November, 2004 Slide 1 doc.: IEEE 802.15- 04/0641r0 Submission Project: IEEE P802.15 Working Group for Wireless Personal Area Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Networks (WPANs) Submission Title: [MB-OFDM No Vote Responses] Date Submitted: [Nov 15, 2004] Source: [Matthew B. Shoemake and John Terry, Joy Kelly and Jim Lansford, David Leeper and Jeff Forrester, Joe Decuir, Charles Razzell] Company [WiQuest, Alereon, Intel, MCCI, Philips] Address [8 Prestige Circle, Suite 110, Allen, Texas 75013] Voice:[+1 214-547-1600], FAX: [+1 214-547-1606] E-Mail:[Provided throughout document] Re: [IEEE 802.15.3a No Vote Responses from September 2004 Vote] Abstract: [This presentation contains no vote responses to comments submitted after the IEEE 802.15.3a downselect vote in September 2004. These responses have been complied by multiple supporters of the Multiband OFDM approach as indicated throughout the document.] Purpose: [The purpose of this presentation is to address no vote responses thereby enabling an affirmative vote during the confirmation step and thereby enabling IEEE 802.15.3a to move forward into the working group balloting stage of standardization.] Notice: This document has been prepared to assist the IEEE P802.15. 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
Transcript
November, 2004
Slide 1
doc.: IEEE 802.15-04/0641r0
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [MB-OFDM No Vote Responses]Date Submitted: [Nov 15, 2004]Source: [Matthew B. Shoemake and John Terry, Joy Kelly and Jim Lansford, David Leeper and Jeff Forrester, Joe Decuir, Charles Razzell] Company [WiQuest, Alereon, Intel, MCCI, Philips]Address [8 Prestige Circle, Suite 110, Allen, Texas 75013]Voice:[+1 214-547-1600], FAX: [+1 214-547-1606] E-Mail:[Provided throughout document]
Re: [IEEE 802.15.3a No Vote Responses from September 2004 Vote]
Abstract: [This presentation contains no vote responses to comments submitted after the IEEE 802.15.3a downselect vote in September 2004. These responses have been complied by multiple supporters of the Multiband OFDM approach as indicated throughout the document.]
Purpose: [The purpose of this presentation is to address no vote responses thereby enabling an affirmative vote during the confirmation step and thereby enabling IEEE 802.15.3a to move forward into the working group balloting stage of standardization.]
Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15.
November, 2004
Slide 2
doc.: IEEE 802.15-04/0641r0
Submission
Outline
1. Introduction – Matthew Shoemake, WiQuest
2. Regulatory Compliance and Interference – Joy Kelly, Alereon
3. MAC – Matthew Shoemake
4. Location Awareness – Joe Decuir, MCCI5. Harmonization or Coexistence – David Leeper, Intel
6. Multipath Performance – Charles Razzell, Philips 7. Time to Market – Jim Lansford, Alereon
Many no vote comments have been elaborated on in reply comments made in response to the MBOA waiver request
Following slides review significant points raised and provide technical analysis, simulations, lab measurements, and field measurements demonstrating that MB-OFDM waveforms, as proposed in the
Waiver, will not cause greater interference than waveforms already allowed by rules
– This body of work is precisely what was requested by FCC/OET (i.e. to demonstrate no greater interference potential than waveforms allowed by the rules)
MB-OFDM devices operating under the proposed Waiver will comply with the Part 15f limits on peak and average power
Overview of FCC Compliance / Interference Section
November, 2004
Slide 5
doc.: IEEE 802.15-04/0641r0
Submission
Summary of main opposing comments & claims
MB-OFDM will increase the potential for interference Not true, as will be shown here
Granting the Waiver will give MB-OFDM an unfair advantage (increased range) relative to other UWB technologies Not true, even by opposer’s claims
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 on the 3-band MB-OFDM waveforms
Waiver is not in the public interest and will negatively impact small businesses MBOA SIG represents 170+ companies, including many
small start-ups
November, 2004
Slide 6
doc.: IEEE 802.15-04/0641r0
Submission
Summary of main opposing comments & 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 because they included noise Noise is a reality and simulation results are
supported by lab and field measurements APD analysis is erroneous
Shown to be technically accurate using NTIA code
November, 2004
Slide 7
doc.: IEEE 802.15-04/0641r0
Submission
Summary of technical points No greater interference than systems allowed by FCC rules
All UWB signals will be well below the system noise floor of C-band satellite receivers Makes differences between waveforms negligible
MB-OFDM looks 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 have less interference 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 Bandwidth of information-carrying tones is 503.25 MHz
November, 2004
Slide 8
doc.: IEEE 802.15-04/0641r0
Submission
Summary of technical points (cont) MB-OFDM technology advantages
Band switching (the multi-band concept)
increases frequency diversity
provides coarse spectrum flexibility at Tx
enables efficient CMOS designs
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
November, 2004
Slide 9
doc.: IEEE 802.15-04/0641r0
Submission
No greater interference:
C-band satellites802.11a devices
Other UWB devices No risk of aggregation
November, 2004
Slide 10
doc.: IEEE 802.15-04/0641r0
Submission
C-band Satellites C-band satellite systems have little margin
MBOA field measurements have confirmed this (only 2.5 dB margin)
Table 1: Power spectral density limits for some US government bands
System
Freque
ncy (MHz)
Maximum UWB EIRP (dBm/MHz)
UWB Indoors
2 m height
Maximum UWB EIRP
(dBm/MHz) UWB
Indoors 30 m height
IF Bandwidth Margin from current Part 15 limits
ARSR-4 1240-1370
-52 -73 690 KHz 23.3 dB (2 m) 2.3 dB (30 m)
SARSAT 1544-1545
-60 -57 800 KHz 15.3 dB (2 m) 18.3 dB (30 m)
ASR-9 2700-2900
-37 -57 653 KHz 14.3 dB (2 m)
NEXRAD 2700-2900
-33 -67 550 KHz 18.3 dB (2 m)
Marine Radar
2900-3100
-34 -45 4-20 MHz 17.3 dB (2 m) 6.3 dB (30 m)
FSS, 20 degrees
3700-4200
-24 -30 40 MHz 17.3 dB (2 m) 11.3 dB (30 m)
FSS*, 5 degrees
3700-4200
-39 -65 40 MHz 2.1 dB (2 m)
CW Altimeters
4200-4400
37 Not Applicable N/A 78.3 dB (2 m)
Pulsed Altimeters
4200-4400
26 Not Applicable 30 MHz 67.3 dB (2 m)
MLS 5030-5091
-42 Not Applicable 150 KHz -
TDWR 5600-5650
-23 -51 910 KHz 18.3 dB (2 m)
November, 2004
Slide 11
doc.: IEEE 802.15-04/0641r0
Submission
C-band Satellites (cont) C-band satellites have low margin due to challenges of
communicating over long satellite link (see Petition for reconsideration of Satellite Industry Association in docket 98-153) Low margin requires interference to be below systems noise
floor of C-band satellite receiver What is system noise floor for C-band satellites?
From SIA, Isat is defined as the interference at a given C-band receiver caused by adjacent C-band channel interference and cross polarization noise from the satellite link
Isat/N = 1.4 dB (1.38) N_sys = N + I_sat where N is the thermal noise floor
FCC adopted criterion of IUWB /N < 0 dB (docket 98-153 March 12, 2003) N_sys = N + I_sat = (1 + 1.38)= 2.38 IUWB /N_sys = 10*log10(1/2.38) = -3.8dB
November, 2004
Slide 12
doc.: IEEE 802.15-04/0641r0
Submission
C-band Satellites (cont) FCC criterion, when incorporating total satellite system noise
experienced (as defined by SIA) is thus IUWB /N_sys = -3.8dB
Further support of appropriate protection levels for C-band satellites XtremeSpectrum filed response to SIA Petition for
Reconsideration (Sept 4, 2003 in docket 98-153) stating that
– “Using SIA’s stated operating levels, XSI [now part of Freescale] demonstrates that an I/N of –6 dB assigned to a UWB device is an appropriate protection level”
– IUWB /N = -6 dB IUWB /N_sys = -9.8dB
November, 2004
Slide 13
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Submission
C-band Satellites (cont) Simulation results from an Alion report presented to FCC (Feb
11, 2004) Based on simulation results, coalition of C-band constituents
proposed reducing current FCC limits by 21dB (98-153 & 02-380 February 18, 2004)
Motorola (in ET Docket No. 98-153, April 9, 2004) provided analysis in response to Alion report which took into account more realistic factors into the simulations. Motorola concluded that ”Based on the revised simulations with the more realistic
path loss models, building blockage effects for devices of high in the air (and near the antenna main beam), the inclusion of a realistic duty cycle (<10%) and realistic density projections, it is clear that no significant interference will result. The aggregate UWB signal power levels drop by 25-60 dB when more realistic assumptions are made in the simulations.”
November, 2004
Slide 14
doc.: IEEE 802.15-04/0641r0
Submission
C-band Satellites (cont) UWB average interference power will be well
below system noise floor when considering realistic deployment scenarios
When I/Nsys << 0 dB, simulations, lab measurements, and field measurements show little difference between MB-OFDM, impulse, and DS-UWB waveforms Results also consistently show MB-OFDM
causes less interference than impulse radios already allowed by the rules
November, 2004
Slide 15
doc.: IEEE 802.15-04/0641r0
Submission
C-band Satellites (cont) Supporting analysis from other companies
Freescale commented that “…when you mix one part MB-OFDM energy with 20 parts Gaussian noise, the result is a composite signal that looks very much like noise.”
TimeDerivative commented that “At very low I/N ratios the noise dominates and little can be said about the difference between various interferers.”
This is precisely the point: to simulate, analyze, and measure the interference potential of alternative UWB waveform types in a realistic operating environment
November, 2004
Slide 16
doc.: IEEE 802.15-04/0641r0
Submission
MBOA C-band Satellite field test results
Field test objectives Measure interference potential to C-band TV service
operating in the FSS C-band 3.7-4.2GHz Compare White Gaussian Noise (WGN), MB-OFDM &
Impulse UWB signals Quantify relative interference potential of each UWB
signal Determine safe distance from dish antenna to avoid
interference Two separate tests were conducted.
First test: compared the different UWB signals in terms interference potential to the FSS receiving system.
Second test: determined the safe distance from the dish that must be maintained to avoid interference to the FSS receiver
November, 2004
Slide 17
doc.: IEEE 802.15-04/0641r0
Submission
MBOA C-band Satellite field test results
• Same position testing• Set UWB emissions to -41.3 dBm/MHz for each waveform
type• Measure interference power of each UWB waveform type
required to yield visible block artifacts on TV monitor• Interference power measurement to produce visible
block artifacts accurate to within 0.1 dB• Shows relative differences between waveforms• Devices being in ‘near-field’ of antenna is irrelevant
• Separation distance testing• Devices had to be very close to antenna (in the ‘near-
field’) to see measurable interference levels• Results are not ‘random’ and show UWB devices must be
very close before interference is measurable
November, 2004
Slide 18
doc.: IEEE 802.15-04/0641r0
Submission
MBOA C-band Satellite field test results: Same Position Testing
Emission 0.5dB above sensitivity
1dB above sensitivity
2.5dB above sensitivity
3MHz PRF impulse
0.0dB 0.0dB 0.0dB
MB-OFDM 3 band
0.8dB 2.6dB 2.4dB
WGN (DSSS) 1.9dB 3.8dB 4.0dB
• MB-OFDM has less interference than impulse radio and within 1-1.6 dB from WGN• Simulations and lab measurements support this result
November, 2004
Slide 19
doc.: IEEE 802.15-04/0641r0
Submission
MBOA C-band Satellite field test results:Safe Distance Tests
DishOrientation
Scale in feet 25
20
15
10
5
0
5
10
15
20
25
5 0 5 10 15 20 25
"awgn.dat""ofdm.dat"
MB-OFDM
WGN
November, 2004
Slide 20
doc.: IEEE 802.15-04/0641r0
Submission
Interference to 802.11a interference measurements were conducted, using
an IEEE802.11a device
Two types of the interfering signals were considered MB-OFDM signal AWGN
November, 2004
Slide 21
doc.: IEEE 802.15-04/0641r0
Submission
Test Set-up for Interference Measurements to 802.11a
802.11aData Source
at RF
InterferenceSourceat RF
AdjustableGain
802.11aReceiver
(Radio + PHY)
AdjustableGain
DigitalScope
BERTester
AWGNChannel
DigitalScope
November, 2004
Slide 22
doc.: IEEE 802.15-04/0641r0
Submission
Test Description An IEEE802.11a device was configured with the data-rate
of 36 Mbps (16 QAM, R=3/4) The IEEE802.11a signal power was calibrated to the
sensitivity level (0 dB at BER=10-5) in the absence of the interference. This defines the operation thermal noise level.
IEEE802.11a signal level was adjusted to different levels in order to measure the impact of the interference signal and its power.
With the interference added to the calibrated thermal noise, its power level (maximum tolerable interference power (MTIP)) was measured to maintain the IEEE802.11a reception at BER=10-5.
November, 2004
Slide 23
doc.: IEEE 802.15-04/0641r0
Submission
Interference to 802.11a
MB-OFDM produces no more interference to IEEE 802.11a WLANs than AWGN 802.11a is OFDM based and uses symbol periods of 4 usec
This results in integration over several MB-OFDM symbols, so only average interference power matters
Signal Power of 802.11a above
sensitivityI/N
Difference between AWGN and MB-
OFDM Interference
10 dB 9.5 dB 0.5 dB
3 dB 0 dB 0.5 dB
2 dB -2.3 dB 0 dB
1 dB -5.9 dB 0 dB
0.5 dB -9.1 dB -1.5 dB
Measurement results
November, 2004
Slide 24
doc.: IEEE 802.15-04/0641r0
Submission
Example BER results for 802.11a comparing MB-OFDM & AWGN
November, 2004
Slide 25
doc.: IEEE 802.15-04/0641r0
Submission
802.11a AGC Performance in the Presence of MB-OFDM Transmission
Contention that the MB-OFDM signal would cause performance degradation of the AGC in the IEEE802.11a receiver.
Comparison was made in the IEEE802.11a packet detection and the AGC convergence performances between the MB-OFDM signal and AWGN.
Measurement was conducted with the IEEE802.11a device operating at 3 dB above sensitivity. conducted with the MB-OFDM signal level set to the MTIP
level as well as to 10 dB higher than the MTIP level. There was no detectable impact whatsoever of the MB-OFDM
signal to the IEEE802.11a packet detection and AGC performance.
November, 2004
Slide 26
doc.: IEEE 802.15-04/0641r0
Submission
802.11a Packet Detection & AGC Performance in Presence of AWGN & MB-OFDM Interference
SIFS
MB-OFDM Interferer
Packet Detected
AGC LockedStart of Packet
AWGN Interferer
Packet Detected
November, 2004
Slide 27
doc.: IEEE 802.15-04/0641r0
Submission
MB-OFDM Interference Impacts to 802.11a Systems: Conclusions
Measurement results already presented to this IEEE body confirm that:
MB-OFDM signal and AWGN have similar interference impact to IEEE802.11a receiver
MB-OFDM signal does not adversely affect packet detection and AGC convergence performance of IEEE802.11a devices
November, 2004
Slide 28
doc.: IEEE 802.15-04/0641r0
Submission
Opponents’ Claims regarding MB-OFDM Interference to other UWB systems
Freescale states (4.4.2, p. 23 of “Technical Analysis …”): ‘Other UWB receivers will be injured by the MB-OFDM emissions at least as much and often more than all the other victim systems since their bandwidths are so similar. While on its face, one would expect the 6dB higher emission limits to single out MB-OFDM devices for a 2X range advantage, the actual outcome is even worse. The noise floor of all other UWB devices would be raised far more by MB-OFDM devices than other classes of UWB devices.’
Pulse-Link states in Section III of their “Comments …” : ‘Granting the waiver would allow the MBOA radio to more successfully jam the DS-UWB radio since it will be allowed an increase of power in band.’
TimeDerivative states: ‘This additional power poses a significant additional risk to other UWB communications equipment.’
No evidence has been shown to support these claims.
November, 2004
Slide 29
doc.: IEEE 802.15-04/0641r0
Submission
Reality: MB-OFDM Interference to other UWB systems
On the contrary, consider the following example: Assume an MB-OFDM signal which occupies a total
bandwidth of 3*528 = 1584 MHz peak power spectral density (PSD) during the OFDM
symbol ‘on’ time is 5.8 dB above average PSD occupied bandwidth of one symbol is ~500 MHz.
Evaluate interference experienced due to this signal by an impulse radio system occupying the same total bandwidth of 1584 MHz (for comparison, Freescale’s proposed DS-UWB system defines impulse radio modulation using impulses of bandwidth 1320 MHz and a PRF of 220 MHz to deliver a data rate of 110 Mbps.).
Assume interference much higher than system noise.
November, 2004
Slide 30
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Submission
Reality: MB-OFDM Interference to other UWB systems
At any given instant, one 500 MHz portion of impulse radio’s occupied band is impacted by an MB-OFDM symbol
Impulse radio receiver matched filter integrates all interference power over the full bandwidth of 1584 MHz.
Thus, the total instantaneous interferer power[1] at the output of a 1584 MHz matched filter is
[1] Instantaneous interference power refers to the maximum interference power to be expected while the interference source is active or ‘on’.
November, 2004
Slide 31
doc.: IEEE 802.15-04/0641r0
Submission
Reality: MB-OFDM Interference to other UWB systems
total instantaneous interferer power at the matched filter output from another impulse UWB radio system occupying the same 1584 MHz bandwidth would be
IDS-UWB = (-41.3) + 10*log10(1584) = -9.3 dBm
MB-OFDM system offers at worst 0.8 dB higher potential interference in this example
Furthermore, if we consider a more realistic set of conditions, this modest impact would be reduced still further. including system noise in addition to the interference Accounting for target DS-UWB system FEC protection
November, 2004
Slide 32
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Submission
MB-OFDM systems will not increase aggregate interference levels
Freescale and others claim a MBOA device “seeks out and transmits on channels momentarily left vacant by others” This requires nanosecond time-scale
synchronization between devices belonging to different networks: NOT facilitated by MBOA protocols
Uncoordinated MBOA devices pick different time-frequency codes (TFC) using similar protocols as other UWB devices do in order to select logical channels corresponding to their PHYs
timing offsets between uncoordinated devices are random
timing drifts between uncoordinated devices further randomize emissions
Aggregation results for MB-OFDM devices are no different than those for pulse based UWB devices
Unrealistic fine-scale Synchronization:NOT facilitated for MBOA
devices belonging to different networks
Net #3
Net #1
Net #1
Net #1
Net #1
Net #1
Net #1
Net #2
Net #2
Net #2
Net #2
Net #2
Net #3
Net #3
Net #3
Net #3f1
f2
f3
Net #3
Net #2
November, 2004
Slide 33
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Submission
No greater interference:
Comparisons of various UWB waveforms impact to a generic
wideband DVB receiver
November, 2004
Slide 34
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Submission
Victim Receiver The victim receiver chosen for study was a Digital Video
Broadcasting receiver with the following characteristics: QPSK modulation with a transmission symbol rate RS of 33
Msymbols/second Root Raised Cosine Filtering at Tx and Rx Viterbi FEC, with rates of 1/2, 2/3, 3/4, 5/6 and 7/8.
Representative of the most vulnerable class of victim receivers Very wide bandwidth and low error rate requirement
BER at output of Viterbi decoder for comparisons = 2 x 10-
4 (Quasi-error free operating point for satellite systems employing standard concatenated code)
November, 2004
Slide 35
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Submission
BER Criterion for Digital Video Freescale claims that the MBOA analysis is based upon the
wrong BER criterion and stated that the BER used in our comparisons were ‘7 orders of magnitude higher than the specification’. They claimed that ‘the curves and corresponding conclusions are misleading, and to a skilled communications engineer, they are fatally flawed and have no technical merit.’
It is well-known that digital video needs a low BER.
it is also well-known that a BER of 2 x 10-4 at the output of the Viterbi decoder yields quasi-error free performance at the output of the Reed-Solomon decoder (meaning a BER of 10-10 to 10-11)[1].
Therefore, comparing the performance at the output of the Viterbi decoder at a BER of greater than or equal 2 x 10-4 is completely relevant to this discussion
November, 2004
Slide 36
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Submission
Fundamental assumptions:What is the right BER criterion?
• MBOA, Freescale, and TimeDerivative each proposed different BER operating points to do comparisons• Alion studies, MBOA studies, and Motorola studies all used digital C-band
satellite equipment employing the same FEC as described in ETSI EN 300 421 V1.1.2
• Requirements suggest interference impacts would occur somewhere above a BER of 2 x 10-4 after the Viterbi decoder
• MBOA has provided substantial data at this operating point as well as at other operating points
*The following table and text is copied from ETSI EN 300 421 V1.1.2
November, 2004
Slide 37
doc.: IEEE 802.15-04/0641r0
Submission
Fundamental assumptions: System Noise must be considered in the analysis
MBOA and Freescale have a fundamental difference of opinion with respect to inclusion of system noise in comparisons of different waveforms
MBOA position is simple: System noise is a reality…why ignore it?
System noise = thermal noise + intra-system interference• When average UWB interference power is well below the system
noise floor, differences between UWB waveforms are negligible (even Freescale agrees)
• Even at moderate I/N levels, differences between various UWB waveforms are small
• Misleading conclusions result when not considering realistic environments
• Differences between waveforms are highly exaggerated when measured in unrealistic, noise-less environments
System noise must be considered in any interference analysis
November, 2004
Slide 38
doc.: IEEE 802.15-04/0641r0
Submission
Noiseless 7/8-Rate Coded Results
-2 0 2 4 6 8 1010
-6
10-5
10-4
10-3
10-2
10-1
100
Eb/Io [dB]
7/8
-ra
te c
od
ed
QP
SK
BE
R
impulse simulation
MB-OFDM 1,2,3,1,2,3
WGN noise only
MB-OFDM 1,1,3,3,2,2,
Impulse radio at 1MHz PRF
MB-OFDM 1,1,3,3,2,2
MB-OFDM 1,2,3,1,2,3
WGN only
INTERFERER ONLY: NO THERMAL NOISE!
Why was the impulse-induced error rate not completely corrected by the FEC? Easily explained by looking at free distance of code and collision properties
November, 2004
Slide 39
doc.: IEEE 802.15-04/0641r0
Submission
Impulsive Interference and FEC
1600 1700 1800 1900 2000 2100 2200 2300 2400
-4
-3
-2
-1
0
1
2
3
4X: 1633
Y: 4.546
X: 2145
Y: -4.546
X: 2145
Y: 0.7067
X: 1633
Y: -0.7079
Real part of received QPSK
waveform
Real part Interfering
Impulse
At equal power levels, impulse amplitude is 16dB greater than wanted QPSK signal.
Soft decisions associated with collisions will be highly confident (and wrong).
Impulse interference “pollution” of the Viterbi path metrics may last for quite some time and cause an associated error burst.
The duration of the negative impact of an impulse is much longer than that of the impacted bits, especially where Viterbi decoding with soft metrics is used.
Soft decisions must be clipped in magnitude to prevent excessive error propagation.
November, 2004
Slide 40
doc.: IEEE 802.15-04/0641r0
Submission
¾-rate Coded Results (with noise)
-1 0 1 2 3 4 5 6 7 810
-6
10-5
10-4
10-3
10-2
10-1
100
Eb/No [dB]
0.7
5-r
ate
co
de
d Q
PS
K B
ER
I/Nsys = -10.0, soft metric clipping
impulse simulation
MB-OFDM 1,2,3,1,2,3,
WGN noise + WGN int.
MB-OFDM 1,1,3,3,2,2,
At I/Nsys=-10dB, there is very little difference between the impact of extra Gaussian noise and any of the other types of interference studied.
# XSI (now Freescale) filed comments in support of this I/N level:
“Using SIA’s stated operating levels, XSI demonstrates that an I/N of –6 dB assigned to a UWB device is an appropriate protection level.”
I/N=-6 dB corresponds to I/Nsys=-10 dBNsys = thermal noise + intra-system interference
At I/Nsys=-5dB, we begin to see a clear ordering, with the impulse radio being the worst case. The spread, however, is only 1dB.
this is quite a severe case, requiring very close proximity to the victim satellite receiver dish.
November, 2004
Slide 42
doc.: IEEE 802.15-04/0641r0
Submission
¾-rate Coded Results (with noise)
3 4 5 6 7 8 9 10 11 1210
-6
10-5
10-4
10-3
10-2
10-1
100
Eb/No [dB]
0.7
5-r
ate
co
de
d Q
PS
K B
ER
I/Nsys = 0.0, soft metric clipping
impulse simulation
MB-OFDM 1,2,3,1,2,3,WGN noise + WGN int.
MB-OFDM 1,1,3,3,2,2,
At I/Nsys=0dB, the same ordering is maintained, with the impulse radio being the (co-equal) worst case.
This is a highly exaggerated and very unlikely case, considering that even the White Gaussian interferer has reduced the available link margin by 3dB, enough to cause link failure in many installations.
November, 2004
Slide 43
doc.: IEEE 802.15-04/0641r0
Submission
½-rate Coded Results (with noise)
1 2 3 4 5 6 7 8 9 10
10-4
10-3
10-2
10-1
Eb/No [dB]
½-r
ate
co
de
d Q
PS
K B
ER
I/N = 0.0, soft metric clipping
impulse simulation
MB-OFDM 1,2,3,1,2,3
WGN noise only
MB-OFDM 1,1,3,3,2,2,
This is (again) a highly exaggerated and very unlikely case, considering that even the White Gaussian interferer has reduced the available link margin by 3dB, enough to cause link failure in many installations.
Nevertheless, the spread in susceptibility to the various waveforms is <2.1dB at the target BER of 2x10-4.
November, 2004
Slide 44
doc.: IEEE 802.15-04/0641r0
Submission
½-rate Coded Results (with noise)The ability of the FEC to deal with impulsive interference depends on its strength.
With a very strong FEC, such as the ½-rate code used here (dfree=10), it can happen that the impulsive interference is better tolerated than the MB-OFDM waveforms.
However, the absolute difference remains small (the spread between all waveforms is less than 1dB).
Differences of ~ 2 dB or less are WITHIN measurement tolerance of instrumentation
November, 2004
Slide 45
doc.: IEEE 802.15-04/0641r0
Submission
LAB Measurement Results
1.00E-05
1.00E-04
1.00E-03
1.00E-02
-15 -10 -5 0
Iuwb /(N+Isat)
Vit
erb
i BE
R
AWGN
CP MB -OFDM
ZP MB -OFDM
Pulse 1M
Pulse 3M
Results show that the order of interference impact starting with most benign is:
• AWGN
• 3MHz PRF impulses
• Cyclic Prefix MB-OFDM
• Zero Prefix MB-OFDM
• 1MHz PRF impulses
Relative impact and degree of impact from lab measurements resemble those from the simulations.
November, 2004
Slide 46
doc.: IEEE 802.15-04/0641r0
Submission
For rate ¾ and 7/8 codes, MB-OFDM is more benign than a 1MHz impulse radio.
Our simulations and measurements focused mainly on the ¾-rate code as being a representative choice from the available rates [1/2, 2/3, 3/4, 5/6, 7/8].
Low rate codes (½-rate code, for example) are slightly more tolerant to the 1MHz PRF impulses than to MB-OFDM waveforms Differences are still small among all the waveforms, when
realistic I/Nsys ratios are used. Interference analysis with a low rate code is not
representative of a ‘worst-case’ situation (i.e., a UWB device needs to be much closer to a victim using a low rate code compared a victim using a high rate code)
Conclusions on Interference Impact on Wideband DVB Receiver
Under realistic, worst-case scenarios, MB-OFDM produces consistently less interference than a class of
impulse radios already allowed by the rules
November, 2004
Slide 47
doc.: IEEE 802.15-04/0641r0
Submission
No greater interference:
APD Analysis
November, 2004
Slide 48
doc.: IEEE 802.15-04/0641r0
Submission
APD Analysis APD plots have been used by the NTIA in the course
of interference studies and have been described as “a very informative measurand.” (See NTIA Report 01-383.)
It is important to be aware of the limitations of APD plots, and we agree that they are not susceptibility tests and should be viewed in conjunction with detailed simulations, lab measurements, and field measurements supplied by the MBOA.
However, we do still value APD plots (as does the NTIA) for their ability to describe the potency of an interfering waveform, irrespective of the particular modulation and channel coding scheme used
The plotted curves all show rather high (and in some cases extremely high) I/N ratios.
In order to observe differences in susceptibility of as much as 5dB relative to AWGN:
• The I/N ratio must be at least 8dB AND
• The receiver must respond to peak events with a probability as low 10-6 AND
• The bandwidth of the victim must exceed 16MHz
APD analysis proves large impact (5 dB as claimed by Freescale) is only possiblewhen a large bandwidth receiver with no FEC is in extremely close proximity
to a MB-OFDM device. Joint probability of this event is vanishingly small.
• In bandwidths of 4MHz or less, the MB-OFDM waveforms are nearly identical to an ideal AWGN source for any given probability.
• For large bandwidths, the APDs are almost identical regardless of which TFI code is used (1,2,3,1,2,3 or 1,1,3,3,2,2).
jrfoerst
Delete
November, 2004
Slide 51
doc.: IEEE 802.15-04/0641r0
Submission
Summary of APD results
APD analysis is correct and verified using NTIA code APD results for various receiver bandwidths and
different TFI codes provided in back-up slides for more information In bandwidths of 4MHz or less, the MB-OFDM
waveforms are nearly identical to an ideal AWGN source for any given probability.
For large bandwidths, the APDs are almost identical regardless of which TFI code is used (1,2,3,1,2,3 or 1,1,3,3,2,2).
November, 2004
Slide 52
doc.: IEEE 802.15-04/0641r0
Submission
Summary of APD results
A very specific (and unlikely) combination of circumstances must occur to support a required SIR protection difference of 5dB as claimed by opponents of this waiver including: Very wide victim receiver bandwidth Extraordinary and improbable I/N ratios not
anticipated by the 2002 UWB R&O No error correction capability for the victim
receiver.
Under realistic I/Nsys ratios, APD analysis shows MB-OFDM only deviates from WGN by a few dBs a small percentage of time
November, 2004
Slide 53
doc.: IEEE 802.15-04/0641r0
Submission
MB-OFDM Power Levels
November, 2004
Slide 54
doc.: IEEE 802.15-04/0641r0
Submission
Claims regarding Power Level (1)
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 misleading:
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.
November, 2004
Slide 55
doc.: IEEE 802.15-04/0641r0
Submission
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
November, 2004
Slide 56
doc.: IEEE 802.15-04/0641r0
Submission
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
November, 2004
Slide 57
doc.: IEEE 802.15-04/0641r0
Submission
Claim regarding Power Level (2)Freescale claims the waiver would open the door to waveforms with much higher emission levels than the current rules allow. Freescale gives an example of a “3-hop” system that is 12.5% of the time “gated on” and 87.5% of the time “gated off.”
Why this is false:
1. Freescale’s example would clearly violate existing peak power limits and would not be permitted under the rules.
2. The waiver does not seek change to any existing power limits.
3. The waiver narrowly seeks FCC approval to have measurements for a 3-band MB-OFDM system made under authentic operating conditions as it would actually be deployed.
November, 2004
Slide 58
doc.: IEEE 802.15-04/0641r0
Submission
MB-OFDM Bandwidth
November, 2004
Slide 59
doc.: IEEE 802.15-04/0641r0
Submission
Claim Regarding Bandwidth
Freescale claims the MB-OFDM waveform with “hopping” turned off may not meet the minimum 500 MHz bandwidth requirement.
Why this is false:
Each MB-OFDM symbol consists of 122 data-bearing sub-carriers (110 data + 12 pilot). Each sub-carrier is 4.125 MHz from its nearest neighbor.
122 * 4.125 MHz = 503.25 MHz
The MB-OFDM waveform meets the minimum 500 MHz bandwidth requirement at all times with or without frequency sequencing
turned off.
November, 2004
Slide 60
doc.: IEEE 802.15-04/0641r0
Submission
MB-OFDM Technology Advantages for Coexistence
with Existing & Future Services
November, 2004
Slide 61
doc.: IEEE 802.15-04/0641r0
Submission
Benefits of MB-OFDM Systems Superior multipath performance of OFDM signals
Advantages of OFDM well-known to the industry and is used in WiFi, WiMax, DSL, and other communications systems
Implementation much less complex than rake receiver required for impulse radios
Innovative use of spectrum by partitioning into 528 MHz bands (band switching is fundamental to the design) Reduces overall system complexity and power consumption due to
lower bandwidth filters, analog-to-digital and digital-to-analog converters, etc.
Enables CMOS friendly designs utilizing lower bandwidth baseband analog components
Interleaved 3 bands sequenced in time provides 1.5 GHz spectrum use for improved frequency diversity
Enables suppression of strong narrowband interferers at the receiver by utilizing lower bandwidth analog baseband filters to limit compression of ADC (allows for designs with steep filter roll-offs), strong FEC coding, and digital signal processing techniques
November, 2004
Slide 62
doc.: IEEE 802.15-04/0641r0
Submission
Coexistence Benefits of MB-OFDM Systems (1) Spectral emissions advantages
Inherent properties of OFDM waveform produces lower out of band emissions than other types of UWB waveforms
Fine grained ability to sculpt emissions spectrum via software to meet worldwide regulatory requirements and extremely stringent coexistence requirements for some applications (operation within 1 foot of another wireless system or multiple radios in the same device)
3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8
-80
-75
-70
-65
-60
-55
-50
-45
Frequency (GHz)
dB
m/M
Hz
Power Spectral Density Estimate via W elch
3 3.2 3.4 3.6 3.8 4 4.2 4.4 4.6 4.8
-90
-85
-80
-75
-70
-65
-60
-55
-50
-45
Frequency (GHz)
dB
m/M
Hz
Power Spectral Density Estimate via W elch
Added protectionby dropping a whole bandSoftware controlled
‘notch’
November, 2004
Slide 63
doc.: IEEE 802.15-04/0641r0
Submission
Coexistence Benefits of MB-OFDM Systems (2) Why is spectrum flexibility critical?
Desire single solution to support worldwide regulations and interoperability Benefits of scaling (single SKU supports larger population
of devices) Interoperability between devices in different regions (take
a devices from the US to Europe and it can still work via software control mechanisms)
Challenges: different frequency allocations worldwide may require different emissions limits
– Indoor WiMax systems in Europe operate in 3.4-3.6 GHz band
– RAS bands in EU and Japan span large part of 3-10 GHz bands (uncertain what regulatory bodies will require for these bands)
1. As a (potential) IEEE standard, MB-OFDM must show that it is specified to work with the current IEEE 802.15.3 MAC, with minimum modifications.
2. Public statements by both the companies and industry organizations referenced by the MB-OFDM proposers make it clear that they intend to develop and deploy a different MAC layer for their UWB products. This means that the companies and organizations that are referenced as backing the MB-OFDM proposal do not intend to use the 802.15.3a MAC and therefore would not use the 802.15.3a standard.
3. It appears from multiple sources in the popular press as well as MBOA-SIG Press Releases that the MBOA MAC specification will be the only one certified by the WiMedia to work in the MBOA ecosystem. If there is no intention to use the IEEE Std 802.15.3™-2003 and this is merely a blatant attempt to hijack the IEEE brand then I submit that the IEEE 802.15 mandate withdrawal of the Merged Proposal #1 and confirm Merged Proposal #2.
November, 2004
Slide 67
doc.: IEEE 802.15-04/0641r0
Submission
Comment #1: Support of .15.3 MAC ?
The MultiBand OFDM PHY proposal is designed to work with the IEEE 802.15.3 MAC
The proposers of the MB-OFDM solution are not aware of any issues that would prohibit operation of the MB-OFDM PHY with the IEEE 802.15.3 MAC
If the commenter has specific technical concerns about interface of the MB-OFDM proposal to the IEEE 802.15.3 MAC, those detailed comments are solicited
November, 2004
Slide 68
doc.: IEEE 802.15-04/0641r0
Submission
Comment #2: There’s a different MAC
IEEE can not control external organizations nor should that be our goal
The goal of IEEE 802.15.3a is to help organizations and companies by setting standards, not to force anything upon them
The existence of multiple MACs should not be a distraction to the IEEE 802.15.3a deliberations
IEEE 802.15.3a can do a service to the industry by confirming a new PHY standard
November, 2004
Slide 69
doc.: IEEE 802.15-04/0641r0
Submission
Comment #3: WiMedia Certification
The success of a standard often depends on interoperability testing and certification
The IEEE 802 Standards body has abdicated responsibility for testing and certifying compliance of products
Given that, there is no direct control over organizations such as Wi-Fi, DOCSIS, WiMedia, WiMAX, UNH, etc.
IEEE standards are intended to help companies and the population as a whole including organizations like WiMedia
The IEEE should be supportive and appreciative of external organizations that test and certify IEEE standards based products
1. I suggest that the Merged Proposal #1 and Merged Proposal #2 merge and become Merged Proposal #3.
2. The clock frequencies and convolutional coder do not support a common signaling mode.
3. I believe the common signalling mode is a way of providing interoperability and coexistence with other UWB devices.
4. Merge Proposal #2 includes a provision for a base signaling mode that would allow multiple PHYs to coexist. In order for me to vote yes to Merge Proposal #1, there must be some type of coexistence mechanism.
5. The MB-OFDM proposal must make accomodations for the appearance of PHYs in the same space, either by some sort of CSM or by a dual PHY.
6. The best way to break through current dead lock is to adopt a dual PHY standard and let the market choose the better.
November, 2004
Slide 76
doc.: IEEE 802.15-04/0641r0
Submission
Coexistence or Harmonization (1)
I suggest that the Merged Proposal #1 and Merged Proposal #2 merge and become Merged Proposal #3 Customers have indicated preference for a single PHY standard
The clock frequencies and convolutional coder do not support a common signaling mode. CSM is not required for MB-OFDM and will add unnecessary cost and
complexity. Clock frequencies & conv coder do not need to support CSM
I believe the commons signaling mode is a way of providing interoperability and coexistence with other UWB devices See above
Merged Proposal @2 includes provision for a base signaling mord that would allow multiple PHYs to coexist. In order for me to vote yes on Merged Proposal #1, there must be some type of coexistence mechanism See above
November, 2004
Slide 77
doc.: IEEE 802.15-04/0641r0
Submission
Coexistence or Harmonization (2)
The MB-OFDM proposal must make accommodations for the appearance of PHYs in the same space, either by some sort of CSM or by a dual PHY UWB PANs need low power, low cost, and support for QoS.
CSM and/or dual PHYs would unnecessarily impair performance and add cost/power consumption
The best way to break through the current deadlock is to adopt a dual PHY standard and let the market choose the better Customers have indicated they prefer a single PHY to a
dual PHY. The added expense and power consumption brings no benefit to the end user. In WLANs, having FH and DS PHYs only confused the market – no vendor built a viable dual-PHY standard product.
1. The performance in range and survivability even in moderate multipath is absolutely dismal.2. Parallel and serial transport of the same data rate in the same bandwidth can be equally efficient
against white noise, but the performance with multipath is materially weaker. With direct-sequence spreading, the difference is even greater for multipath interference.
3. A single carrier system with “rake” receiver processing will receive and process more power from combined propagation paths than is possible with N multiple parallel paths each carrying 1/N of the message load (before considering the benefits spectrum spreading).
4. The [direct sequence] spreading causes the multipath to appear as an interference signal in particular chips. Errors in some individual chips reduces the power sum or Boolean sum relative to no errors, but does not prevent successful evaluation of the data value carried by that sequence. This tolerance for chip errors is a property not found in OFDM which attempts to get this benefit with FEC. Some fraction of corrupted packets might be saved by FEC, but this will be for those packets with a small number of errors.
5. With MB-OFDM, there will be coverage holes where cancellation fades have occurred, and these will no be helped by more power or better error correction. As a rough estimate based on tests at 5 GHz, there may be 5% of locations where a satisfactory decoding cannot be achieved. At such holes, moving the antenna location a small distance may cause satisfactory signal to reappear.
6. The recent changes to the proposal to map data bits on the guard tones have shown that adding more diversity to the bit-tone mapping could help to improve the poor multipath performance of MB-OFDM. Please come up with a way that can add more diversity to these mappings (especially at higher rates, > 200 Mps) in order to compensate for the degraded performance caused by the Rayleigh-distributed multipath fading. Since the 6 dB degradation (@480 Mbps) identified in various other document has been improved by these recent modifications, please derive the new amount of degradation (e.g. 5 dB?) based on the new mappings for the various data rates proposed.
November, 2004
Slide 80
doc.: IEEE 802.15-04/0641r0
Submission
Multipath Performance
System performance has been compared since March 2003 in standardized channel models CM1-4
MB-OFDM has consistently performed well even in the most severe channel models
Range AWGN LOS: 0 – 4 mCM1
NLOS: 0 – 4 mCM2
NLOS: 4 – 10 mCM3
RMS Delay Spread: 25 ns
CM4
110 Mbps 21.4 m 12.0 m 12.0 m 11.5 m 10.9 m
200 Mbps 14.6 m 7.4 m 7.1 m 7.5 m 6.6 m
480 Mbps 9.3 m 3.2 m 3.0 m N/A N/A
The results speak for themselves: link distance at 110 and 200 Mbps is hardly impacted by multipath
November, 2004
Slide 81
doc.: IEEE 802.15-04/0641r0
Submission
Multipath Performance cont.
So, why the counter claims? Frequency diversity is not inherent in OFDM If all available sub-carriers are used to transmit independent
information (without redundancy), each bit of information is subject to Rayleigh-distributed narrow-band fading
In order to overcome this frequency-domain spreading is needed, which usually implies some redundancy
Why is this not a big issue? Frequency domain spreading in MB-OFDM is provided by a mixture
of repetition coding and convolutional coding Even at 480Mbps (the worst case), sufficient spreading gain is
available to obtain 3m link distances in NLOS channels. At 110Mbps, the scope for spreading has dramatically improved to
approximately 6, partitioned as a factor 3 for FEC and 2 for repetition coding.
1. The earliest availability of silicon for this proposal is 2005. An alternative proposal has ICs available today, which have the ability to be adapted to the precise protocols laid down by the standard, within a very short time of the standard being issued.
2. The DSUWB solution has been shown to work and is commercially available. I will not vote for Merge Proposal #1 unless it can be demonstrated, with real silicon, that it meets the PAR.
3. At least one competing standard has recently geared up it process and is threatening to snatch away a sizeable chunk from this standard’s targeted market. MB-OFDM projects its chipset availability in 2005 (at the earliest). Its counterpart has already cranked out silicon out of the development cycle.
4. It would be interesting to see some, ANY, working hardware demonstrating feasibility of the solution -- even a breadboard, because at this late date I can no longer accept PowerPoint Engineering.
November, 2004
Slide 84
doc.: IEEE 802.15-04/0641r0
Submission
TTM Issues TTM difference between proposals is months, not years.
MB-OFDM chipsets operating at 480Mb/s have been demonstrated over the air, so in some ways, MB-OFDM is ahead of DS-UWB, not behind
MB-OFDM silicon will be available in the market before a draft could complete the balloting process Demonstration silicon is available now Early products will be available in months History shows early chipsets have to be re-spun for standards
compliance anyway
PHYPHY MACMAC
November, 2004
Slide 85
doc.: IEEE 802.15-04/0641r0
Submission
Summary of comments related to market timing (1)
The earliest availability of silicon for this proposal is 2005. An alternative proposal has ICs available today, which have the ability to be adapted to the precise protocols laid down by the standard, within a very short time of the standard being issued. The time difference in availability of silicon is much smaller than has
been stated by MBOA opponents. Commercial availability of chipsets will differ only by a few months, not years. MB-OFDM chipsets will be in the market well before the draft specification could be completed. Note that the IEEE802-SEC has taken the position of being against companies releasing chipsets and calling them "pre-compliant" when a standard has not completed letter ballot and sponsor ballot.
The DSUWB solution has been shown to work and is commercially available. I will not vote for Merge Proposal #1 unless it can be demonstrated, with real silicon, that it meets the PAR. At least one MB-OFDM company has demonstrated MB-OFDM proposal
compliant silicon operating at 480Mb/s over the air. This chipset meets the PAR. May we count on you switching your vote?
November, 2004
Slide 86
doc.: IEEE 802.15-04/0641r0
Submission
Summary of comments related to market timing (2)
At least one competing standard has recently geared up it process and is threatening to snatch away a sizeable chunk from this standard’s targeted market. MB-OFDM projects its chipset availability in 2005 (at the earliest). Its counterpart has already cranked out silicon out of the development cycle. Again, the time difference in availability of silicon is much smaller than
has been stated by MBOA opponents. Commercial availability of chipsets will differ only by a few months, not years. MB-OFDM chipsets will be in the market well before the draft specification could be completed.
It would be interesting to see some, ANY, working hardware demonstrating feasibility of the solution -- even a breadboard, because at this late date I can no longer accept PowerPoint Engineering. We agree. Several MB-OFDM companies now have working silicon. As
mentioned in a previous response, working silicon operating over the air at 480Mb/s has been demonstrated which meets the PAR. We are awaiting something other than Powerpoint for a DS-UWB demonstration
