Gallager Bound for MIMO Channels: Large-N Asymptotics

TL;DR

This paper derives large-system asymptotic expressions for the Gallager error bound in MIMO channels, providing insights into error probabilities for high-dimensional wireless systems under various power constraints.

Contribution

It introduces analytic formulas for the Gallager error exponent in large MIMO systems using random matrix theory, including scenarios with channel variation and multiple fading blocks.

Findings

Gallager error bound approaches the upper error bound at high rates.

Derived explicit asymptotic expressions for error exponents in large MIMO systems.

Accounted for channel variations over multiple Rayleigh fading blocks.

Abstract

The use of multiple antenna arrays in transmission and reception has become an integral part of modern wireless communications. To quantify the performance of such systems, the evaluation of bounds on the error probability of realistic finite length codewords is important. In this paper, we analyze the standard Gallager error bound for both constraints of maximum average power and maximum instantaneous power. Applying techniques from random matrix theory, we obtain analytic expressions of the error exponent when the length of the codeword increases to infinity at a fixed ratio with the antenna array dimensions. Analyzing its behavior at rates close to the ergodic rate, we find that the Gallager error bound becomes asymptotically close to an upper error bound obtained recently by Hoydis et al. 2015. We also obtain an expression for the Gallager exponent in the case when the codelength spans several Rayleigh fading blocks, hence taking into account the situation when the channel varies during each transmission.