Abstract:

To obtain potentials offered by directional antennas which can increase the transmission range of a single hop, reduce interferences, improve the spatial reuse and then expand the capacity of the networks obviously, we propose two new directional neighbor discovery algorithms for MANET. The first is the Transmit Directionally only (TD) mode of the neighbor discovery algorithm with directional transmitting and omni-directional receiving. The second is the Transmit and Receive Directionally (TRD) mode of the neighbor discovery algorithm with directional transmitting and directional receiving. The two algorithms utilize the idea of imitating omni-directional transmission through circular directional transmission to discover neighbors without GPS or other aided information. Based on the CSMA／CA mechanism, a theoretical analysis of the discovery time and probability for a node to discover all neighbors are made, which is validated by NS-2 simulations. The key feature of the algorithms is accomplishing neighbor discovery without any assisted service such as GPS, time synchronization, etc.

Key words: mobile ad hoc network, directional antenna, beam scanning, neighbor discovery