Mobility-Aware Caching Specific to Video Services in Hyper-Dense Heterogeneous Networks

Caching at the network edge has emerged as a promising technique to cope with the dramatic increase of mobile data traffic. It is noted that different types of video applications on mobile devices have different requirements for cached contents, thus corresponding caching policies should be developed accordingly. In hyper-dense heterogeneous networks, due to the user mobility and limited connection duration, the user often could not download the complete cached contents from an associated SBS before it moves away, which makes the design of caching strategy more challenging. In this paper, we propose two different caching strategies to adapt to multimedia applications of different video contents. For ordinary network video files, coded caching is used to increase the efficiency of content access. The caching problem is formulated as an optimization problem to minimize the average transmission cost of cached contents. We first present an optimal caching strategy based on the critical value of validity period of user requests. Then, for the validity period greater than its critical value, an iterative optimization on the basis of the above optimal solution is performed. For typical streaming video, uncoded video fragments is considered to be stored in the caches to meet the needs of online viewing. The principle of the proposed caching scheme is to cache data chunks in advance according to the sequences of SBSs passed by the user based on the mobility prediction results. Simulation results indicate that the proposed mobility-based caching performs better than the existing popularity-based caching scheme.