Performance Analysis of Random Backoff based D2D Discovery in Cellular Networks

Device to Device (D2D) communication is one of the key features of future 5th generation (5G) cellular networks. Most D2D researchers have focused on the data communication phase, assuming the device discovery has already been done. However, there are still many challenges in the discovery phase, with the transmission collision as one of the critical problems to be resolved. Collisions occur when the number of beacon-transmitting D2D user equipment (UEs) exceeds the limited amount of discovery resources, resulting in two or more UEs selecting the same resource to transmit their beacons simultaneously. One promising way of avoiding continuous collisions is to undertake a random backoff upon the occurrence of the first collision. In this paper, the performance of a random-backoff based D2D discovery (RDD) scheme with beta-distributed UE arrivals is analyzed in terms of the discovery rate and discovery latency. The impact of different parameters such as the maximum number of transmission attempts and backoff window length on the performance of the RDD scheme are also investigated.