Adaptive modulation packet radio communication system using nonpersistent CSMA

In radio packet communication systems, the throughput and the average delay performance are greatly degraded when the traffic is high, since a single channel can be shared by multiple users. Another problem is that the transmission performance can vary, since the channel situation greatly depends on the communication distance. It is intended in this study to solve those problems. The concept of adaptive modulation is introduced into the radio packet communication system, and an adaptive modulation radio packet communication system is proposed in which the packet length as well as the modulation parameters are made variable. For the case where the nonpersistent carrier sense multiple access (CSMA) is used, the throughput and the average delay performance are examined by computer simulation.