More distance, less Pringles
"You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat."
-- Albert Einstein, when asked to describe radio (quoted on the Nocat Web site, /).
In response to the fun we've been having with wireless over the last two weeks (see part 1 and part 2), this question from a reader: "What is WiFi and what does it have to do with 802.11b?" The answer: 802.11b is an IEEE standard (approved in 1997 by the IEEE 802 committee) for wireless Ethernet, and WiFi is the name of a certification for 802.11b compatibility given by the Wireless Ethernet Compatibility Alliance.
Remember that 802.11b is a wireless, radio-based system limited to 0.5 watts. It operates in the unlicensed 2.4-GHz band at speeds up to 11M bit/sec. A future incarnation of this technology, 802.11a, promises speeds of up to 54M bit/sec.
In general, an 802.11b net has a range of up to 300 feet when there are no obstructions, but the farther away you travel (and the more noise there is), the lower the data rate; 802.11b adjusts its data rate according to the quality of the radio environment.
Besides distance, performance can be degraded by radio interference, humidity, air temperature, resource contention (lots of PCs accessing an 802.11b net simultaneously) and objects that block the signal.
We found this last factor to be a significant issue at Castle Gearhead, where the walls, built in the 1920s, are of plaster covering an expanded metal lath. This makes each room a sort of Faraday cage. This type of construction attenuates the signal far more dramatically than modern buildings.
Interference from radio noise can be difficult to track down and can be generated by microwave ovens and cordless phones. That said, we have not noticed major problems caused by our Siemens Gigaset telephones (a 2.4-GHz system) and our wireless network.
Another performance consideration is the engineering of 802.11b PC Cards and access points you use: some vendors' engineering is better than others and that can affect throughput significantly. Some PC Card antennas, for example, are stubby extensions that protrude from a PC's side. This configuration is curious, as the antenna is most sensitive when it is vertical.
Thus, we suggest that if your 802.11b signal is poor, you should try rotating your PC 90 degrees and propping it against a wall while you use it. This may improve reception and transmission considerably. Of course, you'll look like a complete dork but that will be a small price to pay.
Anyway, if you want to maximize your range, the design of the antenna connected to your card is crucial. The majority of supplied antennas are omnidirectional, that is, they radiate energy more or less equally in all directions.
But if you replace the supplied antenna with, say, an antenna made from a Pringles container wrapped in wire (see link below), you can create a directional antenna that should be able to reach up to around 2 miles. Some people claim even greater distances (we have seen 20 miles quoted!).
We aren't joking about that Pringles can antenna: You can make an antenna for about $5 that significantly improves the range compared with commercial products that cost $150 or more (see this set of instructions). See also Nocat for a great list of 802.11b links, including a lot more antenna designs and related data.
And just imagine the uses of these antennas! Talk about doing more with less: For just over $200 you could connect buildings up to a couple of miles apart at a speed that rivals wires or laser transceivers (both of which are usually orders of magnitude more expensive). To create a dedicated service requires a router or firewall at both ends running network address translation, and the wireless link must be encrypted.
Of course now that your wireless nets are running you'll want to check them out - what does the traffic look like, why does that PC not get a reliable connection and so on. For this, you'll need a wireless network analyzer, and we have just started looking at a terrific product called AiroPeek from WildPackets that can capture, store, analyze and report on 802.11b wireless systems.
Next week, we'll tell you what we found . . . objects trouvee to gearhead@gibbs.com.
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Less wires, more connections
Wireless networks are often left unsecured because people simply don't understand what they're doing. The default setup for the majority of wireless network products ... Gearhead, 10/29/01.
More networking, less wires
We checked out Agere's client PC Card, external Univeral Serial Bus client module and its AP-500 Access Point. We were very impressed. Gearhead, 10/22/01.
