Introduction to 3G:

Third Generation (3G) will be digital mobile multimedia offering broadband mobile communications with voice, video and graphics, audio and other information.

The mobile communications industry has evolved in three stages, and consequently, three generations of mobile phones have emerged so far. Each has provided more flexibility and usability than the one before.

o (1G) Analog: Analog phones helped to make voice calls within the country itself without roaming services.

o (2G) Digital mobile phone systems have added fax, data, and messaging capabilities, as well as voice phone service in many countries that offer global roaming.

o (3G) Multimedia services add high-speed data transfer to mobile devices, enabling new video, audio and other applications (including Internet services) via mobile phones.

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

3G Features:

1. With 3G, information is broken into separate but related packets before being transmitted 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 main communication interface. People access the Internet for entertainment, services, and information gathering, the intranet to access business information and connect with colleagues, and the extranet to access customers and suppliers. All of these are derivatives of the World Wide Web intended to connect different communities of interest. Information and other resources are stored on remote web servers, which serve the various needs of humans through web browsers at their endpoints.

3. Speeds of up to 2 Megabits per second (Mbps) can be achieved with 3G. Data transmission speeds will depend on the environment; however, the call is made only indoors and in stationary environments where these types of data speeds will be available. For high mobility, data rates of 144 kbps are expected to be available.

Implementation of WCDMA in 3G:

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

The implementation of W-CDMA will be 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 individual algorithm, the complexity of the overall system, and the computational complexity of a receiver. W-CDMA link layer simulations are more than 10 times more computationally intensive than current second generation simulations. On the W-CDMA interface, different users can simultaneously transmit at different data rates, and data rates can even vary over time. UMTS networks must support all current second generation services and many new applications and services.

Different modes of operation in WCDMA:

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

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

o FDD: Uplink and downlink transmissions use two separate frequency bands for this duplex method. A pair of frequency bands with specified spacing is assigned for a connection. Since different regions have different frequency allocation schemes, the ability to operate in FDD or TDD mode allows for efficient utilization of the available spectrum.

WCDMA key features:

The key operational characteristics of the WCDMA radio interface are listed below:

1. Supports high data rate transmission: 384Kbps with wide area coverage, 2Mbps with local coverage.

2. High service flexibility: support of multiple parallel variable rate services in each connection.

3. Frequency division duplex (FDD) and time division duplex (TDD).

4. Built-in support for future capacity and coverage enhancement technologies such as adaptive antennas, advanced receiver fabrics, and transmitter diversity.

5. Support transfer between frequencies and transfer to other systems, including transfer to GSM.

6. Efficient access to packages.

WCDMA Technical Specifications

Multiple Access Scheme: DS-CDMA

Duplex scheme: FDD/TDD

Dual mode packet access: (combined and dedicated channel)

Multiple Rate/Variable Rate Scheme: Variable Spread Factor and Multiple 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

Synchronization between base stations: FDD: No synchronization needed

TDD: Synchronization required

3G mobile communication technology with WCDMA:

Providing good coverage inside buildings plays an important role in attracting and retaining mobile subscribers. Macro network coverage typically extends to buildings, but must be supplemented by dedicated internal systems. Increased data capacity and the ability of third-generation networks to provide high-speed data services increase the demands on the cellular network. Subscribers have high expectations for third generation services.

Therefore, when introduced, new services should (at a minimum) be available everywhere second generation services can be found. However, many 3G networks deployed to date have been primarily designed to provide good coverage in outdoor environments, not inside buildings. As a consequence, third generation services are poorly rated by users of early wideband code division multiple access (WCDMA) implementations compared to second generation services.

Conclusion:

The main advantage is higher capacity through more efficient use of spectrum. Higher capacity allows the WCDMA wireless network to handle higher call density at lower cost. The implementation of WCDMA improved voice quality, system performance, and mobile battery life.

Reference:

1. Rakesh Arora, “Recent Advances in Wireless Data Networks.”

2. Hans Beijner, “The importance of building solutions in third generation networks”.

3. Juha Korhonen, “Introduction to 3G Mobile Communications.”

4. Ramjee Prasad, “Towards a global 3G system”

5. Jeffrey Bannister, Paul Mather, Sebastian Coope, “Converging Technologies for 3G”

6. MR Karim, Mohsen Sarraf, “W CDMA and Cdma2000 for 3G Mobile Networks”

7. Keiji Tachikawa, “W CDMA Mobile Communications System”

8. R Ramachandran, “Evolution to 3G Mobile Communication”