Packet Satellite Technology Reference Sources

Packet Satellite technology was an outgrowth of early work in packet switching on multiaccess radio channels carried out at the University of Hawaii with the support of the Defense Advanced Research Projects Agency (DARPA). The primary difference between the earlier packet-switched ARPANET [1, 2] and the ALOHA system developed at the University of Hawaii [3] was the concept of multiple transmitters dynamically sharing a common and directly-accessible radio channel. In the ARPANET, sources of traffic inserted packets of data into the network through packet switches called Interface Message Processors (IMPs). The IMPs used high speed point-to-point full-duplex telephone circuits [4] on a store-and-forward basis. All packet traffic for a given telephone circuit was queued, if necessary, in the IMP and transmitted as soon as the packet reached the head of the queue. On such full duplex circuits there is exactly one transmitter and one receiver in each direction.