On the performance of device-to-device communication under a composite fading channel

While maintaining a quality of cellular link subject to underlay device-to-device (D2D) communication in the cellular system, it obvious that a performance of proximity-based service over D2D link would be varying with the location of its transmitter. We consider an open-loop fractional power control for the uplink cellular link while limiting the transmit power of D2D link so as to protect the cellular link. In this paper, we provide an analytical framework to compute the average outage probability of D2D link, especially taking both short-term and long-term fading effects into account, as varying the location of D2D transmitter. A main trick in the current analysis is to resort to an approximation of a composite Rayleigh plus log-normal distribution by another log-normal distribution, which allows for modeling a signal-to-interference and noise ratio (SINR) as a Gaussian random variable. Our numerical analysis and simulation results confirm that the D2D links will be operationally valid when they approach the cell edge.