The design of a channel-access protocol for a wireless ad hoc network with sectored directional antennas

A packet scheduler and a medium access control (MAC) protocol are presented for a direct-sequence spread-spectrum, wireless ad hoc network that contains a mix of nodes with directional antennas and nodes with omnidirectional antennas. The scheduler and MAC protocol are designed to prevent the co-site interference problem that arises in some types of nodes employing directional antennas. It is shown that the presence of nodes with directional antennas exacerbates the vulnerability of the network to the receiver blocking problem. A modification of the MAC protocol is presented that mitigates the receiver blocking problem, and it is shown to improve the performance of a network that includes nodes with directional antennas.