An asynchronous neighbor discovery protocol based on double tokens in directional ad hoc networks

Abstract

Aiming at the problem of slow neighbor discovery speed of sector antenna neighbor discovery (SAND) protocol based single token, an asynchronous sector antenna neighbor discovery protocol based double tokens (D-SAND) is proposed. The double tokens include one master token and one slave token. The master token holder (MTH) starts its neighbor nodes discovery process by sending hone-in message through beam scanning, and ends this process when each neighbor node is discovered. Then, MTH passes the master token to the next hop master token holder (nMTH). At the same time, MTH sends the location information of the nMTH node to its parent master token holder (MTP) from which it obtains its token. MTP determines whether to generate a slave token according to that if there exists a neighbor node with a distance greater than 2R from nMTH, where R represents the communication distance. If there exists one such neighbor, MTP generates a slave token and passes it to that neighbor node, who can begin the neighbor discovering process. The time conditions are theoretically derived when these two tokens begin their neighbor discovering process respectively and without interference to each other. Simulation results show that compared to Q-SAND(quick-SAND), the proposed D-SAND protocol reduces the network-wide neighbor discovery time about by 10%.