# Channel Estimation in UAV-Assisted OFDM Systems by Leveraging LoS and Echo Sensing with Carrier Aggregation

## TL;DR

This paper introduces a new channel estimation method for UAV communication systems using LoS and echo sensing with carrier aggregation to improve accuracy and robustness.

## Contribution

A novel CE scheme leveraging LoS and echo sensing for CA-enabled UAV systems is proposed.

## Key findings

- The proposed method improves CE accuracy for both primary and secondary component carriers.
- The scheme is robust against parameter variations in high-mobility UAV scenarios.
- Simulation results validate the effectiveness of the three-stage DD domain reconstruction process.

## Abstract

Unmanned aerial vehicle (UAV)-assisted wireless communication systems often employ the carrier aggregation (CA) technique to alleviate the issue of insufficient bandwidth. However, in high-mobility UAV communication scenarios, the dynamic channel characteristics pose significant challenges to channel estimation (CE). Given these challenges, this paper proposes a line-of-sight (LoS) and echo sensing-based CE scheme for CA-enabled UAV-assisted communication systems. Firstly, LoS sensing and echo sensing are employed to obtain sensing-assisted prior information, which refines the CE for the primary component carrier (PCC). Subsequently, the path-sharing property between the PCC and secondary component carriers (SCCs) is exploited to reconstruct SCC channels in the delay-Doppler (DD) domain through a three-stage process. The simulation results demonstrate that the proposed method effectively enhances the CE accuracy for both the PCC and SCCs. Furthermore, the proposed scheme exhibits robustness against parameter variations.