|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
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.