Uplink delay variation compensation in queue length estimation over mobile data networks

Knowledge of the queue length and link buffer size of the bottleneck link has many potential applications such as congestion control, traffic engineering, traffic policing, content adaptation, QoS monitoring and provisioning, etc. A recent work proposed a new Sum-of-Delay (SoD) algorithm which can accurately estimate such link properties in mobile networks. This work presents a delay variation compensation algorithm - Sum-of-Delay with Timestamp (SoD-TS), to further improve SoD´s estimation accuracy in networks with large uplink delay variations. The proposed algorithm exploits the existing TCP Timestamp option which is widely deployed and thus can be implemented without modification to the receiver´s TCP implementation. By making use of SoD-TS we developed a novel transport layer application - queue-length-based congestion control algorithm (QCC), on top of TCP that tackles the problem of bufferbloat to provide better QoS for applications requiring low end-to-end delay and/or high bandwidth utilization. Trace-driven simulation shows that SoD-TS can effectively eliminate estimation errors caused by uplink delay variations. Moreover, by applying QCC to the widely deployed TCP CUBIC it can reduce the RTT by a factor of over 3.6 while still achieving over 87% bandwidth utilization.