Is There Too Much Enthusiasm Over Wireless?

lukOh asks: "in the US, 802.11b/g (2.4Ghz) devices use an 83Mhz-wide frequency range; in-use channels spanning 22Mhz and centered on one of 11 5Mhz steps (badly named as "channels"). This means there should be no more that 3 networks in close proximity, 5 'channels' far from each other, to avoid harmful interference. Now, in the middle of the mixed area where I am, the number of usable WLANs (SNR>20dBm) has gone from 10 to an unworkable number of 20, in just one month. Has the community/the market overestimated the practicality of wireless networks? Are we generally relying too much on such a young, IMHO immature technology made on 'startups hope' and broken firmwares? How can this mess possibly be handled in a working environment, especially the moment your boss asks you to give him access to 'the wireless'?" "Access points can be easily detected, but the same isn't always true for every single client (or Bluetooth device) searching or using a network. Bluetooth itself employs the same 2.4Ghz range with 1Mhz-wide channels and much less power. To avoid interference a device jumps channel-to-channel, when the currently selected one is busy.

Most WLANs are managed by less-than-perfect SOHO access points. Connecting to an AP in such an environment is a gamble (even from 1ft away), especially when: WPA/WPA2 must be used; 802.11g stability is a dream; anywhere up to 7 networks are on the same 'channel' (1 and 11, being the most used, are standard on many devices); and now 'channel wars' are very common (i.e. 2 or more users concurrently hunting to set a free channel for their network, making the entire range unusable for hours)."

Comments

First come first serve

[Distan]

There are three usable channels. A good engineer will put up a tower with three 120-degree antennas, and put one channel on each side. On alternating towers, arrange the overlap so you are always covering the same zone with the same channel. Ideally you create three overlapping lobes.

Under this scheme, there can be three service providers in an area, and they have to cooperate to avoid interference. The fourth provider is SOL and is on a short train to bankruptcy.

Here is the beauty of wi-fi through; it is effectively first-come, first-serve. If your system worked before, and interference from the new guy makes it stop working, you can force them off the airwaves.

Even more beautiful, once you are incorporated, and your corporation owns this prior claim, you in effect have a sellable asset. In a densely developed area, this could be a valuable asset.

It isn't foolproof though. Unfortunately, although your prior claim to those frequencies overrides any newcomer who wants to use wi-fi, there are other uses that can take priority over wi-fi altogether.

P.S. - If you want to be a complete jerk, you lay out your initial towers so every cell is covered by three lobes, one of each channel. Then there are no channels left for your competition. I bet the FCC would make you rearrange your lobes before forcing the other guy off the air, though.

Re:Site Survey

[HermanAB]

You don't understand how it works. Using 4 overlapping channels, 1, 4, 8 and 11 is just as good as 1, 6, 11. Having a whole bunch of access points on channel 6 isn't necessarily bad either, since the signal strength drops off very rapidly and the spreading codes are all different anyway. This is spread spectrum technology - it is not as prone to interference as other modulation modes. That is why it works.