A novel link buffer size estimation algorithm for bandwidth-varying mobile data networks

The rapidly 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. However these two factors together invalidate the assumptions used in conventional protocol designs, which routers are assumed to have fixed link capacity and a small buffer. Consequently to optimize protocol performance in mobile data networks it is essential to be able to accurately characterize the network properties such as bottleneck link buffer size. This work tackles the challenge in estimating link buffer size 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 link buffer size estimation algorithms such as max-min and loss-pair no longer work well in bandwidth-varying networks. We develop a novel sum-of-delays algorithm to tackle this challenge. Simulation results show that it can accurately estimate the link buffer size under both fixed and varying bandwidth conditions, outperforming the existing algorithms by multiple orders of magnitude.