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Introduction to 3G:

The third generation (3G) will be digital multimedia broadband mobile communications offering wireless voice, video and graphics, audio and other information.

The mobile communications industry has evolved in three stages, and thus three generations mobile phones have emerged so far. Each has provided more flexibility and ease of use than before.

 • (1G) Analog: analog phones helped make voice calls within their country without roaming facilities.

 • (2G) phone systems added digital mobile fax, data and messaging capabilities, and voice telephone service in many countries worldwide roaming.

 • (3G) multimedia services add high-speed data transfer for mobile devices, enabling video, audio and other applications (including Internet services) through mobile phones.

3G, based on WCDMA technology, will bring these incompatible standards together.

3G Features:

1. With 3G, the information is divided into separate packages, but related before transmission and reassembled at the receiving end. Packet switched data formats are much more common than their circuit switched counterparts.

2. The World Wide Web (WWW) is becoming the primary communications interface. People access the Internet for entertainment, services, and information gathering, the company intranet to access information and connecting with colleagues and the extranet for customers and ISPs. These are all derivatives of the World Wide Web aimed at connecting different communities interest. Information and other resources stored on remote Web servers that serve the diverse needs of humans through web browsers at their ends.

3. Speeds up to 2 Megabits per second (Mbps) are achievable with 3G. The data rates depend on the environment, the call is made en, however, only indoors and in stationary environments that these types of data rates available. For high mobility, data rates of 144 kbps is expected to available.

Implementation of 3G WCDMA:

Broadband Code-Division Multiple-Access (W-CDMA) is one of the leading technologies for implementation of third generation (3G) cellular systems.

The application of W-CDMA is a technical challenge due to its complexity and versatility. The complexity of W-CDMA systems can be viewed from different angles: the complexity of each single algorithm, the complexity of the system in general and computational complexity a receiver. W-CDMA link-level simulations are more than 10 times more compute intensive than current second-generation simulations. In the W-CDMA different users can simultaneously transmit different data types and data rates can even vary over time. UMTS networks need to support all existing services secondhand generation and many new applications and services.

Different modes of operation in WCDMA:

In WCDMA, there are two different modes of operation possible:

 • TDD: In this method, duplex, uplink and downlink transmissions are made on the same frequency band using synchronized time intervals. Thus, the slots in a physical channel are divided into transmission and reception part.

 • FDD: the uplink and downlink transmissions use two separate frequency bands for this method to both sides. A pair of spaced frequency bands allocated specified for the connection. Since different regions have different frequency allocation schemes, the ability to operate in either FDD or TDD mode allows the efficient use of the available spectrum

Key Features WCDMA:

The main features of operation of the WCDMA radio interface listed below:

1. Support for data transmission at high speed: 384 kbps with wide area coverage, 2 Mbps with local coverage.

2. Added service flexibility: support of multiple parallel services variable rate for each connection.

3. Both Frequency Division Duplex (FDD) and Time Division Duplex (TDD).

4. Built-in support for future capacity and coverage to improve the technologies such as adaptive antennas, advanced receiver structures and transmitter diversity.

5. Support of inter frequency hand over and surrender to other systems, including hand to GSM.

6. Efficient packet access.

WCDMA Specifications

Multiple Access System: DS-CDMA

Duplex Scheme: FDD / TDD

Packet Mode Dual Access: (Combined and dedicated channel)

Multirate system of variable rate: variable spreading factor and multi-code

Chip Rate: 3.84 Mcps

Carrier Spacing: 4.4-5.2 MHz (200 kHz carrier raster)

Frame Length: 4.4-5.2 MHz (200 kHz carrier raster

Inter Base station synchronization: FDD: No need for synchronization

TDD: synchronization necessary

3G mobile communication with the WCDMA:

Providing good building coverage plays an important role in attracting and retaining mobile subscribers. In general, coverage of macro network extends into buildings, but must be complemented by dedicated building systems. Data from increased capacity and the ability of third-generation networks to provide high speed data services increased demands on the cellular network. Subscribers have great expectations for third-generation services.

Therefore, when introduced, new services that (at least) will be available everywhere second-generation services can be found. Nevertheless, many third-generation networks deployed to date have been designed primarily to provide a good coverage in outdoor environments, not in buildings. As a result, users of the first implementations of wideband code division multiple access (WCDMA) third generation services pales by comparison a second generation services.

Conclusion:

The main advantage is larger capacity through more efficient use of spectrum. Major capability allows wireless WCDMA network to handle increased call density at lower cost. Implementation of WCDMA improved voice quality, system performance and life mobile battery.

Reference:

1. Rakesh Arora, "Recent advances in wireless networking data.

2. Hans Beijner, "the importance of building solutions in third generation networks."

3. Juha Korhonen, "Introduction 3G mobile communications.

4. Ramjee Prasad, "Towards a global 3G system"

5. Jeffrey Bannister, Paul Mather, Sebastian Coope, Convergence Technologies for 3G "

6. Mr. Karim, Mohsen Sarraf, "W CDMA and CDMA2000 for 3G mobile networks"

7. Keiji Tachikawa, "W CDMA mobile communication system"

8. R Ramachandran, "Evolution of 3G mobile communications"

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V Umadevi Chezhian
Lecturer
Department of Computer Science
College of Business and Economics
University of Asmara
Asmara
State of Eritrea
NE Africa

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