Beyond Beam Sweeping: One-Shot Satellite Acquisition with Doppler-Aware Rainbow Beamforming

TL;DR

This paper introduces a novel one-shot satellite acquisition method using rainbow beamforming that exploits Doppler and beam-squint effects, significantly reducing acquisition time and improving accuracy over traditional beam sweeping.

Contribution

It presents a closed-form rainbow beamformer and Doppler-aware angle estimation algorithms, enabling simultaneous satellite acquisition without beam sweeping.

Findings

Outperforms conventional methods in accuracy and speed

Exploits angle-dependent Doppler shifts for full coverage

Achieves satellite acquisition with a single pilot transmission

Abstract

High-gain beamforming (BF) is essential for low Earth orbit (LEO) satellite communications to overcome severe path loss, but this requires acquiring precise satellite positions. Conventional satellite acquisition typically relies on time-domain beam sweeping, which incurs substantial overhead and latency. In this correspondence, we propose an efficient one-shot satellite acquisition framework that capitalizes on two phenomena traditionally regarded as impairments: i) Doppler effects and ii) beam-squint effects. Specifically, we derive a closed-form \emph{rainbow beamformer} that leverages beam-squint effects to align frequency-dependent beam directions with satellite positions inferred from their Doppler shifts. This approach enables reception from multiple satellites at once without requiring beam sweeping. To extract satellite position information, we develop three Doppler-aware angle estimation algorithms based on received signals. Simulation results demonstrate that the proposed method significantly outperforms conventional beam sweeping approaches in both acquisition accuracy and required time slots. These gains stem from the ability of the proposed rainbow BF to exploit the \emph{angle-dependent nature of Doppler shifts}, enabling full angular-domain coverage with a single pilot transmission and reception.