CDMA Technology

Abstract :

CDMA was developed by QUALCOMM Incorporated, a company in San Diego, California. QUALCOMM engineers decided to do something different and applied spread spectrum techniques to a multiple access system, which ultimately became CDMA.
In spread spectrum, instead of giving each person a channel, or each group of 3 or 8 people a time slot, CDMA puts everyone in the same channel at the same time.
At first thought, it would seem to be an impossible task to make work, but it does work. The reason it works is expla ....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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The world is demanding more from wireless communication technologies than ever before. More people around the world are subscribing to wireless services and consumers are using their phones more frequently. Exciting Third-Generation (3G) wireless data services and applications - such as wireless email, web,digital picture taking/sending and assisted-GPS position location applications - and wireless networks have also arrived and asked to do much more than just a few years ago. This is where CDMA technology fits in. CDMA consistently provides be ....etc

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pls sendfull report immediately on ultra capacitors to [email protected] ,with ppt ....etc

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(Code Division Multiple Access) A method for transmitting real-time signals over a shared portion of the spectrum. The foremost application of CDMA is the digital cellular phone technology that operates in the 800MHz band and 1.9GHz . Unlike GSM and TDMA, which divides the spectrum into different time slots CDMA uses a spread spectrum technique to assign a code to each conversation. After the speech codec converts voice to digital, CDMA spreads the voice stream over the full 1.25MHz bandwidth of the CDMA channel coding each stream separately s ....etc

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The Internet and Mobile Wireless are the defining technologies of our times. Today, they are converging and promising to dramatically reshape society. Mobile Internet services will help people work, entertain, and communicate anytime, anywhere-using a variety of devices such as cell phones, Personal Digital Assistants (PDAs), and laptops. Driven by the Wireless Internet?s enormous potential and reacting to declining Mobile voice revenues per subscriber, operators are pegging their future growth on Wireless Internet services.

While operators ....etc

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W-CDMA (Wideband Code-Division Multiple Access), an ITU standard derived from Code Division Multiple Access, is officially known as IMT-2000 direct spread. W-CDMA is a third-generation mobile wireless technology that promises much higher data speeds to mobile and portable wireless devices than commonly offered in today's market. The present seminar discusses the applicability of WCDMA system with respect to 3G mobile system. The reason for the popularity of spread spectrum technique is addressed and the evolu ....etc

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Multiple access (MA) schemes are used to simultaneously share available bandwidth in communication systems. In conventional MA applications a finite and contiguous amount of spectrum which is designated for a particular service is allocated to multiple users. Therefore, the use of designated radio spectrum is unconstrained and can be utilized in many ways to achieve maximum efficiency. Time division multiple access (TDMA), frequency division multiple access (FDMA), and code division multiple access (CDMA) are the three major MA techniques. In r ....etc

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TCP-Aware Channel Allocation in CDMA Networks-IEEE Jan. 2009

Abstract

explores the use of rate adaptation in cellular networks to maximize throughput long-lived TCP sessions. We focus on the problem of maximizing the throughput of TCP connections and propose a joint optimization of MAC and physical layer parameters with respect to TCP sending rate. In particular, propose a simple TCP-aware channel scheduler that adapts the wireless channel rate to changes in the TCP sending rate and explore its performance for both single and multiple co ....etc

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