Ultra-Wideband (UWB) technology’s regulatory framework is intrinsically linked to its unique spectral characteristics.

The U.S. Federal Communications Commission (FCC) established a benchmark definition in 2002, classifying a UWB transmitter as having a fractional bandwidth (Bf​=2(fH​−fL​)/(fH​+fL​)) of ≥ 0.20 or an absolute -10 dB bandwidth (B=fH​−fL​) of ≥ 500 MHz. This definition, while influential globally, contrasts with initial European perspectives considering bandwidths > 50 MHz and Japan’s ARIB STD-T91 specification of ≥ 450 MHz.

While early UWB standardization efforts explored high-data-rate applications using techniques like Multi-Band OFDM (MB-OFDM), the market and subsequent regulatory focus have largely shifted towards impulse radio UWB (IR-UWB), particularly leveraging its superior time-of-flight (ToF) measurement capabilities for precise ranging and localization.

This is reflected in standards like IEEE 802.15.4a/z and the activities of consortia such as FiRa and CCC, which drive current chip development and influence regulatory considerations, especially for applications like vehicular access. (Source)

Regulatory control primarily hinges on limiting the power spectral density (PSD), typically specified as average Equivalent Isotropically Radiated Power (EIRP) in dBm/MHz, to manage interference potential with incumbent services. The widely adopted FCC limit for general communication within 3.1-10.6 GHz is -41.3 dBm/MHz. This low PSD is intended to allow UWB signals to appear as noise to narrowband systems, enabling spectrum overlay.

However, concerns about high peak-to-average power ratios in impulse systems necessitate additional peak EIRP limits, often 0 dBm EIRP measured over 50 MHz in core bands, to protect specific incumbents like radar systems. The potential for aggregate interference from dense UWB deployments remains a key regulatory concern, driving conservative limits and the adoption of mitigation techniques in some regions. (Source)

The Global UWB Spectrum Allocation Framework

The FCC’s 2002 decision to authorize unlicensed UWB operation in the 3.1-10.6 GHz band (Part 15 Subpart F) was a pivotal moment, establishing a 7.5 GHz swath of spectrum and setting a global precedent.

This frequency range became a nominal reference, although actual permitted frequencies, power levels, and technical conditions exhibit significant regional variation. International bodies like ITU-R study UWB , but national and regional regulators (FCC, CEPT/ECC, MIC, MSIT/RRA, MIIT) hold the primary authority. The FCC’s initial rules were explicitly conservative, influenced by NTIA recommendations to protect federal systems, particularly GPS. This cautious approach has often been mirrored or intensified by other regulators.

Globally, UWB operates under unlicensed or license-exempt models (e.g., FCC Part 15 , European SRD framework based on ECC Decisions and ETSI standards). This facilitates innovation and deployment but operates on a crucial “non-interference, non-protected” basis.

UWB devices must not cause harmful interference to authorized services and cannot claim protection from interference they receive. Consequently, the technical regulations themselves—emission masks, operational restrictions, and mandatory mitigation techniques—are the sole mechanisms ensuring coexistence and protecting incumbents.

U.S. Regulatory Landscape: FCC Part 15 Subpart F

The FCC’s Part 15 Subpart F rules define specific UWB device categories with tailored emission masks and operational constraints. For indoor (§15.517) and handheld (§15.519) communication devices, the core regulatory elements are:

Detailed Emission Masks: Average EIRP (dBm/MHz) and Peak EIRP (dBm/50 MHz)

The average EIRP limit within the 3100-10600 MHz band is -41.3 dBm/MHz, measured with a 1 MHz RBW. Outside this band, stricter limits apply, varying slightly between indoor and handheld classes to account for differing deployment assumptions (e.g., building attenuation for indoor use). For instance:

  • 1990-3100 MHz: -51.3 dBm/MHz (Indoor) vs. -61.3 dBm/MHz (Handheld).
  • Above 10.6 GHz: -51.3 dBm/MHz (Indoor) vs. -61.3 dBm/MHz (Handheld).
  • Below 960 MHz: Compliance with §15.209 limits.

A peak EIRP limit of 0 dBm, measured over a 50 MHz bandwidth centered at the frequency of maximum emission (fM​), applies to both indoor and handheld devices to protect against high instantaneous power levels. Procedures for using alternative measurement bandwidths are specified in §15.521.

Protection of Sensitive Bands: Stringent Limits for GPS Frequencies (-85.3 dBm/kHz)

To protect highly sensitive GNSS/GPS services operating near the thermal noise floor, the FCC imposes exceptionally stringent limits within the 1164-1240 MHz and 1559-1610 MHz bands. While the general limit in 960-1610 MHz is -75.3 dBm/MHz, an additional, more restrictive limit of -85.3 dBm EIRP applies within the specific GPS bands, measured using a narrower resolution bandwidth of ≥ 1 kHz. This kHz-bandwidth limit, based on NTIA recommendations, addresses the potential for specific spectral components (e.g., related to UWB PRF) to interfere with GPS receiver correlation processes, even if the broader MHz-bandwidth limit is met.

Technical Requirements for Indoor Systems (47 CFR § 15.517)

Key requirements for devices intended solely for indoor operation:

  • Operation: Strictly indoor; design must enforce indoor use (e.g., AC power connection); no intentional direction of emissions outdoors; no outdoor antennas; transmit only when sending info to associated Rx.
  • Frequency: UWB bandwidth contained within 3.1-10.6 GHz.
  • Emissions: Adhere to §15.517(c) mask above 960 MHz (incl. -41.3 dBm/MHz core limit, stricter OOB limits) and §15.209 below 960 MHz.
  • GPS Protection: -85.3 dBm/kHz limit applies in 1164-1240 MHz & 1559-1610 MHz.
  • Peak Limit: 0 dBm / 50 MHz.
  • Labeling: Warning required restricting use to indoors. (Source)

Technical Requirements for Handheld Systems (47 CFR § 15.519)

Key requirements for portable, handheld devices:

  • Operation: Handheld nature; transmit only when sending info to associated Rx; must cease transmission within 10s unless ACK received (ACKs required every 10s to maintain Tx); no outdoor/fixed antennas; indoor/outdoor operation permitted.
  • Frequency: UWB bandwidth contained within 3.1-10.6 GHz.
  • Emissions: Adhere to §15.519(c) mask above 960 MHz (incl. -41.3 dBm/MHz core limit, slightly relaxed OOB limits vs. indoor) and §15.209 below 960 MHz.
  • GPS Protection: -85.3 dBm/kHz limit applies in 1164-1240 MHz & 1559-1610 MHz.
  • Peak Limit: 0 dBm / 50 MHz. (Source)

Table: Comparison of FCC §15.517 (Indoor) and §15.519 (Handheld) Emission Limits

UWB

Source: 47 CFR §15.517, 47 CFR §15.519

European Regulatory Landscape: ETSI EN 302 065 & ECC Decision (06)04

Europe’s UWB framework, guided by ECC Decision (06)04 (amended multiple times) and implemented via national regulations referencing EC Decisions (e.g., 2007/131/EC, 2019/785, 2024/1467) and ETSI Harmonised Standards (primarily EN 302 065 series), differs significantly from the US approach. It features lower baseline power limits but allows operation at -41.3 dBm/MHz contingent on mandatory interference mitigation techniques.

Harmonised Bands and Emission Limits (Mean and Peak EIRP)

The baseline mask in ECC/DEC/(06)04 (Annex 1) is considerably more restrictive than the FCC’s core limit outside the 6-8.5 GHz band. Examples include:

  • 3.4-3.8 GHz: -80 dBm/MHz mean / -40 dBm peak/50 MHz.
  • 3.8-4.8 GHz & 4.8-6 GHz: -70 dBm/MHz mean / -30 dBm peak/50 MHz.
  • 6-8.5 GHz: -41.3 dBm/MHz mean / 0 dBm peak/50 MHz (baseline).
  • 8.5-10.6 GHz: -65 dBm/MHz mean / -25 dBm peak/50 MHz. These lower limits reflect greater initial caution regarding interference to European incumbents like IMT, BWA, FSS, and aeronautical radar. Compliance with the Radio Equipment Directive (RED) is shown via ETSI EN 302 065 parts (-1 Generic , -2 Location Tracking , -3 Vehicular, -4 Material Sensing, -5 Aircraft).

Mandatory Mitigation Techniques for Enhanced Power Operation (-41.3 dBm/MHz)

Operation at -41.3 dBm/MHz mean EIRP / 0 dBm peak EIRP/50 MHz in specific bands requires implementing Detect And Avoid (DAA), Low Duty Cycle (LDC), or Transmit Power Control (TPC).

Detect And Avoid (DAA): Mandated for -41.3 dBm/MHz in bands shared with BWA (3.1-4.8 GHz, protecting 3.4-4.2 GHz) and Radar (3.1-3.4 GHz, 8.5-9 GHz). Requires UWB devices to detect victim signals above specified thresholds and react (cease Tx, reduce power, change channel). Key parameters (thresholds, zones, check times, avoidance bandwidth) are defined in ECC/DEC/(06)04 Annex 3 and ECC Report 120, with JRC validation. DAA devices in 3.1-4.8 GHz must support channel selection across the band. Verification procedures are in ETSI EN 302 065.

  • BWA Detection Thresholds: -38 dBm (A), -61 dBm (B) in 3.4-4.8 GHz.
  • Radar Detection Thresholds: -38 dBm (3.1-3.4 GHz), -61 dBm (8.5-9 GHz).

Low Duty Cycle (LDC): An alternative to DAA for -41.3 dBm/MHz in 3.1-4.8 GHz. Restricts transmission time according to ECC/DEC/(06)04 Annex 2:

  • Max burst (Ton_max​) ≤ 5 ms.
  • Mean quiet time (Toff_mean​) ≥ 38 ms (avg over 1s).
  • Total quiet time (ΣToff​) > 950 ms per second (< 5% duty cycle/sec).
  • Total Tx time (ΣTon​) < 18 seconds per hour (0.5% duty cycle/hr).

Transmit Power Control (TPC): Requires power adjustment capability, typically reducing power at shorter ranges. ECC/DEC/(06)04 Annex 4 mandates a minimum 12 dB control range (e.g., -41.3 dBm/MHz down to -53.3 dBm/MHz). Often required with DAA/LDC, especially for vehicular use.

This conditional, mitigation-centric approach contrasts with the FCC’s static model but introduces significant device complexity and testing burdens.

Specific Rules for Vehicular and Other Applications

European regulations feature granular rules for specific UWB use cases:

Vehicular UWB (ECC/DEC/(06)04 Annex 1, ETSI EN 302 065-3 ):

  • Baseline: Generally follows generic mask, but lower limit (-53.3 dBm/MHz mean) in 6-8.5 GHz.
  • Mitigation for -41.3 dBm/MHz:
  • 3.1-4.8 GHz: LDC or DAA+TPC, plus Exterior Limit (e.l.) -53.3 dBm/MHz.
  • 6-8.5 GHz: LDC or TPC, plus e.l.
  • 8.5-9 GHz: DAA+TPC, plus e.l.
  • Vehicular Access Systems (Trigger-before-transmit): Allows -41.3 dBm/MHz in 3.8-4.2 GHz & 6-8.5 GHz with very low duty cycle (≤ 0.5%/hr) or TPC.
  • Vehicle-to-X (6-8.5 GHz): Allows -41.3 dBm/MHz with duty cycle limits (5%/s fixed infra, 1%/s vehicle) and antenna restrictions.

Other Applications:

  • Location Tracking (LT) (EN 302 065-2): Specific rules for fixed outdoor/enhanced indoor LT, often involving duty cycle limits, antenna constraints, networked operation.
  • Material Sensing (MS) (EN 302 065-4): Different frequency ranges/limits for GPR, BMA, etc.
  • Aircraft Use (EN 302 065-5 ): Permitted under strict air safety/certification requirements.

Table: ETSI/ECC Emission Limits and Mitigation Requirements for Generic UWB

UWB

Notes:

LDC mitigation allows operation at -41.3 dBm/MHz mean / 0 dBm peak only within the 3.1-4.8 GHz band. See Annex 2 of ECC/DEC/(06)04.

DAA mitigation allows operation at -41.3 dBm/MHz mean / 0 dBm peak only within the 3.1-4.8 GHz and 8.5-9 GHz bands. See Annex 3 of ECC/DEC/(06)04 and ECC Report 120.

*Source: ECC Decision (06)04, amended 18 Nov 2022 *

Asia-Pacific Regulatory Landscape: Key National Frameworks

UWB regulation in Asia-Pacific varies significantly by country, with distinct approaches in Japan, South Korea, and China.

Japan (MIC / ARIB STD-T91): Indoor/Outdoor Bands, Power Limits, Specific Constraints

Japan’s MIC regulates UWB via ARIB STD-T91 (latest referenced: V4.0, 2022). Key features include:

  • Band Segmentation: Distinct indoor/outdoor bands:
  • Indoor: 3.4-4.8 GHz AND 7.25-10.25 GHz.
  • Outdoor: 7.587-8.4 GHz AND 7.25-9 GHz.
  • Power Limits: Generally aligns with -41.3 dBm/MHz average EIRP in higher bands (e.g., Ch 9). Peak limit is 0 dBm/50 MHz in 7.25-10.25 GHz, but -64 dBm/1 MHz below 7.25 GHz.
  • Mitigation: Historically required DAA or reduced power (-70 dBm/MHz) in 3.4-4.2 GHz. Current status under V4.0 requires confirmation from the full standard.
  • Bandwidth Definition: Minimum -10 dB BW of ≥ 450 MHz.

South Korea (MSIT / RRA): Historical Context, Recent Rules for Portable Devices (6-8.8 GHz), Operational Restrictions

South Korea’s MSIT/RRA initially mirrored FCC bands but mandated DAA in 3.1-4.8 GHz. Recent rules (eff. Mar 31, 2023) target portable devices (smartphones):

  • Portable Device Band: 6 GHz to 8.8 GHz.
  • Power Limit: Likely -41.3 dBm/MHz average EIRP, but needs confirmation.
  • Operational Restrictions (Portables):
  • Transmit only on user request.
  • Auto Tx stop within 10s if no ACK/data transfer.
  • Mandatory function to halt Tx on aircraft/ships + user manual warning.
  • Associated device transmits only upon request.
  • Other Uses: Still permitted in 4.2-4.8 GHz & 6-10.2 GHz under respective rules Recent unrelated updates expanded WLAN bandwidth in 6 GHz. (Source)

China (MIIT): Evolution from MIIT No. 354 to MIIT No. 77 (Focus on 7163-8812 MHz), Key Restrictions

China is transitioning from MIIT Notice No. 354 (allowing 4.2-4.8 GHz with mitigation, 6-9 GHz generally at -41.3 dBm/MHz) to MIIT Notice No. 77, effective Aug 1, 2025. Key changes:

  • Primary Band: Concentrates UWB operation into 7163-8812 MHz for devices with ≥ 500 MHz BW.
  • Power Limits: Not specified in snippets, likely -41.3 dBm/MHz average EIRP within the band. Requires consulting regulation annex.
  • OOBE/Spurious: Frequencies outside 7163-8812 MHz (within 5.925-10.6 GHz) treated as band edge/spurious with specific limits. General spurious limits tightened.
  • Operational Restrictions:
  • Prohibited within 1 km of RAS sites.
  • Prohibited on aircraft (including drones).
  • Licensing: SRRC Type Approval required; no station license needed; non-interference/non-protected basis.

Tables: Summaries of Key Regulatory Parameters for Japan, South Korea, and China

Japan (ARIB STD-T91 v4.0)

UWB

South Korea (MSIT/RRA)

UWB

China (MIIT No. 77)

UWB

Comparative Analysis: Regional Divergence and Convergence

Global UWB regulations exhibit significant divergence stemming from differing philosophies on spectrum management and incumbent protection, alongside limited areas of convergence.

Juxtaposing Regulatory Philosophies: FCC vs. ETSI vs. Asia-Pacific

  • US (FCC): Established broad 3.1-10.6 GHz allocation with relatively fixed, conservative emission masks differentiated by device class (indoor/handheld/imaging/vehicular), relying on static limits (including deep notches for GPS) rather than mandatory active mitigation for core communication uses.
  • Europe (ECC/ETSI): Adopted lower baseline limits across 3.1-10.6 GHz, making the -41.3 dBm/MHz level conditional on implementing active mitigation (DAA, LDC, TPC) in specific bands. Emphasizes technological solutions within the device, leading to higher complexity but potentially more flexible spectrum use. Highly granular rules for specific applications (vehicular, LT, MS, aircraft).
  • Asia-Pacific (JP, KR, CN): Tailored approaches dominate. Japan uses strict indoor/outdoor band segmentation. South Korea historically mandated DAA and now imposes operational controls on portables in 6-8.8 GHz. China is concentrating future UWB into 7163-8812 MHz with strict OOB limits and operational prohibitions.

Analysis of Differences in Bands, Power Limits, and Mitigation Strategies

  • Frequency Bands: Significant variation from US (3.1-10.6 GHz) to Europe (conditional 3.1-10.6 GHz), Japan (segmented), S. Korea (segmented + portable band), and China (focused 7.163-8.812 GHz).
  • Power Limits (-41.3 dBm/MHz): Unconditional baseline only in US core band. Conditional in Europe (6-8.5 GHz baseline; requires DAA/LDC elsewhere), likely applicable with potential/historical mitigation in Japan/S. Korea, and likely baseline in China’s new band.
  • Mitigation: DAA/LDC central to Europe; historically required in S. Korea/Japan ; not mandated for US comms devices; operational controls in S. Korea portables ; band allocation/restrictions in China. TPC mainly in European vehicular rules.
  • Peak Power: 0 dBm/50 MHz common in US/EU core bands, but Japan has different limits above/below 7.25 GHz.
  • Operational Restrictions: Indoor-only (US §15.517, Japan low band); Outdoor allowed (US §15.519, Europe, Japan high bands); Aircraft prohibition (S. Korea, China, EU requires certification); RAS protection (China zone, EU low limits/radar DAA ); Detailed vehicular rules (Europe).

Table: Comprehensive Comparison of UWB Regulations (US, EU, JP, KR, CN)

TBC = To Be Confirmed from full regulations.

Implications for Global Interoperability and Device Manufacturing

Regulatory fragmentation poses significant challenges:

  • Design Complexity: Requires region-specific hardware (filters) and software (power control, channel selection, mitigation algorithms).
  • Testing/Certification: Increased costs and time due to multiple standards (FCC Part 15F, ETSI EN 302 065, ARIB STD-T91, RRA, MIIT).
  • Interoperability: Complicates efforts by FiRa, UWB Alliance, CCC to build seamless global ecosystems based on standards like IEEE 802.15.4z.
  • Market Strategy: Drives focus on common channels (e.g., Ch 9) potentially underutilizing available spectrum, or necessitates region-specific SKUs.

This lack of harmonization hinders economies of scale and slows deployment.

Coexistence Engineering: Protecting Incumbent Services

Managing coexistence between low-power, wide-bandwidth UWB signals and higher-power, often critical, incumbent services is the central regulatory challenge.

Identifying Key Interference Scenarios

UWB (nominally 3.1-10.6 GHz) potentially impacts:

  • GNSS/GPS (L-band): Extremely vulnerable due to weak signals near thermal noise.
  • Fixed-Satellite Services (FSS) (C-band ~3.4-4.2 GHz, Ku-band ~10.7-14.5 GHz, etc.): Susceptible to receiver saturation or OOBE, especially downlink earth stations.
  • Radio Astronomy Service (RAS) (various bands): Exceptionally sensitive passive receivers require stringent protection, often via exclusion zones or prohibition (RR 5.340).
  • BWA/WiMAX (~3.4-3.8 GHz): Requires protection, driving DAA mandates in Europe.
  • Aeronautical Radars/Radionavigation (S, C, X bands): Safety-critical systems needing protection from average and peak UWB power.
  • Mobile/Cellular (IMT): Primarily adjacent band concerns or future sharing scenarios.

Regulatory Protection Mechanisms

  • Strict Power Limits/Deep Notches: e.g., FCC’s -85.3 dBm/kHz GPS limit; Europe’s lower baseline limits outside 6-8.5 GHz.
  • Mandatory Mitigation (DAA, LDC, TPC): Primarily European approach for higher power operation.
  • Operational Restrictions: Indoor-only (FCC §15.517, Japan low band); Aircraft/ship prohibition (S. Korea, China); RAS exclusion zones (China, CEPT ); Tx control (FCC ACK, S. Korea user trigger).
  • Band Segmentation/Allocation: Japan’s indoor/outdoor split; China’s focus on 7.163-8.812 MHz.

Case Study: GPS Protection (-85.3 dBm/kHz limit rationale)

The FCC’s dual GPS limit (-75.3 dBm/MHz & -85.3 dBm/kHz) stems from NTIA recommendations aiming to protect GPS receivers from aggregate UWB interference raising the noise floor or causing desensitization. The narrower kHz measurement specifically addresses potential quasi-CW or spectral line interference (related to UWB PRF) falling within the GPS receiver processing bandwidth, which might not be captured by the MHz measurement. Though conservative, it reflects the high priority of protecting GNSS.

Case Study: DAA for BWA/Radar Protection (ECC Report 120 insights)

Europe’s DAA mechanism, technically detailed in ECC Report 120, mandates detection thresholds (e.g., BWA: -38/-61 dBm ; Radar: -38/-61 dBm) to trigger avoidance actions. While validation studies (e.g., JRC) support the parameters, challenges remain regarding reliable detection of diverse/intermittent signals (e.g., mobile BWA terminals in sleep modes). DAA represents a complex, technology-driven coexistence strategy.

Table: Protected Services and Primary Mitigation Strategies

Conclusion: The Fragmented Path Towards Global UWB Operation

UWB technology is increasingly prevalent, yet its global deployment is constrained by a fragmented regulatory landscape. While the 3.1-10.6 GHz range and the -41.3 dBm/MHz power target serve as loose benchmarks, significant divergences persist.

Assessment of the Current State of Global Harmonization

Harmonization remains limited. Key fragmentation points include:

  • Allowed Bands: Broad (US) vs. conditional (EU) vs. segmented (Japan, S. Korea) vs. focused (China).
  • Power Limits: -41.3 dBm/MHz availability varies widely (unconditional US vs. conditional EU vs. potential mitigation JP/KR).
  • Mitigation: Mandatory active mitigation (DAA/LDC) in Europe contrasts with US static masks, S. Korean operational controls, and Chinese band allocation/restrictions.
  • Operational Restrictions: Significant differences in indoor/outdoor, vehicular, RAS, and aircraft rules.

Convergence exists mainly around the core ranging application and industry focus on widely accepted channels (e.g., Ch 9).

Technical and Regulatory Hurdles for Seamless Deployment

Fragmentation creates major hurdles: increased design/software complexit, costly multi-standard testing/certification, and challenges to global interoperability efforts. Ensuring robust coexistence, particularly validating mitigation techniques like DAA and managing aggregate interference from dense deployments, remains an ongoing challenge.

Future Outlook and Potential Regulatory Evolution

The regulatory landscape continues to evolve (e.g., FCC VLP considerations, potential EU updates). Industry advocates for expanded use cases and greater harmonization. Future trends may involve gradual convergence, new mitigation techniques, adaptation for novel applications, or integration into dynamic spectrum access frameworks. However, achieving substantial harmonization requires reconciling differing regional priorities and ensuring continued protection for diverse incumbent services. The interplay between technological advancement and regulatory adaptation will critically shape UWB’s future trajectory.