Design and analysis of collaborative EPC and RAN caching for LTE mobile networks

The explosive growth of mobile video traffic brings a great pressure on LTE mobile networks. Deploying caches at the evolved packet core (EPC) and radio access network (RAN) in LTE mobile networks can efficiently relieve this pressure by reducing duplicate content transmissions. In this paper, we propose a collaborative caching framework for the LIE mobile network with caches deployed at the EPC and RAN to reduce the bandwidth cost of Internet access and improve the end-user experience in terms of delay and congestion. Based on this framework, we decompose the caching problem into a content placement subproblem and a request routing subproblem. We solve the content placement subproblem with a greedy placement algorithm by utilizing the matroid and submodular properties. As for the request routing subproblem, we solve it by transforming it into the problem of maximizing a submodular function subject to a matroid constraint and present a greedy algorithm that schedules request routing with short time slot. The proposed CollaCache scheme can achieve at least 1/2 of the optimal solution in terms of bandwidth cost saving. Experimental results show that CollaCache can save more costs and support more requests compared with other schemes. (C) 2015 Elsevier B.V. All rights reserved.