Adaptive rate control over mobile data networks with heuristic rate compensations

Abstract

Mobile data networks exhibit highly variable data rates and stochastic non-congestion-related packet loss. These challenges result in key performance bottlenecks in current Transmission Control Protocol (TCP) implementations: bandwidth inefficiency and large end-to-end delay. This work addresses these challenges by first developing a Sliding Interval based Rate Adaptation (SIRA) that tracks bandwidths with a fixed time interval and applies them to its transmission rate periodically. Extensive experiments confirmed that SIRA achieves 96.3% bandwidth utilization and reduces the average queueing delay by a factor of 1.37, compared to TCP CUBIC, the preferred variant for Internet servers. However, the resultant end-to-end delay is still much larger for interactive applications, thus we complement SIRA with two heuristic rate compensation algorithms (SIRA-H) given that the bandwidth does not vary significantly in long time scales. Specifically, SIRA-H first reduces the transmission rate of SIRA if the estimated RTT is above a prefigured threshold. Meanwhile, it computes the amount of unsent data that would be transmitted if SIRA were used, and compensates the rate reduction with those unsent data as if their ACKs were received, when the queue is detected to be empty. We evaluated SIRA-H through a combination of trace-driven emulations and real-world experiments, and showed that it reduces the 95th percentile queueing delay by a factor of over 3.9, while maintains a similar throughput compared to the original SIRA. In comparison to state of the art protocols such as Sprout and Verus, SIRA-H also reduces the 95th percentile queueing delay by a factor of over 0.8.