Transcript 15-04-0140-07-003a-merger2-proposal-ds-uwb-presentation.ppt

July 2004
doc.: IEEE 802.15-04/140r7
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [DS-UWB Proposal Update]
Date Submitted: [July 2004]
Source: [Reed Fisher(1), Ryuji Kohno(2), Hiroyo Ogawa(2), Honggang Zhang(2), Kenichi Takizawa(2)] Company
[ (1) Oki Industry Co.,Inc.,(2)National Institute of Information and Communications Technology (NICT) & NICTUWB Consortium ]Connector’s Address [(1)2415E. Maddox Rd., Buford, GA 30519,USA, (2)3-4, Hikarino-oka,
Yokosuka, 239-0847, Japan]
Voice:[(1)+1-770-271-0529, (2)+81-468-47-5101], FAX: [(2)+81-468-47-5431],
E-Mail:[(1)reedfisher@juno.com, (2)kohno@nict.go.jp, honggang@nict.go.jp, takizawa@nict.go.jp ]
Source: [Michael Mc Laughlin] Company [decaWave, Ltd.]
Voice:[+353-1-295-4937], FAX: [-], E-Mail:[michael@decawave.com]
Source: [Matt Welborn] Company [Freescale Semiconductor, Inc]
Address [8133 Leesburg Pike Vienna, VA USA]
Voice:[703-269-3000], E-Mail:[matt.welborn@freescal.com]
Re: []
Abstract: [Technical update on DS-UWB (Merger #2) Proposal]
Purpose: [Provide technical information to the TG3a voters regarding DS-UWB (Merger #2) Proposal]
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.
Submission
Slide 1
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Outline
• Merger #2 Proposal Overview
– DS-UWB + option of [Common Signaling Mode (CSM) + MBOFDM]
• Complexity/Scalability of UWB implementations
• Spectral control options for DS-UWB
• Performance
Submission
Slide 2
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Overview of DS-UWB Proposal
• One of the goals of Merged Proposal #2 is DS-UWB
and MB-OFDM harmonization & interoperability
through a Common Signaling Mode (CSM)
– High rate modes using either DS-UWB or MB-OFDM
• Best characteristics of both approaches with most flexibility
• A piconet could have a pair of DS and a pair of MB devices
– CSM waveform provides control & interoperation between
DS-UWB and MB-OFDM
• All devices work through an 802.15.3 MAC
– User/device only sees common MAC interface
– Hides the actual PHY waveform in use
Submission
Slide 3
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
The Common Signaling Mode:
What Is The Goal?
• The common signaling mode (CSM) allows the 802.15.3
MAC to arbitrate between multiple UWB PHYs
– It is an “etiquette” to manage peaceful coexistence between the
different UWB PHYs
– Multiple UWB PHYs will exist in the world
• DS-UWB & MB-OFDM are first examples
– CSM improves the case for international regulatory approval
• Common control mechanism for a multitude of applications
• Planned cooperation (i.e. CSM) gives far better QoS and throughput
than allowing un-coordinated operation and interference
– CSM provides flexibility/extensibility within the IEEE standard
• Allows future growth & scalability
• Provides options to meet diverse application needs
• Enables interoperability and controls interference
Submission
Slide 4
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
What Does CSM Look Like?
One of the MB-OFDM bands!
Proposed Common Signaling Mode Band
(500+ MHz bandwidth)
9-cycles per BPSK “chip”
DS-UWB Low Band
Pulse Shape (RRC)
3-cycles per BPSK “chip”
3978
3100
5100
Frequency (MHz)
MB-OFDM (3-band)
Theoretical Spectrum
Submission
Slide 5
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
CSM Specifics
• We have designed a specific waveform for the CSM
–
–
–
–
–
BPSK modulation for simple and reliable performance
Length 24 spreading codes using 442 MHz chip rate
Harmonically related center frequency of 3978 MHz
Rate ½ convolutional code with k=6
Provides 9.2 Mbps throughput
• Extendable up to 110 Mbps using variable code and FEC rates
• 802.15.3 MAC works great with CSM
– CSM can be used for control and beaconing
– Negligible impact on piconet throughput (beacons are <1%)
• Requires negligible additional cost/complexity for either radio
– MB-OFDM already has a DS mode that is used for synchronization
• This proposal is based on DS-UWB operating with a 26 MHz cellphone crystal
– Very low cost yet terrific phase-noise and accuracy (see GSM spec)
Submission
Slide 6
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Overview of DS-UWB Proposal
• DS-UWB proposed as a radio for handheld with
– low-cost,
– ultra high-rate,
– ultra low-power,
• BPSK modulation using variable length spreading
codes
– Scales to 1+ Gbps with low power - essential for mobile &
handheld applications
• Much lower complexity and power consumption
Submission
Slide 7
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Overview of DS-UWB Proposal
• Two wide 50%-bandwidth contiguous bands
• Each captures unique propagation benefits of UWB
• Bandwidth and Center Frequency Programmable
3 4 5 6 7 8 9 10 11
GHz
…
• Low band provides long wavelet
• High band provides short wavelet
• Wavelet = 3 cycles, packed back-to-back
1 1
• Wavelets are modulated with BPSK or QPSK
… • Symbol is made with an N-chip code sequence
• Code is ternary (+1, 0, -1)
-1 -1
N-chips • Result is Not-spiky in either Time or Frequency Domain
volts
time
Submission
Slide 8
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
DS-UWB Signal Generation
Input
Data
Scrambler
K=6 FEC
Encoder
Conv. Bit
Interleaver
K=4 FEC
Encoder
Gray or
Natural
mapping
Bit-to-Code
Mapping
Pulse
Shaping
4-BOK
Mapper
Static
Center
Frequency
Transmitter blocks required to support optional modes
• Data scrambler using 15-bit LFSR (same as 802.15.3)
• Constraint-length k=6 convolutional code
• K=4 encoder can be used for lower complexity at high rates or to
support iterative decoding for enhanced performance (e.g. CIDD)
• Convolutional bit interleaver protects against burst errors
• Variable length codes provide scalable data rates using BPSK
• Support for optional 4-BOK modes with little added complexity
Submission
Slide 9
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Data Rates Supported by DS-UWB
Data Rate
FEC Rate
Code Length
Range (AWGN)
28 Mbps
½
24
29 m
55 Mbps
½
12
23 m
110 Mbps
½
6
18.3 m
220 Mbps
½
3
13 m
500 Mbps
¾
2
7.3 m
660 Mbps
1
2
4.1 m
1000 Mbps
¾
1
5.1 m
1320 Mbps
1
1
2.9 m
Similar Modes defined for high band
Submission
Slide 10
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
DS-UWB Architecture Is Highly Scaleable
1 to 3 bits ADC
Resolution
Pre-Select
Filter
LPF
GA/
VGA
LNA
LPF
Cos
Sin
GA/
VGA
Agile
Clock
1-16 Rake
Fingers
(or more)
Variable
Equalizer
Span
ADC at
Chip Rate
ADC at
Chip Rate
Rake
DFE
Variable
Rate FEC
(or no FEC)
De-interleave
& FEC Decode
Synch/
Track Logic
• DS-UWB provides low & scalable receiver complexity
– ADC can range from 3 bits to 1 bit for super-low power implementation
– Rake pipeline & DFE can be optimized to trade off power & cost in
multipath
• 16 fingers @ 220, 5 fingers @ 500, 2 fingers @ 1326Mbps
• Time duration of DFE scales (shrinks) at shorter range – higher rates.
– FEC can scale w/data rate (k=6 & k=4) or be turned-off for ultra low power
– DFE effectiveness and simplicity proven in shipping chips – 3% of area
Submission
Slide 11
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
UWB System Complexity & Power Consumption
• Two primary factors drive complexity & power
consumption
– Processing needed to compensate for multipath channel
– Modulation requirements (e.g. low-order versus high-order)
• DS-UWB designed to operate with simple BPSK
modulation for all rates
– Receiver functions operate at the symbol rate
– Optional 4-BOK has same complexity and BER performance
• MB-OFDM operates at fixed 640 Mbps (raw)
– Designed to operate at high rate, then use carrier diversity
(redundancy) and/or strong FEC to combat multipath fading
– Diversity not used above 200 Mbps
Submission
Slide 12
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Fundamental Design Approach Differences
• Signal bandwidth leads to different operating regimes
– DS-UWB uses 1.326 GHz bandwidth
– MB-OFDM data BW is 412.5 MHz (100 tones x 4.125 MHz/tone)
• Modulation bandwidth induces different fading statistics
– DS-UWB (single carrier UWB) results in frequency-selective fading
with relatively low power fluctuation (variance)
– MB-OFDM (multi-carrier) creates a bank of parallel channels that
experience flat fading with a Rayleigh distribution (deep fades)
• Motivations for different choices
– Different energy capture mechanism (rake vs. FFT)
– Different ISI compensation (time vs. frequency domain EQ)
• These fundamental differences affect both complexity & flexibility
– Significant impact on implementation, especially at high rates
Submission
Slide 13
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Analog Complexity
MB-OFDM Analog
Components
DS-UWB Analog
Components
Similar
characteristics
-Antenna
-Pre-select filter
-LNA
-Antenna
-Pre-select filter
-LNA
Different
characteristics
-Switchable UNII filter
-Hopping Frequency Gen
-Band filter to reject
adjacent channels
-Static UNII filter
-Static Frequency Gen
-Band filter with no
adjacent channels
• Equivalent analog components have similar complexity
Submission
Slide 14
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Implications of Switchable UNII Filter
(slide copied from Doc 03/141r3,p12)
•
•
MB-OFDM is proposed to use the UNII band for Band Group 2
If the operating BW includes the U-NII band, then interference
mitigation strategies have to be included in the receiver design to
prevent analog front-end saturation.
•
Example: Switchable filter architecture.
– When no U-NII interference is present, use standard pre-select filter.
– When U-NII interference is present, pass the receive signal through a
different filter (notch filter) that suppresses the entire U-NII band.
Off-chip Pre-select Filter
Filter
Switch
Filter TX/RX
Switch Switch
 Problems with this approach:
 Extra switches  more insertion
loss in RX/TX chain.
 More external components 
higher BOM cost.
 More testing time.
TX
RX
Off-chip Notch Filter
Submission
Slide 15
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Band-Select Filter Complexity
DS-UWB Filter
Bandwidth of DS-UWB > 1500 MHz
Uses single fixed bandwidth – filter
provides rejection for OOB noise & RFI
MB-OFDM filter complexity
depends on requirements to reject
adjacent-band signal energy
Data tones
Guard tones
• Depends on whether design
is using the guard tones for
real data or just PN modulated
noise
Submission
Slide 16
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
MB-OFDM Band-Select Filter Complexity
Tight filter •
constraint
Filter must reject
MAI for SOP
If guard tones are used for
useful data, band filter must
have very steep cut-off
– Transition region is very narrow
– Only 5 un-modulated tones
between bands (~21 MHz)
• SOP performance also affected
by filter design – rejection of
adjacent band MAI for SOP
Relaxed • If guard tones not used for data,
filter
then filter constraint is relaxed
constraint
Data tones
Guard tones
Filter response
Submission
Slide 17
– Transition region is a wider (15
tones ~62 MHz)
– Energy in guard band is
distorted (not useful)
– May not meet FCC UWB
requirement for 500 MHz
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Comparison of DS-UWB to MB-OFDM Digital
Baseband Complexity for PHY
• Gate count estimates are based on MB-OFDM proposal team
methodology detailed in IEEE Document 03/449r2
– Gate counts converted to common clock (85.5 MHz) for comparison
• Explicit MB-OFDM gates counts have only been reported by
proposers for a 110/200 Mbps implementation
– Other estimates of MB-OFDM Viterbi decoder and FFT engine are
provided in IEEE Document 03/343r0
• Estimates for MB-OFDM 480 Mbps mode complexity are based
on scaling of FFT engine, equalizer and Viterbi decoder
– MB-OFDM estimates of 480 Mbps power available in 03/268r3
– Details available in IEEE Document 04/164r0
• Estimates for MB-OFDM 960 Mbps mode details are based on
linear scaling of decoder and FFT engine to 960 Mbps
– Assumes 6-bit ADC for 16-QAM operation
• DS-UWB gate estimates are detailed in IEEE Document 03/099r4
– Methodology for estimating complexity of 16-finger rake, equalizer
and synchronization blocks are per MB-OFDM methodology
Submission
Slide 18
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
DS-UWB & MB-OFDM Digital Baseband Complexity
•
Component
MB-OFDM
(Doc 03/268r3
or 03/343r1)
110 Mbps
DS-UWB
16-Finger Rake
220 Mbps Raw
3-Bit ADC
DS-UWB
32-Finger Rake
220 Mbps Raw
3-Bit ADC
Matched filter
Rake [DS] or FFT [OFDM]
100K
26K
45K
Viterbi decoder
108K
54K
54K
Synchronization
30K
30K
Channel estimation
24K
24K
30K
30K
Other Miscellaneous
including RAM
247K
Equalizer
(Freq Domain)
20K
20K
Total gates @ 85.5 MHz
455K
184K
203K
Gate counts are normalized to 85.5 MHz Clock speeds to allow comparison
– Based on methodology presented by MB-OFDM proposal team (03/449r3)
– Other details of gate count computations in Documents 04/099 and 04/256r0
Submission
Slide 19
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Digital Baseband Complexity Comparison at ~1 Gbps
Component
MB-OFDM
960 Mbps
using 16-QAM
DS-UWB
2-Finger Rake
1.326 Gbps
3-bit ADC width
DS-UWB
5-Finger Rake
1.326 Gbps
3-bit ADC width
Matched filter [rake] or
FFT
225K
26K
45K
Viterbi decoder
432K
0K*
0K*
30K
30K
24K
24K
30K
30K
Synchronization
Channel estimation
Other Miscellaneous
including RAM
297K
Equalizer
(Freq
Domain)
50K
50K
Total gates @ 85.5 MHz
954K
160K
179K
Assumptions: MB-OFDM using 6-bit ADC, FFT is 2.25x & Viterbi is 4x of low rate.
*DS-UWB operating with no FEC at 1.362 Gbps
Submission
Slide 20
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Optional Improvement for Interference Mitigation (Approach 1):Analog type
of SSA- Notch generation by using a simple analog delay line:
• Example： Just Two taps delay line
p(t)
D
The output signal x(t) is given by
xt   w0 pt   w1 pt   
w0
where p(t) is a pulse signal , and  is delayed time by a delay line D.
By assuming that coefficients w0 and w1 is time- invariant,
then its signal in frequency domain is given by


X ( f )  w0  w1e j 2f P f 
w1
＋ x(t)
Now, we set w0=1 and w1=a (a is in real value), we obtain


X ( f )  1  ae j 2f P f   1  a cos 2f  j  a sin 2f P f 
A notch is generated at a frequency fn where |X(fn)|2=0, then
a 2  2a cos 2f n  1  0
The solutions are given by a   cos 2f n   sin 2 2f n ,
however, the coefficient a can take only real value. Therefore,
f n  m / 2 （m=1,2,3,…）
a   cos m
As you can see, the coefficient a takes +1 or -1.
It leads simple implementation.
The right figure is an example; a is set to 1 and  is set at 0.116nsec.
Submission
Slide 21
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Optional Improvement for Interference Mitigation (Approach 2):
Analog type of SSA- Notch generation by using a spreading code
• DS-UWB systems
Tx model 2
Tx model 1
b(t)
X
X
c(t)
x(t)
X
p(t)
b(t)
X
X
fc
cl(t)
Spreading code Pulse signal Carrier frequency
long code
(Scrambler)
X
c(t)
x(t)
X
fc
p(t)
Spreading code Pulse signal Carrier frequency
Assumption: Chip rate of a long code is the same as bit rate.
Example: c(t)=[-1 -1 -1 1 1 -1 1 1]
Example: cl(t), c(t)=[-1 -1 -1 1 1 -1 1 1]
• Narrow and Repetitive
• Narrow and Repetitive
4.3GHz (EES)
4.3GHz (EES)
Note: These notches are diminished by a bi-phase modulation.
Submission
Slide 22
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Optimization of coding rate and spreading factor
• Original VS-DS-UWB
(Have you already optimized the combinations ?)
Data rate
FEC Rate
Code Length
Range (AWGN)
110Mbps
1/2
6
18.3m
>
220Mbps
1/2
3
12.9m
>=
FEC Rate
Code Length
Range (AWGN)
1/4
3
13.9m
1/3
4
16.1m
3/4
9
16.9m
1/3
2
11.4m
2/3
4
12.9m
• The other combinations
Data rate
110Mbps
220Mbps
FEC Rate=1/2: [53,75]
FEC Rate=1/3: [47,53,75]
FEC Rate=1/4: [53,67,71,75]
Submission
Slide 23
Constraint length is fixed to 6
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Received Power as a Function Of Node Separation
• Real World DS-UWB Measurements Demonstrate Unique
Benefits of UWB
• Not on a 1/R4 curve -- Small dips, no deep fades
– = Very robust in highly cluttered environments
– = Lower power and minimized potential for interference
0
Measured DS-UWB
-3
1
R2
-6
dB
-9
-12
-15
-18
1
-21
R 3 .5
-24
-27
-30
Submission
4
6
8
10
12
14
16
Slide 24
18
20
22
24
26
feet
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
PDF - 1.368 GHz Fading
PDF - 4 MHz Fading
UWB Fading Distributions Are Key
0.1
Large proportion of deep
fades cause bit errors
4 MHz MB-OFDM carrier BW fading
0.08
0.06
0.04
0.02
0
-30
-25
-20
-15
-10
-5
0
5
10
1.368 GHz BW DS-UWB Fading
0.4
NO deep fades!
0.2
0
-30
Submission
DS-UWB Has
NO Raleigh
Fading
-25
-20
-15
-10
-5
0
Received Energy (dB)
Slide 25
5
10
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Many MB-OFDM Tones Suffer Heavy Fading
True coherent UWB like DS-UWB yields significant fading statistics advantage
100
• MB-OFDM tones
suffer heavy fading
P (Received Energy < x)
25% of Narrow Band Channels
are Faded by 6 dB or more
25%
MB-OFDM
1.4 GHz BW
10-1
10-2
-20
• MB-OFDM does
not coherently
process the
bandwidth
DS-UWB
-15
-10
-5
– FEC across tones is
used
0
5
X (dB)
Submission
Slide 26
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
MB-OFDM Performance Loss Due to Fading
• MB-OFDM performance worsens as data rate increases
• DS-UWB maintains performance within 1 dB of optimal with low
complexity RAKE
-3
10
110 Mbps
Rate 11/32 FEC
with 2x Diversity
MB-OFDM 1.3 dB Loss
200 Mbps
Rate 5/8 FEC
with 2x Diversity
MB-OFDM 3.5 dB Loss
0
10
-4
10
-2
10
BER
-1
10
-3
10
10-5
-4
10
~1.3 dB with MRC
~3.5 dB
-5
10
10-6
2
2.5
3
3.5
SNR (dB)
Submission
4
4.5
-6
10 3
4
5
6
7
8
SNR (dB)
Slide 27
9
0
10
-1
10
-2
10
-3
10
-4
10
-5
10
-6
10
-7
10
-8
10
-9
10
10
5
480 Mbps
Rate 3/4 FEC
with No Diversity
MB-OFDM 6 dB Loss
4 MHz BW CM-3
~6 dB
6
7
8
9 10 11 12 13 14
SNR (dB)
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
1
.1
doc.: IEEE 802.15-04/140r7
DS-UWB Takes Full Advantage of UWB Propagation
DS-UWB Performance Excels As Speed Goes Up
25% of Narrow Band
Performance Difference
Channels are Faded by
6 dB or more
is Natural Consequence
25%
MB-OFDM
of Channel Physics
1.4 GHz BW
P (Received Energy < x)
July 2004
Performance
0
DS-UWB
dB
-1
DS-UWB Does Not Fade
.01
-20
-15
-10
-5
X (dB)
0
DS-UWB Naturally Fits
Needs of Multi-Media &
Handheld Devices
Submission
5
The Faster the Radio,
The More DS is Better
-2
-3
-4
-5
11/32 FEC
2x Diversity
5/8 FEC
2x Diversity
3/4 FEC
No Diversity
-6
100 150 200 250 300 350 400 450 500
Mbps
Slide 28
Speed
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
DS-UWB Uses RAKE Receiver with Equalizer
For Optimum Energy Capture and BER
• Use of RAKE is flexible – in receiver, not transmitter
– Short range (CM-1) does not need RAKE -- only 4 dB loss from ideal
• No-Rake DS is less power & outperforms MB-OFDM (by 2 dB at 480 Mbps)
– Media Server can use 16-finger RAKE and capture all but 1 dB of available
energy in CM-3 – Very high performance
0
CM1
-1
CM2
-2
Captured Energy (dB)
-3
CM3
-4
-5
-6
-7
-8
-9
-10
0
5
10
15
20
25
30
Number of Rake Channels
Submission
Slide 29
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
DS-UWB Complexity Takes Advantage Of Propagation
DS-UWB Power Excels More & More As Data Rate Goes Up
• As UWB Gets Faster
– DS – Gets Simpler
– MB-OFDM Requires
Higher Emissions,
More Complexity
As Range
& Speed
High Cost
Complexity
Simpler
Lower Cost
Speed
DS
(Gets Simpler)
MB-OFDM
(Gets More Complex)
Signal gets
Big
Adapts: Uses less processing
Gain
• Shorter codes
• 3 2 1 bits ADC as speed
goes up
• Less bits in processing
Frozen: Req’s more processing
gain to get to high data rate
regardless of SNR
• Higher order QAM
• More bits in ADC/DAC, FFT/IFFT
Rayleigh
Fading
Adapts:
Turn FEC Off, (or leave it out)
or Use Small (k=4) FEC
Frozen: Serious FEC Required
• Speed of K=7 FEC at high rates
killer power & space @ 1Gbps
Delay Spread
goes Down
Adapts:
DFE covers less time
Frozen:
Band Plan Fixed
Submission
Slide 30
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Multipath Performance for 110 Mbps
110 Mbps
90% Outage
Range (meters)
Mean of Top 90%
Range (meters)
CM1
13.5
16.9
CM2
11.7
14.6
CM3
11.4
13.4
CM4
10.8
13.0
Simulation Includes:
16 finger rake with coefficients quantized to 3-bits
3-bit A/D (I and Q channels)
RRC pulse shaping
DFE trained in < 5us in noisy channel
Front-end filter for Tx/Rx + 6.6 dB Noise Figure
Packet loss due to acquisition failure
Submission
Slide 31
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Multipath Performance for 220 Mbps
220 Mbps
90% Outage
Range (m)
8-finger rake
90% Outage
Range (m)
16-finger rake
Mean of Top
90% Range (m)
8-finger rake
Mean of Top
90% Range (m)
16-finger rake
CM1
8.4
-
10.2
-
CM2
5.8
7.2
8.2
8.8
CM3
4.9
7.0
6.2
8.4
Simulation Includes:
8 finger (16 finger) rake with coefficients quantized to 3-bits
3-bit A/D (I and Q channels)
RRC pulse shaping
DFE trained in < 5us in noisy channel
Front-end filter for Tx/Rx + 6.6 dB Noise Figure
Packet loss due to acquisition failure
Submission
Slide 32
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Multipath Performance for 500 Mbps
500 Mbps
90% Outage
Range (m)
Mean of Top
90% Range (m)
CM1
3.0
4.8
CM2
1.9
3.2
Simulation Includes:
16 finger rake with coefficients quantized to 3-bits
3-bit A/D (I and Q channels)
RRC pulse shaping
DFE trained in < 5us in noisy channel
Front-end filter for Tx/Rx + 6.6 dB Noise Figure
Packet loss due to acquisition failure
Submission
Slide 33
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
AWGN SOP Distance Ratios
Test
Distance
1 Interferer
Distance
Ratio
2 Interferer
Distance
Ratio
3 Interferer
Distance
Ratio
110 Mbps
15.7 m
0.65
0.92
1.16
220 Mbps
11.4 m
0.90
1.28
1.60
500 Mbps
5.3 m
2.2
3.3
-
• AWGN distances for low band
• High band ratios expected to be lower
– Operates with 2x bandwidth, so 3 dB more processing gain
Submission
Slide 34
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Multipath SOP Distance Ratios
Test Transmitter: Channels 1-5
Single Interferer: Channels 6-10
Second Interferer: Channel 99
Third Interferer: Channel 100
110
Mbps
1 Interferer
2 Interferer
Distance Ratio Distance Ratio
3 Interferer
Distance Ratio
CM1
0.66
0.86
1.09
CM2
0.64
0.91
1.14
CM3
0.72
0.97
1.24
• High band ratios expected to be lower (3 dB more processing gain)
Submission
Slide 35
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Conclusions
• Our vision: A single PHY with multiple modes to
provide a complete solution for TG3a
– Base mode that is required in all devices, used for control
signaling: “CSM” for beacons and control signaling
– Higher rate modes also required to support 110 & 200+ Mbps:
– Compliant device can implement either DS-UWB or MBOFDM (or both)
• Increases options for innovation and regulatory
flexibility to better address all applications and markets
• DS-UWB is shown to have equal or better
performance to MB-OFDM in all modes and multipath
conditions – for a fraction of the complexity & power
Submission
Slide 36
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
• Back-up slides
Submission
Slide 37
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Notch generation by using a spreading code
• DS-UWB systems
Tx model
b(t)
X
Frequency domain
X
c(t)
x(t)
X
p(t)
fc
X  f  f c   B f   C  f   P f 
Output spectrum is given by convolution
Spreading code Pulse signal Carrier
Spectrum of a spreading code
Example:
Convolution
Submission
Slide 38

Spectrum of a pulse signal
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Notch generation by using a spreading code
• Experimental result by UWB Test bed
MATLAB results
Submission
UWB testbed outputs
Slide 39
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
All-Digital Architecture DS-UWB Receiver
1 to 3 bits ADC
Resolution
Pre-Select
Filter
LPF
GA/
VGA
LNA
LPF
Cos
Sin
•
GA/
VGA
Agile
Clock
1-16 Rake
Fingers
(or more)
Variable
Equalizer
Span
ADC at
Chip Rate
ADC at
Chip Rate
Rake
DFE
Variable
Rate FEC
(or no FEC)
De-interleave
& FEC Decode
Synch/
Track Logic
DS-UWB Digital architecture provides scalable receiver complexity
– ADC can range from 3 bits to 1 bit for super-low power implementation
– Rake & DFE can be optimized to trade off power & cost in multipath
– FEC can scale data rate or be turned-off for low power operation
– DFE effectiveness and simplicity proven in shipping chips
Submission
Slide 40
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Scalability to Varying Multipath Conditions
•
Critical for handheld (battery operated) devices
– Support operation in severe channel conditions, but also…
– Ability to use less processing (& battery power) in less severe environments
•
Multipath conditions determine the processing required for acceptable
performance
– Collection of time-dispersed signal energy (using either FFT or rake processing)
– Forward error correction decoding & Signal equalization
•
Poor: receiver always operates using worst-case assumptions for multipath
– Performs far more processing than necessary when conditions are less severe
– Likely unable to provide low-power operation at high data rates (500-1000+ Mbps)
•
DS-UWB device
– Energy capture (rake) and equalization are performed at symbol rate
– Processing in receiver can be scaled to match existing multipath conditions
•
MB-OFDM device
– Always requires full FFT computation – regardless of multipath conditions
– Channel fading has Rayleigh distribution – even in very short channels
– CP length is chosen at design time, fixed at 60 ns, regardless of actual multipath
Submission
Slide 41
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
Interference Issues (1)
• Hopped versus non-hopped signal characteristics
– ITS and FCC studies are underway
• Goal is to see if interference characteristics of MB-OFDM are
acceptable for certification (using DS-UWB/noise/IR for comparison)
• Use of PN-modulation to meet 500 MHz BW
– Recent statements by NTIA emphasize importance of minimum
– Desire is to ensure protection for restricted bands
– DS-UWB bandwidth is determined by pulse shape and pulse
modulation
• Spectrum exceeds 1500 MHz
– MB-OFDM bandwidth for data and pilot tones is 466 MHz, guard
tones are used to increase bandwidth to 507 MHz
• Guard tones “carry no useful information”, only to meet BW req’t.
• See authors statements in 802.15-03/267r1 (July 2003, page 12)
Submission
Slide 42
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
NTIA Comments on Using Noise to meet
FCC 500 MHz BW Requirement
•
NTIA comments specifically on the possibility that manufacturer would
intentionally add noise to a signal in order to meet the minimum FCC
UBW 500 MHz bandwidth requirements:
“Furthermore, the intentional addition of unnecessary noise to a signal
would violate the Commission’s long-standing rules that devices be
constructed in accordance with good engineering design and
manufacturing practice.”
• And:
– “It is NTIA’s opinion that a device where noise is intentionally injected
into the signal should never be certified by the Commission.”
• Source: NTIA Comments (UWB FNPRM) filed January 16, 2004
available at http://www.ntia.doc.gov/reports.html
Submission
Slide 43
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave
July 2004
doc.: IEEE 802.15-04/140r7
FCC Rules Regarding Unnecessary Emissions
• FCC Rules in 47 CFR Part 15 to which NTIA refers:
Ҥ 15.15 General technical requirements.
(a) An intentional or unintentional radiator shall be constructed in
accordance with good engineering design and manufacturing
practice. Emanations from the device shall be suppressed as much
as practicable, but in no case shall the emanations exceed the
levels specified in these rules.”
Submission
Slide 44
Kohno NICT, Welborn Freescale, Mc Laughlin
decaWave