The technology of combining a number of optical wavelengths and then transmitting the same through a single fibre is called wavelength division multiplexing (WDM). Conceptually, the technology is similar to that of frequency division multiplexing (FDM) used in analogue transmission. Dense wavelength division multiplexing (DWDM) is anew born multiplexing technology in the fibre optic transmission, bringing about a revolution in the bit rate carrying capacity over a single fibre. The emergent of DWDM system is one of the important phenomena in de ....etc

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Frequency Division Multiple Access Used for AMPS and TACS, the two key analog systems and their variants, this system gives each conversation its own unique radio channel. Division of a radio frequency into several channels by splitting the frequency band into distinct segments, which are assigned to various callers. This allows a single base station to serve many callers. For example, a typical AMPS network will have 832 channels spaced approximately 30 kilohertz apart. - Frequency Division Multiple Access, digital transmission technology that ....etc

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i m from anna university doing my 2nd year environmental management. i need to do a project related on environmental. i m much interested on doing project related to ecology or risk assessment or on waste management. so please do help me. ....etc

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Overview
Code division multiple access (CDMA) is a modulation and multiple-access scheme based on spread-spectrum communication. In this scheme, multiple users share the same frequency band at the same time, by spreading the spectrum of their transmitted signals, so that each user's signal is pseudo-orthogonal to the signals of the other users.

CDMA Signals
In a CDMA system, each signal consists of a different pseudorandom binary sequence (called the spreading code) that modulates a carrier, spreading the spectrum of the waveform. A large ....etc

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Introduction
Reducing interference in a cellular system is the most effective approach to increasing radio capacity and transmission data rate in the wireless environment. Therefore, reducing interference is a difficult and important challenge in wireless communications.

In every two-way communication system it is necessary to use separate channels to transmit information in each direction. This is called duplexing. Currently there exist only two duplexing technologies in wireless communications, Frequency division duplexing (FDD) and time ....etc

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This paper deals with the twin concepts of optical networking and dense wavelength division multiplexing. The paper talks about the various optical network architectures and the various components of an all-optical network like Optical Amplifiers, Optical Add/Drop Multiplexers, Optical Splitters etc. Important optical networking concepts like wavelength routing and wavelength conversion are explained in detail. Finally this paper deals with industry related issues like the gap between research and the industry, current and projected market for ....etc

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Definition
Multi Carrier Modulation is a technique for data transmission by dividing a high ?]bit rate data stream is several parallel low bit ]rate data streams and using these low bit rate data streams to modulate several carriers. Multi Carrier Transmission has a lot of useful properties such as delay spread tolerance and spectrum efficiency that encourage their use in untethered broadband communications. OFDM is a multi carrier modulation technique with densely spaced sub carriers that has gained a lot of popularity among the broadband com ....etc

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Definition
Multi Carrier Modulation is a technique for data transmission by dividing a high ?]bit rate data stream is several parallel low bit ]rate data streams and using these low bit rate data streams to modulate several carriers. Multi Carrier Transmission has a lot of useful properties such as delay spread tolerance and spectrum efficiency that encourage their use in untethered broadband communications. OFDM is a multi carrier modulation technique with densely spaced sub carriers that has gained a lot of popularity among the broadband com ....etc

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TDMA, or Time Division Multiple Access was one of the first cell phone digital standards available in the United States. It was the first successor to the original AMPS analog service that was popular throughout the country, and was in popular service from the early-mid 1990's up until roughly 2003 when the last of the TDMA carriers, Cingular and AT&T, switched to the GSM digital standard.

TDMA was a significant leap over the analog wireless service that was in place at the time, and it's chief benefit for carriers was that it used the avail ....etc

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In a WDM system, each of the wavelengths is launched into the fiber, and the signals are demultiplexed at the receiving end. Like TDM, the resulting capacity is an aggregate of the input signals, but WDM carries each input signal independently of the others. This means that each channel has its own dedicated bandwidth; all signals arrive at the same time, rather than being broken up and carried in time slots. The difference between WDM and dense wavelength division multiplexing (DWDM) is fundamentally than does WDM, and therefore has a greater ....etc

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