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How to Avoid Costly Wi-Fi Roaming Mistakes

Eliminating wireless access point hand-offs is the key to preventing delays and problems encountered in home and small office networks.


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The “Connected Home Environment” includes multiple devices for security, entertainment and home office on a single wireless network.

Building a Wi-Fi network that delivers uninterrupted coverage to mobile or “roaming” devices can be a significant challenge - especially as coverage requirements increase. This challenge becomes considerably more manageable when the issue and the deployment alternatives are well understood.

What Is Roaming and How Does It Work?
Roaming occurs when a wireless client device moves outside the usable range of one wireless access point (WAP) and connects to another WAP - usually one with a stronger signal. There is no “roaming” issue as far as the WAP is concerned.

As long as the WAPs are setup properly, client devices can roam seamlessly from one to another. The issue and challenge comes in the actual “hand-off ” process, which, according to the IEEE 802.11 standard [1], is dictated by the client device. This process consists of three phases:

Scanning: As the device moves away from the WAP to which it is connected and the RSSI (Received Signal Strength Indicator) values begin to drop below certain levels, the client device sends out probe packets to identify WAP alternatives. Upon discovery of accessible WAPs, the device then selects its next WAP based on certain criteria, as defined by the device itself.

Authentication: During this phase, the client device sends an authentication request to the new WAP and waits for approval or rejection.

Re-association: Upon approval by the new WAP, the client sends a re-association request and waits for a response. Once the re-association is complete, the new WAP sends out a disassociation packet to the old WAP so that the routing tables can be updated.

If WAPs are properly set up, research has demonstrated that this hand-off process typically takes less than a half second, with the scanning phase contributing to the majority of the delay. And the scanning phase can be reduced substantially simply by ensuring that only valid wireless profiles are stored on the device.

So why does the delay often seem much longer? The answer is that roaming is dependent on the client device’s “roam trigger.” In other words, the client decides when it is time to drop one WAP and move to another. Some client devices are more sophisticated and do a better job of determining at what point to let go, while others will measure only RSSI values and may hang on for longer. The important thing to understand is that the roam trigger is completely client dependent.

Technology Alternatives for Minimizing Hand-off Delays
Given that roaming is a client-dependent function, how can uninterrupted Wi-Fi service be achieved? Under current 802.11 standards, the only reliable method is to keep devices from executing a hand-off. Anytime there is a hand-off, there is risk of dropping packets and delays in service. With most conventional Wi-Fi networking technologies, eliminating the need for hand-offs between WAPs is simply not an option.

So what are the alternatives for minimizing hand-off delays? There are various approaches and technologies:

Non-Controller Multiple WAP Approach: (Fig.1) Perhaps the most common approach to date, installers have traditionally used multiple WAPs set to the same SSID and security level - doing their best to isolate them into logical zones in an attempt to reduce the number of hand-offs a device may require. This generally has the same effect as the “configuration controller” option described below - but at a lower cost. Clients are still responsible for determining when to trigger the hand-off, resulting in some delays.

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Figure 1: Non-Controller Multiple AP Approach

Configuration Controllers: (Fig.2) A configuration controller is used in conjunction with multiple vendor-specific, low-powered WAPs. It typically does little more than optimize the setup by pushing the settings out to the WAPs on the network and ensuring they are all set to the same SSID and security levels. The client device must still determine at what point to jump from one WAP to another and go through the same hand-off process.

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Figure 2: A controller-based Wi-Fi Network





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About the Author

Clark Roundy
Clark Roundy is VP of marketing and product management for Luxul.

18 Comments (displayed in order by date/time)

Posted by EJ Feulner  on  04/06  at  09:54 AM

Man, an advertisement for Luxul disguised as an article?

Posted by dplanz  on  04/06  at  12:51 PM

Not even thinly disguised.  I’m ok with new product announcements here, but give us some actual real information.

Telling us that its 400% ‘better’ is just a crock - tell me WHY and HOW its technically better.  Otherwise, its just the marketing department being full of BS, like they usually are.

Sorry, not planning on buying this product anytime soon.

Posted by WhyReboot  on  04/06  at  01:02 PM

I cannot even begin to comment on how many things were misrepresented or just plain wrong in this article.  I would love to do it some time but there are so many issues I just don’t have the time right now.  Maybe tomorrow.  I’m not hating because I’m an equal opportunity technology enthusiast and evangelist.  If it’s good and it works well then that’s great but don’t misinform people with bunk knowledge to sell your product.  That’s not cool.

As for the comment above by “ej”, have you ever seen the similar articles written by Victor Pak of Pakedge selling the same “virtual” access points?  I wish CE Pro would allow me to write an article about how great WhyReboot is at creating stable and reliable networks for CE pros!  Ha ha.

Posted by Mike R  on  04/06  at  02:14 PM

The new Luxul Xen product has been working excellent, to me it is the best way to go. Spending $8000 on a controller that can control the hand-offs with the access points doesn’t make sense for most residential purposes. If you have anything negative to say, then it is obvious you have not tried Luxul. AND it’s not sold on the internet, so you can actually make a decent margin as well.

Posted by Michael Grady  on  04/06  at  02:17 PM

I wish CEPro would allow anyone that doesn’t have a vested in a product write a true article about the Pro’s and Con’s of each technology.

Actually I would rather a CE Pro writer interview all companies that consider their wireless product the best, ask what the issue is with the competitors technology, compile all data and reinterview the companies asking specific questions that the competitor said was an issue with their technology. I believe that would be called journalism.

Posted by John Nemesh  on  04/06  at  03:54 PM

@dplanz The “up to 400%” statement refers to overall range.  This access point will cover up to 400% larger area than your normal off the shelf access point.

What Luxul is doing is taking regular Wifi access points and putting a much better antenna on it and add a signal booster.  There are other technologies in play…because you need to have good RECEPTION over the coverage area not just boosted transmission.  I am sure a lot of the “how” part is proprietary information that they won’t want to share…but the upshot is that in most of your residential installations…even multi-level dwellings, a SINGLE Luxul access point will give you strong, consistent coverage over the entire home. 

I have plenty of dealers who have used Luxul’s products, and the vast majority of them have had EXCELLENT results using it!  If you have any doubts, you should get one and try it for yourself!

Posted by TonyNoOne  on  04/06  at  07:11 PM

I have also tried the Luxul line (still sitting on a $1K between two pieces that I would NOT put in a client’s home). Thankfully, I was smart enough to test in my own home and see real world results (or lack thereof) before foisting it on unsuspecting customers. Luxul’s gear is anything but reliable.

Posted by WhyReboot  on  04/06  at  07:40 PM

I for one would love to try one out.  I’m curious how it performs against some of the products we use.  Yes we also sell controllers that run up to $8000 or more (eg. Cisco 5508 WLC) but we try not to because for most clients there is no benefit and only do when a client asks for it or needs something particular like ridiculous security.  Normally we sell Ruckus controllers at a fraction of that cost.

However, we’re always looking for ways to cut costs to our clients while providing them with something that works reliably with the systems they put in.  For most of our jobs this may not work because they may not cover the entire property.  For the smaller jobs though this could be a welcome addition to our toolbelt if it works well enough.

My gripe was not whether or not the product is good because I don’t know.  I would only know if I tried it myself or had experience working with it.  My gripe was only the way it was presented in the article.  That being said, I would love to see this product out in the field and see how it matches up to a Ruckus 7962, without a LAN controller.  wink

Posted by Mike R  on  04/07  at  10:58 AM

I do want to add that if anyone was having any issues with the product, there was a new firmware update about a month or so ago (v1.1) that really seemed to clear up all of the problems and I have not had any issues since.

And I do agree that this article was presented poorly, it’s a shame if that reflects negatively on this product. It really has been working great for myself and other dealers I know using it.

Posted by Chris  on  04/07  at  11:27 AM

WhyReboot,  So why not get one in and test it out?  In our experience they don’t live up to the hype and do not perform well enough for our installs.  I know a couple other companies that brought them in and have regretted it as well.  I suppose their 1 WAP approach outlined above would be great…if your jobs were saltbox style homes but unfortunately if you have homes that sprawl out over 5,000+ sq feet you need virtual cell technology especially with roaming touchpanels and other network devices.

Posted by 39 Cent Stamp  on  04/08  at  10:47 AM

I personally dont mind arti-tisements (article based advertising). Its done everywhere… radio especially. I dont (and dont care to) know enough about the technology mentioned in the article to know if there are lots of incorrect statements but after reading it…its basically what we have been dealing with. Using a competing products controller and apswe have been able to build a robust wi-fi network that allows for easy roaming.

We used a Bountiful router once at a clients home. This was about 6 years ago when we were still looking for a stable product to use for wi-fi. It was a single device with greater range than your typical wi-fi router or access point.

Clients home was an open floor plan and the bountiful router sat on top of a loft area and not in a closet or cabinet. Range was insane. Crestron TPMC-10’s and TPMC-8xs were able to stay connected in any room of the house except the furthest bedroom.

We ended up replacing it because the fan on it was so loud that you could hear it all around the house. This isnt an issue if its hidden in a control room. But.. if it were hidden in a control room it probably wouldnt have gotten the same range/results.

I dont have any experience with luxul but i assume they have the same issue with their single device product. “it either works or it doesnt”. If it doesnt cover the entire property then what do you do? Add an additional access point bringing you right back to square one?

The issue with spec’n something like Luxul is that if it doesnt work your proposal can end up being off by thousands of dollars. At the project we used bountiful the cost for wi-fi went from a few hundred to a few thousand when we swapped the single device for 3 APs and a controller.

Posted by David Vanwert  on  04/08  at  12:00 PM

I just finished a project where the integrator and myself decided to deploy the Luxul solution for the clients home. The project is a 3200 sqft tri-level home, and the AP was mounted directly in the middle of the home on the second floor in the Master Bedroom closet.

Although there were no roaming issues, obviously, the signal especially on the bottom floor was actually fairly poor. The client has an office directly below the AP location and the signal in that room is virtually unusable.

I was hoping to have this be a great solution when the client budget doesn’t warrant a more robust solution, but I guess I’ll keep looking.

Although the system isn’t horrible and the top floor seems to have good coverage and speed, I doubt I will be specifying this solution for my clients again.

Posted by DVANWERT  on  04/08  at  12:13 PM

I just finished a project where the integrator and myself decided to deploy the Luxul solution for the clients home. The project is a 3200 sqft tri-level home, and the AP was mounted directly in the middle of the home on the second floor in the Master Bedroom closet.
Although there were no roaming issues, obviously, the signal especially on the bottom floor was actually fairly poor. The client has an office directly below the AP location and the signal in that room is virtually unusable.
I was hoping to have this be a great solution when the client budget doesn’t warrant a more robust solution, but I guess I’ll keep looking.
Although the system isn’t horrible and the top floor seems to have good coverage and speed, I doubt I will be specifying this solution for my clients again.

Posted by WhyReboot  on  04/09  at  06:51 AM

@Chris, well I was thinking of maybe testing one out but 39 cent stamp makes a very good point.  I wouldn’t want a client to come back to me saying that there isn’t enough coverage for whatever reason (maybe a safe room with thick poured concrete in the way of the signal) and then have to tell them to spend at least $2k more to get it working right.  We’re in business because our networks work every time and I can’t take that risk in not following through with a client.  If it came to that I would pay for the upgrade myself and that just isn’t cool either.

As for virtual cell technology I’m not really a fan.  In theory it is excellent but try using the same channel in a New York highrise.  It is problematic to say the least.  At least that’s what I’ve heard from clients who have used it and it makes sense considering how the tech works.  Right now I’m VERY comfortable using Ruckus WAP’s with their controllers.  If clients demand it then I will sell Cisco but the price difference is ridiculous compared to Ruckus with the same, if not better performance compared to the latest Cisco has to offer.

That said, if you have the money and require a more secure solution then Cisco or Aruba would be a great alternative and work really well.

Posted by Rob G  on  04/09  at  01:58 PM

I find this discussion of great interest.

I work for the Multimedia over Coax Alliance, MoCA (full disclosure intended). I often hear from installers and home owners asking about how to extend their wireless network.

I am a firm believer in the benefits of wireless especially with respect to the onslaught of portable devices such as tablets and smartphones onto the home net. Afterall, I am a consumer, too.

But, I also note the increased need for a wire to supplement, not replace, wireless networks, espcially for video applications.

MoCA technology, implemented via CE branded devices, is finding success among the installers who are implementing adapters to augment an existing wireless network.

The need for a wire will continue to exist for the foreseable future. Why not use the coax? It is already in your house and it was originally intended for video.

Granted, coaxial outlets are not in every room but they are generally found where you watch TV. If you want to extend TV programming to other devices, MoCA is used as an in-home backbone extending the reach of wireless networks.

Don’t throw out the wireless. Just add MoCA.

For more information, please visit http://www.moca4installers.org

Rob

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