CHANNEL ASSIGNMENT WITH CAPTURE FOR PERSONAL SATELLITE-COMMUNICATIONS

We investigate the multipacket message transmissions acid variable len gth message transmissions in slotted ALOHA systems with capture effect . First, we propose an approach that the transmission power level is c ontrolled probabilistically depending on message length for multipacke t messages. We consider the multipacket messages model with capture. W e derive explicit equations of the effective channel utilization of th e model. It is demonstrated that if we increase the number of power le vels, we can get more effective channel utilization of the system. Sec ondly, we propose how to assign the slot size and show that the effect ive utilization of the channel is improved for variable length message s using the approach proposed for multipacket messages. Channel design issue about length of the slot depending on the number of power level s used for transmission is discussed. Thirdly, we propose the multiple messages per slot model with capture. The analytical results show tha t the multiple messages per slot model can achieve the highest channel utilization among the models discussed in this paper.