Performance Analysis of On-board Content Caching and Retrieval for High-Speed Railways

With the rapid development of high-speed railway (HSR), more and more people tend to choose High-Speed Train (HST) for the benefit of its high efficiency and safety. During long-distance journeys, passengers expect to have real-time and high-quality multi-media services for working and entertainment. However, direct cellular connections between on-board User Equipments (UEs) and wayside Base Stations (BSs) are hard to provide continuous and assured Quality of Service (QoS) due to the high mobility of HST and high penetration loss of carriages. The multi-hop network architecture and in-network caching enabled by information-centric networks (ICN) are regarded as efficient methods to solve above problems. Based on the above observations, to improve quality of experience (QoE) for passengers and content dissemination in HST, we propose an onboard content caching and retrieval scheme for a multi-hop HST $\mathrm{WiFi}$ network architecture, in which multi-media contents are optionally cached in HSTs through a distributed or centralized method. Simulation results suggest that the caching policy is necessary, and the centralized caching policy outperforms the distributed one in terms of cache hit ratio.