On energy-efficient caching at the wireless edge

In this paper we study the problem of content placement for caching at the wireless edge with the goal to maximize the energy efficiency (EE) of heterogeneous wireless networks. We derive the EE performance of an MDS-encoded caching scheme, and we formulate the optimal caching scheme as a convex optimization problem. We then thoroughly study the performance of this optimal scheme for an important heterogeneous network scenario. In particular we compare it to several other sub-optimal caching strategies, such as the caching scheme minimizing the backhaul rate, and we analyze how the system parameters affect the overall performance. As demonstrated by our results, our optimal placement of MDS-encoded content in caches at the wireless edge increases significantly the EE, and hence careful design of edge caching in heterogeneous networks yields significant energy savings.