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Topic: Code division multiple access

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	CDMA \| TelecomSpace
		CDMA is a form of spread-spectrum, a family of digital communication techniques that have been used in military applications for many years.
		CDMA receivers do not eliminate analog processing entirely, but they separate communication channels by means of a pseudo-random modulation that is applied and removed in the digital domain, not on the basis of frequency.
		The code is generated pseudo-randomly, the receiver knows how to generate the same code, and correlates the received signal with that code to extract the data.
	www.telecomspace.com /cdma.html (1008 words)

	Code division multiple access - Biocrawler (Site not responding. Last check: )
		Generically (as a multiplexing scheme), code division multiple access (CDMA) is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference.
		CDMA (the multiplexing technique) is used as the principle of the W-CDMA air interface.
		This makes CDMA ideally suited to large numbers of transmitters each generating a relatively small amount of traffic at irregular intervals, as it avoids the overhead of continually allocating and deallocating a limited number of orthogonal time slots or frequency channels to individual transmitters.
	www.biocrawler.com /encyclopedia/CDMA (986 words)

	(WO/1998/059458) CHAOTIC DIGITAL CODE-DIVISION MULTIPLE ACCESS (CDMA) COMMUNICATION SYSTEMS
		A code-division access device as in claim 24 wherein said chaotic seed signal is generated by chaotic circuit having the same preselected initial conditions as assigned to said second code-division multiple access device with which communication is established.
		A code-division multiple access communication system as in any one of claims 32-41 wherein: said medium is ether; and said input/output transducer in each of said first and second code-division multiple access devices is an antenna to apply said modulated signal to, and receive a radiated signal from, said ether.
		A code-division multiple access communication system as in any one of claims 32-41 wherein: said medium is a wire cable; and said input/output transducer in each of said first and second code-division multiple access device includes an appropriate connector to apply said modulated signal to, and receive a signal from, said wire cable.
	www.wipo.int /pctdb/en/wo.jsp?IA=WO1998059458&DISPLAY=CLAIMS (1762 words)

	CDMA
		For cellular telephony, CDMA is a digital multiple access technique specified by the Telecommunications Industry Association (TIA) as "IS-95." In March 1992, the TIA established the TR-45.5 subcommittee with the charter of developing a spread-spectrum digital cellular standard.
		CDMA has been used in many military applications, such as anti-jamming (because of the spread signal, it is difficult to jam or interfere with a CDMA signal), ranging (measuring the distance of the transmission to know when it will be received), and secure communications (the spread spectrum signal is very hard to detect).
		CDMA is a "spread spectrum" technology, which means that it spreads the information contained in a particular signal of interest over a much greater bandwidth than the original signal.
	www.geocities.com /rizj03/cdma.html (1484 words)

	Orthogonal code division multiple access communications systems - Patent 4494228
		An orthogonal code division multiple-access communications system comprised of a plurality of transceivers respectively employing orthogonal noise code mate pairs of a type having autocorrelation functions upon detection which when linearly added together compress into a lobeless impulse and wherein the same single time slot is utilized by all of the users in the system.
		Such codes are of particular applicability in a mobile subscriber access system for a plurality of users which transmit to a central node at a first frequency which retransmits therefrom to the intended recipient at a second frequency.
		Code (a) is generated by means of time delay circuits 56, 58 and 60 as well as four phase control circuits 62, 64, 66 and 68 which couple to a linear adder 70.
	www.freepatentsonline.com /4494228.html (6003 words)

	Lighting the Local Area: Optical Code-Division Multiple Access and Quality of Service Provisioning
		CDMA was originally investigated in the context of radio frequency (RF) communications systems, and was first applied to the optical domain in the mid-1980s by Prucnal, Salehi, and others [2—4].
		The most efficient use of the multiple access channel is not achieved by creating many orthogonal or nearly orthogonal subchannels; rather, it is better for every user to superimpose its signal onto the shared channel, and for a decorrelator to determine the unique hypothesis that would give rise to the measured superposition of signals.
		Preskewing would ensure that the code arrived with the correct temporal alignment only at its intended destination; in fact, if such preskewing were integrated with the code design process, it might well be possible to exploit the effects of dispersion in effectively randomizing the received signal at all but the intended destination node.
	www.comsoc.org /~ni/private/2000/nov/stok.html (4522 words)

	Code Division Multiple Access
		CDMA is presently on par with TDMA in the U.S. with respect to total number of users [4].
		Also realized was the fact that "...optimal multiple access communications requires that all user stations (mobiles) regulate their transmitter powers to the lowest levels that will achieve adequate signal quality." [6].
		CDMA has better potential for data movement, which is obviously a big plus as we move into an era of wireless e-mail, internet, and other data transfer needs.
	oak.cats.ohiou.edu /~mh865/final.htm (1375 words)

	Code division multiple access system providing enhanced load and interference based demand assignment service to users ...
		An access controller receives a data burst request (from either a requesting mobile station or from an external network already in connection with the mobile station) requesting a first data rate in excess of the basic data rate B allocated to a mobile station of a first cell.
		In another feature, the access controller processes a data burst request received from a mobile station involved in a soft handoff between multiple base stations and negotiates with those base stations for an increased data rate which may be granted to the requesting mobile station.
		The access controller receives a data burst request (from either a requesting mobile station or from a network, external to the system, already in connection with the mobile station) requesting a first data rate in excess of the basic data rate B allocated to a mobile station of a first cell.
	www.freepatentsonline.com /6069883.html (13019 words)

	Mobile/Cellular Technology - CDMA IS-95 (Code Division Multiple Access) Digital Mobile Telephone Standard
		CDMA (code division multiple access) is a second-generation digital mobile telephone standard which takes a different approach to the other, competing standards: GSM (Global System for Mobile Communications) and TDMA (Time Division Multiple Access).
		The codes are shared by both the mobile station and the base station and are called "pseudo-random code sequences".
		TDMA (time division multiple access) and GSM systems have to add an extra stage of encryption to the signal to ensure privacy, whereas encryption is inherent to the CDMA system.
	www.mobilecomms-technology.com /projects/cdma_is95 (882 words)

	Research Project Code Division Multiple Access at the Department of Telecommunications at the University of ...
		CDMA is the third multiple access technique among the two more classical schemes FDMA (Frequency Division Multiple Access) and TDMA (Time Division Multiple Access).
		This multiplication with a sequence of higher frequency also yields a resulting signal of higher rate, therefore the spectrum of the original signal is spread by the factor SF.
		CDMA is less prone to deep multipath fading caused by transmissions arriving at the receiver that have followed different propagation paths.
	www.ant.uni-bremen.de /research/cdma (1783 words)

	Code Division Multiple Access - Wikipédia
		CDMA-2000 (Code Division Multiple Access) est une évolution du système CDMAOne utilisé aux États-Unis d'Amérique.
		En remplaçant chaque bit par son code (disons 10 bits par code), on multiplie le débit transmis par 10, ce qui donne 100 kbit/s.
		Alors que le CDMA et CDMA-2000 étaient des systèmes de répartition en mode circuits, l'introduction du mode paquet et l'élargissement du spectre ont débouché sur le Wideband-CDMA (W-CDMA) couche physique du standard UMTS.
	fr.wikipedia.org /wiki/Code_Division_Multiple_Access (1016 words)

	Compareindia-code division multiple access (Site not responding. Last check: )
		Code Division Multiple Access (CDMA) is a very new concept in wireless communications, which has lead to improve both; the system capacity as well as the service quality.
		CDMA phones are just the right option for people who don't travel much as these mobile phones do not have a full roaming facility on the handsets.
		CDMA technology contributes to overall voice quality, which is further enhanced by the microprocessors inside the phones.
	www.compareindia.com /tips/code-division-multiple-access.htm (696 words)

	Code division multiple access - Wikipedia, the free encyclopedia
		This CDMA system is frequently confused with a similar but incompatible technology called Wideband Code Division Multiple Access (W-CDMA) which forms the basis of the W-CDMA air interface.
		In other words, Asynchronous CDMA is ideally suited to a mobile network where large numbers of transmitters each generate a relatively small amount of traffic at irregular intervals.
		By comparison, Asynchronous CDMA transmitters simply send when they have something to say, and go off the air when they don't, keeping the same PN signature sequence as long as they are connected to the system.
	en.wikipedia.org /wiki/Code_division_multiple_access (2938 words)

	* CDMA (Code Division Multiple Access) (Site not responding. Last check: )
		CDMA has been used in many military applications, such as anti-jamming (because of the spread signal, it is difficult to jam or interfere with a CDMA signal), ranging (measuring the distance of the transmission to know when it will be received), and secure communications (the spread spectrum signal is very hard to detect).
		CDMA is a form of spread-spectrum, a family of digital communication techniques that have been used in military applications for many years.
		CDMA receivers do not eliminate analog processing entirely, but they separate communication channels by means of a pseudo-random modulation that is applied and removed in the digital domain, not on the basis of frequency.
	tony.donetsk.ua /mac/_telco/cdma/cdma.html (2443 words)

	Define CDMA - Code Division Multiple Access
		Meaning of CDMA - "Code Division Multiple Access", is a digital wireless transmission technology that allows for a large amount of users to share access to a single radio channel.
		CDMA is most broadly used by the protocol IS-95, also known by it's "brand" name cdmaOne, as a cellular phone technology.
		CDMA is a form of multiplexing, allowing numerous signals to occupy a single transmission channel.
	www.birds-eye.net /definition/c/cdma-code_division_multiple_access.shtml (734 words)

	What is CDMA? - a definition from Whatis.com - see also: code-division multiple access
		As the term implies, CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth.
		CDMA networks use a scheme called soft handoff, which minimizes signal breakup as a handset passes from one cell to another.
		The original CDMA standard, also known as CDMA One and still common in cellular telephones in the U.S., offers a transmission speed of only up to 14.4 Kbps in its single channel form and up to 115 Kbps in an eight-channel form.
	searchtelecom.techtarget.com /sDefinition/0,,sid103_gci213842,00.html (467 words)

	Basics of Code Division Multiple Access (CDMA) - Rao: Browse Publications: SPIE.org
		Code division multiple access (CDMA) has proven to be a viable enabling technique for the simultaneous transmission and reception of data over a shared channel.
		Code division multiple access (CDMA) has proven itself to be a viable technique for enabling the simultaneous transmission and reception of data over a shared channel.
		The concept of code division multiplexing is introduced in Chapter 3 through orthogonal waveforms, and the notion of direct sequence spreading is then explained.
	spie.org /x648.xml?product_id=626142&origin_id=x651 (763 words)

	CDMA (Code-Division Multiple Access) : Teledatacom Glossary
		CDMA refers to any of several protocols used in so-called second-generation (2G) and third-generation (3G) wireless communications.
		As the term implies, CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth.
		The frequency of the transmitted signal is then made to vary according to a defined pattern (code), so it can be intercepted only by a receiver whose frequency response is programmed with the same code, so it follows exactly along with the transmitter frequency.
	www.artesyncp.com /resources/glossary/cdma.html (154 words)

	Code Division Multiple Access (CDMA)(Prasanth Bollepally)
		Code Division Multiple Access (CDMA) is a digital technology that provides crystal clear voice quality in a new generation of wireless communications products and services.
		A CDMA vocoder varies compression of the voice signal into one of four data rates based on the rate of the user's speech activity.
		CDMA phones use a hard handoff when moving from a CDMA system to an analog system because soft handoffs are not possible in analog systems.
	web.indstate.edu /ect/fall02/PrashanthBollepally.htm (1579 words)

	CDMA2000 (Code Division Multiple Access)
		The Third Generation of mobile communications (3G) is a concept outlined in a set of proposals called International Mobile Telecommunications-2000 (IMT2000), to define an "anywhere, anytime" standard for the future of universal personal communications.
		Ideal for mobile professionals needing remote access to email, the Internet and corporate networks, CDMA2000 1X allows users to increase productivity and stay connected to customers and colleagues while they are working away from their office.
		The CDMA path to 3G is through CDMA2000 1X, then on to 1xEV-DO and 1xEV-DV.
	www.novatelwireless.com /technology/cdma2000-1x.html (276 words)

	Code Division Multiple Access
		Also realized was the fact that "...optimal multiple access communications requires that all user stations (mobiles) regulate their transmitter powers to the lowest levels that will achieve adequate signal quality." (
		CDMA also has better potential for data movement, and this is obviously a big plus as we move into an era of wireless e-mail, internet, and other data transfer needs.
		CDMA’s method of spread spectrum is called direct sequence spread spectrum, or DSSS (the other is frequency hopping).
	oak.cats.ohiou.edu /~mh865/rdraft.htm (778 words)

	Definition: code-division multiple access (Site not responding. Last check: )
		code-division multiple access (CDMA): A coding scheme, used as a modulation technique, in which multiple channels are independently coded for transmission over a single wideband channel.
		(188) Note 1: In some communication systems, CDMA is used as an access method that permits carriers from different stations to use the same transmission equipment by using a wider bandwidth than the individual carriers.
		On reception, each carrier can be distinguished from the others by means of a specific modulation code, thereby allowing for the reception of signals that were originally overlapping in frequency and time.
	www.its.bldrdoc.gov /fs-1037/dir-007/_1033.htm (150 words)

	CDMA (Code Division Multiple Access) (Linktionary term)
		CDMA is an access technology and air interface for wireless digital cellular systems and other communication systems.
		CDMA was originally developed by Qualcomm, although the underlying technology has been around since the 1940.
		CDMA was approved as a digital multiple access technique for cellular telephony by the TIA (Telecommunications Industry Association) in 1993.
	www.linktionary.com /c/cdma.html (338 words)

	Wiley::Theory of Code Division Multiple Access Communication
		Code division multiple access (CDMA) communication is rapidly replacing time- and frequency-division methods as the cornerstone of wireless communication and mobile radio.
		Theory of Code Division Multiple Access Communication provides a lucid introduction and overview of CDMA concepts and methods for both the professional and the advanced student.
		Emphasizing the role CDMA has played in the development of wireless communication and cellular mobile radio systems, the author leads you through the basic concepts of mobile radio systems and considers the different principles of multiple access–time division, frequency division, and code division.
	www.wiley.com /WileyCDA/WileyTitle/productCd-0471457124.html (233 words)

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