A multi-token sector antenna neighbor discovery protocol for directional ad hoc networks

In this paper, we propose a Multi-token Sector Antenna Neighbor Discovery (M-SAND) protocol to enhance the efficiency of neighbor discovery in asynchronous directional ad hoc networks. The central concept of our work involves maintaining multiple tokens across the network. To prevent mutual interference among multi-token holders, we introduce the time and space non-interference theorems. Furthermore, we propose a master-slave strategy between tokens. When the master token holder (MTH) performs the neighbor discovery, it decides which 1-hop neighbor is the next MTH and which 2-hop neighbors can be the new slave token holders (STHs). Using this approach, the MTH and multiple STHs can simultaneously discover their neighbors without causing interference with each other. Building on this foundation, we provide a comprehensive procedure for the M-SAND protocol. We also conduct theoretical analyses on the maximum number of STHs and the lower bound of multi-token generation probability. Finally, simulation results demonstrate the time efficiency of the M-SAND protocol. When compared to the Q-SAND protocol, which uses only one token, the total neighbor discovery time is reduced by 28% when 6 beams and 112 nodes are employed.