Tom Billhartz

A link scheduling and ad hoc networking approach using directional antennas

There is strong interest within DoD to utilize high-gain, directional antennas at both the transmitting and receiving end of the link in a dynamic, ad hoc network environment. However, the application of directional antennas (e.g., phased-array or sectorized antennas) in a dynamic network of mobile nodes requires coordination of antenna steering at both the receiver and transmitter ends of the link. Our solution is to apply adaptive, link-state routing (be performed by the OLSR ad hoc routing protocol [T. Clausen et. al., September 1, 2001]) supported by a distributed, adaptive time division multiple access (TDMA) scheduler, which determines schedules based on cooperative decisions between each pair of neighbor nodes. The architecture that has been developed contains a high rate mission data channel with an adaptive TDMA link scheduling protocol designed to take advantage of high-gain directional antennas. Time slots on this channel are adaptively scheduled to meet dynamic traffic demand requirements and to avoid interference from adjacent transmitting nodes. In addition, the link scheduling protocol must adapt to changes in node neighborhood topology caused by node mobility and link obstructions. This architecture was tested and evaluated in two ways: by OPNET simulations and by field demonstrations.