ALOHAnet
Sign in to saveALOHAnet, also known as the ALOHA System, or simply ALOHA, was a pioneering computer networking system developed at the University of Hawaiʻi. ALOHAnet became operational in June 1971, providing the first public demonstration of a wireless packet data network.
Article
15 sectionsContents
- History
- Protocol
- Pure ALOHA
- Slotted ALOHA
- Reservation ALOHA
- Packet Reservation Multiple Access
- Demand Assigned Multiple Access
- Mobile Slotted Aloha
- Other protocols
- Hardware
- Network architecture
- Legacy
- References
- Further reading
- External links
ALOHAnet, also known as the ALOHA System, or simply ALOHA, was a pioneering computer networking system developed at the University of Hawaiʻi. ALOHAnet became operational in June 1971, providing the first public demonstration of a wireless packet data network.
The ALOHAnet used a new method of medium access, called ALOHA random access, and experimental ultra high frequency (UHF) for its operation. In its simplest form, later known as Pure ALOHA, remote units communicated with a base station (Menehune) over two separate radio frequencies (for inbound and outbound, respectively). Nodes did not wait for the channel to be clear before sending, but instead waited for acknowledgement of successful receipt of a message, and re-sent it if this was not received. Nodes would also stop and re-transmit data if they detected any other messages while transmitting. While simple to implement, this results in an efficiency of only 18.4%. A later advancement, Slotted ALOHA, improved the efficiency of the protocol by reducing the chance of collision, improving throughput to 36.8%.