Optimal Caching with Content Broadcast in Cache-and-Forward Networks

With the rapid advance in the technology area of data storage, storage capacities have increased substantially while the price has been dropping fast. Motivated by this trend, it has been proposed in the Cache-and-Forward architecture that storage is incorporated into each intermediate CNF router. Content can be cached at CNF routers when they flow through the network, and therefore, routers can serve the subsequent requests later on, without forwarding the requests to the host server, we refer to this caching paradigm as In-Network Caching. In this paper, the content caching is enhanced by Content Broadcast(CB), by which a CNF router broadcasts the information of cached content to its neighboring nodes. In order to solve the problem that with limited storage, how an intermediate CNF router optimally decides which passing content should be cached, we develop a mathematical model for CB to minimize the average content retrieval latency, and propose the Independent Allocation algorithm. We compare the average content retrieval latencies of the proposed caching scheme with two other commonly used cache replacement policies. We study the impact of cache size and locality parameter. The proposed scheme is shown to provide significant performance improvement under various settings by as large as 65%.