In digital communications, chirp spread spectrum (CSS) is a spread spectrum technique that uses wideband linear frequency modulated chirp pulses to encode information.[1] A chirp is a sinusoidal signal whose frequency increases or decreases over time (often with a polynomial expression for the relationship between time and frequency).
Chirp Spread Spectrum iconA linear frequency modulated upchirp in the time domain. Other types of upchirps may increase exponentially over time.
As with other spread spectrum methods, chirp spread spectrum uses its entire allocated bandwidth to broadcast a signal, making it robust to channel noise. Further, because the chirps utilize a broad band of the spectrum, chirp spread spectrum is also resistant to multi-path fading even when operating at very low power. However, it is unlike direct-sequence spread spectrum (DSSS) or frequency-hopping spread spectrum (FHSS) in that it does not add any pseudo-random elements to the signal to help distinguish it from noise on the channel, instead relying on the linear nature of the chirp pulse. Additionally, chirp spread spectrum is resistant to the Doppler effect, which is typical in mobile radio applications.[2]
Usesedit
Chirp spread spectrum was originally designed to compete with ultra-wideband for precision ranging and low-rate wireless networks in the 2.45 GHz band. However, since the release of IEEE 802.15.4a (also known as IEEE 802.15.4a-2007), it is no longer actively being considered by the IEEE for standardization in the area of precision ranging.
Chirp spread spectrum is ideal for applications requiring low power usage and needing relatively low data rates (1 Mbit/s or less). In particular, IEEE 802.15.4a specifies CSS as a technique for use in low-rate wireless personal area networks (LR-WPAN). However, whereas IEEE 802.15.4-2006 standard specifies that WPANs encompass an area of 10 m or less, IEEE 802.15.4a-2007, specifies CSS as a physical layer to be used when longer ranges and devices moving at high speeds are part of your network. Nanotron's CSS implementation was actually seen to work at a range of 570 meters between devices.[3] Further, Nanotron's implementation can work at data rates of up to 2 Mbit/s - higher than specified in 802.15.4a.[4] Finally, the IEEE 802.15.4a PHY standard actually mixes CSS encoding techniques with differential phase shift keyingmodulation (DPSK) to achieve better data rates.
Chirp spread spectrum may also be used in the future for military applications as it is very difficult to detect and intercept when operating at low power.[5]
Very similar frequency swept waveforms are used in frequency modulated continuous wave radars to measure range (distance); an unmodulated continuous wave Doppler radar can only measure range-rate (relative velocity along the line of sight). FM-CW radars are very widely used as radio altimeters in aircraft.
One application of chirp spread spectrum is LoRa.[6][7]
^IEEE Computer Society, (August 31, 2007). IEEE Standard 802.15.4a-2007. New York, NY: IEEE.
^Berni, A. J., & Gregg, W. D. (June 1973). On the utility of chirp modulation for digital signaling, IEEE Transactions on Communications. Volume COM-21, 748-751
About coexistence of IEEE 802.15.4aCSS with IEEE 802.11b/g (2.45 GHz WLAN)
January 01, 1970
chirp, spread, spectrum, digital, communications, chirp, spread, spectrum, spread, spectrum, technique, that, uses, wideband, linear, frequency, modulated, chirp, pulses, encode, information, chirp, sinusoidal, signal, whose, frequency, increases, decreases, o. In digital communications chirp spread spectrum CSS is a spread spectrum technique that uses wideband linear frequency modulated chirp pulses to encode information 1 A chirp is a sinusoidal signal whose frequency increases or decreases over time often with a polynomial expression for the relationship between time and frequency Chirp Spread Spectrum icon A linear frequency modulated upchirp in the time domain Other types of upchirps may increase exponentially over time Contents 1 Overview 2 Uses 3 See also 4 References 5 External linksOverview editAs with other spread spectrum methods chirp spread spectrum uses its entire allocated bandwidth to broadcast a signal making it robust to channel noise Further because the chirps utilize a broad band of the spectrum chirp spread spectrum is also resistant to multi path fading even when operating at very low power However it is unlike direct sequence spread spectrum DSSS or frequency hopping spread spectrum FHSS in that it does not add any pseudo random elements to the signal to help distinguish it from noise on the channel instead relying on the linear nature of the chirp pulse Additionally chirp spread spectrum is resistant to the Doppler effect which is typical in mobile radio applications 2 Uses editChirp spread spectrum was originally designed to compete with ultra wideband for precision ranging and low rate wireless networks in the 2 45 GHz band However since the release of IEEE 802 15 4a also known as IEEE 802 15 4a 2007 it is no longer actively being considered by the IEEE for standardization in the area of precision ranging Chirp spread spectrum is ideal for applications requiring low power usage and needing relatively low data rates 1 Mbit s or less In particular IEEE 802 15 4a specifies CSS as a technique for use in low rate wireless personal area networks LR WPAN However whereas IEEE 802 15 4 2006 standard specifies that WPANs encompass an area of 10 m or less IEEE 802 15 4a 2007 specifies CSS as a physical layer to be used when longer ranges and devices moving at high speeds are part of your network Nanotron s CSS implementation was actually seen to work at a range of 570 meters between devices 3 Further Nanotron s implementation can work at data rates of up to 2 Mbit s higher than specified in 802 15 4a 4 Finally the IEEE 802 15 4a PHY standard actually mixes CSS encoding techniques with differential phase shift keying modulation DPSK to achieve better data rates Chirp spread spectrum may also be used in the future for military applications as it is very difficult to detect and intercept when operating at low power 5 Very similar frequency swept waveforms are used in frequency modulated continuous wave radars to measure range distance an unmodulated continuous wave Doppler radar can only measure range rate relative velocity along the line of sight FM CW radars are very widely used as radio altimeters in aircraft One application of chirp spread spectrum is LoRa 6 7 See also editBluetooth IEEE 802 11 IEEE 802 15 4 IEEE 802 15 4a IEEE 802 16 IEEE 802 20 IEEE 802 22 Spectral efficiency comparison table ZigbeeReferences edit IEEE Computer Society August 31 2007 IEEE Standard 802 15 4a 2007 New York NY IEEE Berni A J amp Gregg W D June 1973 On the utility of chirp modulation for digital signaling IEEE Transactions on Communications Volume COM 21 748 751 http www autoid org SC31 wg5 06 WG5 200603 010 InfoCSS ppt Archived 2007 10 21 at the Wayback Machine Nanotron Mine Test slide 22 Nanotron Technologies 2007 nanoNET chirp based wireless networks Retrieved from http www nanotron com EN docs WP WP CSS pdf permanent dead link The Revenge of Chirp Spread Spectrum Military applications Archived 2008 05 15 at the Wayback Machine RF Modulation Crash Course for Hackers 28 January 2020 Ikpehai Augustine Adebisi Bamidele Rabie Khaled M Anoh Kelvin Ande Ruth E Hammoudeh Mohammad Gacanin Haris Mbanaso Uche M April 2019 Low Power Wide Area Network Technologies for Internet of Things A Comparative Review IEEE Internet of Things Journal 6 2 2225 2240 doi 10 1109 JIOT 2018 2883728 ISSN 2327 4662 S2CID 69444615 External links editDownload the 802 15 standards from IEEE IEEE 802 15 WPAN Low Rate Alternative PHY Task Group 4a TG4a Nanotron Technologies Frequently asked Questions page Nanotron Chirp Spread Spectrum page Nanotron nanoNET Chirp Based Wireless Networks permanent dead link About coexistence of IEEE 802 15 4aCSS with IEEE 802 11b g 2 45 GHz WLAN Retrieved from https en wikipedia org w index php title Chirp spread spectrum amp oldid 1220792100, wikipedia, wiki, book, books, library,
