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Ask Slashdot: Can Any Wireless Tech Challenge Fiber To the Home?
New submitter danielmorrison writes: In Holland, MI (birthplace of Slashdot) we're working toward fiber to the home. A handful of people have asked why not go wireless instead? I know my reasons (speed, privacy, and we have an existing fiber loop) but are any wireless technologies good enough that cities should consider them? If so, what technologies and what cities have had success stories?
When I briefly worked at Cisco's wireless division a few years ago, I learned that their ideal customer was a hospital. Medical devices on a wireless network requires a higher level of reliability and uptime than the typical corporate or home environment. If Cisco gets wireless right for the hospital environment, they get it right for everyone else.
Although hospitals are willing replace their wireless access points (APs) with newer models every X years, they're reluctant to upgrade the closet switches that connects the APs into the network. The more bandwidth is pushed through the APs, the more bandwidth capacity is needed for the switch. Higher bandwidth switches are much more expensive. That was the problem for the new 1Gb APs in 2013. You can connect 32 1GB APs to a switch, but the fiber link for the average switch maxes out at 10Gb. If bandwidth is constrained in the closet, the benefits to upgrading to high-speed APs will be limited. A big problem for the marketing department to figure out.
If you think a hospital scenario is bad, trying getting local government to pony up a fat pipe for everyone in the neighborhood to have high-speed wireless.
Do those same techniques work on frequencies through all different mediums, or do they only work in the air? (this is a rhetorical question by the way).
Whatever you can get in the air, you can get more in a cable or fibre. Sorry, that is just how it is going to be. Find the fastest wireless technology on the market, and then compare it to what you can get over a copper or fibre. Do it at any given point in history, and you see that it is always behind.
There's a reason for that, and I gave the reason.
It's worth noting that current trends in wifi technology are moving in a direction which overcomes Shannon's law. The theorem assumes a shared communications channel. That is, if you transmit your signal at -45 dB, then everyone else using that same channel sees -45 dB of noise (your signal is noise to them).
Beam-forming and MIMO (multipath) techniques subvert this assumption. For a visual analogy, it's why you can see your smartphone display in the sunlight, even though the sun is much, much brighter (its signal strength at optical wavelengths far exceeds your phone display's signal strength). Although the sun is very bright, the light it gives off is highly directional. By using sensors (the lens structure of your eyes) which can "tune in" to light coming from a narrow angle, you can basically filter out all that sunlight noise and pull out a clear signal from the smartphone display.
We're still a long way from this being able to beat out a direct fiber connection. But with phased array antennas (basically what MIMO does except using a lot more transceivers for much finer angular resolution) acting like a "lens" to "focus" radio waves, it's not outlandish to think that in the future all wireless communications could effectively be point-to-point with little to no interference from other wireless sources. Even though everyone is transmitting at the same frequencies, the highly directional nature of the transmissions would mean Shannon's law almost never comes into play, and you get to use all that bandwidth as if you were the only one transmitting on it.