A white paper on the technology, named DIDO last iteration before rebranding.
http://www.rearden.com/DIDO/DIDO_White_Paper_110727.pdf On my reading, this looks like a good, even radical, technology because it overcomes the problem of interference by treating all antennas on the band as an array and so works with interference rather than treating it as a hard limit to antenna density. It squeezes a lot more data transmission out of limited spectrum. However, it's a bit oversold or, surprise, under-explained in the press articles. What they don't mention is that the system needs to add an antenna to the array for each receiver, or rather, for each additional 100%-of-bandwidth user. If these users are doing HD video chat you probably need (like) an antenna per user, but for lower bandwidth applications you would get a lot of punters per antenna. These antennas can be low power - and thus much cheaper - because the user receives a part on his composite signal from each of the antennas in the array and because they can be closer. However, all the antennas must connect to a single big data centre that would be doing some serious real time Fourier-type number crunching to compose/decompose the signal to/from each antenna. I wonder how the multi-antenna-multi-receiver-moving-client-changing-transmission-environment maths problem scales? The connection between the antennas and the data centre will require some mysterious as yet unknown technology - or alternately a fibre network. Since phone frequencies have wavelengths of the order of 10 cm it should be possible to place antennas in clusters on a rooftop to reduce the costs (I think). It should also allow low-cost antenna drops into black spots and inside buildings without screwing up the rest of the suburb. The low power antenna and reduced spectrum would lower the cost of entry into the cell network business, especially if there's an existing fibre network to plug your antennas into. There are some interesting business models there. The system would work with existing phones/protocols but I'd guess that there would be advantages in new phone protocols down the track. I don't see this as removing the need for a fibre network but it could postpone or even eliminate the looming max-out time for cell networks. If it flies, it certainly hits one of the big problems of cell networks. You might get a version of this on your home wifi router before long too. Come to think of it, probably sooner. - Jim _______________________________________________ Link mailing list [email protected] http://mailman.anu.edu.au/mailman/listinfo/link
