Reservation ALOHA

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Reservation ALOHA, or R-ALOHA, is a channel access method for wireless transmission which allows uncoordinated users to share a common transmission resource. Reservation ALOHA (and its parent scheme, Slotted ALOHA) is a schema or rule set for the division of transmission resources over fixed time increments, also known as slots.^{[citation needed]} It is via this rule set or schema that, if followed, allows the bandwidth users to cooperatively utilize a shared transmission resource—in this case, it is the allocation of transmission time.

Reservation ALOHA is an effort to improve the efficiency of Slotted ALOHA. The improvements with Reservation ALOHA are markedly shorter delays and ability to efficiently support higher levels of utilization.^{[citation needed]} As a contrast of efficiency, simulations have shown that Reservation ALOHA exhibits less delay at 80% utilization than Slotted ALOHA at 20-36% utilization.^{[citation needed]}

The chief difference between Slotted ALOHA and Reservation ALOHA is that with Slotted ALOHA, any slot is available for utilization without regards to prior usage. Under Reservation ALOHA's contention-based reservation schema, the slot is temporarily considered "owned" by the station that successfully used it.^{[citation needed]} Also with Reservation ALOHA, once the station has completed its transmission, it simply stops sending data. As a rule, idle slots are considered available to all stations that may then implicitly reserve (utilize) the slot on a contention basis.^{[citation needed]}

See also

• Channel access method
• Dynamic bandwidth allocation
• Media Access Control
• General Packet Radio Service

References

• Roberts, L.G. "ALOHA Packet System with and without Slots and Capture" ARPA Network Information Center, Stanford Research Institute, Menlo Park, California, ASS Note 8 (NIC 11290), June 1972
• ALOHA simulations
• Queuing Theory and Telecommunications: Networks and Applications By Giovanni Giambene
• Milosh Ivanovich , Moshe Zukerman , Fraser Cameron, A study of deadlock models for a multiservice medium access protocol employing a Slotted Aloha signalling channel, IEEE/ACM Transactions on Networking (TON), v.8 n.6, p.800-811, Dec. 2000
• Performance Evaluation of R-ALOHA in Distributed Packet Radio Networks with Hard Real-time Communications (1999) Te-Kai Liu, J. Silvester, A. Polydoros