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Alohanet

Alohanet was the first star terminal interconnection system developed by the University of Hawaii in 1970. It was an RF carrier-based communications network that used multiple radio channels. It had a decentralized access method - ALOHA - with collision detection, and in some ways formed the predecessor to the classic Ethernet.

The radio channel collision detection method used in Alohanet was based on the fact that the station that first occupied the carrier frequency was allowed to transmit.The stations determined whether the radio channel was free by listening to it. In case of collisions, the transmission attempt was aborted and repeated after a random waiting period.

With the Alohanet, transmission was in the form of data packet switching. A data packet had a fixed packet length and consisted of 32 bits of header information, a 16-bit block save for the header information, a data part up to 80 bytes long and a 16-bit block save character. Transmission was in two 100 kHz channels with a transmission speed of 9.6 kbit/s. In the event of collisions, three further transmission attempts were made at random intervals.

The Aloha method is also used in RFID. Here, the data packets available to the transponder are transmitted from it to the reader.

Informations:
Englisch: Alohanet
Updated at: 20.07.2011
#Words: 203
Links: terminal, system, carrier, network, method
Translations: DE
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