Network Throughput Gain of Multicast With User Caching in Heavy Traffic Downlink

In order to cope with the recent dramatic growth in mobile traffic, it is important to understand and exploit its unique features in wireless communications. For example, the fact that a relatively small number of popular contents accounts for most of the traffic is considered one of the most promising factors to explore. This paper proposes a multicast system with user caching in a heavy traffic model. Through the efficient combination of caching and multicasting, the proposed system reduces the redundant communication resource consumptions for the duplicated requests of the same content from different users. The performance of the proposed system is analyzed in closed-form expressions in terms of outage probability and average network throughput by means of the asymptotic analysis. The derived expressions provide insight into the impact of system parameters on performance and can be used to capture the gains in performance obtained from user caching and multicasting in the proposed system. Furthermore, the simulation results confirm the convergence of the asymptotic analysis results in the heavy traffic model and provide additional information on the average network throughput in general cases.