tion capacity North America Latin America Europe and CIS Africa and ME Gbps capacity Projected Note: Chart assumes that a pair of 36-MHz equivalent transponders will yield approximately 40 Mbps transmission capacity. Transponder inventory refers to available capacity in orbit (minus satellites retired) or already under construction in March 2000. Source: RAND 2000, Submarine cable infrastructure, and Euroconsult. requirements may be lower than cellular if lower output power is transmitted. They may even be autonomous from local power supplies, as solar powered transceivers (or "access points") have arrived. The propagation performance, as ever, sets the density of access points required, but this propagation can be further than with conventional mobile cells, for lower density. As support infrastructure demand is in general much lighter, AWT networks for Internet access, with VoIP, are springing up in an ad hoc, guerrilla fashion across Europe and especially the United States. In the latter case, this is often in a non- operator centric situation, in that they are financed, built and operated by the local municipality as shown below (while raising ire and opposition from the incumbents RBOC, who have moved to have them banned in many US cities). Naturally these technologies put pressure on the spectrum apparently available. Using spread spectrum techniques for bandwidth sharing and the cognitive radio (CR) techniques, which adapt to other users, they promise to bring far more efficient use of the spectrum. The concepts of a larger "commons" in spectrum in the form of more or wider unlicensed bands is under debate in the EU. Meanwhile the United States and the United Kingdom currently prefer a market driven approach, perhaps for reasons of financial gain for government, 61 despite the gathering forces from the computing and data communications world who have demonstrated with WiFi the success of the data communications/ Internet model of an unlicensed, unregulated spectrum infrastructure. INFRASTRUCTURE TO 2030: T