Device-to-Device assisted wireless video delivery with network coding

Broadcasting popular data content such as videos to multiple users is widely used in mobile wireless networks. We consider a group of mobile users, within proximity of each other, who are interested in the same video or cloud services. In this scenario, users are able to use device-to-device (D2D) connections, e.g., WiFi or Bluetooth, to get the video in a cooperative way. In this paper we consider the D2D-assisted wireless network coded video broadcast problem for users with multiple interfaces to minimize the number of transmission slots. In order to obtain all needed videos, user can receive encoded packet according to cellular link and local cooperative D2D links simultaneously. We analyze the lower bound and upper bound of number of transmission slots under two different receiver models. In the first model, receiver just drop the encoded packet which cannot be decoded immediately, and we propose a joint broadcast and D2D encoding solution based on the clique partition in the graph. In the second model that receiver can buffer all received encoded packets and decode when enough packets are received, we propose an optimal solution using an integer linear programming (ILP) formulation, and we also propose an effective heuristic encoding solution based on random linear coding. Simulation results show that the proposed transmission strategy can significantly reduce the number of transmission slots in most cases, which is an important performance metric in wireless video delivery.