A Small-Cell Caching System in Mobile Cellular Networks With LoS and NLoS Channels

Small-cell caching utilizes the embedded storage of small-cell base stations (SBS) to cache popular network contents, for the purpose of reducing duplicate transmissions in mobile networks and offloading the data traffic from macro-cell base stations. In this paper, we propose a random small-cell caching system, where each SBS randomly caches a subset of popular contents with a specified caching probability. We particularly focus on the probability that mobile users can successfully download their requested files from the SBSs, namely, successfully downloading probability (SDP). A sophisticated path-loss model incorporating both line-of-sight (LoS) and non-LoS (NLoS) transmissions is introduced into the SDP analysis. By modeling the distribution of the SBSs as a Poisson point process, we develop theoretical results of the SDP performance based on stochastic geometry theory. Additionally, we investigate the impacts of the parameters of the SBSs, i.e., transmission power and deployment intensity, on the SDP. Monte Carlo simulations show the consistency with our derived SDP. Also, numerical results validate our analysis on the related parameters and their impacts on the SDP performance.