Transcript 15-03-0460-00-0000-css-tutorial.ppt

November 2003
doc.: IEEE 802.15-03-0460-00-0000
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: Introduction to Chirp Spread Spectrum (CSS) Technology
Date Submitted: November 11, 2003
Source: John Lampe, Zbigniew Ianelli Company: Nanotron Technologies
Address: Alt-Moabit 61, 10555 Berlin, Germany
Voice: +49 30 399 954 135, FAX: +49 30 399 954 188, E-Mail: [email protected]
Re: Discussion of interesting RF technology
Abstract: Tutorial Presentation on CSS for IEEE 802 – part 1
Purpose: November Plenary Tutorial #4.
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
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Introduction to
Chirp Spread Spectrum (CSS)
Technology
presented by
Zbigniew Ianelli
Nanotron Technologies GmbH
Berlin, Germany
www.nanotron.com
Submission
Slide 2
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Contents
•
•
•
•
•
•
•
A brief history of Chirp pulses
Characteristics of Chirp pulses
The basic Chirp signal
Properties of signal forms
Scalable technology
How to code using CSS
Key Properties of CSS
Submission
Slide 3
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
A brief history of Chirp pulses
• Used by whales and dolphins
• Patent for radar applications in 1944 by Prof.
Hoffmann
• Further developed by Sidney Darlington (Lifetime
IEEE Fellow) in 1947 („Pulse Compression Radar“)
• Patented by Canon for data transmission in fiber
optic systems
• Chirp Spread Spectrum for commercial wireless data
transmission is investigated since 1997
Submission
Slide 4
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Characteristics of Chirp pulses
• A chirp pulse is a frequency modulated pulse.
• Its duration is T; within this time the frequency is changing in a
monotonic manner from a lower value to a higher one („Up-Chirp“) or
reverse („Down-Chirp“).
• The difference between these two frequencies is a good
approximation for the bandwidth B of the chirp pulse.
S(f)
f
B
Spectrum of the chirp pulse with
bandwidth B and a roll-off factor of 0.25
Submission
Up-Chirp in the time domain
(roll-off factor 0.25)
Slide 5
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
The basic Chirp signal
Chirp pulse:
U0
t 2
U (t ) 
cos( 0t 
 )
2
BT
Sinc pulse (baseband):
U (t )  U 0
sin( Bt )
Bt
Sinc pulse (RF band):
U (t )  U 0
Submission
Slide 6
sin( Bt )
cos( 0t   )
Bt
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Properties of signal forms in the air and
baseband interfaces
Chirp pulses for the RF channel:
• High robustness (BT>>1)
• Wideband signal
• Constant envelope of the RF waveform
• Constant, uniform PSD (Power Spectral Density)
well controlled spectrum in very simple way
Sinc pulses in the baseband:
• High speed (Bδ=1)
• Easy signal processing (threshold detector)
Submission
Slide 7
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Scalable Technology
Frequency spreading:
Basic information theory tells us that CSS benefits when
the bandwidth B of the Chirp pulse is much higher than the
data rate R: B >> R
Time spreading:
The data rate can scale independently of the BT product.
The duration T of the Chirp pulse can be chosen freely. A signal with a
very high BT product can be achieved, which transforms into a very
robust signal in the channel.
Submission
Slide 8
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Scalable Technology (continued)
Excellent range – data rate scalability:
Preferred for system where range and/or data rate requirement
varies rapidly.
Especially promising for wideband or ultra wideband system
where available frequency bandwidth B is much higher than
the data rate R
Submission
Slide 9
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
How to code using CSS
f
Modulation techniques:
fHI
On-Off-Keying (OOK), for example:
1 0 1 0 0 1
fLO
t
Up-Chirp = „1“; Null = „0“
allows 2 independent coexisting networks
Superposed Chirps (4 possible states):
Chirp pulse
Null/Up-Chirp/Down-Chirp/
Superposition of Up- and Down-Chirp
allows one network with double the data rate
Submission
Slide 10
OOK with Null and Up-Chirp
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Key Properties of CSS
High robustness:
Due to the high BT product, chirp pulses are very resistant against
disturbances.
Multipath resistant:
Due to the broadband chirp pulse, CSS is very immune against
multipath fading; CSS can even take advantage of RF echoes.
Low power consumption:
CSS allows the designer to choose an analog implementation,
which often consumes much less power.
Low latency:
CSS needs no synchronization; a wireless connection can be
established very quickly.
Submission
Slide 11
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Mobility Properties of CSS
Resistance against Doppler effect:
The Doppler effect causes a frequency shift of the chirp pulse, which
introduces a negligible shift of the baseband signal on the time axis.
Example:
Bandwidth of the chirp
Duration of the chirp
Center frequency of the chirp (ISM band)
Relative speed between transmitter and receiver
Frequency shift due to Doppler effect
Equivalent shift of the message on the time axis
80 MHz
1 µs
2.442 GHz
2000 km/h
4.52 kHz
56.5 ps
Note:
2000 km/h is equivalent to 1243 miles/hour
Submission
Slide 12
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Coexistence Properties of CSS
Immune to in-band interferer:
Scalable processing gain (determined by BT product of the chirp)
enables selection of appropriate immunity level against in-band
interferences.
Example:
Bandwidth B of the chirp
Duration time T of the chirp
Center frequency of the chirp (ISM band)
Processing gain, BT product of the chirp
Eb/N0 at detector input (BER=0.001)
In-band carrier to interferer ratio (C/I @ BER=0.001)
64 MHz
1 µs
2.442 GHz
18 dB
14 dB
-4 dB
Submission
Lampe, Ianelli, Nanotron
Slide 13
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Some Applications and Measurements of
Chirp Spread Spectrum (CSS)
Technology
presented by
John Lampe
Nanotron Technologies GmbH
Berlin, Germany
www.nanotron.com
Submission
Slide 14
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
New Applications / Global Markets
•
Applications requiring mobility faster than 11 mph, such as:
– Tire pressure
– Assets in vehicles (in-car communications)
– Drive-by
• Drop boxes
• Drive-by AMR
– Toll booths
•
Applications requiring robustness or fewer retransmissions in multipath
environments, such as:
–
–
–
–
–
•
Industrial mission-critical
Airplanes
Ships / engine rooms
Gaming
New WINA alliance one example of this need
Applications requiring ranging accuracy better than 0.5 meters, such as:
–
–
–
–
Submission
Asset tracking (active RFID)
Personnel tracking
Motion detection
Automatic network installation
Slide 15
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Enhanced Applications / Markets
• Applications desiring extended range, such as:
– Meter Reading
– Building Automation
– And other longer-range applications where repeaters
are not practical
Submission
Slide 16
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Evaluation Board
Includes:
• RF IC
• SAW filter
• Optimized balun for
asymmetrical antenna
operation
• Crystals
Submission
Slide 17
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Comparing CSS to DECT Outdoors
CSS vs. DECT
1,00E+00
CSS
DECT
1,00E-01
BER
1,00E-02
1,00E-03
1,00E-04
1,00E-05
1,00E-06
0
100
200
300
400
500
600
700
800
900
1000
Distance [m]
Submission
Slide 19
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Indoor testing with CSS
Result:
d = 23 m with Pout = -15 dBm
Calculated: d = 50 m with Pout = +10 dBm, a = 3
Submission
Slide 20
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Indoor testing with CSS
d=5 m, Pout = -30 dBm= 1 µW, G = 1,5 dB, BER = 10-4
Load-bearing Walls
CSS transmits 1Mbps with Pout = 1 µW over 5m and with 6,3mW over 26m
Submission
Slide 21
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Outdoor Link-Budget
• Link budget without cable losses or antenna-gain, best
case: LBbest = 103 dB
Outdoor-Propagation, a = 2,1
120
110
100
attenuation [dB] for outdoor
• Outdoor free space
propagation: distance ~ linkbudget with a = 2.1 … 2.3
• But:
Outdoor propagation is not
always free space
propagation, due to e.g. hills,
trees, houses, …
• Therefore:
Measurements have to be
done!
90
d1( r )
103
d = 940 m
80
70
60
50
40
0
500
1000
1500
2000
2500
r
m
distance between transmitter and receiver
Submission
Slide 22
Lampe, Ianelli, Nanotron
3000
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Testing CSS on Hahneberg, Berlin-Spandau
P2
P3
3404±10 m
P1
4626±10 m
739±10 m
P4
940±10 m Ref
Submission
Slide 23
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Outdoor testing with CSS
P2
3404±10 m
P3
P1
4626±10 m
Pout = 24 dBm = 250 mW
739±10 m
Pout = 7 dBm = 5 mW
P4
Ref
940±10 m
Pout = 9 dBm = 7.9 mW
Submission
Slide 24
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Outdoor testing with CSS
Measurement Challenge: Teufelsberg
•6483 m distance
• 7.7 dBm output power
• 18 dB antenna gain
• No FEC
• BER 10E-3
Submission
Slide 25
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
CSS Outdoor Test Summary
Outdoor-Propagation; a = 2.1
130
Pout = 30 dBm,
d = 9.8 km
120
110
Pout = 26 dBm,
d = 6.4 km
attenuation [dB] for outdoor
100
Gant = 1 dB
Output Power
@ antenna
7 dBm =
d1( r )
101
90
103
120
Range @
BER=10-3
740 m
9 dBm = 7.9 mW
940 m
26 dBm = 400 mW
6400 m
Submission
W
Pout = 9 dBm,
d = 940 m
80
124
5 mW
30 dBm = 1
Pout = 7 dBm,
d = 740 m
70
60
50
40
0.01
0.1
9800 m
1
r
Slide 26
km
distance between transmitter and receive
Lampe, Ianelli, Nanotron
10
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Need for Standardization
Ole Ploug
R&D Manager
Central Controls R&D
Refrigeration and Air Conditioning
www.danfoss.com
Submission
Slide 27
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Summary
• Introduced CSS technology
• Explained behavior and benefits
• Suggested some additional applications
that can be satisfied
• Shown test results that demonstrate
some of CSS’ capabilities
• Shown one customer’s application
requirements
Submission
Slide 28
Lampe, Ianelli, Nanotron
November 2003
doc.: IEEE 802.15-03-0460-00-0000
Conclusions
• CSS has qualities of both spread
spectrum and UWB.
• CSS enhances robustness and range
• CSS adds mobility
• CSS can be implemented with today’s
technologies
• CSS is a global solution
Submission
Slide 29
Lampe, Ianelli, Nanotron