Design of Caching Content Replacement in Base Station Assisted Wireless D2D Caching Networks

Due to the concentrated popularity distribution of video files, caching of popular files on devices, and distributing them via device-to-device (D2D) communications allows a dramatic increase in the throughput of wireless video networks. However, since the popularity distribution is not static and the caching policy might be outdated, there is a need for replacement of cache content. In this work, by exploiting the broadcasting of the base station (BS), we model the caching content replacement in BS assisted wireless D2D caching networks and propose a practically realizable replacement procedure. Subsequently, by introducing a queuing system, the replacement problem is formulated as a sequential decision making problem, in which the long term average service rate is optimized under average cost constraint and queue stability. We propose a replacement design using Lyapunov optimization, which effectively solves the problem and makes decisions. Using simulations, we evaluate the proposed design. The results clearly indicate that, when dynamics exist, the systems exploiting replacement can significantly outperform the systems using merely the static policy.