Reservation

ALOHA ''Aloha'' ( , ) is the Hawaiian word for love, affection, peace, compassion and mercy, that is commonly used as a simple greeting but has a deeper cultural and spiritual significance to native Hawaiians, for whom the term is used to define ...

, or R-ALOHA, is a

channel access method In telecommunications and computer networks, a channel access method or multiple access method allows more than two terminals connected to the same transmission medium to transmit over it and to share its capacity. Examples of shared physical ...

for

wireless Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The mos ...

(or other shared channel)

transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...

that allows uncoordinated users to share a common transmission resource. Reservation ALOHA (and its parent scheme,

Slotted ALOHA ALOHAnet, also known as the ALOHA System, or simply ALOHA, was a pioneering computer networking system developed at the University of Hawaii. ALOHAnet became operational in June 1971, providing the first public demonstration of a wireless packe ...

) is a schema or rule set for the division of transmission resources over fixed time increments, also known as slots. If followed by all devices, this scheme allows the channel's users to cooperatively use 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. As a contrast of efficiency, simulations have shown that Reservation ALOHA exhibits less delay at 80% utilization than Slotted ALOHA at 20–36% utilization. The chief difference between Slotted 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. Additionally, Reservation ALOHA simply stops sending data once the station has completed its transmission. As a rule, idle slots are considered available to all stations that may then implicitly reserve (utilize) the slot on a contention basis.

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

*
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

Analysis of Priority R‐ALOHA (PR‐ALOHA) protocol, Alsbou, Nesreen and Prigent, Sylvain and Refai, Hazem H., Wireless Communications and Mobile Computing 15 (4), 716-725, 2015
{{Channel access methods

See also

References