24-11-2012, 06:26 PM
WCDMA – Technology for 3G Cellular Systems
[attachment=41107]
What is 3G Mobile System
Broadband Service
Packet Based Transmission
Transmission of text, digitized voice,
video at data rate higher than 2 Mbps
Consisten set of services to mobile
computer and phone users wherever
they are located in the world
Spread Spectrum System
• A kind of modulation system in which the
modulated (spread spectrum) signal bandwidth
is much greater than the message signal
bandwidth
• The spectral spreading is performed by a code
that is independent of the message signal. The
same code is used at receiver to despread the
received signal and to recover the message
signal.
Advantages of Spread Spectrum
System
• It is Secure, difficult to intercept
• A large number of codes can support a
large number of users
• As a large bandwidth is used the system is
less prone to distortion
• Resistant to jamming
• Asynchronous multiple access technology
Why WCDMA
• WCDMA is a step further in the CDMA
technology. It uses a 5 MHz wide radio
signal and a chip rate of 3.84 Mcps, which
is about three times higher than the chip
rate of CDMA2000 (1.22 Mcps)
• Higher spectrum efficiency thanks to
improved trunking efficiency (i.e. a better
statistical averaging)
• Higher QoS
WCDMA Protocol Architecture
• Three separate channels concepts in the UTRA:
logical, transport, and physical channels.
• Logical channels define what type of data is
transferred.
• Transport channels define how and with which
type of characteristics the data is transferred by
the physical layer.
• Physical data define the exact physical
characteristics of the radio channel.
WCDMA System Overview
RAN Architecture
• The main purpose of the WCDMA Radio
Access Network is to provide a connection
between the hand-set and the core
network and to isolate all the radio issues
from the core network. The advantage is
one core network supporting multiple
access technologies.
[attachment=41107]
What is 3G Mobile System
Broadband Service
Packet Based Transmission
Transmission of text, digitized voice,
video at data rate higher than 2 Mbps
Consisten set of services to mobile
computer and phone users wherever
they are located in the world
Spread Spectrum System
• A kind of modulation system in which the
modulated (spread spectrum) signal bandwidth
is much greater than the message signal
bandwidth
• The spectral spreading is performed by a code
that is independent of the message signal. The
same code is used at receiver to despread the
received signal and to recover the message
signal.
Advantages of Spread Spectrum
System
• It is Secure, difficult to intercept
• A large number of codes can support a
large number of users
• As a large bandwidth is used the system is
less prone to distortion
• Resistant to jamming
• Asynchronous multiple access technology
Why WCDMA
• WCDMA is a step further in the CDMA
technology. It uses a 5 MHz wide radio
signal and a chip rate of 3.84 Mcps, which
is about three times higher than the chip
rate of CDMA2000 (1.22 Mcps)
• Higher spectrum efficiency thanks to
improved trunking efficiency (i.e. a better
statistical averaging)
• Higher QoS
WCDMA Protocol Architecture
• Three separate channels concepts in the UTRA:
logical, transport, and physical channels.
• Logical channels define what type of data is
transferred.
• Transport channels define how and with which
type of characteristics the data is transferred by
the physical layer.
• Physical data define the exact physical
characteristics of the radio channel.
WCDMA System Overview
RAN Architecture
• The main purpose of the WCDMA Radio
Access Network is to provide a connection
between the hand-set and the core
network and to isolate all the radio issues
from the core network. The advantage is
one core network supporting multiple
access technologies.