Channel Estimation Study for Block - Pilot Insertion in OFDM Systems under Slowly Time Varying Conditions

TL;DR

This paper evaluates various channel estimation algorithms in OFDM systems with block pilot insertion under high mobility, showing LMMSE's superior performance especially with high SNR and large FFT sizes.

Contribution

It provides a comparative analysis of LS, MMSE, LMMSE, and low-rank LMMSE algorithms for channel estimation in high-mobility OFDM systems, highlighting LMMSE's effectiveness.

Findings

LMMSE performs best at high SNR for 16-QAM modulation.

All algorithms perform similarly at high SNR for certain modulations.

Low-rank LMMSE is effective with large FFT sizes.

Abstract

In this paper, we propose a study of performance of the channel estimation using LS, MMSE, LMMSE and Lr-LMMSE algorithms in OFDM (Orthogonal Frequency Division Multiplexing) system which, as known suffers from the time variation of the channel under high mobility conditions, using block pilot insertion. The loss of sub channel orthogonality leads to inter-carrier interference (ICI). Using many algorithms for channel estimation, we will show that, for a 16- QAM modulation, the LMMSE algorithm performs well to achieve this estimation but when the SNR (Signal Noise Rate) is high, the four algorithms (LS, MMSE, LMMSE and Lr-LMMSE) perform similarly, this is not always the case for another scheme of modulation. We will improve also the mean squared error for these algorithms. It will be illustrious in this paper that the LMMSE algorithm performs well with the block- pilot insertion as well as its low rank version which behave very good even when the size of FFT is very high.