proposed precoding schemes. Simulation results show that at low SNRs, both precoders give significant performance improvement over a non-precoded system for small antenna aperture sizes.