A novel D2D data offloading scheme for LTE networks

Downloading remote files (e.g., pictures, videos) from online social networks via smart user equipments (UEs) (e.g., smartphones, tablets) is becoming popular. Friends who are nearby may want to download the same files shared by their mutual acquaintance. People can obtain these files in a device-to-device (D2D) manner via opportunistic connections to reduce their payment for data service. This is referred to as D2D data offloading. However, D2D communications on unlicensed spectrum using Bluetooth or WiFi-Direct may not maintain high data rate when many D2D pairs nearby need to communicate simultaneously. Since D2D connections are transient, it is important to improve spatial reuse of communication resources and increase the data rate of opportunistic D2D communications. In this paper, we propose a scheme to reuse the downlink licensed spectrum of cellular networks for D2D data offloading. Our proposed scheme includes determining the availability of digital files on neighbouring devices, estimating the channel gains, and performing channel allocation and power control for D2D pairs. Simulation results show that our proposed scheme does not affect the existing cellular UEs and it can also offload more data traffic when compared with WiFi-Direct on an unlicensed spectrum.