Question

802.11N Overlapping Channels

Asked by: jimbecher

  Unless I am doing something incredibly stupid (which has been known to happen) I find the range of 802.11n in the 5GHz band so limiting it is almost useless either indoor or outdoor. So the brief question is have I done something incredibly stupid or is everyone finding the range in the 5GHz band to be very limited?

   So assuming it isn't just me :) I am back to the 2.4GHz band. The specific application is outdoor WDS. There are only 3 non-overlapping 22MHz channels in the 2.4GHz band. The first obvious question is will the 40MHz channel with work in the 2.4GHz  band and if so that would force the use of overlapping channels would it not?

   Would I be better off not using the 40MHz width or letting it us the 40MHz width and putting up with what ever degredation is caused by using overlapping channels?

   Lastly ... when setting the channel on the AP and using 40MHz channel width does it really make much difference what channel I set it at? Is channel 6 as good as any and does the AP at that point figure out which other channels to use to get the 40MHZ width?

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-09-12 at 14:53:08ID24727262
Topic

Wireless Technologies

Participating Experts
2
Points
500
Comments
5

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. How many wireless hops can I use on Wireless Access Poi…
    I would like to know how many wirelesss hops I can achieve without serious signal degradation. Imagine a VERY long, straight hallway with apartments/units on both sides. There is a telco room on one end of the hallway where an AP can be wired into the switch. However, wiring ...
  2. searching for best seting up 2 AP's channels combination
    Dear Expeerts, im in my way to set up 2 AP's Linksys WAP54G , but im getting same problems to conect to one of them i have this set up: AP 1 : channel 1 AP2 : channel 7 Same users dont find AP2 and i think maybe a problem on the channel combination, maybe interfering . c...
  3. Wireless N channel overlapping and multiple fat AP's
    I've learned that runnng a wireless AP with 802.11n on 2.4GHz typically uses all three non-overlapping channels. Two channels would be bonded for 802.11n MIMO while the third would be available for b/g backward compatibility. Am I correct so far? To provide roaming access ...
  4. Need 802.11N 5Ghz Outdoor WDS/AP
    Can anyone recommend an 802.11N outdoor WDS/AP unit? I have at the outside 500 feet to cross. Would prefer Point to Multi-point. I am trying to achieve the full 300Mbps throughput so I want to stay in the 5Ghz band. What scares me is that if the same holds true for indoor ...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: ShootaPosted on 2009-09-13 at 12:46:47ID: 25321463

Jim, you are neither wrong nor stupid...the range of the 5GHz band is definitely going to be significantly less than the 2.4GHz band.  Especially if you have any obstacles in the path.  The problem with wireless is it is very situational specific.  If interference is an issue, as it often is in the 2.4GHz range, you may need to go with 5GHz and add range extenders.  However, if 2.4GHz is clear in your area, then you should be fine with it.  The next question is how much bandwidth do you need and how many APs are going to be connecting to your WDS.  Also, what kind of equipment are you using?  Some devices that are specifically made for WDS have multiple antennae that can use different channels or even different bands simultaneously.  If you're using one of these and you need the throughput, your best bet would probably be to use 40MHz channels on channel 3 and 9 to reduce the overlap as much as possible.  Or you may even be able to use 2.4GHz for one and 5GHz for another.  (A good, albeit biased, explanation can be found here: http://www.3com.com/other/pdfs/products/en_US/104108.pdf.)  If you don't have one of these and your hub AP is just a standard wireless router, then you're best bet is to use a 40MHz channel that has the least interference.  You can use NetStumbler (http://www.netstumbler.com/downloads/) to get an idea of the radio traffic in your area.  And I'm not endorsing any of these products; they're just good sources of information.

 

by: Darr247Posted on 2009-09-13 at 16:27:21ID: 25322280

Try channels 149, 153, 157 and 161 - those can use 4x the power level as allowed on the lower channels (and 16x the power as allowed on the bottom 4 channels). Actually, those *should* be the only 4 channels you can 'lock' the device to, as the lower channels are supposed to be restricted to a mode that switches between them automatically to keep from interfering with police/military radar. Since 2004, anyway, if I recall correctly.

What wireless router/AP are you using?
You may need to use 3rd party firmware to adjust the power levels... or, depending what brand/model you have, it may not be possible to change those power levels at all.

 

by: jimbecherPosted on 2009-09-13 at 16:35:24ID: 25322297

  This is kind if in response to both comments. In the 2.4MHz band (on 99% or the wireless routers and APs) you can either select Auto channel or select channel 1-11.

   @Shoota I can not select 3 and 9. I can only select 1 channel. I would have to assume the other channel used for channel bonding would somehow be automatically selected by the router or AP? Since I can only select 1 channel whould you still recommend 3 OR 9?

   @Darr247 where are you comming up with these channels? I only have 1-11 available.

 

by: ShootaPosted on 2009-09-13 at 17:05:52ID: 25322360

My suggestion for using channels 3 and 9 was only if you had a piece of equipment that was specifically for WDS and supported transmitting/receiving on multiple channels and/or frequencies.  If you're just using a standard wireless router (and from your comment I gather that you are) then you're right, you can only select one channel (although some routers/APs support a secondary standard channel in addition to the primary wide channel) and so you shouldn't have any issues with overlapping channels anyway, other than interference from other wireless devices in the area.  

There normally isn't any reason to use a 20MHz channel unless you're using non-802.11n equipment or you have a lot of interference.  If you are only using 802.11n devices, my recommendation would be to start with a 40MHz channel, especially if you need the additional bandwidth.  (Which channel you start with doesn't really matter unless you get NetStumbler or something like it that can tell which frequency is the least congested.)  If you're getting low throughput or problems connecting, try changing channels to see if it improves.

 

by: Darr247Posted on 2009-09-13 at 21:09:30ID: 25322905

The channels I listed are 5GHz channels.  The reason the bottom 4 channels have such short range is because they're limited to about 2% of the maximum power allowed in the 2.4GHz band, while the highest 4 channels (149, 153, 157 and 161) are limited to only about 20% of the 11g maximum power. 5GHz is also absorbed/blocked by walls and other objects more than 2.4GHz, but if you are able to add access points where signal is poor, you can get away from the overcrowded 2.4GHz band and still have good coverage.

You should be aware that some manufacturers (Apple, Intel, Cisco, et al) have stated they will not support 40MHz-wide (bonded) channels in the 2.4GHz band (as allowed in the 802.11n spec), in order to lessen interference with installed legacy 11b/11g devices... they will support only 20MHz-wide channels in the 2.4GHz band for 11n, which still allows doubling the 11g speeds (e.g. up to 130Mbps or 150Mbps, currently).

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...