An Efficient Two-User Multicast Pushing Policy for Cache Hit Ratio Maximization

Pro-active pushing is a promising emerging communication technology to improve the resource efficiency and quality of service provisioning in mobile networks. This paper characterizes users' requests with request delay information (RDI), and proposes to use the cache-hit ratio (CHR) as the metric of the system performance in pushing strategy design. Different from conventional instant on-demand services, the pro-active pushing system can merge different users' requests for the same file at different time instants. The base station can therefore push files more efficiently by employing multicasting technologies. However, it is revealed that if one of the users' channel condition is significantly poor, it is a better choice to ignore the user in the pushing system from the overall CHR performance perspective. In the two-user one-file scenario, we derive analytical expressions of the CHR to help the BS determine the optimal pushing rate, which is shown to be a two-value-selection. In particular, for two users with uniformly distributed RDIs, the decision space is specifically characterized through analysis and calculation.