OFDMA Based Angle-Constrained Underlay Device-to-Device Communication

Device-to-Device (D2D) communication, an influential addition to long term evolution-advanced (LTE-A) standards enables direct communication between the closely located cellular users to improve the throughput, latency, and spectral efficiency of a cellular network. In this paper, we augment the development of D2D by proposing the orthogonal frequency division multiple access (OFDMA) based underlay and overlay D2D frameworks wherein multiple D2D users coexist with the cellular users in the same cell. A general mathematical probability model is developed to analyze the performance of both frameworks. Specifically, closed form expression to find minimum angle θ (an angle between the cellular link and D2D interference link) is derived for which the target rate and outage probability constraint of both cellular and D2D users are satisfied. By deducing the value of θ, BS can select an optimal cellular user to facilitate D2D communication in a cellular network.