Formal Verification of a Generic Algorithm for TDM Communication Over Inter Satellite Links

2025-11-12

AI Summary

This work addresses the reliability verification challenge of a generic time-division multiplexing (TDM) slot-scheduling algorithm for inter-satellite links (ISLs). We propose a formal modeling and verification approach based on Communicating Sequential Processes (CSP) process algebra. By constructing a precise CSP model that faithfully captures the semantics of the Python implementation and leveraging the PAT model checker for automated analysis, we achieve the first staged formal verification of a generic TDM scheduling algorithm tailored to ISLs. Key safety and liveness properties—specifically deadlock-freedom and strong termination—are rigorously verified. This work fills a critical gap in formal assurance for TDM protocols in onboard distributed edge systems, establishing a verifiable algorithmic foundation and supporting toolchain for ultra-reliable interplanetary communication.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization
• Multiagent Systems: Agent Communication

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Security and Privacy: Data transparency and provenance
• Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphs

Abstract

The Python Testbed for Federated Learning Algorithms is a simple FL framework targeting edge systems, which provides the three generic algorithms: the centralized federated learning, the decentralized federated learning, and the universal TDM communication in the current time slot. The first two were formally verified in a previous paper using the CSP process algebra, and in this paper, we use the same approach to formally verify the third one, in two phases. In the first phase, we construct the CSP model as a faithful representation of the real Python code. In the second phase, the model checker PAT automatically proves correctness of the third generic algorithm by proving its deadlock freeness (safety property) and successful termination (liveness property).

Problem

• Formally verifying TDM communication algorithm correctness
• Ensuring deadlock-free operation in satellite links
• Proving successful termination for distributed systems

Innovation

• Formally verified TDM communication algorithm using CSP
• Modeled Python code as CSP process algebra representation
• Automatically proved deadlock freedom and termination properties