Cooperative Content Delivery in Multicast Multihop Device-to-Device Networks

The increasing demand of mobile devices (MDs) for data services brings tremendous pressure to cellular networks. It has become a great challenge for traditional offloading techniques to balance the energy efficiency and quality of service. The concept of device-to-device (D2D) communication shows a huge potential in cellular offloading. In this paper, we investigate the scenario where MDs have the same demand for a common content and they cooperate to download the content by multihop relaying. We aim to minimize the total power consumption by grouping MDs in multihop D2D networks, while satisfying the minimum rate required by each MD. As the problem is NP-complete and the optimal solution cannot be found in polynomial time, we propose three greedy algorithms with different grouping strategies to trade off the performance and complexity. Simulation results demonstrate that the total power consumption can be saved significantly in the content delivery situation using cooperative D2D communication, and the proposed algorithms are suitable for static and dynamic networks with different advantages.