RESERVATION SCHEME FOR CRMA HIGH-SPEED NETWORKS

Cyclic-Reservation Multiple-Access (CRMA) is an access scheme for high speed local and metropolitan area networks based on a slotted unidire ctional dual-bus structure. In CRMA, the headend generates reserve com mands periodically. Each node reserves a number of slots in each reser ve command. Finally, the headend generates a sequence of cycles, each of which is used to service the reservations on the corresponding rese rve command. The length of each cycle is equal to the total number of slots reserved by the nodes in the corresponding reserve command. Gene rally, a longer cycle length will have a lower slot utilization and lo nger access delay. It has been shown that the problem of finding a sho rtest cycle length is NP-complete1. In this paper, we propose a new re servation scheme for CRMA high-speed networks to make a shorter cycle length. Simulation results show that compared with the original CRMA r eservation scheme, this new scheme does result in a much shorter avera ge cycle length. Furthermore, the proposed scheme also obtains better throughput (slot utilization), as well as a lower access delay.