Introduction to WCDMA



Properties of the Spread Spectrum

• Transmission bandwidth is much larger than information bandwidth.
• Bandwidth does not depend on the informational signal.
• Processing gain = Transmitted bandwidth/ Information bandwidth.
• Classification:
– Direct sequence: Data is scrambled by user specific pseudo noise code at the
transmitter side.
– Frequency Hopping: The signal is spread by changing the frequency over the
transmitted time of the signal:
• Fast frequency ....etc

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Presented by:
Rodger E. Ziemer


3G CDMA - WCDMA and cdma2000
Rules for Efficient Multiple Access
Three laws
 Know the channel
 Minimize interference to others
 Mitigate interference received from others
 Requirements of wireless multiple access
 Channel measurement
 Channel control and modification
 Multiple user channel isolation
Why CDMA?
 Higher capacity
 Improved performance in multipath by diversity
 Lower mobile transmit power = longer battery life
 ....etc

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please help me out soon within 12 hrs as i have to attend an exam please help me out.......... ....etc

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Efficient Channelization Code Management in WCDMA




Introduction

In order to support variable rates of data multimedia in CDMA system, a set of orthogonal codes with
different lengths must be used, because the rate of information varies and the available bandwidth is
fixed . It is possible to support higher data rates in direct sequence CDMA (DS-CDMA) systems
by assigning multiple fixed-length orthogonal codes to a call . In an alternative CDMA scheme
witch is ....etc

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WCDMA System



Air Interfaces for 3rd Generation Systems


Since 1985, ITU (International Telecommunications Union) has
been developing IMT-2000, previously termed Future Public Land
Mobile Telephone System (FPLMTS).
In 1992, the World Administrative Radio Conference (WARC) of
the ITU identified the frequencies around 2 GHz for future 3rd
generation mobile systems, both terrestrial and satellite.
Within the ITU, the 3rd generation systems are called
....etc

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In third generation WCDMA systems, shared channels allow many users to jointly utilize a single Orthogonal Variable Spreading Factor (OVSF) code. In this paper, we propose a Scheduling Algorithm with Dynamic Priority Assignment (DPA) which is designed for the Downlink-Shared channel (DSCH) of 3G WCDMA systems and operates within a cross layer framework. The DPA scheduler has low computational complexity and is able to provide QoS differentiation among traffic flows based on their delay sensitivity. Through the cross layer framework, DPA takes i ....etc

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Efficiency Improvement of WCDMA Base Station Transmitters using Class-F power amplifiers


Muthuswamy Venkataramani



(ABSTRACT)
Universal Mobile Telecommunications Systems (UMTS) is the preferred third generation (3G) communication standard for mobile communications and will provide worldwide coverage, a convenient software technology and very high data rate. The high data rate, especially, requires the use of bandwidth-efficient modulation schemes such as Quadrature Phase Shift Keying (QPSK). But ....etc

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Please show me links where i can see open source wcdma stack
Godspower Inibu ....etc

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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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Power control is one of the technologies used to utilize the radio resources as efficient as possible in WCDMA. The transmission power is adjusted to transmit with the lowest power level possible while the required received signal quality is maintained. Since there are large variation in channel quality over time, the power has to be adjusted to compensate for these variations. During moments of bad channel conditions a high transmission power has to be used which will to a greater extent interfere with other users in the system.To solve this ....etc

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