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You Can't Perform a Correct Wi-Fi Wireless LAN Site Survey By Drawing Circles On a Floorplan

Connect802 on-site survey consulting is based on the application of predictive,
3-dimensional RF CAD modeling and simulation for an accurate wireless LAN site survey

Buy Your Wireless LAN from Connect802 to Take Advantage of our Wi-Fi Design and Consulting Experience

A "poker chip" design consists of fixed-radius circles of theoretical access point coverage cell size overlaid on a building floorplan. This type of design will result in catastrophic channel overlap and co-channel interference.
This is a "site survey" created by drawing overlapping circles of fixed radius on a floorplan. This design won't work. There are too many access points and they're too close together. Even a sophisticated automated wireless LAN switch system (i.e. Aruba, Cisco, Colubris, etc). is not going to be able to compensate for the problems with this design.
Don't' gamble with your Wi-Fi design! Let Connect802 create a system design using our unique Connect EZ Predictive RF CAD Design methodology - it's cost-effective and accurate! Connect802 is a recognized leader in predictive modeling and on-site survey consulting for wireless LAN site surveys. Our virtual Wi-Fi site survey services provide stand-alone WLAN site surveys and also serve as the basis for Connect802 on-site RF engineering, spectrum analysis, 802.11 site survey, and post-installation verification projects.
Wi-Fi 802.11 access point manufacturers often include an estimated indoor and outdoor range  

Determining 802.11 Coverage Cell Size and Shape During a Wi-Fi Site Survey

The range boundary of an access point can be measured accurately during an on-site survey and the WLAN coverage zone created by the transmitter can be mapped onto a floorplan. There are two basic methods of determining the shape and extent of an 802.11 coverage zone. The first method uses a tool that reports RF signal strength (like AirMagnet Laptop, NetStumbler, or the Cisco AiroNet Site Survey Utility) and individual measurements can be written down on a floorplan to create the Wi-Fi site survey report. The second method uses an automated tool in which you load a floorplan image and then click with the mouse to record measurements. This creates a graphic "heat map" where the color legend represents signal strength. Tools like AirMagnet SurveyPro provide this capability.

Individual measurement points (red dots) are extrapolated to
create a coverage "heat map" showing signal strength across
the entire floor area. (AirMagnet SurveyPRO)
   

Questions to ask when considering any vendor's automated Wi-Fi design and planning tools:

  • Does the design system create a virtual Wi-Fi site survey in 3-dimensions or are the site survey estimates based solely on 2-dimensional signal propagation? (Since signals propagate in 3-dimensions a design based solely on 2-dimensional propagation estimates can introduce some significant errors!)
  • Does the WLAN site survey report that's produced provide coverage patterns that show up as generally concentric circular enclosed areas? (Since RF signals don't propagate in circular paths in the presence of obstructions and points of reflection an accurate representation of signal coverage doesn't have generally circular areas!)
  • Is the planning tool able to consider signal reflections? (If not then you're not able to anticipate multi-path reflection problems and you're not able to design for 802.11n which is dependent on reflections and scattering to provide multiple spatial streams in MIMO.)
  • Can the planning tool factor in microwave oven interference, Bluetooth or cordless phone interference, or other interference and noise sources? (If not then it's going to be impossible to integrate on-site wireless LAN site survey findings and on-site RF spectrum analysis findings into the Predictive RF CAD Design model).
  • Does the planning tool allow you to specify the type of construction material used in each AutoCAD drawing layer for a building's plans? (If the tool only provides a general or limited ability to differentiate between construction materials then the accuracy of the predicted design will be general and limited as well).
   
Learn More from Connect802
Design Services: 3-Dimensional RF CAD Modeling and Simulation
On-Site Survey Engineering: RF Spectrum Analysis and Throughput Testing
Product Sales: Enterprise-Class Equipment For Your Wireless LAN Deployment
Connect EZ Turnkey Wireless LAN Bundles: Complete Turnkey Product and Service Bundles
On-Line Tutorials: Articles and Discussions About Wi-Fi Wireless Networking
 
What is a Predictive RF CAD Model?

Wireless site surveys are performed to determine correct equipment installation locations and to identify RF interference and noise issues in the environment. A manual site survey, with an engineer walking around a building, is not the way to develop an initial installation plan. That plan should be created before any on-site engagement is scheduled. There are a number of useful products on the market to aid an engineer when they perform a wireless LAN, Wi-Fi site survey. These tools capture signal strength measurements from access points installed at a sites wireless LAN and display the results in a graphical format. These tools can't help with a site that's not yet built!

A virtual site survey, using RF CAD predictive models, starts with a building floorplan (typically an AutoCAD drawing file). Connect802 uses the most sophisticated RF design software on the market today to format individual elements of the building so that both the attenuation and reflection radio frequency properties are considered. Predictive modeling allows the RF engineer to identify the number and placement of access points without wasting time during an on-site engagement. In addition, the types of "What If?" scenarios that can be considered in the virtual environment would require unreasonable amounts of time if attempted with real equipment during a manual site survey. Applying RF CAD modeling and simulation to the task of performing a Wi-Fi site survey makes the Wi-Fi site survey process significantly more cost effective than a manual Wi-Fi site survey.

Why Use Connect802 For Your Virtual Wi-Fi Site Survey?

Years of Practical Experience: Since 1994, Connect802 has specialized in network system design consulting. When you need experts in wireless Ethernet, WAN/LAN networking for Wi-Fi integration, security products and Wi-Fi site survey consulting - We've Got You Covered! We are a full-service design, sales, and installation company providing wireless broadband design consulting services and product provisioning. If you need Wi-Fi for the enterprise, K-12 and higher education, hospital Wi-Fi site surveys (also for Computer on Wheels COW carts), Connect802 provides proven wireless consultants.

When you look at a "heat map" (coverage prediction model) produced by a wireless consultant, ask yourself this question, "Do I see generally circular or elliptical areas surrounding each access point?" If the answer is Yes, there's a fundamental problem. RF signals do not propagate outwards in circular paths unless you're in unobstructed, free space. Inside a building the signal strength is impacted by the attenuation of partitions and the reflection of signals, and the effects occur in three dimensions, not just horizontally on the floor.

An accurate predictive Wi-Fi site survey must be able to take reflection and attenuation into consideration. Unless the software being used considers the three-dimensional environment the results will be skewed - often dramatically. Consider the fact that an access point mounted 8-feet up a wall must transmit signals that propagate downwards to service a user with a notebook computer on a desk, a wireless VoIP phone at their ear, and possibly an inventory or medical equipment cart with a client radio at some other height. The important signal paths are diagonal, coming down from the access point - not horizontal, propagating outwards at the height of the access point. Don't settle for a cheap WiFi site survey that does little more than give a generalized indication of access point placement. Get accurate results from Connect802 because we use the only full-scale, predictive RF CAD modeling and simulation software that's available for Wi-Fi design today - Wireless Valley Enterprise Planner from Motorola.

What Does the Industry Say About RF Site Survey Steps?

Start with a scaled floorplan. Get the blueprints and use these as the basis for any Wi-Fi site survey project whether it's a manual site survey or a virtual Wi-Fi site survey.

Visually inspect the facility. Either perform an on-site engagement to perform tests, calibrate the predictive RF CAD model, and identify unique obstructions, or combine digital photographs of the site with help from an on-site partner who can capture RF data for later analysis using tools like AirMagnet, NetStumbler, Cognio, AiroPeek, or Sniffer Wireless.

Identify user areas. Be sure you differentiate those areas that require 802.11 coverage from those that don't. A Wi-Fi site survey that develops installation plans for an unnecessary area is not the way to produce a cost-effective design.

Determine preliminary access point locations. Do NOT draw circles on a floorplan to estimate coverage zones. Access points don't create circular coverage patterns and a Wi-Fi wireless network design that is based on a fixed radius of coverage will not work for today's advanced wireless applications like Voice-over-IP, high user-density environments, and streaming video over WLAN.

Verify access point locations. When you install the first access point, using your virtual Wi-Fi site survey as a guide, you must verify that the installation location provides the predicted level of coverage. If an RF CAD model is created as part of a virtual site survey (using the right predictive RF CAD modeling and simulation software like that from Motorola Wireless Valley Enterprise and LAN Planner) it is expected to be accurate to within +/- 3 dB. Often, the virtual RF CAD modeling software must be calibrated by on-site Wi-Fi signal strength, noise, and interference measurements to create the most accurate predictive model and virtual site survey results.

Document findings. A Wi-Fi site survey report must fully document the findings. It's not sufficient to simply identify the installation locations for each access point. The predicted signal coverage and any actual on-site Wi-Fi site survey measurements must be incorporated into the system documentation.