Understanding Dynamic Frequency Selection (DFS)
Dynamic Frequency Selection (DFS) ensures that wireless devices operating in the 5 GHz bands can detect radar systems and automatically avoid interfering frequencies. Devices such as Wi-Fi access points, point-to-point radios, and outdoor mesh systems must comply with DFS requirements such as FCC Part 15 Subpart E, ISED Canada, or ETSI EN 301 893 for the European Union.
Proper DFS test sample preparation is critical for accurate and efficient certification. A well-configured device helps avoid costly retests, delays, and non-compliance during radar detection and channel-availability checks.
Table A: MiCOM Labs Regulatory Appointments (ISO/IEC 17065 Capabilities)
| Region | Acronym | Full Name | MiCOM Labs Appointment |
| USA | FCC | Federal Communications Commission | TCB – Telecommunication Certification Body |
| Canada | ISED | Innovation, Science and Economic Development | FCB – Foreign Certification Body |
| European Union | RED | Radio Equipment Directive | NB – Notified Body |
| UK | UKCA | United Kingdom Conformity Assessment | CA – Conformity Assessment Body |
| Japan | MIC | Ministry of Internal Affairs and Communications | RCB – Registered Certification Body |
Table B: Acronyms & Technical Terms
| Acronym | Full Name | Description / Context |
| DFS | Dynamic Frequency Selection | Radar detection |
| MiTest® | MiCOM Labs proprietary automated test system | Internal platform |
| RF | Radio Frequency | Technical domain |
| SSH | Secure Shell | Cryptographic network protocol used for secure remote login, file transfer, and other network services over an encrypted channel |
1. DFS Test Overview
DFS compliance testing evaluates the ability of the Equipment Under Test (EUT) to:
- Detect predetermined radar pulse patterns across specific frequency bands
- Cease transmission (channel move time and channel closing transmission time) when radar is detected
- Remain off the affected channel for the non-occupancy period (30 minutes)
- Demonstrate robust link operation with a companion device during radar events
| Region / Standard | Regulatory Reference | Frequency Bands (GHz) | Key DFS Tests |
| FCC (U.S.) | FCC 47 CFR §15.407 (U-NII-2A / U-NII-2C) | 5.25–5.35, 5.47–5.725 | Radar detection, channel move/closing, non-occupancy |
| ISED Canada | RSS-247 §6.3 | 5.25–5.35, 5.47–5.725 | Equivalent to FCC Part 15E |
| European Union | ETSI EN 301 893 | 5.25–5.35, 5.47–5.725 | Radar detection, CAC time, channel availability check |
**Pro Tip – MiCOM Labs also offers DFS services for Japan, Taiwan and S.Korea
2. DFS Test Sample Requirements
| Item | Requirement | Details / Notes |
| Test Samples | Minimum one sample with 50-ohm RF connector (SMA preferred) | Allows direct connection to test equipment during conducted radar detection tests. |
| Configuration Access | Ability to adjust modulation, data rate, bandwidth, and country code | Lab must configure all relevant parameters for each DFS test condition. |
| Companion Device | Required to establish communication link | – If EUT is a Master, provide a Client device. – If EUT is a Client, provide a Master device. Both must support all operational modes and should include a 50-ohm antenna connector. |
| Test Script | High-traffic generation between EUT and companion device | Enables continuous data flow to simulate active channel use during radar detection. |
| DFS Control | Ability to enable/disable DFS functionality | Needed for baseline and functional comparison tests. |
| Operational Instructions | Step-by-step setup for all modes | Include start-up, pairing, and test-mode initialization instructions. |
3. Preparing the EUT for DFS Testing
DFS testing requires precise control over radio behavior to ensure compliance with radar detection criteria.
Before shipping your samples, ensure the following:
- Fixed frequency control for each DFS channel under test
- Continuous transmit mode with active data link
- Access to firmware or software tools to trigger DFS enable/disable functions
- Logging or debug access (via serial or SSH) to confirm radar detection events
- Label each unit with serial number, firmware version, and configuration details
Properly documenting operational steps minimizes setup delays and ensures the lab can immediately begin verification.
4. Regional Considerations: U.S. vs EU DFS Requirements
While DFS principles are consistent worldwide, regulatory details vary slightly:
| Aspect | FCC / ISED (Part 15 Subpart E) | ETSI EN 301 893 (EU) |
| Radar Patterns | 6 defined pulse types (0 – 5) | 5 defined radar waveforms (1 – 5) |
| Channel Move Time | ≤ 10 seconds | ≤ 10 seconds |
| Channel Closing Transmission Time | ≤ 200 ms cumulative | ≤ 200 ms cumulative |
| Non-Occupancy Period | 30 minutes | 30 minutes |
| CAC (Channel Availability Check) | Not applicable | Required (60 seconds before use) |
5. Common DFS Test Challenges
Many devices fail DFS testing due to inadequate configuration or missing support files.
Avoid these common pitfalls:
- Missing DFS disable function (cannot verify radar detection behavior)
- No companion device or unsupported operational mode
- Test script does not generate consistent traffic between units
- Insufficient logging or visibility into radar detection events
- Incorrect firmware region (U.S. DFS vs EU DFS rules differ)
Preparing thoroughly ensures a smooth compliance process and eliminates unnecessary repeat testing.
6. Documentation and Support Materials
To streamline the DFS certification process, provide:
- Configuration and operational instructions for each test mode
- Test scripts or command lists for transmit control
- Companion device setup and communication details
- Firmware/driver versions used during testing
- Remote access credentials if required (TeamViewer, Remote Desktop)
- Photos of hardware, ports, and label locations
7. Partner with MiCOM Labs for Global DFS Compliance
MiCOM Labs offers comprehensive DFS testing for Wi-Fi and radar-sharing devices in the U.S., Canada, Europe, Japan, Taiwan and S.Korea. Our engineers ensure your device meets every technical requirement, from radar detection thresholds to channel-move timing verification.
Why Choose MiCOM Labs:
- Accredited testing for FCC, ISED, and EU RED, Japan MIC, Taiwan NCC, S.Korea KCC DFS requirements
- Experienced engineers with in-depth knowledge of radar simulation procedures
- MiTest® automatically generates and injects each radar signature. Injected signature profiles are logged together with EUT response and are delivered to the test report
- Remote test support and live configuration assistance
- DFS measurement results accepted globally by regulatory administrations
- Streamlined workflows that reduce project turnaround time
Whether your product operates as an access point, outdoor client bridge, or mesh controller, MiCOM Labs can help ensure Dynamic Frequency Selection compliance across all global regions.
Ready to begin your DFS testing?