Leveraging Multi-rate Multicast for Content Caching and Transmission Rate Allocation in Cache-Enabled Networks

As one of the significant features in the cache-enabled networks, in-network caching improves the efficiency of content dissemination by offloading content from the remote content provider onto the network that is closer to the users, and creates an opportunity for multicast. Since the multicast paradigm is a promising method for sending data to multiple users while saving bandwidth, this paper exploits the multi-rate multicast paradigm to address the caching problem in the cache-enabled environment which jointly considers the content caching and transmission rate allocation. The pure caching design, which is developed in most existing works, can only achieve limited performance; therefore, we argue that caching should be jointly designed. Our joint model can accommodate the diverse requirements of users by serving them with content in the nearby cache at different transmission rates, which is different from the single-rate multicast paradigm where users can only share the same rate in the same multicast group. We prove that the proposed maximization problem is a biconvex optimization problem. To solve this problem, we exploit the decomposable structure of the joint maximization to develop a heuristic solution that consists of caching decision and rate allocation algorithms. We reduce the search space of the heuristic algorithm to further reduce computation and communication complexity. We carry out an extensive packet-level simulation to evaluate the performance of our proposal compared with some benchmark schemes. Simulation results show that the proposed heuristic algorithm performs well compared with the benchmarks.