# Frequency Offset Estimation and Training Sequence Design for MIMO OFDM

## TL;DR

This paper proposes a novel method for estimating carrier frequency offset in MIMO OFDM systems by designing special training sequences, improving estimation accuracy over frequency selective channels.

## Contribution

It introduces a new training sequence design based on Chu sequences and a combined approach for integer and fractional CFO estimation in MIMO OFDM systems.

## Key findings

- Accurate CFO estimation demonstrated through simulations
- Training sequences ensure identifiability of CFO parameters
- Proposed sequences outperform existing methods in robustness

## Abstract

This paper addresses carrier frequency offset (CFO) estimation and training sequence design for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over frequency selective fading channels. By exploiting the orthogonality of the training sequences in the frequency domain, integer CFO (ICFO) is estimated. {With the uniformly spaced non-zero pilots in the training sequences} and the corresponding geometric mapping, fractional CFO (FCFO) is estimated through the roots of a real polynomial. Furthermore, the condition for the training sequences to guarantee estimation identifiability is developed. Through the analysis of the correlation property of the training sequences, two types of sub-optimal training sequences generated from the Chu sequence are constructed. Simulation results verify the good performance of the CFO estimator assisted by the proposed training sequences.

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Source: https://tomesphere.com/paper/1703.07482