Sufficient bandwidth to support multiple simultaneous voice, data and other connections. Low cost and readily available components. Utilise standard protocols to enable rapid deployment and development. Linux is a freely available operating system. Because Linux and the majority of applications which run under it are released with their source code, this is an ideal development platform.
Ethernet is a standard, well known networking system, normally used in LANs.
While probably not ideal for radio based systems, surplus Ethernet cards are easy to come by and driver support is generally very good. Speeds other than the standard 10 Mbps are being considered. Gunn diode transceivers. While not the latest and greatest, Gunn diode transceivers are relatively simple for newcomers to setup and offer reasonable modulation bandwidth, so are a good candidate for the first generation link transceivers while more specific hardware is being developed. With a reasonably sized dish antenna, they are capable of achieving ranges in the 10's of km region.