The Area Spectral Efficiency of CSMA Ad-Hoc Networks

Wireless ad hoc networks (WANETs) allow users to communicate, sharing the same wireless channel, without the need of any infrastructure. The performance of wireless ad-hoc networks (WANET) is mainly limited by its self-interference. The talk will focus on the performance of WANETs applying slotted carrier sense multiple access (CSMA) mechanism and possibly utilizing also directional antennas. The CSMA protocol is based on RTS/CTS messages, which allow each node to evaluate the amount of interference that it will cause to other active nodes, and provide a powerful tool for network coordination.
Our analysis gives simple expressions for the network area spectral efficiency (ASE). The presented ASE expressions allow an evaluation of the optimal system parameters, and give insight on the behavior of the ASE as a function of the various system parameters. In particular we show that the ASE of a CSMA WANET is well approximated by the ASE of an optimized ALOHA WANET, multiplied by the exponent of the network back-off probability. We also show that if the network has a maximal delay constraint then the ASE grows linearly with the allowed delay.