Resource Allocation for Device-to-Device Communications Overlaying Two-Way Cellular Networks

TLDR

Device‑to‑device (D2D) communication enables direct transmission between nearby cellular devices as an underlay to cellular networks. This study proposes a spectrum‑sharing protocol that allows bi‑directional D2D communication while supporting two‑way cellular links between a base station and a user. The protocol’s performance is analyzed by deriving the achievable rate region for D2D versus cellular transmissions, optimizing the Pareto boundary through transmit‑power and power‑splitting control at the base station, user, and relay D2D node, and incorporating relay‑selection among multiple D2D pairs. Numerical results demonstrate that the proposed protocol with power control improves the sum rate for both D2D and cellular users, and that relay selection yields additional gains for cellular links.

Abstract

Device-to-device (D2D) communications has been proposed in the literature as an underlay approach to cellular networks to allow direct transmission between two cellular devices with local communication needs. In this paper, we consider a scenario of D2D communications overlaying a cellular network and propose a new spectrum sharing protocol, which allows the D2D users to communicate bi-directionally with each other while assisting the two-way communications between the cellular base station (BS) and the cellular user (CU). We derive the achievable rate region of the sum rate of the D2D transmissions versus that of the cellular transmissions. The Pareto boundary of the region is found by optimizing the transmit power at BS and CU as well as the power splitting factor at the relay D2D node. Since either of the two D2D users can be the relay and there can exist multiple pairs of D2D users, we also consider the relay selection from the potential D2D users. We find through numerical results that the proposed two-way protocol with power control at the BS and CU is effective to improve the sum rate for both the D2D and cellular users. In addition, relay selection can achieve further improvement in the sum rate of the cellular links.