On the Cramer-Rao Lower Bound for Spatial Correlation Matrices of Doubly Selective Fading Channels for MIMO OFDM Systems

TL;DR

This paper derives the Cramer-Rao Lower Bound and maximum likelihood estimator for spatial correlation matrices in MIMO OFDM channels, highlighting how sample size, frequency selectivity, pilot tones, SNR, and Doppler spread affect estimation accuracy.

Contribution

It provides an analytical expression for CRLB and an estimator tailored for time-varying multipath channels in MIMO OFDM systems, emphasizing key influencing factors.

Findings

CRLB depends mainly on sample size and frequency selectivity

Number of pilot tones and SNR influence the effective frequency selectivity

Analytical and numerical results validate the impact of channel parameters

Abstract

The analytic expression of CRLB and the maximum likelihood estimator for spatial correlation matrices in time-varying multipath fading channels for MIMO OFDM systems are reported in this paper. The analytical and numerical results reveal that the amount of samples and the order of frequency selectivity have dominant impact on the CRLB. Moreover, the number of pilot tones, SNR as well as the normalized maximum Doppler spread together influence the effective order of frequency selectivity.