Hybrid 3-Way Neighbor Discovery Algorithm in UAV Networks with Directional Antennas

Neighbor discovery is a crucial step to establish links among the nodes in wireless ad hoc network, such as Unmanned Aerial Vehicle (UAV) networks. Most existing studies on neighbor discovery are based on 1-way or 2-way handshake mechanism, where nodes send 1-way or 2-way handshake packets without getting acknowledgement from their neighbors. The nodes will not stop transmitting handshake packets until the end of the neighbor discovery. However, when the node scale becomes huge, this procedure may increase the collisions and deteriorate the discovery efficiency. In this paper, considering the multi-carrier system, we analyze a Hybrid 3-way handshake Synchronous Algorithm (HAS-3-way) to reduce the discovery time. Hybrid 3-way handshake is a combination of 2-way and 3-way handshake. When the neighbor node confirms that it has been found by the discovery node, it will stop transmitting unnecessary handshake packets. In this situation, collision probability is decreased and the discovery efficiency is enhanced. Besides, the effect of sleep probability is also taken into account in the hybrid 3-way handshake. Through extensive simulations, we demonstrate that HAS-3-way can significantly decrease the expected time to discovery all the neighbors.