On Queue Length and Link Buffer Size Estimation in 3G/4G Mobile Data Networks

The emerging mobile data networks fueled by the world-wide deployment of 3G, HSPA, and LTE networks created new challenges for the development of Internet applications. Unlike their wired counterpart, mobile data networks are known to exhibit highly variable bandwidth. Moreover, base stations are often equipped with large buffers to absorb bandwidth fluctuations to prevent unnecessary packet losses. Consequently to optimize protocol performance in mobile data networks it is essential to be able to accurately characterize two key network properties: queue length and buffer size of the bottleneck link. This work tackles the challenge in estimating these two network properties in modern mobile data networks. Using extensive trace-driven simulations based on actual bandwidth trace data measured from production mobile data networks, we show that existing queue-length and link buffer size estimation algorithms no longer work well in bandwidth-varying networks. We develop a novel sum-of-delays algorithm which incorporates the effect of bandwidth variations into its estimation. Extensive trace-driven simulation results show that it can accurately estimate the queue length and link buffer size under both fixed and varying bandwidth conditions, outperforming existing algorithms by up to two orders of magnitude.