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cdma: Definition and Recommended Links

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Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply 'CDMA'), that use CDMA as their underlying channel access methods.

One of the basic concepts in data communication is the idea of allowing several transmitters to send information simultaneously over a single communication channel. This allows several users to share a bandwidth of frequencies. This concept is called multiplexing. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency. CDMA is a form of 'spread-spectrum' signaling, since the modulated coded signal has a much higher data bandwidth than the data being communicated.

Source: Wikipedia (http://en.wikipedia.org/wiki/CDMA)

other great electronics sites:ee toolbox site

• • cdma
    • Code division multiple access (CDMA) is a channel access method utilized by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne and CDMA2000 (which are often referred to as simply 'CDMA'), that use CDMA as their underlying channel access methods.

      One of the basic concepts in data communication is the idea of allowing several transmitters to send information simultaneously over a single communication channel. This allows several users to share a bandwidth of frequencies. This concept is called multiplexing. CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code) to allow multiple users to be multiplexed over the same physical channel. By contrast, time division multiple access (TDMA) divides access by time, while frequency-division multiple access (FDMA) divides it by frequency. CDMA is a form of 'spread-spectrum' signaling, since the modulated coded signal has a much higher data bandwidth than the data being communicated.

      Source: Wikipedia (http://en.wikipedia.org/wiki/CDMA)

      (Note: The Electronic Engineers Toolbox provides an alternative set of featured links for this word at http://www.cera2.com/cdma.htm)

      Featured Links:

      The ABCs of Spread Spectrum -- A Tutorial

      Over the last eight or nine years a new commercial marketplace has been emerging. Called spread spectrum, this field covers the art of secure digital communications that is now being exploited for commercial and industrial purposes. In the next several years hardly anyone will escape being involved, in some way, with spread spectrum communications. Applications for commercial spread spectrum range from 'wireless' LAN's (computer to computer...
      http://sss-mag.com/ss.html

      CDMA Certification Forum

      The CDMA Certification Forum (CCF) is a global forum consisting of leading organizations within the telecommunications industry working towards improving the way CDMA2000 devices are prepared for commercialization. Using a streamlined and globally standardized certification process, the CCF will enable devices to be adequately tested and certified to be ready for commercialization in an affordable and timely manner.
      http://www.globalccf.org/

      White Paper: CDMA Network Technologies: A Decade of Advances and Challenges

      This paper will briefly describe the origins of CDMA technology and the emergence of 3G implementations such as cdma2000 1X and cdma2000 1x EV-DO. An overview of network topology is included, with a detailed explanation of the role of each element and interface in the network and of protocol testing to address the changing requirements of the network.
      http://www.tek.com/ir/whitepaper/WP_CDMA.pdf

      CDMA Development Group

      The CDMA Development Group (CDG) is an international consortium of companies who have joined together to lead the adoption and evolution of CDMA wireless systems around the world. The CDG is comprised of the world's leading CDMA service providers and manufacturers.
      http://www.cdg.org/

      What is CDMA-2000 1xRTT?

      CDMA-2000 1xRTT is a 3G wireless technology based on the CDMA platform. The 1x in 1xRTT refers to 1x the number of 1.25MHz channels. The RTT in 1xRTT stands for Radio Transmission Technology. The CDMA-2000 1xRTT protocol was developed by Qualcomm. CDMA-2000 1xRTT is a CDMA version of the IMT-2000 standard which was developed by the International Telecommunication
      http://www.tech-faq.com/cdma-2000-1xrtt.shtml

      Wideband Code Division Multiple Access (W-CDMA)

      For a mobile communication system, a key parameter is the system capacity. A number of methods to increase system capacity in a W-CDMA network are discussed. This tutorial presents results from different antenna pattern parameters and sectorization techniques for optimizing the maximum number of active subscribers.
      http://www.iec.org/online/tutorials/wcdma/

      CDMA Online

      CDMA IS-95 Implementation and Operational Issues. CDMA Call processing: 5 mins in the Life of a CDMA Handset. CDMA Optimization Seminars: Our newly upgraded CDMA Optimization Series includes Drive Test Examples, Optimization and Trade-offs. It explains and provides practical tips on how to Fine-tune CDMA Networks for Optimum Performance.
      http://www.cdmaonline.com/

      myRF.org - Free Telecommunications Books

      Introduction to Telecommunications Network Engineering * Introduction to RF Equipment and System Design * Wireless A to Z * Introduction to 3G Mobile Communications * Introduction to RF Propagation * Theory of Code Division Multiple Access Communication * Theory and Applications of OFDM and CDMA: Wideband Wireless Communications * Signal Processing for Mobile Communications Handbook * Mobile and Wireless Systems Beyond 3G: Managing New...
      http://www.myrf.org/

      CDMA Overview

      For radio systems there are two resources, frequency and time. Division by frequency, so that each pair of communicators is allocated part of the spectrum for all of the time, results in Frequency Division Multiple Access (FDMA).
      http://www.umtsworld.com/technology/cdmabasics.htm

      Which Technology is Better: GSM or CDMA?

      Introduction Before deciding which technology is superior, let's talk a little more about these two tecnologies: CDMA: stands for Code Division Multiple Access. Both data and voice are separated from signals using codes and then transmited using a wide frequency range. Because of this, there are more space left for data transfer (this was one of the reasons why CDMA is the prefered technology for the 3G generation, which is broadband...
      http://www.hardwaresecrets.com/article/151

      Explanation: these links are provided as part of our EE glossary project, which seeks to identify the most prominent keywords in embedded systems, embedded software, realtime and rtos, dsp (digital signal processing), system-on-a-chip, microprocessors and microcontrollers, and other constituent elements for embedded systems. While we seek to keep most of the links up-to-date, the user is refered to other primary electronic-based search sites such as: cera2.com, embedded.com, or EDN Magazine. If you have any suggestions of links or definitions, please email!

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