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ALOHA History Section

ALOHA

  • In the late 1960s, Norman Abramson and his colleagues from the University of Hawaii developed a radio network for communications among the Hawaiin islands. This system was an early experiment in the development of mechanisms for sharing a common communications channel.

  • In 1995, Abramson received the IEEEs Koji Kobayashi Computers and Communications Award "for development of the concept of the Aloha System, which led to modern local area networks".

ALOHA Map

An Aloha station could send whenever it liked, and then waited for an acknowledgement. If an acknowledgement wasn't received within a short amount of time, the station assumed that another station had also transmitted simultaneously, causing a collision in which the combined transmissions were garbled so that the receiving station did not hear them and did not return an acknowledgement. Upon detecting a collision, both transmitting stations would choose a random back-off time and then retransmit their packets with a good probability of success. However as traffic increased on the Aloha channel the collision rate would rapidly increase as well.

Follow this link to see a more detailed animation of the ALOHANet.