Demonstrator Testbed for Effective Precoding in MEO Multibeam Satellites

2025-08-27

AI Summary

In medium Earth orbit (MEO) multibeam satellite systems employing full-frequency reuse, forward-link precoding performance degrades significantly due to orbital dynamics—specifically Doppler shifts and payload phase noise. Method: This paper develops a software-defined radio (SDR)-based ground testbed integrating high-fidelity orbital dynamics modeling, direct radiating array (DRA) antenna characterization, and payload phase noise modeling. It proposes a novel dynamic precoding compensation mechanism featuring a synchronized loop that jointly corrects Doppler-induced distortions and suppresses phase noise. Contribution/Results: The mechanism enables real-time adaptation of multi-user MISO precoding under MEO conditions. Experimental validation demonstrates substantial mitigation of channel time-variation effects, improved precoding stability, and enhanced spectral efficiency. The framework provides an engineering-ready signal processing solution for non-geostationary orbit (NGSO) satellite communication systems.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Mixture of Experts (MoE)
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
• Security and Privacy: Large-scale security measurements

Abstract

The use of communication satellites in medium Earth orbit (MEO) is foreseen to provide quasi-global broadband Internet connectivity in the coming networking ecosystems. Multi-user multiple-input single-output (MU-MISO) digital signal processing techniques, such as precoding, emerge as appealing technological enablers in the forward link of multi-beam satellite systems operating in full frequency reuse (FFR). However, the orbit dynamics of MEO satellites pose additional challenges that must be carefully evaluated and addressed. This work presents the design of an in-lab testbed based on software-defined radio (SDR) platforms and the corresponding adaptations required for efficient precoding in a MEO scenario. The setup incorporates a precise orbit model and the radiation pattern of a custom-designed direct radiating array (DRA). We analyze the main impairments affecting precoding performance, including Doppler shifts and payload phase noise, and propose a synchronization loop to mitigate these effects. Preliminary experimental results validate the feasibility and effectiveness of the proposed solution.

Problem

• Addressing MEO satellite orbit dynamics challenges for precoding
• Mitigating Doppler shifts and phase noise in satellite communications
• Designing testbed for effective precoding in multibeam satellite systems

Innovation

• SDR-based testbed for MEO precoding
• Synchronization loop for Doppler compensation
• Direct radiating array with orbit modeling