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Ensure your Wi-Fi device is compliant with international dynamic frequency selection (DFS) requirements.

To avoid hampering the functionality of important radio-based technologies like weather radar, Wi-Fi signals must be able to proactively avoid interfering with other signals on the same band. Dynamic frequency selection (DFS) technology ensures that wireless devices operating in unlicensed WLAN 5 GHz bands can detect when they may be interfering with military or weather radar systems and automatically switch over to a different frequency. Formal requirements for DFS are in effect in the USA, Canada, Europe, Japan, Australia, Korea and other markets around the world.

Key factors in DFS testing

Depending on the standard applied in testing for your device, dynamic frequency selection testing may look at many potential factors:

• Channel availability check time, or CAC, which is the length of time a system is required to monitor a channel for other devices before initiating a communications link.
• Interference detection threshold, which is the minimum signal level that must be present before the system is triggered to move to another channel. Interference detection threshold is calculated based on a 0dBi antenna.
• Channel move time, which is the maximum amount of time — measured from the end of the radar burst to the final transmission — the system may take to clear a channel once an interfering signal is detected.
• Channel closing transmission time, which is the amount of time a system spends transmitting during a channel move.
• Non-occupancy time, which is the length of time following the detection of radar on a channel in which that channel may not be used.

In addition to these factors, load uniformity or load spreading is a requirement of many international dynamic frequency selection testing standards. It requires that devices employ either a random channel selection to distribute a signal evenly over the available spectrum or a planned selection mechanism to coordinate the use of a series of devices on a distrusted network.

The Element advantage

Element’s experts participated directly in DFS standards development processes with the FCC, Department of Defense, and other industry representatives. We have the equipment, personnel, and authorization to test to all current North American, Japanese, Korean and European Union standards for DFS, including the latest versions of the European standard EN 301 893 V1.5.1. We test a wide range of devices employing dynamic frequency selection technology and can develop a testing protocol that ensures you maintain compliance and meet your objectives. To discuss the specific requirements of your project with one of our engineers, contact our experts today.