Successful Transmission Probability Analysis for Cache-Enabled Users in Mobile Networks

Caching popular contents in the storage of users is deemed as an efficient approach to increase energy efficiency, decrease latency, as well as offload backhauls. Due to the mobility feature of use terminals in the real environment, the analysis of successful transmission is particular important in mobile networks. In this paper, the position of cache-enabled users are distributed as a Homogeneous Poisson Point Process (HPPP) and user moves following the random walk mobility (RWM) model. Then, the successful transmission probability is analyzed through the observation of the one step movement of the typical user using stochastic geometry methods. Meanwhile, in order to optimize the successful transmission probability, two methods are considered, i.e., file segmentation transmission (FST) and retransmission mechanism (RM). Simulation results show that the successful transmission probability can be improved by several network parameters, e.g., user density, transmission zone radius and caching probability, but exhibits a decline with increasing velocity or downloading time. Besides, considering segmentation cost, there is a tradeoff for the optimal segment number for the FST and RM schemes.