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Transcript of 15 03-0460-00-0000-css-tutorial
November 2003
Lampe, Ianelli, NanotronSlide 1
doc.: IEEE 802.15-03-0460-00-0000
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: Introduction to Chirp Spread Spectrum (CSS) TechnologyDate Submitted: November 11, 2003Source: John Lampe, Zbigniew Ianelli Company: Nanotron TechnologiesAddress: Alt-Moabit 61, 10555 Berlin, GermanyVoice: +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.
November 2003
Lampe, Ianelli, NanotronSlide 2
doc.: IEEE 802.15-03-0460-00-0000
Submission
Introduction toChirp Spread Spectrum (CSS)
Technology
presented by
Zbigniew Ianelli Nanotron Technologies GmbH
Berlin, Germany
www.nanotron.com
November 2003
Lampe, Ianelli, NanotronSlide 3
doc.: IEEE 802.15-03-0460-00-0000
Submission
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
November 2003
Lampe, Ianelli, NanotronSlide 4
doc.: IEEE 802.15-03-0460-00-0000
Submission
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
November 2003
Lampe, Ianelli, NanotronSlide 5
doc.: IEEE 802.15-03-0460-00-0000
Submission
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.
Up-Chirp in the time domain(roll-off factor 0.25)
Spectrum of the chirp pulse withbandwidth B and a roll-off factor of 0.25
B
S(f)
f
November 2003
Lampe, Ianelli, NanotronSlide 6
doc.: IEEE 802.15-03-0460-00-0000
Submission
The basic Chirp signal
Bt
BtUtU
)sin(
)( 0
)cos()sin(
)( 00
tBt
BtUtU
)2
cos()(2
0
0 t
tBT
UtU
Chirp pulse:
Sinc pulse (baseband):
Sinc pulse (RF band):
November 2003
Lampe, Ianelli, NanotronSlide 7
doc.: IEEE 802.15-03-0460-00-0000
Submission
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)
November 2003
Lampe, Ianelli, NanotronSlide 8
doc.: IEEE 802.15-03-0460-00-0000
Submission
Scalable Technology
Frequency spreading:
Basic information theory tells us that CSS benefits whenthe bandwidth B of the Chirp pulse is much higher than thedata 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 avery high BT product can be achieved, which transforms into a very robust signal in the channel.
November 2003
Lampe, Ianelli, NanotronSlide 9
doc.: IEEE 802.15-03-0460-00-0000
Submission
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 systemwhere available frequency bandwidth B is much higher thanthe data rate R
November 2003
Lampe, Ianelli, NanotronSlide 10
doc.: IEEE 802.15-03-0460-00-0000
Submission
How to code using CSS
Modulation techniques:
On-Off-Keying (OOK), for example:
Up-Chirp = „1“; Null = „0“allows 2 independent coexisting networks
Superposed Chirps (4 possible states):
Null/Up-Chirp/Down-Chirp/Superposition of Up- and Down-Chirpallows one network with double the data rate
t
f1 0 1 0 0 1
fLO
fHI
Chirp pulse
OOK with Null and Up-Chirp
November 2003
Lampe, Ianelli, NanotronSlide 11
doc.: IEEE 802.15-03-0460-00-0000
Submission
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 beestablished very quickly.
November 2003
Lampe, Ianelli, NanotronSlide 12
doc.: IEEE 802.15-03-0460-00-0000
Submission
Mobility Properties of CSS
Resistance against Doppler effect:The Doppler effect causes a frequency shift of the chirp pulse, whichintroduces a negligible shift of the baseband signal on the time axis.
Example:Bandwidth of the chirp 80 MHzDuration of the chirp 1 µsCenter frequency of the chirp (ISM band) 2.442 GHzRelative speed between transmitter and receiver2000 km/hFrequency shift due to Doppler effect 4.52 kHzEquivalent shift of the message on the time axis 56.5 ps
Note:2000 km/h is equivalent to 1243 miles/hour
November 2003
Lampe, Ianelli, NanotronSlide 13
doc.: IEEE 802.15-03-0460-00-0000
Submission
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-bandinterferences.
Example:Bandwidth B of the chirp 64 MHzDuration time T of the chirp 1 µsCenter frequency of the chirp (ISM band) 2.442 GHzProcessing gain, BT product of the chirp 18 dB
Eb/N0 at detector input (BER=0.001) 14 dB In-band carrier to interferer ratio (C/I @ BER=0.001) -4 dB
November 2003
Lampe, Ianelli, NanotronSlide 14
doc.: IEEE 802.15-03-0460-00-0000
Submission
Some Applications and Measurements ofChirp Spread Spectrum (CSS)
Technology
presented by
John LampeNanotron Technologies GmbH
Berlin, Germany
www.nanotron.com
November 2003
Lampe, Ianelli, NanotronSlide 15
doc.: IEEE 802.15-03-0460-00-0000
Submission
• 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:– Asset tracking (active RFID)– Personnel tracking– Motion detection– Automatic network installation
New Applications / Global Markets
November 2003
Lampe, Ianelli, NanotronSlide 16
doc.: IEEE 802.15-03-0460-00-0000
Submission
• Applications desiring extended range, such as:– Meter Reading– Building Automation– And other longer-range applications where repeaters
are not practical
Enhanced Applications / Markets
November 2003
Lampe, Ianelli, NanotronSlide 17
doc.: IEEE 802.15-03-0460-00-0000
Submission
Evaluation BoardIncludes:
• RF IC
• SAW filter
• Optimized balun for asymmetrical antenna operation
• Crystals
November 2003
Lampe, Ianelli, NanotronSlide 19
doc.: IEEE 802.15-03-0460-00-0000
Submission
CSS vs. DECT
1,00E-06
1,00E-05
1,00E-04
1,00E-03
1,00E-02
1,00E-01
1,00E+00
0 100 200 300 400 500 600 700 800 900 1000
Distance [m]
C SS D EC T
BE
R
Comparing CSS to DECT Outdoors
November 2003
Lampe, Ianelli, NanotronSlide 20
doc.: IEEE 802.15-03-0460-00-0000
Submission
d=23 m, Pout = -15 dBm = 32 µW, G=1,5 dB, BER
= 10-3
d=15 m, Pout = -15 dBm = 32
µW, G=1,5 dB, BER = 10-3
Result: d = 23 m with Pout = -15 dBmCalculated: d = 50 m with Pout = +10 dBm, = 3
Indoor testing with CSS
November 2003
Lampe, Ianelli, NanotronSlide 21
doc.: IEEE 802.15-03-0460-00-0000
Submission
Indoor testing with CSS
d=5 m, Pout = -30 dBm= 1 µW, G = 1,5 dB, BER = 10-4
d=26 m, Pout = 8 dBm = 6,3 mW, G = 1,5 dB, BER =
10 -3
CSS transmits 1Mbps with Pout = 1 µW over 5m and with 6,3mW over 26m
Load-bearing Walls
November 2003
Lampe, Ianelli, NanotronSlide 22
doc.: IEEE 802.15-03-0460-00-0000
Submission
Outdoor Link-Budget
• Link budget without cable losses or antenna-gain, best case: LBbest = 103 dB
• Outdoor free space propagation: distance ~ link-budget with = 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! 0 500 1000 1500 2000 2500 3000
40
50
60
70
80
90
100
110
120Outdoor-Propagation, a = 2,1
distance between transmitter and receiver
atte
nuat
ion
[dB
] fo
r ou
tdoo
r
d1( )r
103
r
m
d = 940 m
November 2003
Lampe, Ianelli, NanotronSlide 23
doc.: IEEE 802.15-03-0460-00-0000
Submission
Testing CSS on Hahneberg, Berlin-Spandau
4626±10 m
3404±10 m
739±10 m
Ref
P1
P2
P3
P4940±10 m
November 2003
Lampe, Ianelli, NanotronSlide 24
doc.: IEEE 802.15-03-0460-00-0000
Submission
Outdoor testing with CSS
4626±10 m Pout = 24 dBm = 250 mW
3404±10 m
739±10 mPout = 7 dBm = 5 mW
Ref
P1
P2
P3
P4
940±10 m Pout = 9 dBm = 7.9 mW
November 2003
Lampe, Ianelli, NanotronSlide 25
doc.: IEEE 802.15-03-0460-00-0000
Submission
Outdoor testing with CSS
Measurement Challenge: Teufelsberg
•6483 m distance
• 7.7 dBm output power
• 18 dB antenna gain
• No FEC
• BER 10E-3
November 2003
Lampe, Ianelli, NanotronSlide 26
doc.: IEEE 802.15-03-0460-00-0000
Submission
0.01 0.1 1 1040
50
60
70
80
90
100
110
120
130Outdoor-Propagation; a = 2.1
distance between transmitter and receive
atte
nuat
ion
[dB
] for
out
door
d1( )r
101
103
120
124
r
km
Output Power @ antenna
Range @ BER=10-3
7 dBm = 5 mW 740 m
9 dBm = 7.9 mW 940 m
26 dBm = 400 mW 6400 m
30 dBm = 1 W 9800 m
Gant = 1 dB Pout = 9 dBm,d = 940 m
Pout = 7 dBm,d = 740 m
Pout = 26 dBm,d = 6.4 km
Pout = 30 dBm,d = 9.8 km
CSS Outdoor Test Summary
November 2003
Lampe, Ianelli, NanotronSlide 27
doc.: IEEE 802.15-03-0460-00-0000
Submission
Need for Standardization
Ole PlougR&D Manager
Central Controls R&DRefrigeration and Air Conditioning
www.danfoss.com
November 2003
Lampe, Ianelli, NanotronSlide 28
doc.: IEEE 802.15-03-0460-00-0000
Submission
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