The impact of device-to-device communication on the capacity of cellular systems

In this paper, the capacity of underlaying cellular networks is analyzed by considering the impact of Device-to-Device (D2D) mode, which is shown to be capable of substantially enhancing the sum transmission rate of the cellular network. Based on the theory of stochastic geometry, the successful transmission probabilities of both the D2D users and the conventional cellular users(CUs) are derived, with the D2D transmission rate as well as the sum rate given out simultaneously. Furthermore, the optimal D2D-users(DUs) density that maximizes the sum rate is also derived. In addition, we extend the analysis from single-cell scenario to the multicell environment. Numerical results demonstrate the relationship between D2D-contributed capacity and the D2D-users density. It is shown that the network capacity can be enhanced by increasing the density D2D users when the D2D-users density is relatively low, until a break-even point is approach, in which case further increasing D2D users may even erode the sum rate.