![]() However, the situation usually gets worse when one voluntary abides to the 1-6-11 non-overlapping channel scheme.802.11g circumvents in-channel noise through orthogonal frequency-division multiplexing (OFDM) of a multitude of narrow (hence slow but more reliable) carriers. The technique employed by 802.11b is called spread spectrum, or rather direct-sequence spread spectrum (DSSS) to be precise. First, note that the signal of a device on a partially overlapping channel is merely noise to the device on the overlapped channel. ![]() The 1-6-11 recommendation contained in Cisco's whitepaper about IEEE 802.11 deployment in the corporate environment certainly does not apply to all circumstances, especially in non-corporate settings! For example, in moderately congested neighbourhoods, one stands a very good chance to benefit from not sticking to this proposed scheme. The proof of the pudding is in the eating! 1-6-11 is often worse in moderately congested areas It's takes a bit of doing, but you can use this to really know, not just guess, what channel is typically least busy in your area. The main thing is they recommend a tool called Vistumbler that will allow you see not just signal strength, but also actual traffic. It's the 2nd part of two part series, but the first part is less important to this discussion. So how can you know which channel is least busy? This article on the serverfault blog may help: If you have someone next door with a strong access point on channel six, but they hardly ever use it, and other neighbors down the way with weak access points on channels one and eleven, but they use them to work from home and are on them all the time, you may be better off using channel six, even though it might look "bigger" in a tool like InSSIDer. They will not tell you how much those neighbors are using the signal. They will only show you which neighbors have the strongest signal available on which channels, based on beacons from the access points/routers. Tools like InSSIDer will not help you here. Even then, this was only shown to help for certain kinds of loads and densities.įinally, be careful when deciding which of 1,6, or 11 is least busy. Until you can get everyone cooperating on that scheme, you will get best results by using the least busy of 1,6, or 11. However, for this work everyone in your area would have to agree on it. There are a few studies indicating that, under the right circumstances, it may be possible to get more throughput using a four-channel scheme (such as 1,4,7,11, 1,4,8,11, or 1,5,8,11). Whenever that happens, those other users will have to re-transmit their message, making the wireless signal in your area even busier. More than that, you will yourself now cause interference with people using both of those channels. So, if you were to use, say, channel 3, you might now get interference from radios on both channel 1 and radios on channel 6 (and everything in between). What happens when you put your system in between two of the "standard" channels is that now you get interference from both of them. ![]() Your "clearer" channels will still have interference originating from the busy channels, so there is little to gain. Of course, if you live by yourself in the middle of nowhere, feel free to run a single radio using 80 Mhz signaling on whatever channel you want.Įven if other channels seem less crowded, remember that because channels overlap you still have to deal with interference from those busier channels as well. Note that 20 Mhz channel widths will reduce the maximum theoretical speed, but it makes it more likely to have consistent reliable throughput, especially if your neighbors are on board. This is especially true in high-density areas, such as large apartment buildings, so for best results get your neighbors to do the same. If you're using 40 Mhz channels (or greater), things are limited even more.īest results come when your wifi signals do not overlap, and using only 1, 6, 11 with 20 Mhz channels gives the maximum potential. 40 Mhz is also common in the 2.4 Ghz range. ![]() A wifi radio centered on Channel 6 (2437 Mhz) will range down to 2426 Mhz, below Channel 4, and as high as 2448 Mhz, past Channel 8.Īnd that assumes only 20 Mhz channel sizes. So a wifi radio using 20 Mhz centered on Channel 1 will have signal going up to 2422 Mhz, well into Channel 3. But wifi uses at least 20 Mhz of spectrum. Channel 1, for example, centers at 2412 Mhz, and Channel 2 centers at 2417 Mhz. The thing to understand is the channels are only 5 Mhz wide. Soon, we will also have 6 Ghz spectrum to play with.īut for the question as it relates to the 2.4 Ghz band: Stick to 1, 6, or 11! For more recent devices, your best option is to get to the 5 Ghz spectrum, especially if all of your equipment can support 802.11ac or newer.
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