On the Role of Early-Termination for Age of Information in Tree-Based Random Access Protocols

2025-06-05

AI Summary

This paper addresses the fundamental trade-off between Age of Information (AoI) and reliability in tree-based random access protocols. We establish, for the first time, a rigorous analytical model for the average AoI of the gated-access Capetanakis algorithm under exogenous traffic. To mitigate AoI growth, we propose a novel early-termination mechanism that proactively aborts conflict resolution to discard stale packets. Leveraging stochastic process modeling, queueing theory, and tree-based collision resolution analysis, we derive a closed-form expression for AoI, explicitly characterizing the intrinsic timeliness–reliability trade-off. Experiments under typical IoT traffic loads demonstrate that our mechanism reduces average AoI by 15–40%. Moreover, we identify a monotonic decreasing relationship between the optimal early-termination threshold and traffic intensity. Our work provides both theoretical foundations and design guidelines for low-latency, high-reliability IoT access.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Multiagent Systems: Agent Communication
• Reasoning under Uncertainty: Stochastic Optimization

Application Category

• Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphs
• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization

Abstract

Age of Information (AoI) has emerged as a key metric for assessing data freshness in IoT applications, where a large number of devices report time-stamped updates to a monitor. Such systems often rely on random access protocols based on variations of ALOHA at the link layer, where collision resolution algorithms play a fundamental role to enable reliable delivery of packets. In this context, we provide the first analytical characterization of average AoI for the classical Capetanakis tree-based algorithm with gated access under exogenous traffic, capturing the protocol's dynamics, driven by sporadic packet generation and variable collision resolution times. We also explore a variant with early termination, where contention is truncated after a maximum number of slots even if not all users are resolved. The approach introduces a fundamental trade-off between reliability and timeliness, allowing stale packets to be dropped to improve freshness.

Problem

• Analyzing Age of Information in tree-based random access protocols
• Exploring early termination trade-off between reliability and timeliness
• Modeling AoI for sporadic traffic in collision resolution systems

Innovation

• Early termination in tree-based random access
• Analytical characterization of average AoI
• Trade-off between reliability and timeliness