Joint optimization of content placement and request redirection in Mobile-CDN
Jiayi Liu, Qinghai Yang, Gwendal Simon · 2017
In a Mobile-CDN, Base Stations (BSs) are equipped with storages for replicating content, and they are allowed to cooperate in replying user requests through backhaul links. In this paper, we investigate the joint optimization problem of content placement and user request redirection for such a BS-based mobile CDN system. Specifically, each BS maintains a transmission queue for replying user requests issued from other BSs. Due to the limited link capacity and the dynamic network environment, the optimization problem should be jointly considered with the transmission queue states. We employ the Stochastic optimization model to minimize the long-term time-average transmission cost under content availability and network stability constraints. By applying the Lyapunov optimization technique, we transform the long-term problem into a set of linear programming (LP) problems, which are solved in each short time duration. Further, we propose a semi-distributed online algorithm to jointly decide content placement and user request redirection. The evaluation confirms that our solution guarantees network stability comparing to the traditional user request redirection scheme.