Co-Operative Caching in Dynamic Shared Spectrum Networks

This paper considers co-operation between primary and secondary users in shared spectrum radio networks via caching. We first consider a network with one channel shared between a single macro (primary) base station and multiple micro (secondary) base stations. Secondary base stations can cache some primary files and thereby satisfy content requests generated from nearby primary users. For this co-operative scenario, we develop two caching and scheduling policies under which the set of primary and secondary request generation rates that can be supported increases from the case without cooperation. The first of these algorithms, fixed primary caching policy (FPCP), provides more gain in the set of supportable request generation rates. However under this algorithm primary packet transmissions from secondary base stations have the same priority of access as secondary packets and thus might suffer in terms of delay. In the second algorithm, variable primary caching policy (VPCP), primary packet transmissions from the secondary base stations have higher priority of access than that of secondary packets. We find that the set of request generation rate vectors for which all queues in the network are stable under each of these algorithms is greater than that under any non-cooperative algorithm. We conduct extensive simulations to compare the performance of both algorithms against that of an optimal noncooperative algorithm. Finally, we extend the analysis to a network with multiple channels.