**Before the**

**Federal Communications Commission**

**Washington, D.C. 20554**

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| In the matter of                 | *  | ET Docket No. 04-352         |
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| Petition for Waiver of the Part  | ** |                              |
| 15 UWB Regulations Filed by the  |    |                              |
| Multi-band OFDM Alliance Special | *  |                              |
| Interest Group                   | *) |                              |
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**ORDER**

**Adopted: March 10, 2005 Released: March 11, 2005**

By the Commission:

# Introduction

1.  By this action, we are granting a waiver of the certain emission
    measurement procedures applicable to ultra-wideband ("UWB")
    transmitters that operate under Part 15 of our rules.[^1]
    Specifically, we are permitting the emissions from UWB transmitters
    operating in the 3.1-5.03 GHz and 5.65-10.6 GHz bands that employ
    frequency hopping or stepped frequency modulation techniques, or
    that gate the transmitted signal,[^2] to be measured with the
    transmitter operating in its normal transmission mode. This waiver
    applies to the measurement procedure applicable to UWB devices,
    permitting products to be tested based on the manner in which they
    are operated. This action is taken in response to a Petition for
    Waiver that was filed by the Multi-band OFDM Alliance Special
    Interest Group ("MBOA-SIG")[^3] on August 26, 2004.

# BACKGROUND

2.  On February 14, 2002, the Commission adopted regulations to permit
    the operation of UWB transmitters.[^4] Several categories of UWB
    devices are permitted to be operated under the Part 15 regulations
    without a requirement for an individual license: imaging
    systems,[^5] vehicular radars and indoor and outdoor communication
    systems. UWB transmitters operate using spectrum that is allocated
    to various radio services, including frequency bands that are
    allocated both to U.S. Government and to non-government
    operations.[^6] UWB transmitters also operate in several restricted
    frequency bands within which the operation of other types of Part 15
    transmitters are prohibited.[^7] UWB devices are not allocated
    spectrum but share these frequency bands with the authorized radio
    services on a sufferance basis.[^8] Consequently, before the
    Commission implemented its standards for UWB operation, it evaluated
    several measured and simulated analyses regarding the potential for
    UWB devices to cause harmful interference to the authorized
    services.[^9] As stated in the *1^st^ R&O*, this was an unusually
    controversial proceeding involving a variety of UWB advocates and
    opponents that were unable to agree on the emission levels necessary
    to protect Federal Government-operated, safety-of-life and
    commercial radio systems from harmful interference.[^10] Because of
    this, the Commission implemented standards that it categorized as
    extremely conservative, in addition to applying additional
    restrictions on operating parameters,[^11] to ensure that UWB
    devices can coexist with the authorized radio services without the
    risk of harmful interference while it gains additional experience
    with this technology.

3.  The emission standards applied to UWB operations are more stringent
    than those applied to non-UWB devices. Non-UWB transmitters
    operating under the Part 15 regulations are subject to emission
    limits above 1000 MHz that are based on the use of a linear average
    detector. In no case, are emissions from non-UWB devices required to
    be reduced below the Part 15 general emission limits.[^12]
    Transmitters employing swept frequency modulation techniques are
    required to demonstrate compliance with the average emission limits
    with the frequency sweep function disabled.[^13] However, pulsed
    emissions may be averaged over a 100 millisecond period and this
    period may include any effects from gating the signal. On the other
    hand, emissions from UWB transmitters, at the request of the
    National Telecommunications and Information Administration ("NTIA"),
    are subject to emission limits above 960 MHz that are based on the
    use of a root-mean-squared ("RMS") detector and a one millisecond
    averaging period.[^14] NTIA employed RMS levels in its interference
    analyses,[^15] indicating that measurements made using instruments
    having a linear average detector but using logarithm amplifiers are
    largely insensitive to energy contained in low duty cycle, high
    amplitude signals. NTIA added that no single average detector
    function adequately describes the interference effects of UWB
    signals but believes that this is better quantified by use of an RMS
    detector. Further, NTIA indicated that RMS levels are proportional
    to the measured bandwidth and the spectral power density,
    irrespective of pulse rate or modulation.[^16]

4.  In addition to differences in the measurement procedures, the
    emission limits adopted for UWB devices generally are considerably
    lower than those applied to other Part 15 applications. Unwanted
    emissions from UWB devices are required to be reduced below the Part
    15 general emission limits by as much as 34 dB.[^17] Further, the
    average emission levels[^18] must be measured with the transmitter
    operating continuously at a set fundamental frequency with any
    frequency hop, frequency sweep, or frequency step disabled.[^19]
    Similarly, emissions from gated UWB transmitters must be measured
    with the gating disabled.[^20] These measurement procedures can
    result in the measurement of higher average emission levels in a one
    millisecond period than what are actually emitted by a UWB
    transmitter under its normal operating conditions.

5.  Since the adoption of the UWB regulations, two primary formats for
    communications systems have been developed. Freescale Semiconductor,
    Inc. ("Freescale") has obtained certification for a UWB transmitter
    based on the direct sequence UWB ("DS-UWB") modulation system that
    was pioneered by XtremeSpectrum.[^21] DS-UWB employs direct-sequence
    spreading of binary-phase-shift-keyed pulses and supports operation
    in two different bands. The lower band occupies the spectrum from
    3.1 GHz to 4.85 GHz, and the upper band is from 6.2 GHz to 9.7 GHz.
    Within each band there is support for up to six piconets (*i.e.*,
    overlapping wireless networks). Each piconet channel has a
    designated operating frequency and direct sequence code word of
    length 1, 2, 3, 6, 12, or 24. Data is used to modulate the direct
    sequence code. These modulated code words, in turn, modulate a
    carrier whose frequency is three times the chipping rate. The
    resulting signal is band-limited by a root-raised-cosine
    filter.  DS-UWB also employs error correction, interleaving,
    multiplexing, and synchronization techniques.

6.  Another type of UWB system has been developed by the several members
    of the Multi-band OFDM Alliance Special Interest Group ("MBOA-SIG").
    The MBOA-SIG transmitter employs multiband orthogonal frequency
    division multiplexing ("MB-OFDM") modulation. This modulation format
    consists of QPSK-modulated OFDM signals occupying a 528 MHz
    bandwidth.[^22] These signals are shifted to different frequency
    bands (or channels) within the 3168-10560 MHz band. At least three
    separate transmission frequencies are employed. For a transmission
    employing three channels of operation, the transmission on a single
    channel lasts for 242.4 nanoseconds followed by an "off" period of
    695.1 nanoseconds, resulting in a complete transmission cycle of
    937.5 nanoseconds.

7.  On August 26, 2004, the MBOA-SIG filed a Petition for Waiver
    requesting that the Commission permit the average radiated emission
    levels for its MB-OFDM waveform to be measured under normal
    operating conditions, *i.e.*, with the frequency hop or step
    function active and not disabled as required in the measurement
    procedure established in the *1^st^ R&O*.[^23] MBOA-SIG states that
    it is not clear if the UWB test procedures, which it claims were
    designed for pulse-based systems, apply to MB-OFDM systems.
    Consequently, it seeks a waiver of the measurement procedures,
    including the pulse gating procedures in 47 C.F.R. § 15.521(d), to
    the extent that they apply to MB-OFDM systems. The MBOA-SIG requests
    that this waiver apply only to a specific MB-OFDM architecture
    consisting of three non-overlapping operating bands.[^24]
    Transmitters using this MB-OFDM format would operate under the
    provisions for indoor and handheld UWB devices.[^25]

8.  On August 30, 2004, the Commission released a public notice inviting
    comments on the MBOA-SIG petition for waiver. In response, 17
    parties filed comments and 4 filed reply comments.[^26] A list of
    the commenting parties, along with the abbreviations used to
    identify them, is attached as an Appendix to this Order.

# Discussion

9.  Although MBOA-SIG questions whether the UWB measurement procedures
    established in the *1^st^ R&O* apply to MB-OFDM systems, we believe
    that the prudent course of action here is to analyze the requested
    relief under a waiver standard. We note, in particular, that the
    Commission was quite clear in its discussion in the *1^st^ R&O* that
    the requirement to perform measurements with the frequency sweep,
    hop or step function inactive was because no measurement procedures
    had been proposed or established nor had the interference effects of
    these modulation types been evaluated based on the results that
    would be obtained should measurements be performed with the system
    functioning normally.[^27] Further, the change in operating
    frequency in the MB-OFDM system, which the petitioner refers to as
    "band sequencing," is equivalent to a frequency hopping or a stepped
    frequency modulation technique. It is a well-established principle
    that the Commission will waive its rules in specific cases only if
    it determines, after careful consideration of all pertinent factors,
    that such a grant would serve the public interest without
    undermining the policy which the rule in question is intended to
    serve.[^28] We agree with the petitioner that a waiver of the
    measurement procedures will ensure that MB-OFDM systems are not
    unfairly burdened in the marketplace. The question is whether such a
    waiver would undermine Commission policy by causing an increase in
    the interference potential of UWB operations, and thus not serve the
    public interest.

10. In the *1^st^ R&O*, the Commission specified a measurement procedure
    that required the average radiated emissions from UWB systems
    employing frequency hop, frequency sweep or stepped frequency
    modulation techniques to be measured with the hop, sweep or step
    function disabled.[^29] The Commission indicated that this method of
    measurement was necessary since pertinent measurement procedures had
    not been proposed or established for these modulation types and
    because their interference aspects had not been evaluated.
    Furthermore, the various interference analyses regarding UWB
    operation were performed without consideration of the additional
    time averaging that would occur if the emission measurements were
    performed with the sweep, hop, step or gating active.[^30] In
    addition, NTIA expressed concern that the emissions might not be
    maximized during the measurement, *i.e.*, that a swept frequency
    analyzer might not completely synchronize with a frequency hopped
    waveform, resulting in a measurement that is less than the maximum
    emission level. However, since the adoption of the *1^st^ R&O*, NTIA
    provided comments that the measurements of systems with the
    frequency hopping, sweeping, stepping or gating function turned on
    provides a more meaningful representation of the emissions generated
    by a device.[^31] NTIA also has suggested measurement procedures
    that should be applied to frequency hopping and stepped frequency
    systems.[^32] NTIA recommended that the measurement procedure be
    modified to require that the measurement be performed over multiple
    sweeps with the maximum hold function enabled until the observed
    amplitude stabilizes. This measurement procedure ensures that the
    maximum radiated emissions are detected.[^33]

11. In its comments, Cingular Wireless LLC opposes the petition, arguing
    that such a waiver can not be justified without tests comparing the
    measurements that would result with and without the frequency
    hopping stopped.[^34] The Coalition of C-Band Constituents opposes
    the waiver claiming that it would permit an almost four-fold
    increase in the UWB power levels with materially greater
    interference.[^35] The Satellite Industry Association argues that
    appropriate measurement procedures and emission masks must be
    developed to control interference potential and that a waiver to the
    current measurement procedures will not accomplish this
    objective.[^36] Freescale and decaWave also oppose the requested
    waiver, claiming that MB-OFDM causes more interference than would a
    pulsed modulation or direct sequence modulated system.[^37]

12. The MBOA-SIG members conducted simulated and actual testing of
    devices employing the MB-OFDM format to demonstrate that, under
    normal operating conditions, there is no greater interference
    potential from an MB-OFDM UWB waveform than from an
    impulse-generated UWB waveform, even when compliance with the
    emission limits is demonstrated with the frequency hop or step
    function active.[^38] These simulations and tests address the
    interference concerns expressed by Cingular Wireless, the Coalition
    of C-Band Constituents and other commenting parties. Several of the
    comments contained technical discussions on whether or not the
    MB-OFDM modulation format resulted in greater or lesser interference
    than the DS-UWB format.[^39] While the comments argue this issue
    based on different criteria, it is clear from the measurement and
    analyses results that the interference potential of the MB-OFDM
    format, based on compliance with the rules being demonstrated with
    the frequency hop active, is no greater, if not less, than that of
    an impulse UWB emission.[^40] These results are consistent with the
    theory, as stated by NTIA, that RMS measured emission levels are
    proportional to the measured bandwidth and the spectral power
    density, irrespective of pulse rate or modulation. Indeed, an
    integrated RMS measurement provides true average power readings,
    even for non-continuous signals such as frequency hopped UWB
    waveforms.

13. The UWB emission limits were established to prevent harmful
    interference to the authorized radio services from UWB transmitters
    employing impulse modulation. As previously noted, the Commission
    observed that these UWB emission standards were extremely
    conservative.[^41] The MBOA-SIG demonstrated that the interference
    potential of frequency hopped, stepped or sequenced systems,
    measured in their normal operating modes, is less than that of a UWB
    transmitter employing impulse modulation. Thus, any requirement to
    stop the frequency hop or band sequencing or system gating serves
    only to add another unnecessary level of conservatism.

14. We thus conclude that concerns regarding potential increased
    interference levels and proper detection of the radiated emissions
    have been addressed. Frequency hopping, stepped frequency, and
    sequenced UWB operations may be employed, with a minor change to the
    existing measurement procedures, without an increase in the
    potential for harmful interference to the authorized services.
    Accordingly, the request from MBOA-SIG for a waiver of the UWB
    measurement procedures for hopped frequency UWB systems has been
    shown to satisfy the criteria in *WAIT Radio v. FCC* and that a
    waiver is appropriate. However, while we agree with MBOA-SIG that
    its requested waiver should be granted, we also recognize, as the
    Commission has expressed throughout the UWB rule making proceeding,
    that we should continue to follow a conservative approach until such
    time as we have gained additional experience with UWB operations.
    For this reason, we believe that some conditions need to be applied
    to this waiver of the measurement procedures to further ensure that
    there is no increase in interference potential.

15. First, we are requiring that the transmitter continue to comply with
    all applicable UWB standards, as measured with the transmitter
    functioning normally. Second, we are concerned about the possible
    impact should an MB-OFDM system encounter interference on one of its
    channels and decrease the number of hopping or sequenced channels,
    *e.g.*, from the proposed three channel system to two channels or to
    a single channel.[^42] Such a change could result in a higher signal
    level that exceeds the emission limits, as measured with the system
    actively hopping or sequencing between channels.[^43] Thus, if
    provisions are made to operate using a different number of hopped or
    sequenced channels, the system must be designed to ensure that it
    complies with the emission levels under all possible operating
    conditions. Further, we see no technical reason to limit operation
    of the MB-OFDM system to only three channels. As long as the system
    complies with the standards set forth under this waiver, harmful
    interference should not occur.

16. NTIA expressed concern regarding two Federal systems that operate in
    the 3.1‑10.6 GHz frequency range. The Microwave Landing System
    ("MLS") operates in the 5030‑5091 MHz frequency band and is used for
    the precision approach and landing of aircraft. The Terminal Doppler
    Weather Radar ("TDWR") operates in the 5600-5650 MHz band to provide
    quantitative measurements of gust fronts, wind shears, microbursts,
    and other weather hazards for major airports. Because of these
    Federal operations, NTIA requests that we not permit UWB devices to
    operate under this waiver in the 5030-5650 MHz band until such time
    that the Institute for Telecommunication Sciences ("ITS"), a branch
    of NTIA, completes its measurement program.[^44] At this time, we
    are implementing NTIA's request, limiting this waiver to UWB systems
    that operate in the 3.1-5.03 GHz and/or 5.65-10.6 GHz bands. We note
    that the three-hop system described in the MB-OFDM petition is
    capable of avoiding operation in the 5030‑5650 MHz band and would
    not be adversely impacted by NTIA's request.

17. Freescale states that granting the requested waiver to MBOA-SIG will
    result in an unfair competitive advantage by permitting MB-OFDM
    systems to effectively operate at a power level 6 dB greater than
    what is permitted for other UWB devices.[^45] Freescale notes that
    its systems employ gated transmissions. Since all devices in close
    proximity must share a single channel, data is sent in bursts, one
    packet at a time, with the system listening for acknowledgement of
    reception and making room for other transmissions during these
    blanking intervals. Freescale states that the duty cycle for each
    device rarely exceeds 25%, *i.e.*, -6 dB. The requirement to perform
    emission measurements with the gating disabled results in the power
    during actual use being at least 6 dB below what is determined
    during the compliance measurements.[^46] Thus, Freescale, while
    opposing the petition from MBOA-SIG, states that should the
    Commission grant a waiver to MBOA-SIG it must do so in a
    technology-neutral manner, allowing any UWB device, not just
    MB-OFDM, to be measured under normal operating conditions.[^47] We
    agree. The interference aspects of a transmitter employing frequency
    hopping, stepped frequency modulation or gating are quite similar,
    as viewed by a receiver, in that both appear to the receiver to emit
    for a short period of time followed by a quiet period. We recognize
    that a waiver of the measurement procedures in 47 C.F.R. § 15.521(d)
    that require gated systems to be measured with the system gated on,
    permitting them to operate under the same measurement procedures
    being applied to MB-OFDM systems, will ensure that gated DS-UWB
    systems are not unfairly burdened in the marketplace. Further,
    granting such a waiver will not undermine the Commission's policy as
    it also would not result in any increase to the interference
    potential of UWB operations for the same reasons attributed to the
    MB-OFDM modulation format, and thus would serve the public interest.
    Accordingly, we are also granting a waiver of the requirement to
    disable the gating, as specified in 47 C.F.R. § 15.521(d), subject
    to the operating conditions applied to the MBOA-SIG waiver.[^48] In
    addition, we see no technical justification to restrict these
    waivers only to gated DS-UWB devices or to MB-OFDM systems.
    Frequency hopped, frequency stepped, band sequenced and gated
    emissions all appear similar to a receiver and should be treated
    equally under the conditions of this waiver.

18. In summary, we are waiving the UWB measurement procedure that
    requires the emissions from UWB devices employing hopped, stepped or
    sequenced operation to be measured with the hop, step or sequenced
    function stopped. In addition, we are waiving that portion of 47
    C.F.R. § 15.521(d) that requires the emissions from UWB devices that
    employ gating to be measured with the emission gated on. The
    emissions from such systems shall be measured in their normal
    operating mode. These waivers do not apply to systems that employ
    swept frequency modulation.[^49] Further, UWB transmitters certified
    under these waiver provisions also shall comply with the following
    provisions:

-   Operation under the provisions of this waiver shall apply only to
    indoor or handheld UWB devices under 47 C.F.R. §§ 15.517 or 15.519
    that operate in the 3.1-5.03 GHz and/or 5.65‑10.6 GHz frequency
    bands. The fundamental emission of the UWB device shall not be
    located within the 5030-5650 MHz band. All other provisions of the
    UWB regulations shall continue to apply to these devices.

-   The measurement of the average and peak emission levels for hopped,
    stepped, sequenced or gated systems shall be performed with the
    equipment operating in its normal mode and shall be repeated over
    multiple sweeps with the analyzer set for maximum hold until the
    amplitude stabilizes.

-   If provisions are made to operate using a different number of
    hopped, stepped or sequenced channels, the system shall be designed
    to ensure that it complies with the emission levels under all
    possible operating conditions.

-   This waiver shall not apply to the determination of the UWB
    bandwidth or the classification of a device as an ultra-wideband
    transmitter. The requirements in 47 C.F.R. § 15.503(a) and (d)
    continue to apply based on measurements performed with any frequency
    hop, step or band sequencing function stopped.

-   These waivers are effective until such time as the Commission
    finalizes a rule making proceeding dealing with these issues.

19. We are confident at this juncture that there is no significant risk
    of interference under the terms of this waiver. We believe the
    public interest is served by granting a waiver at this time to
    enable this new technology to be introduced to the market to the
    benefit of businesses and consumers. We also believe this is vitally
    important so that we can gain more experience with UWB technology.
    As the Commission has stated previously, we plan to closely monitor
    the introduction of UWB technology and may make appropriate
    modifications to our rules in the future if necessary to correct any
    harmful interference that occur. Upon completion of the ITS study
    and advisement by NTIA that it has no objections, we intend to
    modify the conditions of this waiver to permit operation within the
    5.03‑5.65 GHz band. We therefore delegate authority to the Office of
    Engineering and Technology to modify this waiver for the 5.03-5.65
    GHz band accordingly. In addition, we plan at an appropriate time in
    the future to initiate a rule making to codify the provisions of
    this waiver for UWB communications devices.

# ORDERING CLAUSES

20. IT IS ORDERED that the Petition for Waiver from the Multi-band OFDM
    Alliance Special Interest Group IS GRANTED, to the extent described
    above.[^50] IT IS FURTHER ORDERED that, on our own motion, a waiver
    of that portion of 47 C.F.R. § 15.521(d) which requires gated UWB
    transmitters to be measured with the system gated on IS GRANTED, to
    the extent described above. These actions are taken pursuant to
    Sections 4(i), 301, 302, 303(e), and 303(r) of the Communications
    Act of 1934, as amended, 47 U.S.C. Sections 154(i), 301, 302,
    303(e), and 303(r).

21. IT IS FURTHER ORDERED that these waivers are effective upon release
    of this Order. IT IS FURTHER ORDERED that delegated authority is
    extended to the Office of Engineering and Technology to modify this
    waiver to permit operation within the 5.03-5.65 GHz band.

22. For further information regarding this Order, contact John A. Reed,
    Office of Engineering and Technology, (202) 418-2455,
    [john.reed@fcc.gov](mailto:jreed@fcc.gov).

    FEDERAL COMMUNICATIONS COMMISSION

Marlene H. Dortch

Secretary

**Comments and Reply Comments Filed in Response to the**

**MBOA-SIG Petition for Waiver**

Comments:

1\. Alereon, Inc. (Alereon)

2\. Centro de Techologia de las Comunicaciones, S.A. (CETECOM)

3\. Cingular Wíreles LLC (Cingular)

4\. Coalition of C-Band Constituents (Coalition)

5\. decaWave

6\. FOCUS Enhancements, Inc. (FOCUS)

7\. Freescale Semiconductor, Inc. (Freescale)

8\. Harris Corporation (Harris)

9\. Hewlett-Packard Company

10\. Philips Electronics North America Corporation (Philips)

11\. Pulse-LINK

12\. Renesas Technology American, Inc.

13\. Satellite Industry Association (SIA)

14\. TimeDerivative Inc.

15\. Time Domain Corporation (TDC)

16\. WiLinx Corporation

17\. WiMedia Alliance

Reply Comments:

1\. decaWave

2\. Freescale Semiconductor, Inc.

3\. Motorola, Inc.

4\. Multi-band OFDM Alliance Special Interest Group (MBOA-SIG)

[^1]: *See* 47 C.F.R. §§ 15.501 *et seq*.

[^2]: Gating refers to the use of burst transmissions where a
    transmitter is turned on and off for selected time intervals. The
    transmitter generally is turned off to listen for a response or to
    permit other transmitters to operate, such as through time division
    multiple access operations.

[^3]: The MBOA-SIG represents approximately 160 domestic and foreign
    companies seeking adoption by the IEEE 802.15 Task Group 3a of a UWB
    standard specifying the use of its MB-OFDM modulation. Similarly,
    the UWB Forum, also consisting of several domestic and foreign
    companies, is seeking adoption by the IEEE 802.15 Task Group 3a of a
    UWB standard specifying the use of its DS-UWB modulation

[^4]: *See First Report and Order* ("*1^st^ R&O*") in ET Docket No.
    98-153, 17 FCC Rcd 7435 (2002); *Erratum* in ET Docket No. 98-153,
    17 FCC Rcd 10505 (2002); *Memorandum Opinion and Order and Further
    Notice of Proposed Rule Making* in ET Docket No. 98‑153, 18 FCC Rcd
    3857 (2003); and *Second Report and Order and Second Memorandum
    Opinion and Order* ("*2^nd^ R&O*") in ET Docket No. 98-153, 19 FCC
    Rcd 24525 (2004). *See*, also, 47 C.F.R. §§ 15.501-15.525.

[^5]: Imaging systems consist of GPRs, wall imaging systems,
    through-wall imaging systems, surveillance systems, and medical
    imaging systems.

[^6]: The operation of Federal Government radio stations is regulated by
    the National Telecommunications and Information Administration
    ("NTIA"), while operation of stations by commercial entities, state
    and local governments, and the general public is regulated by the
    Commission.

[^7]: 47 C.F.R. § 15.205.

[^8]: 47 C.F.R. § 15.5.

[^9]: These analyses and tests are filed in the record for the UWB
    proceeding in ET Docket No. 98-153. *See*, for example, NTIA Special
    Publication 01-43, *Assessment of Compatibility between
    Ultrawideband Devices and Selected Federal Systems*, January 2001;
    NTIA Special Publication 01-45, *Assessment of Compatibility between
    Ultrawideband (UWB) Systems and Global Positioning System (GPS)
    Receivers*, February 2001; NTIA Special Publication 01-47,
    *Assessment of Compatibility between Ultrawideband (UWB) Systems and
    Global Positioning System (GPS) Receivers (Report Adendum)*,
    November 2001; NTIA Report 01-383, *The Temporal and Special
    Characteristics of Ultrawideband Signals*, January 2001; NTIA Report
    01-384, *Measurements to Determine Potential Interference to GPS
    Receivers from Ultrawideband Transmission Systems*, February 2001;
    NTIA Report 01-389, *Addendum to NTIA Report 01-384: Measurements to
    Determine Potential Interference to GPS Receivers from Ultrawideband
    Transmission Systems*, September 2001; *Final Report UWB-GPS
    Compatibility Analysis Project*, 8 March 2001, Strategic Systems
    Department, The Johns Hopkins University/Applied Physics Laboratory;
    the study submitted by NTIA on March 21, 2001, on behalf of the
    Department of Transportation regarding tests performed at Stanford
    University; *A Model for Calculating the Effect of UWB Interference
    on a CDMA PCS System*, September 12, 2000, Dr. Jay Padgett, Senior
    Research Scientist, Telcordia Technologies attached to the Sprint
    comments of September 12, 2000; measurements and analysis submitted
    by Qualcomm in its comments of March 5, 2001; the analyses submitted
    by the Satellite Industry Association in several of its comments;
    and multiple others.

[^10]: *1^st^ R&O*, *supra*, at para. 2.

[^11]: For example, UWB communications systems that are designed to
    operate outdoors are restricted to hand-held devices and fixed
    outdoor infrastructures are prohibited.

[^12]: 47 C.F.R. § 15.209.

[^13]: 47 C.F.R. § 15.31(c). This rule paragraph references only swept
    frequency devices. In addition, the Commission normally would apply
    a similar requirement to average emission measurements for
    transmitters employing step function or frequency hopping modulation
    techniques due to the lack of appropriate test procedures and the
    lack of interference studies regarding these modulation types.
    However, the Commission, in the *2^nd^ R&O*, recently amended its
    regulations to permit non-UWB frequency hopping and stepped
    frequency systems operating in the 6 GHz, 17 GHz and 24 GHz bands to
    be measured in their normal operating modes.

[^14]: Depending on the modulation type, emissions measured using an RMS
    detector may be higher than those measured using a linear average
    detector.

[^15]: *See* NTIA Report 01-383, *supra*, at pg. 6-18 through 6-25 and
    A-1 through A-21. *See*, *also*, NTIA Special Publication 01-43,
    *supra*, at pg. 2-1 through 2-2.

[^16]: *See* NTIA Report 01-383, *supra*, at pg. 8-44. In addition,
    Agilent states that an RMS detector reports the true average power
    for each part of the measurement span which is particularly useful
    when measuring non-continuous waveforms such as those produced by
    frequency switching or packet based transmissions. Agilent adds that
    the RMS average detector also is well behaved when measuring
    noise-like signals. *See* Agilent APP Note 1488, *Ultra-Wideband
    Communication RF Measurements*, at pg. 43.

[^17]: This 34 dB reduction does not include any differences that may
    result from the UWB measurement procedures.

[^18]: The reference to average emission levels for UWB intentional
    radiators refers to emissions measured using an RMS detector with a
    1 MHz resolution bandwidth and a one millisecond or less averaging
    time. *See* 47 C.F.R. § 15.521(d).

[^19]: *See*, *1^st^ R&O*, *supra*, at para. 32.

[^20]: 47 C.F.R. §15.521(d).

[^21]: Freescale, through Motorola, acquired substantially all of the
    assets and intellectual property of XtremeSpectrum, Inc. A grant of
    certification, FCC ID RUN-XSUWBWDK, was issued by the Commission to
    Freescale on August 5, 2004, for a UWB transmitter operating under
    47 C.F.R. § 15.517.

[^22]: MBOA-SIG petition for waiver at pg. 1-2. A detailed explanation
    of the modulation format is contained in Attachment B of the
    MBOA-SIG reply comments.

[^23]: *1^st^ R&O*, *supra*, at para. 32.

[^24]: MBOA-SIG petition for waiver at pg. 10. Various methods of
    sequencing these three bands are shown in Attachment A to the
    MBOA-SIG petition.

[^25]: 47 C.F.R. §§ 15.517 and 15.519.

[^26]: Freescale, MBOA-SIG, and Motorola also filed *ex parte* comments.

[^27]: *1^st^ R&O*, *supra*, at para. 32.

[^28]: *See WAIT Radio v. FCC*, 418 F.2d 1153 (D.C. Cir. 1969);
    *Northeast Cellular Telephone Co. v. FCC*, 897 F.2d 1164 (D.C. Cir.
    1990).

[^29]: *1^st^ R&O*, *supra*, at para. 32. This procedure was not
    codified in the rules.

[^30]: Average emission measurements performed on a system that employs
    a frequency hopping, frequency sweep or stepped frequency modulation
    format will be reduced proportional to the time period that the
    transmitter is active on the frequency being measured divided either
    by the length of time that it takes for a complete cycle through the
    operating frequency bands or the averaging time period of the
    measurement instrument, whichever is shorter.

[^31]: NTIA comments of 12/10/04 in ET Docket No. 98-153 at pg. 3-4.

[^32]: NTIA comments of 12/10/04 in ET Docket No. 98-153 at Enclosure B
    and NTIA comments of 1/15/04 in ET Docket No. 98-153 at pg. 13-19
    and at Appendices C and D.

[^33]: The Commission recently amended its rules to permit wideband
    systems operating in the 5925-7250 MHz, 16.2‑17.7 GHz and 23.12‑29.0
    GHz bands to be measured, using NTIA's suggested procedures, with
    any frequency hopping, stepped frequency or signal gating active.
    *See 2^nd^ R&O*, *supra*.

[^34]: Cingular comments at pg. 5.

[^35]: Coalition of C-Band Constituents comments at pg. 1 and A4.

[^36]: Satellite Industry Association comments at pg. 3-4.

[^37]: Freescale comments at pg. 6-7; decaWave comments at pg. 1-3.

[^38]: MBOA-SIG petition for waiver at pg. 3 and 8-9. Actual testing was
    performed using a C-band earth station receiver for the Fixed
    Satellite Service ("FSS"). Interference testing indicated that the
    MB-OFDM emitter had to be located within 20 feet of the C-band earth
    station antenna. *See*, *e.g.*, MBOA-SIG petition for waiver at pg.
    8-9, Philips comments at pg. 13-14, and MBOA-SIG reply comments at
    pg. 4-5 and 9-10 and at Attachments A and C.

[^39]: *See*, *e.g.*, the comments filed by decaWave, Freescale,
    Philips, and TimeDerivative and the reply comments of decaWave,
    Freescale, Motorola, and MBOA-SIG. This issue is not relative to the
    request for waiver. What is important is whether or not the MB-OFDM
    modulation format, when measured in the normal operating mode, has a
    greater interference potential than a UWB transmitter employing
    impulse modulation.

[^40]: If interference potential is evaluated using an improbable
    theoretical basis where no background noise level exists, a zero bit
    error rate is desired, and the bandwidth of the victim receiver is
    greater than the band switching rate of the MB-OFDM emission, it can
    be shown that the increase in interference potential is directly
    related to the additional time averaging that would occur if
    measurements were made with the MB-OFDM system functioning normally.
    The MB-OFDM system transmits only for 242.2 nanoseconds during every
    transmission cycle of 937.5 nanoseconds. Thus, the additional time
    averaging for this modulation format is 10 log (242.2/937.5) = ‑5.9
    dB. During a one millisecond averaging period, *i.e.*, 1066.67
    hopping sequences, the maximum differences in any averaging period
    will be 10 log \[(1066 x 242.2) ns/1000000 ns) = ‑5.9 dB. However,
    this situation will not occur under actual operating conditions. The
    background noise level will mask a low level undesired signal and
    bit error rates are actual values. Further, while the instantaneous
    signal level of a hopped or stepped emission may be higher, it is
    higher only for a very short period of time, *i.e.,* less than one
    millisecond. The actual impact on the interference potential is much
    less than the difference between the instantaneous emission level
    and the emission level averaged over a one millisecond period during
    normal operation.

[^41]: In general, the UWB emission standards were based on modulation
    and operational characteristics that produced worst case
    interference results.

[^42]: While MBOA-SIG requested a waiver for a three channel MB-OFDM
    system, the ability to eliminate operation on one or more channels
    because of interference could result in the MB-OFDM system operating
    with less than three channels.

[^43]: If the system is found to comply with the emission limits while
    actively hopping or sequencing between three channels, the
    instantaneous emission level produced on each channel may be as high
    as (-41.3 dBm + 5.9 dB) = -35.4 dBm/MHz. Under this circumstance,
    the average emission level that is measured with the transmitter
    operating normally would be -41.3 dBm/MHz, the level specified in 47
    C.F.R. §§ 15.517 and 15.519. However, if that same transmitter
    switches to a hopping or sequenced system using only two channels,
    *e.g.*, to avoid interference on one operating channel, the
    instantaneous emission level produced on each channel will remain at
    ‑35.4 dBm/MHz but the average emission level measured with the
    transmitter operating normally will increase to (‑35.4 dBm/MHz -- 3
    dB) = -38.4 dBm/MHz, a level 2.9 dB above the limit.

[^44]: Motorola is funding a study being performed by the ITS to
    characterize different UWB signals, test the relative interference
    potential of various UWB waveforms, and examine compliance
    measurement techniques.

[^45]: Freescale reply comments at pg. 6-7.

[^46]: As with hopping and other similar systems, gated UWB devices are
    required to be tested with the gating turned off. 47 C.F.R. §
    15.521(d).

[^47]: Freescale comments at pg. 11; Freescale reply comments at pg. 7.

[^48]: Our action here applies only to new products and does not any
    previously approved devices.

[^49]: As stated in 47 C.F.R. § 15.31(c), the emissions from
    transmitters employing swept frequency modulation are required to be
    measured with the frequency sweep stopped. Swept frequency systems
    were not addressed in this waiver and are outside of its scope.

[^50]: The Commission will not send a copy of this Order to Congress or
    to the Government Accountability Office pursuant to the
    Congressional Review Act, *see* 5 U.S.C. 801(a)(1)(A), because no
    rules are being adopted.