Performance considerations for slotted spread-spectrum random-access networks with directional antennas

The throughput/delay performance of certain types of spread spectrum random-access (SSRA) networks employing directional antennas is considered. The use of directional antennas in the receiving sites to improve the network performance is presented and analyzed. The basic idea is to reduce the contention of the users (transmitters) by dividing the coverage area into different regions; at the receiving site, a single directional antenna is aimed at one region, so that transmissions from different regions do not interface with each other. In addition to the reduction of the multiuser interference, the directional antennas allow for different classifications, in different regions, of the users according to their physical and link level parameters. The throughput improvement is substantial for heavy-traffic conditions, and the gains are further amplified if the number of available receivers is increased. Numerical results for performance comparison with the case receivers using omnidirectional antennas are also included