Essay: Wide band code division multiple access (WCDMA)

ABSTRACT
Wide band code division multiple access(WCDMA) is the third generation air interface application which is
widely used in present. As the result of this technology communication over network increased. In this paper we
will study about how the communication process improves in compression to last years. This paper present that
how WCDMA radio interface provide and support higher bit rate services .UMTS (Universal mobile
telecommunication system)is a best example to understand WCDMA.WCDMA shows the tremendous growth
of cellular technology with guaranteed quality of services. Inthis paper we will also discussed characteristic of
WCDMA and see that how WCDMA is better than GSM
KEYWORDS: WCDMA, QOS, UMTS, GSM
1. Introduction
Now a day’s WCDMA is a most popular term in the mobile communication sector is WCDMA.In WCDMA
each user have a unique code and transmitted over the same frequency band.WCDMA is a new technology in
present world which is based on 3G And provides high rate to multimedia services to mobile users with multiple
Quality of services. A latest example of WCDMA is UMTS (Universal mobile technology System) which
support many different application and services with equal QOS requirement. Quality is services defined in
different classes ‘Namely, Conversational, Streaming and last is background. INUMTS (Universal mobile
technology system) each and every application is based on these QOS classes and each application gives
appropriate result according to its QOS.WCDMA is use radio interface for UMTS system. In this paper we also
study about the System model of WCDMA in which we can see that how single user and multiple user
communicateby using WCDMA air interface.WCDMA is widely used technology over GSM that people wants
most.
2.The Growth of Mobile and Internet Services: The growth of mobile and
Internet services is Millions which can be shown in following figure 1.
Figure 1. Growth of Mobile & Internet Services
3. Basics of WCDMA
?? WCDMA is a third generation air interface which is popular in present
?? WCDMA was deployed in United States of America in the US frequency band .Its deployment started
in Europe and Asia
?? WCDMA flexible support high bit rate media files like file transfer,vedio teleconferencing,
telemedicine and multiple services
?? WCDMA defined in two parts:
Evolved WCDMA
IJITKM Volume 7 ‘ Number 2 Jan’ June 2014 pp. 202-206 (ISSN 0973-4414)



Basic WCDMA
3.1. Evolved WCDMA: Evolved WCDMA provides linear online access to corporate data By using WLAN
(Wireless local area network), which gives smooth communication and Higher bandwidth and many other
application for end user which is the result of better Performance.
3.2. Basic WCDMA: Basic ECDMA is not provide high bit rate for corporate data Because in basic
WCDMA WLAN (wireless local area network) is not use.Thts why No direct communication is made between
user and it’s a main drawbacks of basic WCDMA.for this reason evolved WCDMA is developed.
Figure 2. WCDMA background
4. Characteristics of WCDMA
?? Frame length is 15 slots per frame
?? Data modulation: QPSK (downlink) and BPSK (uplink)
?? Chip rate: 3.84MHz
?? Coding: Walsh code, Turbo code and no code are used for the spreading sequence
?? Packet data scheduled by load based packet scheduling
?? Power control frequency is 1.5 KHz
?? Channel bandwidth is 5MHz
?? Self-interference System
?? WCDMA system use adaptive multi rate (AMR) speech coding
?? Soft /Hard handover
?? Support synchronous and asynchronous node operations
?? Support UE locating services
?? Power control frequency ‘ 1500Hz
?? Support load based packet scheduling
Figure 3.Basic diagram of WCDMA
IJITKM Volume 7 ‘ Number 2 Jan’ June 2014 pp. 202-206 (ISSN 0973-4414)



5. WCDMA System Model
‘ WCDMA is an air interface for 3rd generation system.
‘ 3rd generation systems are known as IMT-2000 and in Europe it is known as
‘ UMTS(universal mobile telephone service)
‘ WCDMA system is a couple of FDD and TDD
‘ FDD (Frequency division duplexing): It use different frequency band for uplink
‘ And downlink according to the frequencies.
‘ TDD(Time division duplexing):It use same frequency for both uplink and downlink
According to timeslots
Classification of WCDMA system model:
According to the communicating users WCDMA is classified into two system
Models
A: Single user WCDMA system model
B: Multiple users WCDMA system model
Above two system model shows the communication between single user and multiple
User in WCDMA air interface.
5.1.Single user WCDMA system model
Figure 4. Block diagram of WCDMA system model
‘ Input Data: All incoming signals are used as input data which is stored in Memory of system
‘ Spreading Sequence: In WCDMA system walas code is used as spreading system. It’s a coding terminology
which is used in WCDMA Application .It consist n rows And n columns and form
n*nWalascodesquarematrix
‘ Spreader: Spreader is use for spreading data at higher bandwidth And high bit rate
‘ Modulator: QPSK and BPSK is used as a modulater.Modulater, Modulate data sequence which is coming
from spreader
‘ AWGN channel:AWGN channel is depends on single to noise ratio Per sample. It added white Gaussian
noise to the signal
‘ Demodulator: Demodulator ,demodulate the modulated data Sequence to its original form
‘ Error Calculation: error calculation is a method for calculating bit error By comprising input data and
received data
5.2 .Multiuser WCDMA system model
 Multiuser WCDMA shows the communication between multiple users by using different
 channel and with different Quality of services.
 Each User system held a specific Quality of service for an application and
 corporate data.
 Below diagram is shows the way of single processing for starting user to end user:-
IJITKM Volume 7 ‘ Number 2 Jan’ June 2014 pp. 202-206 (ISSN 0973-4414)



Figure 5. Block diagram of multiple user WCDMA system
 Input Data: Audio signal from N user are stored in memory and each user operate
 Signal simultaneously.
 Spreading Sequence: Walsh code is used as spreading sequence .we take an example
 of 4 user
 sequence is (0,5,3,2)
 [0000]=0, [0101]=5,[0011]=3,[0001]=2
 De-Spreading sequence: user date is reform by composite signal.
6. GSMvs. WCDMA
GSM WCDMA
Provide Voice & Data Services Provide Voice Data & Video Services
Its 2G technology It’s a 3G group of technology
Comparatively data speed is low Much faster data speed
GPRS and EDGE data standards Normal 3G and HSPDA standard
Speed: 9.6kbps Speed:12.8kbps-4.5 kbps
Use TDMA access method for
any application
Use Spread spectrum technique with high
Bandwidth
Access media- TDM ACCESS Media- ATM,IP,TDM
Air Interface,Abis,A,Ater,Gb AirInterfacelu,CS,PRACH,DPDCH,DPCCH
Narrow band CDMA Wide band CDMA
Channel bandwidth-1.25MHz Channel bandwidth-5MHz
IJITKM Volume 7 ‘ Number 2 Jan’ June 2014 pp. 202-206 (ISSN 0973-4414)



7. CONCLUSION
This paper describes the WCDMA Architecture and the scope of WCDMA in present. A Discussion according
to this paper shows that WCDMA now the most popular technology Which is widely used by people and it’s a
demanding technology also. This paper first describes Introduction and Basics of WCDMA.then describes Basic
structure, characteristics of WCDMA , System model of WCDMA. In System model of WCDMA we discussed
how single user and multiple user communicate Over WCDMA air interface and how they transfer corporate
data from one hand to another hand. Other topic discussed were background and evolution of WCDMA from
starting year to Present, comparison between GSM and WCDMA system We can see the rapidly growth of
mobile subscribers and it’s a big challenge for us to provide a Best way of communication around the world
REFERENCES
1. Real Time Implementation and Performance Evaluation ofWCDMA System over AWGNChannel on
TMS320C6713DSK C3IT-2012
2. All IP in 3G CDMA Networks the UMTS Infrastructure and ServicePlatforms for Future Mobile Systems
Jonathan P. CastroOrange Communications SA/AG, Switzerland
3. Wideband Code Division Multiple AccessLaurence B. Milstein, Fellow, IEEE
4. WCDMA’the Radio Interface for FutureMobile Multimedia Communications Erik Dahl man, Per Being,
Jens Knutson, Fredrik Ovesj??o, Magnus Person, and ChristianRobot
5. WCDMA ‘ Requirements and Practical Design Edited byRudolf Tanner andJasonWoodardUbieties Ltd,
UK

Source: Essay UK - http://doghouse.net/essays/information-technology/essay-wide-band-code-division-multiple-access-wcdma/


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