Code-division multiple access - Revision history

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2025-08-25T12:17:18Z

Removed URL that duplicated identifier. Removed access-date with no URL. Removed parameters. | Use this bot. Report bugs. | Suggested by Headbomb | Linked from Wikipedia:WikiProject_Academic_Journals/Journals_cited_by_Wikipedia/Sandbox | #UCB_webform_linked 451/1032

← Previous revision		Revision as of 12:17, 25 August 2025
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	The technology of code-division multiple access channels has long been known.		The technology of code-division multiple access channels has long been known.
	===United States===		===United States===
	In the US, one of the earliest descriptions of CDMA can be found in the summary report of Project Hartwell on "The Security of Overseas Transport", which was a summer research project carried out at the [[Massachusetts Institute of Technology]] from June to August 1950.<ref name=Scholtz_1982May_IEEE>{{cite journal\| author=Robert A. Scholtz\| date=May 1982~~\| url=https://ieeexplore.ieee.org/document/1095547~~\| title=The Origins of Spread-Spectrum Communications\| journal=[[IEEE Transactions on Communications]]\| volume=30\| issue=5\| pages=822–854\| doi=10.1109/TCOM.1982.1095547~~\| access-date=30 January 2022\| url-access=subscription~~}}</ref> Further research in the context of [[Radio jamming\|jamming]] and [[Electronic counter-countermeasure\|anti-jamming]] was carried out in 1952 at [[MIT_Lincoln_Laboratory\|Lincoln Lab]].<ref name=Price_Shannon_19820728>{{cite web\| author=Robert Price\| date=28 July 1982\| url=https://ethw.org/Oral-History:Claude_E._Shannon\| title=Oral-History: Claude E. Shannon\| publisher=[[Engineering and Technology History Wiki]]\| access-date=30 January 2022}}</ref>		In the US, one of the earliest descriptions of CDMA can be found in the summary report of Project Hartwell on "The Security of Overseas Transport", which was a summer research project carried out at the [[Massachusetts Institute of Technology]] from June to August 1950.<ref name=Scholtz_1982May_IEEE>{{cite journal\| author=Robert A. Scholtz\| date=May 1982\| title=The Origins of Spread-Spectrum Communications\| journal=[[IEEE Transactions on Communications]]\| volume=30\| issue=5\| pages=822–854\| doi=10.1109/TCOM.1982.1095547}}</ref> Further research in the context of [[Radio jamming\|jamming]] and [[Electronic counter-countermeasure\|anti-jamming]] was carried out in 1952 at [[MIT_Lincoln_Laboratory\|Lincoln Lab]].<ref name=Price_Shannon_19820728>{{cite web\| author=Robert Price\| date=28 July 1982\| url=https://ethw.org/Oral-History:Claude_E._Shannon\| title=Oral-History: Claude E. Shannon\| publisher=[[Engineering and Technology History Wiki]]\| access-date=30 January 2022}}</ref>

	===Soviet Union===		===Soviet Union===

209.205.72.95: disambiguate chip and chirp in digital signals, it's not a typo

2025-06-28T10:01:51Z

disambiguate chip and chirp in digital signals, it's not a typo

← Previous revision		Revision as of 10:01, 28 June 2025
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	It can be also used as a channel or medium access technology, like [[ALOHA]] for example or as a permanent pilot/signalling channel to allow users to synchronize their local oscillators to a common system frequency, thereby also estimating the channel parameters permanently.		It can be also used as a channel or medium access technology, like [[ALOHA]] for example or as a permanent pilot/signalling channel to allow users to synchronize their local oscillators to a common system frequency, thereby also estimating the channel parameters permanently.

	In these schemes, the message is modulated on a longer spreading sequence, consisting of several chips (0s and 1s). Due to their very advantageous auto- and crosscorrelation characteristics, these spreading sequences have also been used for radar applications for many decades, where they are called [[Barker code]]s (with a very short sequence length of typically 8 to 32).		In these schemes, the message is modulated on a longer spreading sequence, consisting of several [[Chip_(CDMA)\|chips]] (0s and 1s). Due to their very advantageous auto- and crosscorrelation characteristics, these spreading sequences have also been used for radar applications for many decades, where they are called [[Barker code]]s (with a very short sequence length of typically 8 to 32).

	For space-based communication applications, CDMA has been used for many decades due to the large path loss and Doppler shift caused by satellite motion. CDMA is often used with [[binary phase-shift keying]] (BPSK) in its simplest form, but can be combined with any modulation scheme like (in advanced cases) [[quadrature amplitude modulation]] (QAM) or [[orthogonal frequency-division multiplexing]] (OFDM), which typically makes it very robust and efficient (and equipping them with accurate ranging capabilities, which is difficult without CDMA). Other schemes use subcarriers based on [[binary offset carrier modulation]] (BOC modulation), which is inspired by [[Manchester code]]s and enable a larger gap between the virtual center frequency and the subcarriers, which is not the case for OFDM subcarriers.		For space-based communication applications, CDMA has been used for many decades due to the large path loss and Doppler shift caused by satellite motion. CDMA is often used with [[binary phase-shift keying]] (BPSK) in its simplest form, but can be combined with any modulation scheme like (in advanced cases) [[quadrature amplitude modulation]] (QAM) or [[orthogonal frequency-division multiplexing]] (OFDM), which typically makes it very robust and efficient (and equipping them with accurate ranging capabilities, which is difficult without CDMA). Other schemes use subcarriers based on [[binary offset carrier modulation]] (BOC modulation), which is inspired by [[Manchester code]]s and enable a larger gap between the virtual center frequency and the subcarriers, which is not the case for OFDM subcarriers.

74.96.154.36 at 05:38, 11 June 2025

2025-06-11T05:38:23Z

← Previous revision		Revision as of 05:38, 11 June 2025
Line 12:		Line 12:
	It can be also used as a channel or medium access technology, like [[ALOHA]] for example or as a permanent pilot/signalling channel to allow users to synchronize their local oscillators to a common system frequency, thereby also estimating the channel parameters permanently.		It can be also used as a channel or medium access technology, like [[ALOHA]] for example or as a permanent pilot/signalling channel to allow users to synchronize their local oscillators to a common system frequency, thereby also estimating the channel parameters permanently.

	In these schemes, the message is modulated on a longer spreading sequence, consisting of several chips (~~0es~~ and ~~1es~~). Due to their very advantageous auto- and crosscorrelation characteristics, these spreading sequences have also been used for radar applications for many decades, where they are called [[Barker code]]s (with a very short sequence length of typically 8 to 32).		In these schemes, the message is modulated on a longer spreading sequence, consisting of several chips (0s and 1s). Due to their very advantageous auto- and crosscorrelation characteristics, these spreading sequences have also been used for radar applications for many decades, where they are called [[Barker code]]s (with a very short sequence length of typically 8 to 32).

	For space-based communication applications, CDMA has been used for many decades due to the large path loss and Doppler shift caused by satellite motion. CDMA is often used with [[binary phase-shift keying]] (BPSK) in its simplest form, but can be combined with any modulation scheme like (in advanced cases) [[quadrature amplitude modulation]] (QAM) or [[orthogonal frequency-division multiplexing]] (OFDM), which typically makes it very robust and efficient (and equipping them with accurate ranging capabilities, which is difficult without CDMA). Other schemes use subcarriers based on [[binary offset carrier modulation]] (BOC modulation), which is inspired by [[Manchester code]]s and enable a larger gap between the virtual center frequency and the subcarriers, which is not the case for OFDM subcarriers.		For space-based communication applications, CDMA has been used for many decades due to the large path loss and Doppler shift caused by satellite motion. CDMA is often used with [[binary phase-shift keying]] (BPSK) in its simplest form, but can be combined with any modulation scheme like (in advanced cases) [[quadrature amplitude modulation]] (QAM) or [[orthogonal frequency-division multiplexing]] (OFDM), which typically makes it very robust and efficient (and equipping them with accurate ranging capabilities, which is difficult without CDMA). Other schemes use subcarriers based on [[binary offset carrier modulation]] (BOC modulation), which is inspired by [[Manchester code]]s and enable a larger gap between the virtual center frequency and the subcarriers, which is not the case for OFDM subcarriers.

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2025-05-25T22:05:41Z

Open access bot: url-access updated in citation with #oabot.

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