A$^3$L-FEC: Age-Aware Application Layer Forward Error Correction Flow Control
Sajjad Baghaee, Elif Uysal
TL;DR
The paper tackles the challenge of sustaining fresh information in time-sensitive networks by introducing A$^3$L-FEC, an application-layer UDP protocol that uses rateless FEC with adaptive, age-aware flow control. It defines two variants, FSFB (fixed sampling/block-length) and VSVB (variable sampling/block-length), each employing a receiver-driven congestion control loop to minimize age violations under varying network conditions. Theoretical limits and extensive MATLAB/ns-3/Mininet-WiFi simulations show that A$^3$L-FEC reduces age violations and end-to-end AoI compared to ACP+, TCP variants (notably BBR), and fixed-sampling TCP configurations, while highlighting the redundancy–delay trade-offs intrinsic to FEC-based freshness strategies. Additionally, a multiserver extension is proposed to coordinate rate allocation across competing flows, enabling scalable freshness improvements in shared networks. Together, these results demonstrate the practicality and effectiveness of age-aware application-layer FEC for real-time IoT and delay-sensitive communications.
Abstract
Age of Information (AoI) is a metric and KPI that has been developed for measuring and controlling data freshness. Optimization of AoI in a real-life network requires adapting the rate and timing of transmissions to varying network conditions. The vast majority of previous research on the control of AoI has been theoretical, using idealized models that ignored certain implementation aspects. As such, there is still a gap between the research on AoI and real-world protocols. In this paper we present an effort toward closing this gap by introducing an age-aware flow control algorithm. The algorithm, Age-Aware Application Layer Forward Error Correction (A$^3$L-FEC), is a packet generation mechanism operating on top of the User Datagram Protocol (UDP). The purpose is to control the peak Age of the end-to-end packet flow, specifically to reduce the rate of so-called "Age Violations," i.e., events where the peak age exceeds a given threshold. Evaluations in Mininet-WiFi and MATLAB indicate that A$3$L-FEC reduces age violations compared to two related protocols in the literature, namely TCP-BBR and ACP+.