Wi-Fi – Technology and Compliance

• Wi-Fi operates in globally harmonized unlicensed bands, including 2.4 GHz (ISM), 5 GHz (UNII), and 6 GHz (Wi-Fi 6E/7), with each band subject to specific regional regulations

• Regulatory RF compliance testing includes bandwidth limits, spectral masks, radiated power (EIRP/TRP), and spurious emissions, varying by region and frequency band

• DFS and TPC are mandatory in many 5 GHz sub-bands, requiring radar detection and dynamic power control as part of the certification process

• Operation in the 6 GHz band is expanding, with standard-power devices subject to Automated Frequency Coordination (AFC) and region-specific access rules (e.g., LPI, VLP)

• Successful certification depends on a structured process, including requirements analysis, lab testing, documentation, and submission to authorities such as FCC, RED, ISED, MIC, and ANATEL

Wi-Fi is based on the IEEE 802.11 family of standards, defining the physical (PHY) and medium access control (MAC) layers for wireless local area networks (WLAN). Over the past two decades, Wi-Fi has evolved significantly, boosting throughput, spectral efficiency, and multi-user capabilities.

With each new Wi-Fi generation, technical advancements such as wider channel bandwidths, higher-order modulation schemes, and expanded frequency ranges significantly impact device design, regulatory compliance, and testing procedures.

The following sections highlight the most critical aspects affecting performance and certification: bandwidth configuration, real-world throughput, and operation in newly allocated spectrum such as the 6 GHz band.

Wi-Fi devices must undergo comprehensive RF testing to demonstrate compliance with regional spectrum regulations and ensure coexistence in unlicensed bands. This section outlines the key test parameters defined by ETSI, FCC, and other frameworks, along with typical evaluation methods used in accredited laboratories.

The occupied bandwidth defines the actual channel usage of a Wi-Fi transmitter and must remain within the legal channel boundaries. Two measurement methods are commonly applied:

• 99% Occupied Bandwidth (ETSI): The frequency range that contains 99% of the total emitted power.

• –26 dB Emission Bandwidth (FCC): The bandwidth measured between the points where the signal falls 26 dB below the peak emission level.

Both methods typically yield comparable results for OFDM-based signals. The applicable method depends on the region.

Compliance Notes

• The measured bandwidth must not exceed the nominal channel width significantly.

• Slight tolerances are acceptable (e.g., due to clocking), but the defined spectral mask must still be met.

• All supported channel widths (20 / 40 / 80 / 160 / 320 MHz) must be tested individually.

• Devices with dynamic bandwidth operation must be tested in all supported configurations.

• For adaptive systems, the worst-case bandwidth (broadest occupied spectrum) must be identified and documented.

• Standards: ETSI EN 301 893, FCC §15.407

Test Method

• The device under test (DUT) is operated in continuous transmission mode, using either an unmodulated carrier (CW) or a predefined modulated test signal (e.g., PRBS).

• The resolution bandwidth (RBW) of the spectrum analyzer must be significantly smaller than the expected signal bandwidth (e.g., 100 kHz).

• Measurement can be performed in conducted mode (via RF port) or radiated setup (in anechoic chamber), depending on antenna configuration.

→ See also the Glossary Entry on Occupied Bandwidth for regulatory definitions and calculation details.

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The transmit spectrum mask defines the permitted emission profile of a Wi-Fi transmitter. It ensures that signal energy remains confined to the allocated channel and does not interfere with adjacent channels or services.

Compliance Notes

• Out-of-band emissions must remain below:

  • –30 dBm/MHz (ETSI, outside 5.47–5.725 GHz)

  • –27 dBm/MHz EIRP (FCC, outside authorized UNII bands)

• Additional constraints may apply in specific bands (e.g., UNII-3).

• Exceeding the mask limits leads to non-compliance.

• Mitigation includes power reduction, modulation changes, or additional RF filtering.

• Spectrum mask tests are typically documented with spectral trace plots.

• Standards: ETSI EN 301 893, FCC §15.407

Test Method

• The DUT is measured using a spectrum analyzer in peak detection mode.

• The resolution bandwidth is set to 100 kHz or 1 MHz, depending on standard.

• The sweep range must cover ±2× the nominal channel bandwidth.

• Measurements are performed:

  • Conducted, if the device has accessible RF ports

  • Radiated, in a semi-anechoic chamber if antennas are integrated or non-detachable

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Frequency stability ensures that a Wi-Fi device maintains its carrier frequency within permissible limits across environmental extremes such as temperature and supply voltage variations. This is essential to prevent interference with adjacent channels or services and to maintain spectral integrity.

Compliance Notes

• The typical frequency deviation must remain within ±20 parts per million (ppm) under all specified operating conditions.

• Compliance is assessed by monitoring frequency drift at the lowest and highest specified operating temperatures and supply voltages.

• For FCC compliance (e.g., §15.407), frequency stability is indirectly verified via emission bandwidth behavior under worst-case conditions.

• Some regulatory domains explicitly require documented proof that the transmitter remains within its allocated band.

• Standards: FCC §15.407, applicable regional requirements

Test Method

• The device under test (DUT) is placed inside a climatic chamber and subjected to temperature extremes as specified by its operating range (e.g., –20 °C to +50 °C).

• Simultaneously, the supply voltage is adjusted to its specified minimum and maximum values using a programmable power supply.

• The center frequency is monitored using a spectrum analyzer, with the DUT in continuous transmission mode (e.g., CW signal).

• Measurements are typically conducted in conducted mode, unless antennas are non-detachable.

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Radiated power measurements determine how much RF energy a Wi-Fi device emits, either in a specific direction or averaged over all directions. These metrics are critical for demonstrating compliance with regulatory power limits and for evaluating device performance.

Compliance Notes

• EIRP (Equivalent Isotropically Radiated Power): The total power radiated in the direction of maximum antenna gain, referenced to an ideal isotropic radiator. Most regulatory power limits (e.g., 100 mW or 30 dBm) are expressed as EIRP.

• ERP (Effective Radiated Power): Equivalent to EIRP minus 2.15 dB, referencing a half-wave dipole instead of an isotropic source. ERP is typically used in FCC regulations for devices operating below 1 GHz.

• TRP (Total Radiated Power): The total power radiated in all directions, integrated over the full 3D space. TRP is relevant for over-the-air (OTA) performance, SAR evaluation, and efficiency measurements.

• Devices with multiple antennas (e.g., MIMO systems) must be evaluated in a mode that represents worst-case total power.

• Standards: RED (EU), FCC §15.407, ANSI C63.10, ISED RSS-Gen

Test Method

• The device under test (DUT) is placed on a motorized rotary table inside a semi-anechoic chamber with calibrated absorber lining.

• For EIRP/ERP, the DUT is rotated to identify the angle of maximum radiation. The peak field strength is measured at a fixed distance (typically 1–3 m).

• The result is converted to EIRP or ERP using the known gain of the measurement antenna and a calibrated substitution method:

  • A reference signal generator replaces the DUT and is connected to a calibrated antenna.

  • The generator output is adjusted until the same field strength is observed at the measurement point.

  • EIRP is calculated from the generator output and antenna gain.

• For TRP, the DUT is rotated in both azimuth and elevation to capture the full 3D radiation pattern. The total radiated power is computed by integrating the measured values over the sphere.

• Conducted measurements may also be used to estimate power per antenna port, but radiated testing is required for TRP and EIRP in over-the-air scenarios.

→ See the Glossary Entry on EIRP for power definitions and conversion references.

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Transmit Power Control (TPC) is a regulatory mechanism designed to reduce the aggregate RF exposure in shared spectrum environments—especially in bands that require radar coexistence. Devices must be able to reduce their transmit power dynamically when required by local regulations or network conditions.

Compliance Notes

• In the European Union, TPC is mandatory in DFS bands according to ETSI EN 301 893. Devices must support a minimum power adjustment range of 6 dB.

• If TPC is not implemented, the device must operate with a 3 dB lower EIRP limit than otherwise permitted. This reduction must be explicitly reflected in the Declaration of Conformity (DoC).

• In the United States (FCC), TPC is not strictly mandatory but may be required to meet DFS sensitivity thresholds and support dynamic spectrum access behavior.

• TPC can be implemented automatically (based on signal feedback) or via software configuration. In many cases, the function is embedded within the radio firmware and may not be externally controllable.

• Standards: ETSI EN 301 893, FCC §15.407, ISED RSS-247

Test Method

• The device is configured to transmit continuously in normal operation mode.

• If the TPC function can be externally triggered, test engineers should verify the power reduction range by comparing the output before and after activation (e.g., via software command or API).

• If the function is internal-only, verification must be based on:

  • Device documentation

  • Manufacturer declarations

  • Indirect observation (e.g., output variation under proximity or interference conditions)

• The total available adjustment range must be at least 6 dB, verified in either conducted or radiated setup depending on antenna accessibility.

• Devices without TPC must be tested against the reduced power limit (–3 dB) and labeled accordingly in regulatory filings.

→ Learn more about Transmit Power Control in the Glossary for definitions and test requirements.

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Dynamic Frequency Selection (DFS) ensures that Wi-Fi devices operating in the 5 GHz band do not interfere with radar systems such as weather, aviation, or military radars. DFS-capable devices must detect radar signals and automatically switch to a different channel to avoid interference.

Compliance Notes

• DFS is mandatory in many 5 GHz sub-bands, such as 5250–5350 MHz and 5470–5725 MHz in the EU and US.

• Devices must comply with strict detection, timing, and channel management requirements, including:

  • Radar detection threshold: typically –62 to –64 dBm (measured at the antenna reference point)

  • CAC (Channel Availability Check): ≥60 seconds of passive scanning before using a DFS channel

  • In-service monitoring: continuous radar detection while transmitting

  • Channel move time: ≤10 seconds from detection to transmission stop

  • Non-occupancy period (NOP): ≥30 minutes during which the affected channel must not be reused

  • False detection resilience: devices must not vacate channels without a valid radar event

• Devices are categorized as:

  • Master devices (e.g., access points) – must detect radar and initiate channel switch

  • Slave/client devices – typically do not detect radar but must respond to channel switch commands

• Standards: ETSI EN 301 893 Annex D, FCC KDB 905462, ISED RSS-247

Test Method

• The DUT is set to operate on a DFS channel with active traffic (e.g., UDP stream).

• Simulated radar pulses are injected via a vector signal generator either radiated or conducted (if supported).

• Multiple radar signal types are used (e.g., ETSI Types 1–5 or FCC Test Waveforms), each with defined:

  • Pulse width

  • Pulse repetition interval

  • Burst duration

• The following device behaviors must be observed and logged:

  • Successful radar detection and channel switch within the specified channel move time

  • Proper execution of the CAC period before first transmission

  • Maintenance of the non-occupancy period (≥30 min) after radar detection

  • Absence of false positives during operation without radar stimulus

• Test logs must include timestamps for radar detection, transmission stop, and channel reinitialization.

• Testing is typically conducted in a semi-anechoic chamber with real traffic and verified timing conditions.

→ See the Glossary Entry on DFS for radar detection criteria and regulatory context.

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In unlicensed frequency bands, Wi-Fi devices must share the spectrum fairly with other users and technologies. Adaptivity mechanisms ensure that a device does not permanently occupy the medium and that it reacts appropriately to other signals.

Compliance Notes

• ETSI EN 300 328 (2.4 GHz):
  Devices must implement either:

  • Listen-Before-Talk (LBT) with Clear Channel Assessment (CCA), or

  • A maximum transmission burst time of 10 ms followed by a mandatory idle period

• ETSI EN 303 687 (6 GHz / Wi-Fi 6E/7):
  Devices must support CCA-based contention access, ensuring coexistence with other unlicensed services such as NR-U or LAA.

• Key technical requirements include:

  • Energy Detect Threshold: typically –73 dBm (signal level below which a channel is considered free)

  • Channel Occupancy Time (COT): must not exceed the defined regulatory limits (measured over a specific observation interval)

  • Minimum idle period: required between consecutive bursts (depends on equipment class)

• Devices using CSMA/CA (802.11 MAC layer) generally fulfill adaptivity requirements by design, but explicit verification is still required.

• Standards: ETSI EN 300 328, ETSI EN 303 687

Test Method

• The DUT is placed in a test environment with simulated traffic from other devices or a signal generator emulating concurrent activity on the same channel.

• The device must:

  • Sense the channel before transmission (LBT behavior)

  • Defer transmission if the channel is busy

  • Resume transmission once the channel is free

• A traffic analyzer or signal logger is used to measure:

  • Total transmission time within a defined window (COT)

  • Presence and duration of idle periods

  • Reaction time to medium activity

• The test confirms that the device:

  • Correctly implements CCA thresholds

  • Does not exceed the permitted channel usage

  • Operates consistently across repeated cycles

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Spurious emissions are unintended radio frequency signals emitted outside the necessary bandwidth of a Wi-Fi transmission. These emissions must remain below regulatory limits to prevent interference with adjacent channels and other wireless services.

Compliance Notes

• Radiated emissions must be measured across a wide frequency range—typically from 30 MHz to 1 GHz (below the operating band) and up to 40 GHz (above band), depending on the device's transmit frequency.

• Conducted emissions must also be evaluated if the device has accessible RF connectors (e.g., SMA, U.FL).

• Regulatory limits vary by region and frequency:

  • FCC:
    – General field strength limits per §15.209 (e.g., –55 dBm equivalent @3 m below 960 MHz)
    – Stricter emission masks in DFS bands per §15.407

  • ETSI:
    – Limits in EN 301 893 and EN 300 328, typically around –30 dBm/MHz outside the allocated band

  • ISED:
    – Refer to RSS-Gen and RSS-247, aligned with FCC but with localized thresholds

• Measurement detectors:

  • Peak detector for identifying worst-case emissions

  • RMS or average detector where specified by standard (e.g., time-averaged limits)

• Emissions must be measured during normal operation or in continuous transmit mode, using actual modulation whenever feasible. Modulated signals better reflect realistic device behavior.

Test Method

• The device under test (DUT) is configured to transmit at maximum power on a fixed channel in normal operation mode.

• Radiated testing is performed inside a semi-anechoic chamber or on an Open Area Test Site (OATS) (especially for frequencies below 1 GHz).

  • The DUT is rotated in azimuth while emissions are recorded using:

    • Peak detector (for maximum observed emission)

    • RMS detector, if applicable

• Conducted testing is performed by connecting the DUT’s RF ports to a spectrum analyzer via calibrated coaxial cables.

• The measurement frequency range depends on the DUT's operating band:

  • 2.4 GHz devices: 30 MHz to 25 GHz

  • 5 / 6 GHz devices: 30 MHz to 40 GHz

• All emissions outside the allocated band must comply with the relevant regional limits and be documented with appropriate spectral plots.

→ See the Glossary Entry on Spurious Emissions for measurement criteria and regulatory limits.

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AFC is a spectrum-sharing mechanism required for standard power Wi-Fi 6E and Wi-Fi 7 devices operating in the 6 GHz band. It ensures that such devices do not cause harmful interference to incumbent licensed users, such as fixed microwave links or satellite ground stations.

Compliance Notes

• AFC applies to standard power devices, which may operate outdoors or indoors with higher transmission power, depending on the regulatory framework and AFC grant.

• Devices must query an FCC-approved AFC system to obtain allowed channels and maximum power levels based on geolocation and elevation.

• Location reporting must be accurate (typically via GPS or manual installation data).

• AFC systems are validated by the FCC through a dedicated approval process, including lab verification and public trials.

• Device testing under FCC §15.407 focuses on:

  • Correct client behavior (e.g., secure communication, request frequency)

  • Proper response to AFC grants

  • Fail-safe mechanisms if the AFC system becomes unreachable

• Interoperability: The Wi-Fi Alliance provides an optional AFC interoperability specification to ensure consistent behavior across vendor ecosystems. While not mandatory, it can be relevant for product compatibility.

Test Method

• The device under test (DUT) is placed in AFC client mode and configured to emulate real-world AFC interactions.

• Test engineers simulate AFC queries and responses, either via over-the-air emulation or via test harnesses using predefined scenarios.

• The test verifies:

  • Accurate location reporting by the DUT

  • Correct interpretation and application of AFC channel and power grants

  • Secure and authenticated AFC communication (e.g., HTTPS)

  • Behavior when no valid AFC response is available (e.g., no transmission)

• Radiated tests are conducted in a semi-anechoic chamber to confirm compliance with assigned power and emission masks, based on AFC-dictated parameters.

→ Learn more about AFC in the Glossary for location-based spectrum sharing rules.

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Depending on the intended use of the device (e.g. handheld, body-worn, or wearable), regulatory authorities (e.g., FCC, RED, ISED) may require an evaluation of power density or Specific Absorption Rate (SAR) to verify compliance with human RF exposure limits. This is particularly relevant for Wi-Fi devices operating at high power levels in close proximity to the user.

→ See the SAR Glossary Entry for definitions and exposure criteria.
→ Learn more about our SAR Testing Services for lab testing and certification support.

Need help with Wi-Fi testing, regulatory approval, or international certification?

Our accredited labs support full compliance testing for IEEE 802.11 devices—covering Wi-Fi 4 to Wi-Fi 7—including DFS verification, AFC validation, and multi-country conformity assessment.

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