Energy efficient and scalable device-to-device discovery protocol with fast discovery

Device-to-device (D2D) discovery is an important step toward numerous applications of device-to-device communications. However, the design of D2D discovery protocols also faces the challenges of distributed nature, energy efficiency, scalability, and fast discovery. In this paper, we propose a D2D discovery protocol called synced distributed protocol that can efficiently resolve these challenges. The key idea behind our protocol is to group devices in a neighborhood such that devices in a group will take turns to announce the existence of other devices in a group. Hence, a device can reduce the period of announcing its existence and have the advantages of energy efficiency and scalability. Further, the transmissions from other devices in the group still guarantee fast discovery. We validate our protocol design by analysis and simulations. Specifically, we prove that our proposed protocol will function correctly in a static environment with minor assumptions and simulate our protocol in the OPNET 802.11n model. Simulation results confirm that our algorithm is scalable and can achieve low duty cycle and fast discovery. For mobile environment, we propose enhanced techniques and use simulation to show that the enhanced techniques has the benefits of increasing the group size.