# Frequency Offset Estimation for OFDM Systems with a Novel Frequency Domain Training Sequence

## TL;DR

This paper introduces a new frequency domain training sequence and CFO estimator for OFDM systems that improves accuracy and reduces complexity by using specially designed pilot tones and exploiting their structure.

## Contribution

A novel frequency domain training sequence with distinctively spaced and uniformly spaced pilot tones is proposed, enhancing CFO estimation accuracy and reducing computational complexity in OFDM systems.

## Key findings

- The proposed CFO estimator achieves good performance in simulations.
- The method effectively combats multipath effects.
- Computational complexity is significantly decreased.

## Abstract

A novel frequency domain training sequence and the corresponding carrier frequency offset (CFO) estimator are proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency-selective fading channels. The proposed frequency domain training sequence comprises two types of pilot tones, namely distinctively spaced pilot tones with high energies and uniformly spaced ones with low energies. Based on the distinctively spaced pilot tones, integer CFO estimation is accomplished. After the subcarriers occupied by the distinctively spaced pilot tones and their adjacent subcarriers are nulled for the sake of interference cancellation, fractional CFO estimation is executed according to the uniformly spaced pilot tones. By exploiting a predefined lookup table making the best of the structure of the distinctively spaced pilot tones, computational complexity of the proposed CFO estimator can be decreased considerably. With the aid of the uniformly spaced pilot tones generated from Chu sequence with cyclically orthogonal property, the ability of the proposed estimator to combat multipath effect is enhanced to a great extent. Simulation results illustrate the good performance of the proposed CFO estimator.