Doc.: IEEE 802.15-04/0627r0 Submission Nov 2004 Aiello, Razzell, KellySlide 1 Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs)

doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Slide 1 Aiello, Razzell, Kelly

Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: [Facts and misconceptions about MBOA waiver request]

Date Submitted: [17Nov2004]

Source: [Roberto Aiello, Charles Razzell, Joy Kelly] Company [Staccato Communications, Philips, Alereon]Address [5893 Oberlin Dr., Suite #105, San Diego, CA 92121]Voice:[+1 858 812-1000], FAX: [+1 858 812-1001], E-Mail:[[email protected]]

Re: []

Abstract: [Facts and misconceptions about MBOA waiver request.]

Purpose: [Provide information about regulatory approval status of Merger Proposal #1.]

Notice: This document has been prepared to assist the IEEE 802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by 802.15.

Aiello, Razzell, KellySlide 2

doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Summary

• Summarize main technical points discussed in the comments and reply to the comments

• Clarification on power measurements and power spectral density

• Clarification on pulse gating


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Summary of Waiver Comments• MBOA- SIG has requested a waiver of the Commission’s frequency

hopping measurement procedures and the “pulse gating” rule in Section 15.521(d), to allow MB-OFDM ultra-wideband (UWB) systems to be tested for average emissions under normal operating conditions, rather than with band sequencing stopped.

• For grant of the waiver:– MBOA-SIG (+170 companies)– Additional individual filings: WiMedia Alliance, Renesas, Time Domain,

Philips, Focus, Cetecom, HP, WiLinx, Alereon, and Harris

• Against UWB as a whole (spectrum users) :– C-Band Coalition, Satellite Industry Association, Cingular

• Against grant of the waiver:– Freescale, Motorola, Pulse~LINK, Time Derivative, decaWave


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Nov 2004

Summary of main opposing comments• MB-OFDM will increase the potential for interference

[not true, as shown on the record]• Granting the Waiver will give MB-OFDM an unfair advantage (increased range) relative to other UWB

technologies [not true, even by opposer’s claims]

• MBOA technical justification is filled with errors– Inclusion of WGN in comparisons ‘masks’ MB-OFDM interference potential

[thermal noise and other interference sources are a reality]– Wrong BER operating point

[BER criterion based on quasi-error free performance]– Field measurements are invalid

[same position and separation distance tests are valid and reflect real systems]– Simulations results are wrong

[simulation results supported by lab and field measurements]– APD analysis is erroneous [shown to be technically accurate using NTIA code]

• Waiver will ‘open the door’ to other systems seeking relief from the rules [scope of Waiver is narrow and does not impact most of the FCC rules]

• FCC should wait for more data and delay making a ruling [reply comments provide comprehensive data; no new information will come from more tests]

• Waiver is not in the public interest and will negatively impact small businesses [MBOA SIG represents 170+ companies, including many small start-ups]

Granting the waiver is in the public interest and is supported by significant technical data showing there will be no increased potential for interference


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Summary of technical points• No greater harmful interference

– All UWB signals will be well below the system noise floor of C-band satellite receivers which makes differences between waveforms negligible

– MB-OFDM will look like WGN to narrow bandwidth systems (less than a few MHz), including OFDM systems with narrow tone spacing

– MB-OFDM systems do not synchronize and will not increase the potential for aggregation of interference

– MB-OFDM has been consistently shown to be less harmful than a class of impulse radios allowed by the rules, supported by analysis, simulations, lab measurements, and field measurements

• Differences between all UWB signals allowed by the rules are within a few dBs when measured in realistic scenarios

• MB-OFDM technology advantages– Band switching (the multi-band concept) increases frequency diversity, provides course

spectrum flexibility at Tx, enables efficient CMOS designs, and provides protection from strong interferers at Rx

– OFDM efficiently captures multipath energy, shares common components with other technologies (WiFi, WiMax, DSL) leveraging best known methods in design and manufacturing, provides fine spectrum flexibility at Tx, and enables efficient signal processing techniques for interference mitigation in Rx

– Spectrum flexibility will be necessary to enable worldwide interoperability and to adapt to future spectrum allocations

MB-OFDM gives unique advantages at practical cost and complexity


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Clarification on power measurements and power spectral density


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

FCC measurements• Peak instantaneous power : operating measurement device uses max hold

that records the peak power in an equivalent 50MHz bandwidth obtained over a window of time, a defined span of frequencies and over all possible of orientations to obtain the maximum instantaneous power over these three parameters (time, frequency, & orientation). This limit is 0dBm.

• Average PSD : is measured in a 1MHz resolution bandwidth and averaged over 1ms of time and is maximized over all possible orientations of the device. This limit is -41.3dBm/MHz.


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Wrong Claim on Power Level

Somewhere in the spectrum, at every instant [emphasis added], the MBOA system would be emitting at three times the [power] level permitted to an impulsive or direct sequence system.

From Freescale waiver comments:

Why this is wrong:

1. “Instantaneous power level” has meaning only in the time domain. Clearly many impulse-based systems permitted by the rules have higher instantaneous time-domain power levels than MB-OFDM does.

2. In the frequency domain, power spectral density (dBm/MHz) cannot be measured in an “instant”. Some averaging time must be specified, such as the 1 ms interval designated in the rules. Even under the shortest interval found on high-end analyzers (10 s), average and peak PSD for MB-OFDM comply with the rules. See charts that follow.


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Average-Power Compliance

Waiver Reply Figure 21: Example average EIRP measurement for a MB-OFDM transmitter using intended operational mode according to the waiver

MB-OFDM waveform, measured under authentic operating conditions, conforms to Part 15 requirements not to exceed -41.3 dBm/MHz PSD.

-41.3 dBm/MHz


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Peak Power Compliance

Waiver Reply Figure 22: Example Peak EIRP measurement for a MB-OFDM transmitter [Measurements taken at a RBW of 3 MHz and compensated by 20Log(3/50) RBW factor to compare with FCC UWB peak limit in a 50 MHz RBW]

MB-OFDM waveform, measured under authentic operating conditions, conforms to Part 15 requirements not to exceed 0 dBm peak power.

0 dBm


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Nov 2004

MB-OFDM Spectrogram (no averaging)


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Nov 2004

MB-OFDM Spectrogram (averaging over 500ns)


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Nov 2004

MB-OFDM Spectrogram (averaging over 750ns)


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Nov 2004

MB-OFDM Spectrogram (averaging over 1us)


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Submission

Nov 2004

Wrong Representation of Peak Power

Average PSD (same for MB-OFDM & DS-UWB)

This plot is wrong because PSD limit refers to average PSD

Plot based on hypothetical instantaneous PSD. By definition PSD limit refers to AVERAGE PSD.


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

For both MB-OFDM and DS-UWB waveforms have the same average PSD for averaging time > 1 us

• This slide represents ANY UWB signal transmitting burst packets of data (example 3k byte packet at 110 Mbps is approximately 225 microseconds

• The average power limit is a PSD measurement over a given bandwidth, averaged over a specified amount of time.

PS

D


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Nov 2004

Pulse gating


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Why pulse gating is different

• Pulse gating is not an inherent and natural consequence of implementing a legitimate bandwidth expansion method

– Slow pulse gating does not increase bandwidth, diversity or interference immunity.

• MB-OFDM waveform explicitly relies on TFI coding to achieve bandwidth expansion design objective

• The peak amplitudes introduced by true pulse gating can be resolved by a much larger class of existing victim receivers (e.g., with 4MHz bandwidth or less).

– MB-OFDM, as proposed, need victim bandwidths >>4MHz to cause the peak values to rise significantly above those for continuous AWGN


doc.: IEEE 802.15-04/0627r0

Submission

Nov 2004

Sidebar:It’s the energy per bit that counts!

• Like the speed of light or conservation of energy in physics, energy per bit is a fundamental constraint.

• This is why engineers rightly compare one scheme to another via their respective BER vs Eb/No curves.

• A UWB design could “cheat” and gain a true advantage over another if, and only if, it somehow allowed for a higher value of Eb.

• MB-OFDM and DS-UWB have identical values for Eb. The waiver aims to keep it that way.

• Not granting the waiver would force ~75% reduction in Eb for MB-OFDM relative to all other schemes. That would handicap MB-OFDM.


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Submission

Nov 2004

Conclusions• MB-OFDM waveforms, when measured as described in the

Waiver, will not cause greater interference than waveforms already allowed by rules

• The properties of MB-OFDM waveform result from the pursuit of legitimate design goals, rather than an attempt to transmit at "5dB higher power than allowed by the rules."

• The average power and associated energy per bit is identical to other waveforms of the same overall bandwidth.

• The potentially increased peak-to-mean ratios compared to a steady-state (stationary) waveform are strictly constrained by the limited scope of the waiver to 3 hopping bands

Documents

Doc.: IEEE 802.15-04/0627r0 Submission Nov 2004 Aiello, Razzell, KellySlide 1 Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs)