Performance analysis of network coding-based content delivery in dual interface cellular networks

We consider a group of mobile users, in closed proximity, who are interested in downloading a common content (e.g., a video file). We address a cooperative solution where each mobile device is equipped with both cellular and Wi-Fi interfaces. The users exploit the cellular link to download different shares of the content from the based-station and leverage on Wi-Fi link to exchange the received data. In order to expedite content delivery, the base-station transmits random linear network-coded data to users. This paper presents an analytical study of the average completion time, i.e., the time necessary for all devices to successfully retrieve the data. We propose an analytical model to address the effect of random access MAC as well as the correlation among the received coded packets on the performance of content delivery. In our model, a p-persistent carrier sense multiple access approximation for IEEE 802.11 MAC is considered. We also derive the probability of a newly received packet to be innovative, where the coding coefficients are selected randomly and uniformly from GF(q). Our simulations confirms the theoretical analysis.