Fast Cooperative Content Distribution over Hybrid Wireless Networks

Abstract

Recently, device-to-device (D2D) communications have been leveraged to offload the traffic on cellular networks. In this paper, we focus on the content distribution problem over a hybrid cellular and local D2D network where mobile devices cooperatively download a same content. We assume that the transmissions over D2D communications are scheduled in a centralized fashion so as to achieve a high transmission efficiency. Aiming at minimizing the content download time, we formulate the minimum content download time (MinCD) problem as an integer linear programming problem, and show its hardness and inapproximability. For the case that only a single channel is available for D2D communications, we propose an asymptotically optimal algorithm. For the multi-channel case, we further propose a heuristic algorithm with low time complexity and demonstrate its efficiency via extensive simulations.