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Wireless Access Control Design 101
An exercise for end-users who are ready to implement the technologyThe Latest from SIW
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By Andy Geremia
The Challenge: You have had a series of thefts in your 84-year-old administration building, and you are ready to implement new technology to secure all perimeter and interior doors on the first floor. You want real-time alarm notification and recording of all access attempts. Your current building has the original mortise locks with skeleton keys on the interior, and you would like to migrate to proximity cards and standardize on an HID Corporate 1000 format.
Creating a wireless access control system for this application isnt as difficult as you might think. Follow this wireless access control design exercise and see for yourself.
Wireless technology should be considered for just about any door access control application if for no other reason than a wireless locking solution takes 45 minutes to install vs. an average of eight hours for a wired solution. That produces savings in materials, as there is no wire to install, and labor, as workers are in and out within the hour.
System Design Guidelines
Wireless systems typically operate up to 200 feet between the door and the wireless panel interface module (PIM) for indoor applications. The PIM is an important element of the system it ties the door you are installing to a new or existing access control system, either wired or wireless. PIMs transmit in an omni-directional pattern and communicate with assigned wireless devices without line-of-sight. The signals can pass through plasterboard walls, cinderblock walls, brick walls and many other materials for simplified system designs.
For ease of design, think of the 200-foot wireless coverage radius as a cell, measuring 275x275 feet (75,625 square-feet). You will lay these square cells directly onto your floor plan to determine the minimum number of PIMs required to cover the space, as shown in Figure 2. You will also count the number of doors that will need access control to ensure you have sufficient PIM capacity. Then, determine the best locations for the PIMs such as IT or telco closets and adjust the squares accordingly. Finally, test your proposed systems layout.
Figure 2
Dont simply put the PIMs anywhere. Here are some guidelines:
Place PIMs in a secure, central location.
Avoid close metal objects, like ductwork and circuit breaker panels.
Mount PIMs at least 6 feet high to broadcast above obstructions.
Consider proximity to your access control interface.
Locate the PIM within 200 feet of the wireless lock.
Do not design a single PIM to be used on multiple floors.
Next, identify any potential RF problems, such as shielded walls, metal lathe, elevator shafts, metal staircases, ventilation ducts, metal clad walls, metal lockers and any other 900 MHz equipment on site. Sometimes you will need to ask the facility manager, otherwise use a wireless test kit to verify if there are any obstructions.
