Neighbor Discovery for Ultraviolet Ad Hoc Networks

The solar blind ultraviolet (UV) scattering channel makes non-line-of-sight UV communications very attractive for military applications, particularly for communication on-the-move with low probability of detection and low probability of interception. Despite significant research effort on the UV physical layer, work on protocol design at the upper layers is quite limited. We consider a mobile ad hoc UV network, with each node equipped with a transceiver capable of transmitting in multiple directions and performing omni-directional receptions. Full-duplexing is enabled. We develop efficient neighbor discovery protocols by accounting for the unique UV physical (PHY) layer characteristics, namely varying channel qualities along different scattering directions. In addition to a list of neighbor nodes' identities, our protocols also construct and maintain a table which contains a ranked list of node pointing directions between each pair of nodes in terms of channel qualities. Our approach does not need support from the global positioning system (GPS) or temporal synchronization across nodes like many radio frequency (RF) protocols. Specifically, two algorithms are proposed with and without the need for direction synchronization. We further improve the latter by more efficiently utilizing neighbor feedback. We perform extensive simulations to evaluate our algorithms.