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Hey all, If I have a router that has "mixed mode" enabled to allow b, g, and n devices, it is true that n devices will suffer in reduced bandwidth if there are any non-n devices connected?

I found one article on the internet after a quick google search: http://www.wi-fiplanet.com/news/article.php/3335801

Can anyone corroborate or give their opinion on the matter?

Thanks!

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article's from 2004, and only discusses 802.11b/g mixed-mode. need something more recent. –  quack quixote Feb 4 '10 at 0:14

6 Answers 6

Just was troubleshooting an old Linksys WRT510N that I am using as a slave AP to cover my backyard (my primary is an Amped 1000mW). Have always had trouble with my iPhones getting dismal bandwidth, although modern laptops were fine (>20Mbps with Comcast primary). Played with channels for several weeks as there is LOTS of interference in my neighborhood (using InSSIDer...great SW) to no avail. Finally on a hunch, I changed it to Mixed-BG from Mixed, and suddenly I'm getting 20Mbps from this AP. Change it back to Mixed and it goes back to <2Mbps.

I was about to go and blow $70-80 on another access point...glad I waited.

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I suggest you try it out and if you notice anything apparent then revert. I had a problem connecting my Blackberry Curve with a mixed mode of b, g, and n, so I changed it to a mixed b-g mode and it didn't have any apparent effects. I used to be able to use my macbook which is N-enabled in my backyard and after changing it to b-g mixed mode, it still was able to work and I didn't see any differences in speed.

This is completely a trial and error situation. I am using a Linksys router, but I've had problems with Netgear routers even on N-only for a small apartment. Try it all out and see if your router is still great at distances. Hope this helps!

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Depends of lots of things in the router itself. I have 2 wireless N routers. I have a Belkin N+ and a Linksys E3000.

Had to disable the N band on the Belkin. I use my Moto Droid, and my HTC Droid Eris on my wireless all the time. The Eris will not connect to the Belkin if it has N band enabled. I have to have B&G only on it for the Eris to see it. The Moto Droid didn't care.

The Linksys works with BG&N on the 2.4 GiHz side at the G rate for both of the Droids.

I dunno why it would be so without more research. So, go figure.

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No need to constantly double-sign posts. You already have that big avatar and signature on the right. –  random Sep 19 '10 at 22:53

At every jump from original IEEE 802.11-1997 DSSS -> 802.11b -> 802.11g -> 802.11n, there have always been small optimizations that the higher-speed devices could use to maximize their throughput when no legacy devices were present. Or to say it the other way around, there have always been small adjustments they'd have to make to not interfere too badly with legacy clients when legacy clients were present. These optimizations and adjustments are generally "minor but measurable", like a 10% speedup/slowdown.

It's a huge myth that the presence of legacy devices forces all clients on the network to completely abandon their higher-speed capabilities and use only legacy rates. That has never been true. So if you had some 802.11n 2x2 clients getting 144mbps on HT20 (20MHz wide channels), the presence of an 802.11b client would not knock them down to 11mbps.

Part of the Wi-FI certification testing (required if you want to use the Wi-Fi logo on your products) ensures that newer higher-rate products do not slow down to legacy rates in the presence of legacy clients, and also ensures that the newer higher-rate products don't destroy the legacy clients' ability to get reasonable rates.

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The problem of interference (and hence reduced bandwidth) due to mixed-mode operation can be avoided if the 802.11n devices operate exclusively within the 5GHz frequency band (and with the a/b/g devices at 2.4GHz). This requires that the access point has separate radio hardware for 2.4GHz and 5GHz operation.

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This depends on the make/model of the router and it is impossible to generalise.

I had one of the early draft-n routers for testing and saw something similar in a few models, but have not seen anything like this for years.... again, not saying it doesn't happen - but I haven't encountered it.

There is no one answer and you are best off just testing it or emailing the manufacturer if you have a pre sales question.

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