Video caching in Radio Access Network: Impact on delay and capacity

In this paper, we introduce distributed caching of videos at the base-stations of the Radio Access Network (RAN) as a way to reduce the need to bring requested videos from Internet CDNs, thereby reducing backhaul transmission, improving video quality of experience - delay and video stalling - and increasing overall network capacity to support more number of simultaneous video requests. Unlike Internet CDNs that can store millions of videos in a relatively few large sized caches, our proposed caching architecture consists of a very large number of micro-caches, with each base-station micro-cache being able to store only 1000s of videos, and hence may not be able to have high cache hit ratio. To address this challenge, we propose two new caching policies based on the User Preference Profile (UPP) of users in a cell: R-UPP (Reactive UPP) and P-UPP (Proactive UPP). Further, for videos that result in cache misses and need to be fetched from Internet CDNs, we develop a video scheduling approach that allocates the RAN backhaul resources to the video requests so as to reduce video latency and increase network capacity. We develop a discrete event statistical simulation framework using MATLAB to study the performance of RAN caching. Our simulation results show that RAN micro-caches with the proposed UPP-based caching policies, together with the proposed scheduling approach, can improve the probability of video requests that can meet initial delay requirements by almost 60%, and the number of concurrent video requests that can be served by up to 100%. The results also show that UPP based policies can enhance network capacity by up to 30% compared to conventional caching policies.