Priority-Aligned Flow Control for IP-Based Telemetry Systems

Abstract

We developed priority-aligned flow control between the queuing system and the radio for IP-based telemetry systems. The approach provides the unified flow control across all nodes and traffic classes in telemetry links to better regulate bandwidth usage without creating oscillations. It combines multiple features: Volume-based flow control ensures consistency between a traffic queue's drain rate and the TDMA slot allocations for this queue. The allocations are translated into the number of packets to be sent to the radio from the router for each QoS class and test mission. In the case of iNET, the necessary capacity allocations are provided by the Link Manager on the ground. Fine-grained queue management allows flow control algorithms to adjust dynamically multiple parameters at the Traffic Engineering Queues as needed. Router- radio interface enhances the existing IETF standard Data Link Exchange Protocol (DLEP) to provide the signaling required for our solution. We defined the queue throughput shortage as the key evaluation metric. Our approach performed significantly better in comparison with the coarse-grained queue control available in Linux kernel. When averaged across links/queues, the reduction was 2-6% and 4-28% for high (8Mbps) and low (1Mbps) channel capacities, respectively. When averaged across multiple channel capacities, the maximum per-queue shortage was reduced from 47% to 4.5%.