This paper proposes a discovery method which utilizes Timing Advance (a standardized parameter) to determine the proximity of the device-to-device (D2D) users in Long Term Evolution Advanced (LTE-A) cellular networks. Timing Advance (TA) is used by the network for synchronizing TDMA frame between eNodeB and mobile users. It indicates the propagation delay and helps us to estimate the distance between eNodeB and mobile users.

With the cooperation among two eNodeBs, the mobile network can specify how far from one user to another user. This calculation is absolutely transparent to the users and efficient when mobile user within the coverage of cellular network. In the rest of paper, we evaluate the accuracy of method with simulation in case of the users are distributed randomly. The simulation results show that this method is applicable for cellular network to support D2D communication.