A new reservation scheme for cyclic reservation multiple access

Cyclic reservation multiple access (CRMA) is an access scheme for high speed local and metropolitan area networks based on slotted unidirectional dual-bus structure. In CRMA, the headend generates the reserve commands periodically. Each node reserves a number of slots in each reserve command. Finally, the headend generates a sequence of cycles each of which is used to service the reservations on the corresponding reserve command. The length of each cycle is equal to the total number of slots reserved by the nodes in the corresponding reserve command. Generally, a longer cycle length will conduct a longer access delay and a lower slots utilization. The authors propose a new reservation scheme to make the cycle length as short as possible. That is, some of used slots can be reused by the downstream nodes and hence the throughput is improved