Design for a Wi-Fi Future with LANPlanner

By Tom Kevan

Figure 1: LANPlanner 11 models the site-specific effects of MIMO and allows the impact of this RFfeature to be easily visualized and understood.

As wireless technology evolves, so must network design and evaluation tools. Perhaps the greatest recent change in wireless networking is the 802.11n draft standard, which not only redefines the throughput and range potential of wireless networks, but demands a completely new mindset for deployment of best practices.

“The 802.11n draft standard turns Wi-Fi design on its head,”  says Joe Bardwell, president and chief scientist of Connect802, a wireless LAN design and consulting firm. “Most of the assumptions that an engineer would make about the best location for an access point and an antenna with a/b/g go out the window. It’s very nonintuitive.”

  To compensate for the expertise shortcomings created by the introduction of 802.11n, Motorola’s newest wireless networking design software,  LANPlanner 11, has been customized to handle the challenges posed by the new standard — and offers the tools needed to design, deploy, and evaluate the new and unfamiliar wireless technology. But the software’s functionality is by no means limited to homogenous 802.11n deployments. Its toolbox includes modeling and simulation tools that allow you to create mixed-technology networks, thus enabling you to build a migration path from legacy WLAN technologies (802.11a/b/g) to the new standard.

Figure 2: With LANPlanner 11, it is easy to evaluate the impact of adding and removing equipment, and determine whether you really need to do a 1:1 replacement for 11n access points. Simply run a new predictionand visualize the results.

Building on Predictive Design
As with previous versions, LANPlanner 11 allows you to design wireless LAN and multiband systems through site-specific 2D/3D modeling and what-if simulations. The software builds on established predictive design technology found in previous versions, which leverages a library of attenuation-characteristic profiles that take into account such environmental factors as layout parameters, building materials, and radio-frequency interference. What makes the software so relevant is the fact that the library’s profiles have been updated to incorporate 802.11n performance traits.

  Motorola has further enhanced LANPlanner’s capabilities by adding two new sophisticated modeling features, which work in concert with and supplement the library-based predictive design technology. These can be used in manual and automated planning sequences.

MIMO Modeling
The first feature is MIMO (multiple-input and multiple-output) modeling. The 802.11n draft standard uses MIMO technology to move multiple data streams from one place to another. Instead of transferring data in a single stream, MIMO uses multipath signals. This approach allows the network to transmit more data faster, over greater distances, but it also requires different access-point placement strategies than those used for legacy 802.11a/b/g networks. MIMO modeling gives LANPlanner 11 users the ability to visualize 802.11n-specific MIMO effects in the deployment environment and optimize access point placement (Figure 1, above).

“Unlike 802.11b/g, which are degraded by signal scattering and multipath reflections, MIMO in 802.11n is augmented by these effects,” says Bardwell. “For most engineers, that makes MIMO completely nonintuitive. So LANPlanner 11’s MIMO modeling feature gives them the ability to overcome their own lack of intuition with the new standard because they can see the radio wave propagation, where the access points should be placed, and what the throughput is going to be. And perhaps equally important, it provides decision makers with an assurance that the 802.11n design — where the access points are not being placed in the same locations that intuition would have told them they should be — is actually going to work.”

Fig. 3: The new Migration Wizard combines an automated process with predictive technology and an easy-to-use interface to enable network engineers to tackle the three most popular 802.11n deployment scenarios: rip and replace (upgrading existing hardware to 11n), mixed deployment(11n and legacy hardware), and clean slate.

Migration Wizard
The second modeling feature in LANPlanner is the Migration Wizard. This automated process uses library-based predictive design, MIMO modeling (only when working with 802.11n), and a graphical interface that enables you to visualize radio-wave propagation, coverage, capacity, SSID,  interference, VoIP handoff regions, and performance improvements (Figure 2) in homogeneous 802.11n and mixed-technology networks. With the wizard, you can set your criteria, and it will add or replace access points until your criteria are satisfied. You don’t have to manually place the access points.

  The big advance in the Migration Wizard is not automatic planning, which exists in previous versions. It’s automatic planning that factors in the condition of your existing network.

  To develop a migration strategy, the wizard offers three choices: rip and replace, partial replacement, and a greenfield (clean slate)  deployment (Figure 3). To evaluate these options, it allows you to visualize what-if scenarios. Based on the results, the wizard helps you create a design that makes good use of 11n and legacy technologies, and understand the cost-benefit tradeoffs.

“If you have an existing plan, you can look for holes in coverage, determine if you have too much coverage and can possibly have a more efficient design, or move some access points around and get more even coverage,” says Eric Reifsnider, Motorola’s principal staff software engineer. “You can visualize where the best server is for each node and how many users it serves. That’s kind of an extension of our existing functionality for other technologies, but once you add the 11n angle, you are able to make the best use of the additional data rates provided by 11n. And the Migration Wizard really helps you to come to terms with that without having to manually tinker with the network quite as much as you would.”

  But the benefits of the Migration Wizard go beyond the simplification of the design process; they also empower the decision-making process. “802.11n is two to three times more expensive than legacy a/b/g,” says Connect802’s Bardwell. “So customers’ first response from a budgetary standpoint is to say, ‘How can we create phased migration to 11n to avoid the dramatic expense of a forklift upgrade.’ It goes without saying that a greenfield deployment of 802.11n will achieve the best 11n capabilities. But as soon as a/b/g is introduced, there are performance hits on the overall network,  and 11n isn’t necessarily able to always take advantage of maximum throughput. So the fact that the Migration Wizard can quickly show various alternatives and what the predicted throughput and capacity of the network would be gives the budgetary decisionmaker data points to make a reasonable decision.”

Fig. 4: With SiteScanner, it is easy to performsite surveys for 11n and visualize live performance.

Validation & Verification
LANPlanner also includes a site survey tool called SiteScanner. This tool allows you to quickly record live network data, run visualizations of the measured data, and identify sources of potential wireless problems (Figure 4, page 62). With SiteScanner’s map-based interface, you can review the survey’s visualizations on a per-access point, per-channel,  per-standard, or per-network basis to ensure network performance conforms to your specifications.

  SiteScanner is used primarily after deployment to validate your design. But there is another role. It can also be used when you think your environment is particularly unusual in terms of material, construction, or conditions, and does not resemble any of the preconfigured parameters in the library. In that case, you can use the SiteScanner up front by deploying a few test access points at a few locations and doing a survey. Then, SiteScanner takes the tuned parameters and rolls them back into the original design.

“The biggest plus is the integration between SiteScanner and the original predictive model,” says Connect802’s Bardwell. “I can take the heat map created by SiteScanner, and I can integrate it back automatically into the original predictive design, where I can look at the deltas between the predictive model and the SiteScanner model. So in a case where gap analysis or remediation is required — a post-installation — coming back with the SiteScanner results automatically fine-tunes the original predictive model. Once that happens, I can continue with prediction and simulation during gap analysis and remediation, knowing that I have a higher level of accuracy in the design.”

  LANPlanner 11’s real strength is its inclusion of 802.11n technology. The beauty of it, though, is that you don’t have to be working solely with draft standard technology.

  Motorola realistically assumes that not everyone is going to deploy an 802.11n greenfield implementation. Many will have to move from previous Wi-Fi versions to the new standard through a phased migration and will need a design tool that will help them reach their destination.

More Info:
Connect802 Corp.
San Ramon, CA

Motorola,  Inc.
Schaumburg, IL

Recommended Min. System Requirements:
> Intel Pentium 4 1.5 GHz (or better or equivalent)
> Microsoft Windows XP (Professional, Home Edition, and Tablet PC Edition)  or Windows 2000 Professional
> Microsoft Word XP (Word 2002) or later (required for generating reports)
> 1GB RAM
> 300MB free disk space for installation
> 1024 x 768 VGA with true color
> Mouse, trackball, or compatible pointing device, with scroll wheel
> Microsoft Internet Explorer 6.0 or later
> CD-ROM drive

To use WLAN measurement functionality, a WLAN card is required. The specific measurement functionality depends on the type (and chipset) of the specific card.

Tom Kevan is a New Hampshire-based freelance writer specializing in technology. Send your comments about this article to [email protected].