modulation type of CDMA?
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I don't believe there is modulation within CDMA.  You are confusing yourself.\n\nCode division multiple access (CDMA) is a form of multiplexing (not a modulation scheme) and a method of multiple access that does not divide up the channel by time (as in TDMA), or frequency (as in FDMA), but instead encodes data with a special code associated with each channel and uses the constructive interference properties of the special codes to perform the multiplexing. CDMA also refers to digital cellular telephony systems that make use of this multiple access scheme, such as those pioneered by Qualcomm, or W-CDMA.
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Full duplex transmission is functionally much simpler than half-duplex transmission because it involves no media contention, no collisions, no need to schedule retransmissions, and no need for extension bits on the end of short frames.The only restriction is that there must be a minimum-length interframe gap between successive frames.\n\nAlso, such networks are usually "Switched Networks", which means seperate collision domain for each line, thus eliminating the need of CSMA/CD.
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http://electronics.howstuffworks.com/cell-phone-jammer.htm
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http://en.wikipedia.org/wiki/Modulation_index
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Code division multiple access, it's a broadcasting method used by certian mobile phone carriers. Sprint and Verizon are the two major carriers in the US that use it.
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http://en.wikipedia.org/wiki/Time-division_multiplexing
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This sounds like it came out of a textbook. What is the name of the various propagation models?
519811
it is a unit regarding telephone signals
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You can find all of the relevant standards for GSM and the WCDMA form of 3G on the 3G Partnership Project website at http://www.3gpp.org/specs/numbering.htm. For understanding selection of the base station, look at the 05.08 spec. under http://www.3gpp.org/ftp/Specs/html-info/05-series.htm. This applies specifically to GSM.\n\nIn general, GSM uses a form of ALOHA called "slotted ALOHA" to govern the random access portion of the network access initiation protocol.\n\nCheck out http://www.ee.surrey.ac.uk/Personal/L.Wood/constellations/tables/gsm.html for some overview on GSM. Also http://kbs.cs.tu-berlin.de/~jutta/gsm/js-intro.html.\n\nGoogle "GSM random access protocol" for more papers on Slotted ALOHA.\n\nGoogle "GSM network registration" or "CDMA network registration" for more on the process of finding and registering to the network.\n\nNote that CDMA comes in multiple forms, WCDMA being the 3G extension of GSM and CDMA 2000 being another variety. There may also be other varieties of CDMA...
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1.Low power devices 2.Absence of CSMA/CD 3.SDM using cells\n4.Use of WAP.5.Difference of WAP n TCP/IP.6.frequency reuse
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The simplest form of digitally encoding a telephone bandwidth-limited speech signal is known as pulse code modulation, or PCM.
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Modulation is used in communications because the frequency of the signal must be high enough to travel through the air over great distances.  The power necessary to send a low frequency signal, such as your voice, hundreds of meters away would be too much.  Increasing the frequency by modulating onto a carrier frequency allows us engineers to decrease the required power to send that same message.  Hope this helps.
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Any mobile operator that can support pcmcia GSM cards with UMTS or EDGE services. They are meant for laptops, high DSL speed and high band usage so the cost turns out cheaper for you.
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I know a lot about HF communications, but I don't know what the abbreviation, "Ofdm" means.  You'll have to be more clear...\n\nAddition: "orthogonal frequency division multiplexing"  no wonder I didn't get it.  That's done at UHF/microwave frequencies.  My experience is in the broadcsting (AM/FM/TV) field, and I'm a ham.  HF is 3-30 MHz.
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pulse-code modulation - \na system of radio transmission in which successive electromagnetic waves of short duration are sampled periodically, quantized, and transmitted by code. \nEx. The result was the rapid development of pulse-code modulation ... as a rival to amplitude modulation (AM) and frequency modulation (FM)
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Walsh codes are generated from a Hadamard matrix. Try this link:  http://mathworld.wolfram.com/WalshFunction.html\n\nFor more info on cell phone application, see page 552, Peterson, Ziemer, and Borth, "Introduction to Spread Spectrum Communications", ISBN 0-02-431623-7
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Check out this website for insight.\n\nhttp://home.alltel.net/okrebs/page73.html