Design and Evaluation of Queue Aware RTT-Guided Scheduler for MPTCP

Abstract

Multipath TCP (MPTCP) enables network bandwidth aggregation and failure resilience by maintaining multiple concurrent TCP subflows. While prior work focuses on congestion control coupling and loss latency, existing schedulers often fail under heterogeneous link dynamics because they do not simultaneously optimize for RTT, queue occupancy, and buffer availability. This paper proposes a queue-aware Lowest round trip time (qaLRTT) scheduler with a multi-factor decision logic, which combines congestion window-based queue control and RTT metrics. We present the implementation, and validate the approach through in-lab experiments. Compared against default, redundant, and existing baseline schedulers, qaLRTT achieves high throughput with reduced queuing delay and robust performance under lossy conditions, addressing some limitations identified in recent multipath scheduling.