Using 802.11n with 802.11b/g devices on the wireless network(s)

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Level 1

11 points

Using 802.11n with 802.11b/g devices on the wireless network(s)

I think my current (non-Apple) wireless router is dying and I have a question about the Airport and Airport Extreme.

If I get an AE, can I set up the dual bands such that: a) each one has a different SSID, b) I can force my iPad Wi-Fi + 3G to connect to the 5 GHz band at 802.11n, but have my older iPod touch 2G and older Macbook to the 2.4 GHz band at 802.11b/g speeds? And if so is that how ya'll would recommend that I set this up?

Likewise if I get the Airport (not Extreme) to save a little money, am I correct in assuming that even though the router will support 802.11n I'll be forced to the lowest common denominator because of the two older b/g devices on the WLAN coupled with the fact that it is single band (one at a time)?

Thanks,
Ray

13" 2.4GHz Aluminum Macbook, Mac OS X (10.6.4), iPod touch 2G 16GB, iPad 3G 16GB

Posted on Aug 27, 2010 10:37 PM

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Answer 1

Best reply

Bob Timmons

Community+ 2024

Level 10

159,092 points

Aug 28, 2010 7:10 AM in response to araym

Welcome to the discussions, araym!

If I get an AE, can I set up the dual bands such that: a) each one has a different SSID, b) I can force my iPad Wi-Fi + 3G to connect to the 5 GHz band at 802.11n, but have my older iPod touch 2G and older Macbook to the 2.4 GHz band at 802.11b/g speeds? And if so is that how ya'll would recommend that I set this up?

If you get the dual band AirPort Extreme, by default both the 2.4 GHz and 5 GHz bands are set to use the same network name (SSID). You can change this by using AirPort Utility > Manual Setup > Wireless Tab to set up a separate name for the 5 GHz and 2.4 GHz bands.

Since the 5 GHz band will have a different name (SSID), if you set it up this way, you can point compatible devices to that network to use that band. Likewise, older "b/g" devices will log on to the 2.4 GHz band.

And if so is that how ya'll would recommend that I set this up?

If you want to "force" a device to use a given band, the info above about setting up separate SSIDs would be the only way to accomplish that goal. Otherwise, with both bands using the same SSID, devices will connect to the band with the strongest signal. Depending on their location, compatible devices may or may not connect to the 5 GHz band if they see a stronger signal from the 2.4 GHz band.

Likewise if I get the Airport (not Extreme) to save a little money, am I correct in assuming that even though the router will support 802.11n I'll be forced to the lowest common denominator because of the two older b/g devices on the WLAN coupled with the fact that it is single band (one at a time)?

I think you may be asking about the AirPort Express here, which is single band device capable of both 5 GHz and 2.4 GHz setup, but not both at the same time. You would need to use the 2.4 GHz network and a compatible Radio Mode setting like 802.11n (802.11b/g compatible) so that all of your devices could connect.

Faster "n" devices would connect at "n" speeds and older "b/g" devices would connect at the slower speeds. If you have both "n" and "b/g" devices active on the network at the same time, the slower devices will tend to pull down the speed of the faster devices, but they will usually not drop all the way down to "g" levels unless there is a lot of activity (like a heavy download) occurring at the time.

One final note and that is that you should understand that although 5 GHz signals travel faster, they are not as strong as 2.4 GHz signals. Therefore, 5 GHz does not penetrate walls or other obstructions as well as 2.4 GHz. Many users and are finding that they almost need a line-of-sight situation between the computer and router for 5 GHz to work really well. In other words, forcing a device to use 5 GHz does not necessarily mean that it will perform better than it would at 2.4 GHz unless it has a really good signal from the 5 GHz band.

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Answer 2

araym Author

Level 1

11 points

Aug 28, 2010 10:11 AM in response to Bob Timmons

Thanks, that's very helpful.

I knew about the 5GHz penetration problems but where I plan to put the router is centrally located and I'm cautiously optimistic that I'll have good reception there.

Faster "n" devices would connect at "n" speeds and older "b/g" devices would connect at the slower speeds. If you have both "n" and "b/g" devices active on the network at the same time, the slower devices will tend to pull down the speed of the faster devices, but they will usually not drop all the way down to "g" levels unless there is a lot of activity (like a heavy download) occurring at the time.

This is the core of what I was really trying to get at. I'm far from a wireless networking expert but I had heard that if "b/g" devices were on a network that "n" devices would be forced to downgrade to the slower protocol. You're saying that's not the case. If not I'm assuming the "tend to pull down the speed" is simply related to bandwidth competition? If so I can live with that.

Based on your reply I'm guessing all I really need is an Airport Express not an Airport Extreme. I don't need most of the extra features in the Extreme but was considering it only because I wanted my new iPad to run as fast as it can while still existing in a diverse environment.

Thanks!

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Answer 3

Aug 28, 2010 10:36 AM in response to araym

...but I had heard that if "b/g" devices were on a network that "n" devices would be forced to downgrade to the slower protocol. You're saying that's not the case. If not I'm assuming the "tend to pull down the speed" is simply related to bandwidth competition? If so I can live with that.

I run an extended single band network consisting of an AirPort Extreme and Airport Express. It's set to a Radio Mode of 802.11n (802.11b/g) compatible. We have "n" computers and "g" iPhones. The computers connect at a solid 130 Mbps which about the theoretical maximum for "n" and they maintain that connection if the iPhones are in use, downloading Apps, etc.

If I'm doing a operating system update over wireless, or backing up a large file to the Time Capsule using wireless, the "n" computers tend to drop down to 78-90 Mbps at the time. Since "g" devices run at a maximum of 54 Mbps, I'm still getting "n" speeds, but not quite as good as during normal operation...browsing, email, etc.

Of course, there's no way to predict your wireless performance in advance and results will vary somewhat from home to home, but this should give you a good idea of what to expect if you try the single band setup.

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Answer 4

Cinemagic

Level 2

165 points

Aug 28, 2010 10:42 AM in response to araym

Technically, the frequency of the signal doesn't effect it's speed. Both travel at the sped of light (in a vacuum). It has to do the the wavelength. Different materials can block different wavelengths to differing degrees. A 5 GHz network can carry more data than a 2.4 GHz network assuming the electric power to the higher frequency radios is maintained at a higher level. However, some 802.11g network products match and even exceed this potential speed advantage of 5 GHz 802.11a by utilizing a pair of radios instead of one, increasing capacity up to 108 Mbps under the right conditions. A 5 GHz network has a shorter range than the 2.4 GHz network. Often there are other 2.4 GHz devices within the range of the network, such as garage door openers, cordless telephones, security appliances, etc. These can produce interferences whereas this is usually not the case with the 5 GHz networks, though there are some 5 GHz cordless phones now on the market. If you do not encounter interferences (that can't be corrected by specifying particular channels), the 2.4 GHz network is going to the better network for the home, IMO. I find Airport Extreme devices to be my choice of wireless routers in both my home and office. I have the 5 GHz radio turned off. There is no perfect router but Airport is pretty nice and reliable. I can recommend it.

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Answer 5

araym Author

Level 1

11 points

Aug 29, 2010 9:04 PM in response to araym

Thanks. Ya'll answered my questions very well.

I think I'm going to go with the Airport Express as it looks like it will meet my needs of running multi-speed devices on the same network. I don't need the extra bells & whistles of the Extreme now that I better understand how all of this works.

Thanks again!
Ray

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Answer 6

cyvi937

Level 1

104 points

Aug 30, 2010 12:51 AM in response to Bob Timmons

Bob Timmons wrote:

I run an extended single band network consisting of an AirPort Extreme and Airport Express. It's set to a Radio Mode of 802.11n (802.11b/g) compatible. We have "n" computers and "g" iPhones. The computers connect at a solid 130 Mbps which about the theoretical maximum for "n" and they maintain that connection if the iPhones are in use, downloading Apps, etc.

130 Mbps isn't the maximum for "n". My Apple TV connects at 270-300 Mbps, so too does my MacBook Pro if it's near the AirPort Extreme. But these devices will only do this if I take the AirPort Extreme's radio mode off of "Automatic" and select "802.11a/n - 802.11b/g" instead. This splits the 2.4 GHz and 5 GHz bands and allows it to transmit in both bands at the same time. For some reason, the "Automatic" setting doesn't give you the highest possible throughput.

If you want the really high "n" speeds you'll have to get a router that allows simultaneous dual band, i.e. the AirPort Extreme.

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Answer 7

Oct 26, 2010 6:59 AM in response to cyvi937

What effect will an 802.11b device have? I'm trying to figure out why my Apple TV 2 occasionally slows down to a crawl. When it happened last night, I noticed that my wife's G3 laptop was on. It was not doing anything, just sitting there awake. In such a situation could it affect the network that much?

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