CLOUD RADIO ACCESS NETWORK WITH OPTIMIZED BASE-STATION CACHING

The performance of cloud radio access networks (CRAN) is limited by the finite capacities of the backhaul links connecting the cloud with the base-stations (BSs). A promising approach to improving the performance of C-RAN is to augment the backhaul through BS caching, where the BSs pre-store some of the popular contents. In this paper, we first derive a multicast backhaul rate expression based on a joint cache-channel coding scheme, and show that, as compared to the uniform cache allocation, it is better to allocate larger cache sizes to the weaker BSs. Then, by leveraging the sample approximation method and the alternating direction method of multipliers, we develop an efficient algorithm to optimize the cache allocation by maximizing the BS expected file downloading rate from the cloud. Numerical results show considerable performance improvement of the optimized cache allocation scheme over heuristic schemes.