Performance Analysis of Two-Way AF MIMO Relaying of OSTBCs with Imperfect Channel Gains

TL;DR

This paper analyzes the performance of two-way AF MIMO relay systems using OSTBCs with imperfect CSI, deriving error performance and diversity order, and showing that channel estimation errors do not affect diversity.

Contribution

It provides analytical expressions for error performance and diversity order in two-way AF MIMO relaying with OSTBCs under imperfect CSI, which was not previously detailed.

Findings

Channel estimation errors do not affect the diversity order.

Derived tight approximations for the MGF of the received SNR.

Analytical average error performance matches simulations.

Abstract

In this paper, we consider the relaying of orthogonal space time block codes (OSTBCs) in a two-way amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay system with estimated channel state information (CSI). A simple four phase protocol is used for training and OSTBC data transmission. Decoding of OSTBC data at a user terminal is performed by replacing the exact CSI by the estimated CSI, in a maximum likelihood decoder. Tight approximations for the moment generating function (m.g.f.) of the received signal-to-noise ratio at a user is derived under Rayleigh fading by ignoring the higher order noise terms. Analytical average error performance of the considered cooperative scheme is derived by using the m.g.f. expression. Moreover, the analytical diversity order of the considered scheme is also obtained for certain system configurations. It is shown by simulations and analysis that the channel estimation does not affect the diversity order of the OSTBC based two-way AF MIMO relay system.