PRNET

The earlier ALOHAnet served as an inspiration, but PRNET tackled a significantly harder set of problems, namely, multi-hop communications between mobile vehicles without a central station.

In today's terminology, this might be called a router or a packet switch, rather than a radio repeater.

The first PRNET was established under the auspices of SRI in the San Francisco Bay Area, with BBN contributing network technology and Collins creating the Experimental Packet Radios (EPRs), which implemented L-band spread-spectrum waveforms and supported half-duplex communications at 100 or 400 kilobits/second.

PRNET was sufficiently advanced by 1977 to participate in the initial three-way internetworking demonstration, which linked a mobile vehicle in PRNET with nodes in the ARPANET, and via SATNET, to nodes in London run by Peter Kirstein's research group at University College London.

[1] Afterwards, it was usually attached to the ARPANET so that BBN software developers could access and update it from Cambridge.