The Wiress Router has become common place due to a variety of reasons, but to most folks it rightfully remains a magic box. You shouldn’t really care about how it works inside, or how magic airwaves go from it to your various wireless devices and magically make the internet work. I hope to highlight a bit of the underlying magic to help you out with your router.
Wireless routers are made by a variety of manufacturers, but they all need to work together. If you have a router from Linksys, and a network card from Netgear, they both need to operate without hiccup. The way companies do this is by implementing a standard, which is just an agreement on how things will communicate/built/etc. Wireless routers are tied to the 802.11 standard. Because they are wireless, they communicate with radio waves. Radio waves are governed by the FCC, as there are a very finite “band” or “spectrums”. Thus, TV signals take one chunk of the availible spectrum, and Radio Talk shows take a different slice, and since they aren’t sharing the same spectrum, they can communicate as if the other didn’t exist. Wireless routers are very similar, and are primarily split across 2 wavelengths of what’s called “free spectrum”. Basically, it’s unlicensed wireless airwaves that any consumer device can live in. We’ll get into the problems this cause later, but first, lets go over the flavors of 802.11. This is meaningless gobblygook, so here’s the Too Long Didn’t Read:
802.11a (802.11 standard, part A) routers give a maximum throughput(Higher number here means a faster transfer) of 54mbps (Megabits per second, NOT megabytes per second. Roughly 6.75 Megabytes Per Second. For comparison, your hard drive gets about 20-50 on average for a regular hard drive.). It operates in the 5ghz spectrum. (the band it operates in.)
802.11b routers give a maximum throughput of 11mbps. It operates in the lower 2.4ghz spectrum.
802.11g routers give a maximum throughput of 54mbps. It operates in the 2.4ghz spectrum.
802.11n routers give a maximum throughput of 300mpbs. It operates in either the 2.4 or 5 ghz spectrum.
Here’s the even shorter version: Wireless routers have to play in 2 spectrums, the 2.4 ghz spectrum, which travels well through walls and travels a long distance, and the 5ghz band, which doesn’t travel through walls nearly as well as the 2.4ghz, but supports theoretical higher throughput (higher data rates). Unfortunately, the 2.4 ghz spectrum is *so small*, that there are only “11″ channels.
“Umm, i see 14 channels there smart one…”
Channels 12, 13, and 14 are international channels, and *YOU SHOULD NOT USE THEM IN THE USA*. They drift into HAM radio spectrum, and the FCC will come investigate if some HAM radio operator is complaining about interference.
So, we’re left with 11 channels in the common 2.4ghz spectrum. Notice how the circles overlap one another? That means that certain channels actually share spectrum space, and interfere with each other. We really only have 3 non-overlapping channels, channel 1, 6 and 11.
The unfortunate part of Wireless networking is that the channels *drastically interfere with one another*. It’s part of the whole “it’s unlicensed” thing.. Lets take an example:
You’re driving down the road and listening to your favorite radio station. Like, 99.5 or 93.9. These numbers represent the assigned band the radio station has rights to. The FCC has licensed that specific band to that particular radio station, and will actively seek and prosecute anyone who violates that license, for instance if another radio station starts broadcasting on the same band. Unlicensed spectrum, on the other hand, means that anyone and their grandmother can actively live in that space. Microwave ovens, Phone handsets for landlines, your gerbil’s wireless playpen.
Lets take another example, this time of two wireless routers and two clients. Wireless router A and Client A are trying to talk to each other, and standing shoulder to shoulder with, Wireless router B and client B.
Wireless routers A and B are operating on channel 6. The routers can each only use *half* of the available spectrum, and they actually chat with one another in a very gentlemanly way. One goes, then it waits for the other to go, then the first goes again in talking with their respective clients A and B. BUT, if router A switches over to channel 5 (because you set it to 5), BOTH routers A and B, and clients A and B will try and transmit at the same time. It’s like four people yelling while standing next to each other. They both have to repeat themselves multiple times to be understood, and the effective throughput is a fraction of the whole.
So, stick to channels 1, 6, or 11, unless you feel like legally jamming your neighbors ;-)