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The Capacity of Device-to-Device Communication Underlaying Cellular Networks With Relay Links

With the rapid development of mobile communication technology, the pressure of core network from wireless traffic is explosively growing. Meanwhile, ultra-low latency and real-time user experience are urgently demanded, which gives raise to the severe challenge of traditional cellular networks. As one of the key technologies in 5G, device-to-device (D2D) communication underlaying cellular networks is a promising way to elevate the network system performance, improve the user experience and expand the applications. In this paper, we present an architecture for analyzing the network capacity when D2D communication shares the channel resources with cellular links. This architecture consists of three types of links: cellular links, D2D links, and relay links. We mathematically model the network capacity of the three different links. Moreover, a cooperative caching strategy is proposed, which caches the files with the greatest popularity in the D2D group to improve the network capacity. Finally, we conduct the numerical simulations and the results show the proposed architecture improves the network capacity significantly.