A cost-oriented cooperative caching for software-defined radio access networks

In this paper, a software-defined radio access network (SD-RAN) is considered where content caching is performed at the small-cell base stations (SBSs) under the coordination of a central macro-cell base station (MBS). Two benchmark algorithms are firstly discussed to maximize the content hit ratio within the associated small cells locally and to maximize the content hit ratio within the macro cell, respectively. In order to minimize the content provisioning cost of the entire SD-RAN, it needs to strike a balance between the local hit ratio and the hit ratio within the macro cell. With this inspiration, a heuristic cooperative caching algorithm is proposed by dividing the cache space at each SBS into two portions for storing the duplicated contents and unique contents respectively. The optimal partition factor at which the average content provisioning cost of SD-RAN is minimized is analytically obtained in a closed form.