1. 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: j.lampe@nanotron.com 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.
2. Introduction to Chirp Spread Spectrum (CSS) Technology presented by Zbigniew Ianelli Nanotron Technologies GmbH Berlin, Germany www.nanotron.com
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6. The basic Chirp signal Chirp pulse: Sinc pulse (baseband): Sinc pulse (RF band):
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8. 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.
9. 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
10. 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-Chirp allows one network with double the data rate t f 1 0 1 0 0 1 f LO f HI Chirp pulse OOK with Null and Up-Chirp
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14. Some Applications and Measurements of Chirp Spread Spectrum (CSS) Technology presented by John Lampe Nanotron Technologies GmbH Berlin, Germany www.nanotron.com
20. d=23 m, P out = -15 dBm = 32 µW, G=1,5 dB, BER = 10 -3 d=15 m, P out = -15 dBm = 32 µW, G=1,5 dB, BER = 10 -3 Result: d = 23 m with P out = -15 dBm Calculated: d = 50 m with P out = +10 dBm, = 3 Indoor testing with CSS
21. Indoor testing with CSS d=5 m, P out = -30 dBm= 1 µW, G = 1,5 dB, BER = 10 -4 d=26 m, P out = 8 dBm = 6,3 mW, G = 1,5 dB, BER = 10 -3 CSS transmits 1Mbps with P out = 1 µW over 5m and with 6,3mW over 26m Load-bearing Walls
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23. Testing CSS on Hahneberg, Berlin-Spandau 4626 ±10 m 3404±10 m 739±10 m Ref P1 P2 P3 P4 940±10 m
24. Outdoor testing with CSS 4626 ±10 m P out = 24 dBm = 250 mW 3404±10 m 739±10 m P out = 7 dBm = 5 mW Ref P1 P2 P3 P4 940±10 m P out = 9 dBm = 7.9 mW
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26. CSS Outdoor Test Summary G ant = 1 dB P out = 9 dBm, d = 940 m P out = 7 dBm, d = 740 m P out = 26 dBm, d = 6.4 km P out = 30 dBm, d = 9.8 km 6400 m 26 dBm = 400 mW 9800 m 940 m 740 m Range @ BER=10 -3 30 dBm = 1 W 9 dBm = 7.9 mW 7 dBm = 5 mW Output Power @ antenna
27. Need for Standardization Ole Ploug R&D Manager Central Controls R&D Refrigeration and Air Conditioning www.danfoss.com
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Editor's Notes
Here is the same spectra represented in two extremely different ways. The sinc pulse is also used in some UWB implementations, so there are some similarities.
Benefits of constant power: 1. Cheaper to implement. 2. Lower human exposure.
CSS is appropriate for global markets because it operates well in global bands, such as 2.4. Robustness – latency intolerant
Used for some of the measurements
Page In the heart of Berlin. Cars, fences and street lamps in the trees along the street.
Page Output power is about 13 dBir. Only two measurement points because we have no BER measurement – these are finished consumer products. 10 -3 (first cracks in voice transmitted), then complete loss of voice transmission. Dect is also 2.4 GHz. Output power is 22 – 24 dBm Result – CSS has 2.5 times longer range
Page European office. Hall walls are stronger, inner walls are lighter. G = antenna gain (asymmetric rod antenna) Blue = Tx, Red = Rx. Locations not cherry-picked.
Page -93 dBm input sensitivity, +10 dBm output power = 103 dB link budget 2 is the perfect free space value. We used 2.1 as a conservative estimate.
Page Rod antennas were used for P1 and P4, directional antennas (18 dBi antenna gain) for P2 and P3. P2 is next to a railroad station with a 900 MHz / 1.8 GHz GSM base station. P3 is on top of a shopping center with two computer stores and a cell phone store. Ref is about 3 miles from Tegel international airport. There were many disturbers – ground radar from the airport, etc.
Page At P1, we varied the height of the Rx from 1.5 – 5 meters, saw no difference. P2 output power was approximately the same as P3, perhaps a bit lower. P3 had Bluetooth disturbers from the stores below.
This is the old eavesdropping site in Berlin during the cold war, now an airport radar location.
Page Measurements indicate that with 30 dBm output power, CSS can reach 9.8 km.
