On the Effect of Redundant Caching Policy on Multimedia Streaming in D2D Underlay Network
Suvadip Batabyal · 2023
Device-to-device (D2D) communication underlay cellular network improves spectral efficiency by reusing cellular resources over short low-powered links between the devices. These D2D links can be used to fetch cached contents and therefore improve the application experiences, especially for multimedia contents. In this article, we investigate the effect of caching policies on the offloading probability (also known as the hit-rate), and hence the buffering time, for video streaming applications. Designing a caching policy to maximize the hit-rate depends on several factors such as device storage capacity, instantaneous number of devices available to act as a D2D transmitter, resource allocation policy, etc. We first model the D2D links as a simple birth-death process to realize the dynamicity of the D2D links, and derive the steady-state distribution of the number of D2D links. We show that the hit-rate can be improved by increasing the caching redundancy (number of copies of a given content to be cached). Finally, through simulation we show that there exists an optimal group size and redundancy, beyond which the hit-rate do not improve.