WCDMA

GuideMs. Aekta singh

ELECTRONICS AND COMMUNICATION DEPT.

Made by:Ajay raman(1011042808)

What is WCDMA

• W-wideband• C-code • D-division • M-multiple• A-access

It’s an evolved version of CDMA

CDMA(BRIEF INTRODUCTION)

• CDMA stands for CODE DIVISION MULTIPLE ACCESS• Multiple users occupying the same band simultaneously by having

different codes is known as Code Division Multiple Access or CDMA.

• This leads to universal frequency reuse.• CDMA is a Spread Spectrum technique.• Fast and accurate power control

Merits of CDMA• Exploits voice inactivity.• More suited for the mobile communication channel. Not susceptible to frequency selective fades.• Transmitted power levels are low. Battery life longer.• Rake receiver.• Soft Handoff.• All this leads to significant capacity gains in mobile

channels.

Demerits

• Strict power control requirement.

• Near – Far problemThe near-far problem is particularly difficult in CDMA systems where transmitters share transmission frequencies and transmission time.In contrast, FDMA and TDMA systems are less vulnerable.

History of WCDMA• W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular

network. W-CDMA is the technology behind UMTS (a.k.a. 3GSM) and is allied with the 2G GSM standard.

More technically, W-CDMA is a wideband spread-spectrum 3G mobile telecommunication air interface that utilizes code division multiple access (or CDMA the general multiplexing scheme, not to be confused with CDMA the standard).

• W-CDMA was developed by ETSI NTT DoCoMo as the air interface for their 3G network FOMA. Later NTT Docomo submitted the specification to ITU as a candidate for the international 3G standard known as IMT-2000. The ITU eventually accepted W-CDMA as part of the IMT-2000 family of 3G standards. Later, W-CDMA was selected as the air interface for UMTS, the 3G successor to GSM.

Network arcitecutre of WCDMA

It consists of • Core network: it supports switching• RNS:radio network service comprises of RNC and RBS• MS: mobile stations

GSM and WCDMA network

Key Features of WCDMA

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

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

• High service flexibility: supports multiple parallel variable rate services on each connection.

• Both Frequency Division Duplex (FDD) and Time Division Duplex (TDD).• Built in support for future capacity and coverage enhancing technologies

like adaptive antennas, advanced receiver structures, and transmitter diversity.

• Supports inter frequency hand over and hand over to other systems, including hand over to GSM.

• Efficient packet access.

TECHNICAL FEATURES

• 3.5 TECHNICAL FEATURES• Radio channels are 5 MHz wide.• Supported mode of duplex: frequency division (FDD), Time Division (TDD)

Employs coherent detection on both the uplink and downlink based on the use of pilot symbols and channels.

• Supports inter-cell asynchronous operation.• Variable rate transmission on a 10 ms frame basis.• Multicode transmission.• Adaptive power control based on SIR (Signal-to-Interference Ratio).• Multiuser detection and smart antennas can be used to increase capacity

and coverag• Multiple types of handoff (or handover) between different cells including

soft handoff, softer handoff and hard handoff.

Years

WCDMA -3G

1st generation

Analogue speech

NMT, AMPS, TACS

2nd generation

Digital speech + medium-rate data

GSM

3rd generation

1990 20001980

High speed dataMultiple servicesGlobal roaming

IMT-2000/UMTS

From 1st to 3rd Generation

Evolution 2G Evolution 2G 3G / IMT 3G / IMT - - 2000 2000

cdmaOne cdmaOne

GSM GSM

TDMA CDPD

TDMA CDPD

cdma2000 1X cdma2000 1X

EDGE EDGE

WCDMA (FDD/TDD) WCDMA

(FDD/TDD)

cdma2000 3X cdma2000 3X

2G First step into 3G 3G phase 1

GPRS GPRS

PDC / PDC - P PDC / PDC - P

Existing spectrum

“New” spectrum

Existing spectrum

64 - 144 kbps 3G real time IP

384 kbps - 2 Mbps 384 kbps - 2 Mbps Time 2000/2001 2001/2002 2003+

28.8 kbps

The Evolution 2G to 3G

Wcdma market

The figure shows the increasing demand of WCDMA technology in the market with time

Conclusion An overview of the development of the WCDMA standard, starting with pioneering contributions in CDMA-based 3G in the early 1990s. WCDMA resulted from parallel European and Japanese 3G developments which were finally merged in 1997 to create the global WCDMA standard we know today, released in its first version in 1999. We then specifically described a number of important technical challenges and features of WCDMA. We showed that while the WCDMA and IS-95 standards both use the old CDMA technology, specific technical solutions adopted within the two standards are different. The main reason for this is differences in the overall requirements placed on the standards – 3G versus 2G requirements. Also, since commercial deployment of WCDMA was expected several years later than that of IS- 95, more advanced solutions could be used in WCDMA due to the advances in signal processing technology.

References

• Vishwanathan, T.(2006) “Telecommunication Network and Switching”,PHI Learning Pvt. Ltd,4th Edition.

• www.ericsson.com/thecompany/company_facts/organization

• http://www.ericsson.com/thecompany/company_facts/history

• http://en.wikipedia.org/wiki/Code_division_multiple_access

• O’Brien, J. A. & Marakas, G. M. (2008). Management Information Systems. New York: McGraw-Hill Irwin,3rd Edition.