Exploiting Geographical Context in D2D Communications

In this paper, we present a framework for including geographical context information within the process of relay selection, where both the relay and destination can be user equipment (UE) hence enabling relaying via device-to-device (D2D) communication. Geographical information, acquired through positioning systems and radio maps, are used to infer pathloss, link budgets and relay generated interference. Thus, this information becomes available at the core network without the aid of extra signaling and channel sounding. Tools from image processing can be exploited to analyze the radio map and determine so called isolated regions. Then, these regions are used by the proposed framework to effectively select the relay. Three different relay selection policies that exploit geographical context via the knowledge of the spatial isolated regions are introduced. Each of these policies is analyzed via simulation and performance is compared with respect to baseline schemes. The pertinence of adopting geographical information is confirmed by the gain in terms of useful power and reduced interference level generated.