Introduction of an Efficiency Metric for Device-to-Device Communication in Cellular Networks

Device-to-Device (D2D) communication is the latest of a series of attempts to combine cellular and ad-hoc networks and is seen as a promising concept in the wireless research community. However, the commonly used evaluation metrics for optimization do not capture the expected advantages of D2D. In this paper, a flow-based resource efficiency is defined and applied to a D2D scenario. It is shown that the already formulated gain-expectations proximity-, hop- and reuse-gain can be captured using this efficiency metric. Applying the metric to D2D, it is found that the three gains can be traded off against each other. As a proof of concept, D2D is re-evaluated in a single cell setup. It is motivated that around each D2D transmitter there are two regions, the Tradeoff- and the Win-Win-Region, in which D2D communication is advantageous.