In Florida, a Cell Phone Network With No Need For a Spectrum License 107
holy_calamity writes "Technology Review reports on a cell phone network in Fort Lauderdale, Florida, like no other. Instead of paying to reserve a section of wireless spectrum its owner, xG Technology, uses cognitive radios that steer signals through the unlicensed 900MHz band more normally used by cordless phones and baby monitors. The radios in both handset and base station scan for gaps left by other devices in that band and make dynamic connections that constantly hop frequencies to ensure a good link. The network is designed to show off the tech, which the company says could be used in conventional cellphones to access extra spectrum or white spaces devices."
It isn't going to work (Score:5, Interesting)
It's never going to work in the long term. I work for a wireless ISP, and our 900 mhz band is getting killed by utility/electriticy companies rolling out things like smart electric meters that exist in every home and do the same thing: hunt for the least noisy band and transmit. We've seen noise floors in the -40s straight across the spectrum on our worse days. We can't beat the noise more than a couple of miles from a cell tower using fixed, directional antennas. What makes them think they can beat it with tiny, handheld devices?
Re:It isn't going to work (Score:3, Interesting)
Came in here to mention this. I worked for a WISP a couple of years ago, and while it was in a rural area in Kansas (but i repeat myself) we were already aware of possible issues with public spectrum transmissions and signal-hopping competition from god only knows what. We had a 900mhz unit in town, aimed at an AP on the other side of town with a clear LOS (i dont know why they did this is town, it happened before I was there) and we couldnt get it to work for our life. We had a spectrum analyzer and couldnt even get a lock on what was causing the issue.
Stuff outside of town aimed at the AP worked dandy, but nothing in the city limits.
Ricochet did this a decade ago (Score:4, Interesting)
Ricochet [qsl.net] did this in the 900MHz band using spread spectrum a decade ago, for wireless Internet access. They put up little nodes on street light poles, using a deal where the municipality got free data access. It worked fine, but only delivered dial-up speeds, so it was overrun by DSL and cable. Even back then, getting around narrowband interference was no big deal.
Re:From the article . . . (Score:3, Interesting)
That's true. The "whitespace" idea only works in rural regions, not heavily-populated areas like the North, northeast, or mid-atlantic which use every channel from 1-51 (including the FM band).
Note that Channel 37 is not used for over the air tv broadcasting in North America and the few other uses area very limited (things like low-power indoor hospital equipment. It's being kept very quiet for those listening for interesting things from deep space. The signal that one would get on Earth from a hand-held garage door remote on the moon would be comparable to a very strong signal from deep space. The spectrum has to be kept very quiet to be able to hear faint signals, so scratch channel 37.
I'm curious when the FCC is going to figure out that hardly any broadcasters remained on their former analog channels 2 through 6. (54 to 88 MHz, minus a 4 MHz gap between channels 4 and 5) Most still display the old number as a virtual channel number, but are actually on UHF. For those with mountains to deal with, the change severely degraded coverage. Broadcasters apparently figured few people would be willing to put up big tv antennas with the longer elements needed for those low channels. High band VHF (7 - 13, 176 to 216 Mhz) and UHF (470 MHz and up) signals use much smaller antennas. I'd like to see more of the rural area served by the low-band channels. If they allowed power levels close to what they used with analog service, many could easily get well over 100 miles on those channels. Even at the currently allowed power levels coverage is better than the other channels if people have the proper antennas (but often worse with the wrong antennas). A half-wavelength dipole at 54 MHz (channel 2) is near 3 meters long so the biggest elements near the back of a tv antenna should be about that length. The length at channel 14 is about 1/9th as much.
The FM band, 88 - 108 MHz is not used by the tv channels. It's between tv channels 6 and 7, as are a number of public services and the 2 meter ham band. There's a much bigger gap between channels 13 and 14 (216 to 470 MHz), but that is allocated to various government and commercial service, and a little there for ham use also.