Cooperative Activation and Caching Strategy for Low-Latency and Energy-Efficient Small-Cell Networks

Traffic load can be largely alleviated by content caching in densely deployed small-cell base stations (SBSs), which however require significant energy expenses for operation. In this letter, we investigate the cooperative activation and caching problem for dense small-cell networks with unknown user demands. A key issue is to make activation and caching decisions, which is proved to be NP-hard even if user demands are perfectly known. While existing works on joint optimization of activation and caching make decisions based on estimated user demands, we consider to learn activation and caching strategy in an online manner. We take into account the cooperation among SBSs. In particular, an active SBS that serves a user should share the observed rewards to the SBSs that are nearer to the user. In this way, an inactive SBS can keep learning the information of its surrounding users, and will become active again when its surrounding users have sufficient requests. The simulation results demonstrate the superior performance of the proposed strategy in terms of delay and energy consumption.