Large-System Analysis of Joint Channel and Data Estimation for MIMO DS-CDMA Systems

TL;DR

This paper analyzes the performance of joint channel estimation and multiuser detection in large MIMO DS-CDMA systems using the replica method, showing significant gains over traditional methods especially in multi-antenna setups.

Contribution

It introduces a large-system analysis of joint CE-MUDD with LMMSE estimation for MIMO DS-CDMA, demonstrating its advantages over one-shot estimation approaches.

Findings

Joint CE-MUDD reduces rate loss from pilot signals.

Performance gains are significant in multi-antenna systems.

Replica method effectively evaluates large-system performance.

Abstract

This paper presents a large-system analysis of the performance of joint channel estimation, multiuser detection, and per-user decoding (CE-MUDD) for randomly-spread multiple-input multiple-output (MIMO) direct-sequence code-division multiple-access (DS-CDMA) systems. A suboptimal receiver based on successive decoding in conjunction with linear minimum mean-squared error (LMMSE) channel estimation is investigated. The replica method, developed in statistical mechanics, is used to evaluate the performance in the large-system limit, where the number of users and the spreading factor tend to infinity while their ratio and the number of transmit and receive antennas are kept constant. The performance of the joint CE-MUDD based on LMMSE channel estimation is compared to the spectral efficiencies of several receivers based on one-shot LMMSE channel estimation, in which the decoded data symbols are not utilized to refine the initial channel estimates. The results imply that the use of joint CE-MUDD significantly reduces rate loss due to transmission of pilot signals, especially for multiple-antenna systems. As a result, joint CE-MUDD can provide significant performance gains, compared to the receivers based on one-shot channel estimation.