-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-0
www.huawei.com
Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA RAN Fundamental
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-1
Page1Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Objectives
l Upon completion of this course, you will be able to:
p Describe the development of 3G
p Outline the advantage of CDMA principle
p Characterize code sequence
p Outline the fundamentals of RAN
p Describe feature of wireless propagation
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-2
Page2Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Network Architecture and protocol structure
4. WCDMA Wireless Fundamental
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-3
Page3Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Network Architecture and protocol structure
4. WCDMA Wireless Fundamental
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-4
Page4Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Different Service, Different Technology
AMPS
TACS
NMT
Others
1G 1980sAnalog
GSMGSM
CDMA CDMA IS-95IS-95
TDMATDMAIS-136IS-136
PDCPDC
2G 1990sDigital
Technologies drive
3G IMT-2000
UMTSUMTSWCDMAWCDMA
cdmacdma20002000
Demands drive
TD-SCDMATD-SCDMA
3G provides compositive services for both operators and
subscribers
l The first generation is the analog cellular mobile
communication network in the time period from the middle of 1970s
to the middle of 1980s. The most important breakthrough in this
period is the concept of cellular networks put forward by the Bell
Labs in the 1970s, as compared to the former mobile communication
systems. The cellular network system is based on cells to implement
frequency reuse and thus greatly enhances the system capacity.
l The typical examples of the first generation mobile
communication systems are the AMPS system and the later enhanced
TACS of USA, the NMT and the others. The AMPS (Advanced Mobile
Phone System) uses the 800 MHz band of the analog cellular
transmission system and it is widely applied in North America,
South America and some Circum-Pacific countries. The TACS (Total
Access Communication System) uses the 900 MHz band. It is widely
applied in Britain, Japan and some Asian countries.
l The main feature of the first generation mobile communication
systems is that they use the frequency reuse technology, adopt
analog modulation for voice signals and provide an analog
subscriber channel every other 30 kHz/25 kHz.
l However, their defects are also obvious:
p Low utilization of the frequency spectrum
p Limited types of services
p No high-speed data services
p Poor confidentiality and high vulnerability to interception
and number embezzlement
p High equipment cost
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-5
l To solve these fundamental technical defects of the analog
systems, the digital mobile
communication technologies emerged and the second generation
mobile
communication systems represented by GSM and IS-95 came into
being in the middle
of 1980s. The typical examples of the second generation cellular
mobile
communication systems are the DAMPS of USA, the IS-95 and the
European GSM
system.
l The GSM (Global System for Mobile Communications) is
originated from Europe.
Designed as the TDMA standard for mobile digital cellular
communications, it supports
the 64 kbps data rate and can interconnect with the ISDN. It
uses the 900 MHz band
while the DCS1800 system uses the 1800 MHz band. The GSM system
uses the FDD
and TDMA modes and each carrier supports eight channels with the
signal bandwidth
of 200 kHz.
l The DAMPS (Digital Advanced Mobile Phone System) is also
called the IS-54 (North
America Digital Cellular System). Using the 800 MHz bandwidth,
it is the earlier of the
two North America digital cellular standards and specifies the
use of the TDMA mode.
l The IS-95 standard is another digital cellular standard of
North America. Using the 800
MHz or 1900 MHz band, it specifies the use of the CDMA mode and
has already
become the first choice among the technologies of American PCS
(Personal
Communication System) networks.
l Since the 2G mobile communication systems focus on the
transmission of voice and
low-speed data services, the 2.5G mobile communication systems
emerged in 1996 to
address the medium-rate data transmission needs. These systems
include GPRS and IS-
95B.
l The CDMA system has a very large capacity that is equivalent
to ten or even twenty
times that of the analog systems. But the narrowband CDMA
technologies come into
maturity at a time later than the GSM technologies, their
application far lags behind
the GSM ones and currently they have only found large-scale
commercial applications
in North America, Korea and China. The major services of mobile
communications are
currently still voice services and low-speed data services.
l With the development of networks, data and multimedia
communications have also
witnessed rapid development; therefore, the target of the 3G
mobile communication
is to implement broadband multimedia communication.
l The 3G mobile communication systems are a kind of
communication system that can
provide multiple kinds of high quality multimedia services and
implement global
seamless coverage and global roaming. They are compatible with
the fixed networks
and can implement any kind of communication at any time and any
place with
portable terminals.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-6
Page6Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
3G Evolution
l Proposal of 3G
p IMT-2000: the general name of third generation mobile
communication system
p The third generation mobile communication was first proposed
in
1985and was renamed as IMT-2000 in the year of 1996
n Commercialization: around the year of 2000
n Work band : around 2000MHz
n The highest service rate :up to 2000Kbps
l Put forward in 1985 by the ITU (International
Telecommunication Union), the 3G mobile communication system was
called the FPLMTS (Future Public Land Mobile
Telecommunication System) and was later renamed as IMT-2000
(International Mobile Telecommunication-2000). The major systems
include WCDMA, cdma2000 and UWC-
136. On November 5, 1999, the 18th conference of ITU-R TG8/1
passed the Recommended Specification of Radio Interfaces of
IMT-2000 and the TD-SCDMA
technologies put forward by China were incorporated into the
IMT-2000 CDMA TDD part of the technical specification. This showed
that the work of the TG8/1 in
formulating the technical specifications of radio interfaces in
3G mobile communication systems had basically come into an end and
the development and
application of the 3G mobile communication systems would enter a
new and essential phase.
l The 3GPP is an organization that develops specifications for a
3G system based on the
UTRA radio interface and on the enhanced GSM core network.
l The 3GPP2 initiative is the other major 3G standardization
organization. It promotes
the CDMA2000 system, which is also based on a form of WCDMA
technology. In the world of IMT-2000, this proposal is known as
IMT-MC. The major difference between
the 3GPP and the 3GPP2 approaches into the air interface
specification development is that 3GPP has specified a completely
new air interface without any constraints from
the past, whereas 3GPP2 has specified a system that is backward
compatible with IS-95 systems.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-7
Page7Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
3G Spectrum Allocation
l ITU has allocated 230 MHz frequency for the 3G mobile
communication system IMT-
2000: 1885 ~ 2025MHz in the uplink and 2110~ 2200 MHz in the
downlink. Of them,
the frequency range of 1980 MHz ~ 2010 MHz (uplink) and that of
2170 MHz ~ 2200
MHz (downlink) are used for mobile satellite services. As the
uplink and the downlink
bands are asymmetrical, the use of dual-frequency FDD mode or
the single-frequency
TDD mode may be considered. This plan was passed in WRC92 and
new additional
bands were approved on the basis of the WRC-92 in the WRC2000
conference in the
year 2000: 806 MHz ~ 960 MHz, 1710 MHz ~ 1885 MHz and 2500 MHz ~
2690 MHz.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-8
Page8Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Bands WCDMA Used
l Main bands
p 1920 ~ 1980MHz / 2110 ~ 2170MHz
l Supplementary bands: different country maybe different
p 1850 ~ 1910 MHz / 1930 MHz ~ 1990 MHz (USA)
p 1710 ~ 1785MHz / 1805 ~ 1880MHz (Japan)
p 890 ~ 915MHz / 935 ~ 960MHz (Australia)
p . . .
l Frequency channel numbercentral frequency5, for main band:
p UL frequency channel number 96129888p DL frequency channel
number : 1056210838
l The WCDMA system uses the following frequency spectrum (bands
other than those
specified by 3GPP may also be used): Uplink 1920 MHz ~ 1980 MHz
and downlink
2110 MHz ~ 2170 MHz. Each carrier frequency has the 5M band and
the duplex
spacing is 190 MHz. In America, the used frequency spectrum is
1850 MHz ~ 1910
MHz in the uplink and 1930 MHz ~ 1990 MHz in the downlink and
the duplex spacing
is 80 MHz.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-9
Page9Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
3G Application Service
Time Delay
Error Ratio
background
conversational
streaming
interactive
l Compatible with abundant services and applications of 2G, 3G
system has an open
integrated service platform to provide a wide prospect for
various 3G services.
l Features of 3G Services
l 3G services are inherited from 2G services. In a new
architecture, new service
capabilities are generated, and more service types are
available. Service characteristics
vary greatly, so each service features differently. Generally,
there are several features
as follows:
p Compatible backward with all the services provided by GSM.
p The real-time services (conversational) such as voice
service
generally have the QoS requirement.
p The concept of multimedia service (streaming, interactive,
background) is introduced.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-10
Page10Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
The Core technology of 3G: CDMA
CDMA
WCDMAWCDMACN: based on MAP and GPRS
RTT: WCDMA
TD-SCDMACN: based on MAP and GPRS
RTT: TD-SCDMA
cdma2000CN: based on ANSI 41 and MIP
RTT: cdma2000
l Formulated by the European standardization organization 3GPP,
the core network
evolves on the basis of GSM/GPRS and can thus be compatible with
the existing
GSM/GPRS networks. It can be based on the TDM, ATM and IP
technologies to evolve
towards the all-IP network architecture. Based on the ATM
technology, the UTRAN
uniformly processes voice and packet services and evolves
towards the IP network
architecture.
l The cdma2000 system is a 3G standard put forward on the basis
of the IS-95 standard.
Its standardization work is currently undertaken by 3GPP2.
Circuit Switched (CS)
domain is adapted from the 2G IS95 CDMA network, Packet Switched
(PS) domain is
A packet network based on the Mobile IP technology. Radio Access
Network (RAN) is
based on the ATM switch platform, it provides abundant
adaptation layer interfaces.
l The TD-SCDMA standard is put forward by the Chinese Wireless
Telecommunication
Standard (CWTS) Group and now it has been merged into the
specifications related to
the WCDMA-TDD of 3GPP. The core network evolves on the basis of
GSM/GPRS. The
air interface adopts the TD-SCDMA mode.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-11
Page11Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Network Architecture and protocol structure
4. WCDMA Wireless Fundamental
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-12
Page12Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Multiple Access and Duplex Technology
l Multiple Access Technology
p Frequency division multiple access (FDMA)
p Time division multiple access (TDMA)
p Code division multiple access (CDMA)
l In mobile communication systems, GSM adopts TDMA; WCDMA,
cdma2000 and TD-
SCDMA adopt CDMA.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-13
Page13Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Multiple Access Technology
Freque
ncy
Time
Power
FDMA
Freque
ncyTime
Power
TDMA
Power
Time
CDMA
Frequency
l Frequency Division Multiple Access means dividing the whole
available spectrum into
many single radio channels (transmit/receive carrier pair). Each
channel can transmit
one-way voice or control information. Analog cellular system is
a typical example of
FDMA structure.
l Time Division Multiple Access means that the wireless carrier
of one bandwidth is
divided into multiple time division channels in terms of time
(or called timeslot). Each
user occupies a timeslot and receives/transmits signals within
this specified timeslot.
Therefore, it is called time division multiple access. This
multiple access mode is
adopted in both digital cellular system and GSM.
l CDMA is a multiple access mode implemented by Spreading
Modulation. Unlike FDMA
and TDMA, both of which separate the user information in terms
of time and
frequency, CDMA can transmit the information of multiple users
on a channel at the
same time. The key is that every information before transmission
should be modulated
by different Spreading Code to broadband signal, then all the
signals should be mixed
and send. The mixed signal would be demodulated by different
Spreading Code at the
different receiver. Because all the Spreading Code is
orthogonal, only the information
that was be demodulated by same Spreading Code can be reverted
in mixed signal.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-14
Page14Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Multiple Access and Duplex Technology
l Duplex Technology
p Frequency division duplex (FDD)
p Time division duplex (TDD)
l In third generation mobile communication systems, WCDMA and
cdma2000 adopt
frequency division duplex (FDD), TD-SCDMA adopts time division
duplex (TDD).
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-15
Page15Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Duplex Technology
Time
Frequency
Power
TDD
USER 2
USER 1
DLUL
DLDL
UL
FDD
Time
Frequency
Power
UL DL
USER 2
USER 1
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-16
Page16Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Network Architecture and protocol structure
4. WCDMA Wireless Fundamental
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-17
Page17Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Network Architecture
RNS
RNC
RNS
RNC
Core Network
Node B Node B Node B Node B
Iu-CS Iu-PS
Iur
Iub IubIub Iub
CN
UTRAN
UEUu
CS PS
Iu-CSIu-PS
CSPS
l WCDMA including the RAN (Radio Access Network) and the CN
(Core Network). The
RAN is used to process all the radio-related functions, while
the CN is used to process
all voice calls and data connections within the UMTS system, and
implements the
function of external network switching and routing.
l Logically, the CN is divided into the CS (Circuit Switched)
Domain and the PS (Packet
Switched) Domain. UTRAN, CN and UE (User Equipment) together
constitute the
whole UMTS system
l A RNS is composed of one RNC and one or several Node Bs. The
Iu interface is used
between RNC and CN while the Iub interface is adopted between
RNC and Node B.
Within UTRAN, RNCs connect with one another through the Iur
interface. The Iur
interface can connect RNCs via the direct physical connections
among them or
connect them through the transport network. RNC is used to
allocate and control the
radio resources of the connected or related Node B. However,
Node B serves to
convert the data flows between the Iub interface and the Uu
interface, and at the
same time, it also participates in part of radio resource
management.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-18
Page18Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Network Version Evolution
3GPP Rel993GPP Rel4
3GPP Rel5
2000 2001 2002
GSM/GPRS CN
WCDMA RTT
IMS
HSDPA 3GPP Rel6
MBMS
HSUPA
2005
CS domain change to NGN
WCDMA RTT
l The overall structure of the WCDMA network is defined in 3GPP
TS 23.002. Now,
there are the following three versions: R99, R4, R5.
l 3GPP began to formulate 3G specifications at the end of 1998
and beginning of 1999.
As scheduled, the R99 version would be completed at the end of
1999, but in fact it
was not completed until March, 2000. To guarantee the investment
benefits of
operators, the CS domain of R99 version do not fundamentally
change., so as to
support the smooth transition of GSM/GPRS/3G.
l After R99, the version was no longer named by the year. At the
same time, the
functions of R2000 are implemented by the following two phases:
R4 and R5. In the
R4 network, MSC as the CS domain of the CN is divided into the
MSC Server and the
MGW, at the same time, a SGW is added, and HLR can be replaced
by HSS (not
explicitly specified in the specification).
l In the R5 network, the end-to-end VOIP is supported and the
core network adopts
plentiful new function entities, which have thus changed the
original call procedures.
With IMS (IP Multimedia Subsystem), the network can use HSS
instead of HLR. In the
R5 network, HSDPA (High Speed Downlink Packet Access) is also
supported, it can
support high speed data service.
l In the R6 network, the HSUPA is supported which can provide UL
service rate up to
5.76Mbps. And MBMS (MultiMedia Broadcast Multicast Service) is
also supported.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-19
Page19Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Network Version Evolution
l Features of R6
p MBMS is introduced
p HSUPA is introduced to achieve the service rate up to
5.76Mbps
l Features of R7
p HSPA+ is introduced, which adopts higher order modulation and
MIMO
p Max DL rate: 28Mbps, Max UL rate:11Mbps
l Features of R8
p WCDMA LTE (Long term evolution) is introduced
p OFDMA is adopted instead of CDMA
p Max DL rate: 100Mbps, Max UL rate: 50Mbps (with 20MHz
bandwidth)
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-20
Page20Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Uu Interface protocol structure
L3
cont
rol
cont
rol
cont
rol
cont
rol
C-plane signaling U-plane information
PHY
L2/MAC
L1
RLC L2/RLC
MAC
RLCRLCRLC
NAS (non-access stratum)
UuS boundary
L2/BMC
control
PDCPPDCP L2/PDCP
RRC
RLCRLCRLC
RLC
BMC
l The layer 1 supports all functions required for the
transmission of bit streams
on the physical medium. It is also in charge of measurements
function
consisting in indicating to higher layers, for example, Frame
Error Rate (FER),
Signal to Interference Ratio (SIR), interference power and
transmit power.
l The layer 2 protocol is responsible for providing functions
such as mapping,
ciphering, retransmission and segmentation. It is made of four
sublayers: MAC
(Medium Access Control), RLC (Radio Link Control), PDCP (Packet
Data
Convergence Protocol) and BMC (Broadcast/Multicast Control).
l The layer 3 is split into 2 parts: the access stratum and the
non access stratum.
The access stratum part is made of RRC (Radio Resource Control)
entity and
duplication avoidance entity. The non access stratum part is
made of CC, MM
parts.
l Not shown on the figure are connections between RRC and all
the other
protocol layers (RLC, MAC, PDCP, BMC and L1), which provide
local inter-layer
control services.
l The protocol layers are located in the UE and the peer
entities are in the NodeB
or the RNC.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-21
Page21Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
General Protocol Mode for UTRAN Terrestrial Interfacel The
structure is based on the principle that the layers and planes
are
logically independent of each other.
Application Protocol
Data Stream(s)
ALCAP(s)
Transport Network
Layer
Physical Layer
Signaling Bearer(s)
Control Plane User Plane
Transport NetworkUser Plane
Transport Network Control Plane
Radio Network
Layer
Signaling Bearer(s)
Data Bearer(s)
Transport NetworkUser Plane
l Protocol structures in UTRAN terrestrial interfaces are
designed according to the same general protocol model. This model
is shown in above slide. The structure is based on the principle
that the layers and planes are logically independent of each other
and, if needed, parts of the protocol structure may be changed in
the future while other parts remain intact.
l Horizontal Layers
p The protocol structure consists of two main layers, the Radio
Network Layer (RNL) and the Transport Network Layer (TNL). All
UTRAN-related issues are visible only in the Radio Network Layer,
and the Transport Network Layer represents standard transport
technology that is selected to be used for UTRAN but without any
UTRAN-specific changes.
l Vertical Planes
p Control Plane
p The Control Plane is used for all UMTS-specific control
signaling. It includes the Application Protocol (i.e. RANAP in Iu,
RNSAP in Iur and NBAP in Iub), and the Signaling Bearer for
transporting the Application Protocol messages. The Application
Protocol is used, among otherthings, for setting up bearers to the
UE (i.e. the Radio Access Bearer in Iu and subsequently the Radio
Link in Iur and Iub). In the three plane structure the bearer
parameters in the Application Protocol are not directly tied to the
User Plane technology, but rather are general bearer parameters.
The Signaling Bearer for the Application Protocol may or may not be
of the same type as the Signaling Bearer for the ALCAP. It is
always set up by O&M actions.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-22
p User Plane
p All information sent and received by the user, such as the
coded voice in a voice call or the packets in an Internet
connection, are transported via the User Plane. The User Plane
includes the Data Stream(s), and the Data Bearer (s) for the Data
Stream(s). Each Data Stream is characterized by one or more frame
protocols specified for that interface.
p Transport Network Control Plane
p The Transport Network Control Plane is used for all control
signaling within the Transport Layer. It does not include any Radio
Network Layer information. It includes the ALCAP protocol that is
needed to set up the transport bearers (Data Bearer) for the User
Plane. It also includes the Signaling Bearer needed for the ALCAP.
The Transport Network Control Plane is a plane that acts between
the Control Plane and the User Plane. The introduction of the
Transport Network Control Plane makes itpossible for the
Application Protocol in the Radio Network Control Plane to be
completely independent of the technology selected for the Data
Bearer in the User Plane.
l About AAl2 and AAL5
p Above the ATM layer we usually find an ATM adaptation layer
(AAL). Its function is to process the data from higher layers for
ATM transmission.
p This means segmenting the data into 48-byte chunks and
reassembling the original data frames on the receiving side. There
are five different AALs (0, 1, 2, 3/4, and 5). AAL0 means that no
adaptation is needed.The other adaptation layers have different
properties based on three parameters:
n Real-time requirements;
n Constant or variable bit rate;
n Connection-oriented or connectionless data transfer.
p The usage of ATM is promoted by the ATM Forum. The Iu
interface uses two AALs: AAL2 and AAL5.
p AAL2 is designed for the transmission of connection oriented,
real-time data streams with variable bit rates.
p AAL5 is designed for the transmission of connectionless data
streams with variable bit rates.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-23
Page23Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iu-CS Interface (based on ATM)
ALCAPALCAP
Control Plane
Transport NetworkControl Plane
User planeRadioNetworkLayer
Transport NetworkUser Plane
TransportNetworkLayer
A B
RANAP
AAL2 PATH
ATM
Physical Layer
SAAL NNI
SCCPMTP3-B
Iu UP
SAAL NNI
MTP3-B
Transport NetworkUser Plane
l Protocol Structure for Iu CS
p The Iu CS overall protocol structure is depicted in above
slide. The three planes in the Iu interface share a common ATM
(Asynchronous Transfer Mode) transport which is used for all
planes. The physical layer is the interface to the physical medium:
optical fiber, radio link or copper cable. The physical layer
implementation can be selected from a variety of standard
off-the-shelf transmission technologies, such as SONET, STM1, or
E1.
l Iu CS Control Plane Protocol Stack
p The Control Plane protocol stack consists of RANAP, on top of
Broadband (BB) SS7 (Signaling System #7) protocols. The applicable
layers are the Signaling Connection Control Part (SCCP), the
Message Transfer Part (MTP3-b) and SAAL-NNI (Signaling ATM
Adaptation Layer for Network to Network Interfaces).
l Iu CS Transport Network Control Plane Protocol Stack
p The Transport Network Control Plane protocol stack consists of
the Signaling Protocol for setting up AAL2 connections (Q.2630.1
andadaptation layer Q.2150.1), on top of BB SS7 protocols. The
applicable BB SS7 are those described above without the SCCP
layer.
l Iu CS User Plane Protocol Stack
p A dedicated AAL2 connection is reserved for each individual CS
service.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-24
Page24Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iu-CS Interface (based on IP)
Control Plane User planeRadioNetworkLayer
Transport NetworkUser Plane
TransportNetworkLayer
RANAP
IP
Physical Layer
IP
SCTP
Iu UP
Transport NetworkUser Plane
DATA LINK DATA LINK
M3UASCCP RTP/RTCP
UDP
l SCTP is streaming control transmission protocol. It is a
reliable transport protocol operating on top of IP.
l M3UA is MTP3 user adaption layer based on IP.
l RTP is real-time transmission protocol. It provides CS data
IP-based transmission
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-25
Page25Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iu-PS Interface (based on ATM)
Control Plane User planeRadioNetworkLayer
Transport NetworkUser PlaneTransport
NetworkLayer
Transport NetworkUser Plane
C
RANAP
ATM
SAAL NNI
SCCP
MTP3-B
Iu UP
AAL Type 5IP
UDPGTP-U
Physical Layer
l Protocol Structure for Iu PS
p The Iu PS protocol structure is represented in above slide.
Again, a common ATM transport is applied for both User and Control
Plane.Also the physical layer is as specified for Iu CS.
l Iu PS Control Plane Protocol Stack
p The Control Plane protocol stack consists of RANAP, on top of
Broadband (BB) SS7 (Signaling System #7) protocols. The applicable
layers are the Signaling Connection Control Part (SCCP), the
Message Transfer Part (MTP3-b) and SAAL-NNI (Signaling ATM
Adaptation Layer for Network to Network Interfaces).
l Iu PS Transport Network Control Plane Protocol Stack
p The Transport Network Control Plane is not applied to Iu PS.
Thesetting up of the GTP tunnel requires only an identifier for the
tunnel, and the IP addresses for both directions, and these are
already included in the RANAP RAB Assignment messages.
l Iu PS User Plane Protocol Stack
p In the Iu PS User Plane, multiple packet data flows are
multiplexed on one or several AAL5 PVCs. The GTP-U (User Plane part
of the GPRS Tunneling Protocol) is the multiplexing layer that
provides identities for individual packet data flow. Each flow uses
UDP connectionless transport and IP addressing.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-26
Page26Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iu-PS Interface (based on IP)
Control Plane User planeRadioNetworkLayer
Transport NetworkUser Plane
TransportNetworkLayer
RANAP
IP
Physical Layer
IP
SCTP
Iu UP
Transport NetworkUser Plane
DATA LINK DATA LINK
M3UASCCP
GTP-U
UDP
l SCTP is streaming control transmission protocol. It is a
reliable transport protocol operating on top of IP.
l M3UA is MTP3 user adaption layer based on IP.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-27
Page27Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iub Interface (based on ATM)
ALCAPALCAP
Control Plane
Transport NetworkControl Plane
User planeRadioNetworkLayer
Transport NetworkUser Plane
TransportNetworkLayer
Transport NetworkUser Plane
NBAP
AAL2 PATH
ATM
Physical Layer
SAAL UNI
Iub FP
SAAL UNI
NCP CCP
l The Iub interface is the terrestrial interface between NodeB
and RNC. The Radio
Network Layer defines procedures related to the operation of the
NodeB. The
Transport Network Layer defines procedures for establishing
physical
connections between the NodeB and the RNC.
l The Iub application protocol, NodeB application part ( NBAP )
initiates the
establishment of a signaling connection over Iub . It is divided
into two
essential components, CCP and NCP.
l NCP is used for signaling that initiates a UE context for a
dedicated UE or
signals that is not related to specific UE. Example of NBAP-C
procedure are cell
configuration , handling of common channels and radio link
setup
l CCP is used for signaling relating to a specific UE
context.
l SAAL is an ATM Adaptation Layer that supports communication
between
signaling entities over an ATM link.
l The user plane Iub Frame Protocol ( FP ), defined the
structure of the frames
and the basic in band control procedure for every type of
transport channel.
There are DCH-FP, RACH-FP, FACH-FP, HS-DSCH FP and PCH FP.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-28
Page28Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iub Interface (based on IP)
Control Plane User planeRadioNetworkLayer
Transport NetworkUser Plane
TransportNetworkLayer
Transport NetworkUser Plane
NBAP
IP
DATA LINK
Physical Layer
IP
Iub FP
NCP CCP
DATA LINK
SCTP UDP
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-29
Page29Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iur Interface (based on ATM)
ALCAPALCAP
Control Plane
Transport NetworkControl Plane
User planeRadioNetworkLayer
TransportNetworkLayer
A B
RNSAP
AAL2 PATH
ATM
Physical Layer
SAAL NNI
SCCPMTP3-B
Iur Data Stream
SAAL NNI
MTP3-B
Transport NetworkUser Plane
Transport NetworkUser Plane
l Iur interface connects two RNCs. The protocol stack for the
Iur is shown in
above slide.
l The RNSAP protocol is the signaling protocol defined for the
Iur interface.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-30
Page30Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Iur Interface (based on IP)
Control Plane User planeRadioNetworkLayer
Transport NetworkUser Plane
TransportNetworkLayer
RNSAP
IP
Physical Layer
IP
SCTP
Iu UP
Transport NetworkUser Plane
DATA LINK DATA LINK
M3UASCCP
UDP
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-31
Page31Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Contents
1. 3G Overview
2. CDMA Principle
3. WCDMA Network Architecture and protocol structure
4. WCDMA Wireless Fundamental
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-32
Page32Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Processing Procedure of WCDMA System
SourceCoding
Channel Coding& Interleaving
Spreading Modulation
SourceDecoding
Channel Decoding& Deinterleaving
Despreading Demodulation
Transmission
Reception
chipmodulated
signalbitsymbol
ServiceSignal
Radio Channel
ServiceSignal
Receiver
l Source coding can increase the transmitting efficiency.
l Channel coding can make the transmission more reliable.
l Spreading can increase the capability of overcoming
interference.
l Through the modulation, the signals will transfer to radio
signals from digital signals.
l Bit, Symbol, Chip
p Bit : data after source coding
p Symbol: data after channel coding and interleaving
p Chip: data after spreading
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-33
Page33Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Source Coding
l AMR (Adaptive Multi-Rate) Speech
p A integrated speech codec with 8
source rates
p The AMR bit rates can be controlled by
the RAN depending on the system load
and quality of the speech connections
l Video Phone Service
p H.324 is used for VP Service in CS
domain
p Includes: video codec, speech codec,
data protocols, multiplexing and etc.
5.15AMR_5.15
4.75AMR_4.75
5.9AMR_5.90
6.7 (PDC EFR)AMR_6.70
7.4 (TDMA EFR)AMR_7.40
7.95AMR_7.95
10.2AMR_10.20
12.2 (GSM EFR)AMR_12.20
Bit Rate (kbps)CODEC
l AMR is compatible with current mobile communication system
(GSM, IS-95, PDC and
so on), thus, it will make multi-mode terminal design
easier.
l The AMR codec offers the possibility to adapt the coding
scheme to the radio channel
conditions. The most robust codec mode is selected in bad
propagation conditions.
The codec mode providing the highest source rate is selected in
good propagation
conditions.
l During an AMR communication, the receiver measures the radio
link quality and must
return to the transmitter either the quality measurements or the
actual codec mode
the transmitter should use during the next frame. That exchange
has to be done as
fast as possible in order to better follow the evolution of the
channels quality.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-34
Page34Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Processing Procedure of WCDMA System
Transmitter
SourceCoding
Channel Coding& Interleaving
Spreading Modulation
SourceDecoding
Channel Decoding& Deinterleaving
Despreading Demodulation
Transmission
Reception
chipmodulated
signalbitsymbol
ServiceSignal
Radio Channel
ServiceSignal
Receiver
l Source coding can increase the transmitting efficiency.
l Channel coding can make the transmission more reliable.
l Spreading can increase the capability of overcoming
interference.
l Scrambling can make transmission in security.
l Through the modulation, the signals will transfer to radio
signals from digital signals.
l Bit, Symbol, Chip
p Bit : data after source coding
p Symbol: data after channel coding and interleaving
p Chip: data after spreading
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-35
Page35Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Block Coding - CRC
l Block coding is used to detect if there are any
uncorrected
errors left after error correction.
l The cyclic redundancy check (CRC) is a common method of
block coding.
l Adding the CRC bits is done before the channel encoding
and
they are checked after the channel decoding.
l During the transmission, there are many interferences and
fading. To guarantee
reliable transmission, system should overcome these influence
through the channel
coding which includes block coding, channel coding and
interleaving.
l Block coding: The encoder adds some redundant bits to the
block of bits and the
decoder uses them to determine whether an error has occurred
during the
transmission. This is used to calculate Block Error Ratio (BLER)
used in the outer loop
power control.
l The CRC (Cyclic Redundancy Check) is used for error checking
of the transport blocks
at the receiving end. The CRC length that can be inserted has
four different values: 0,
8, 12, 16 and 24 bits. The more bits the CRC contains, the lower
is the probability of
an undetected error in the transport block in the receiver.
l Note that certain types of block codes can also be used for
error correction, although
these are not used in WCDMA.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-36
Page36Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Channel Coding
l Effect
p Enhance the correlation among symbols so as to recover the
signal when
interference occurs
p Provides better error correction at receiver, but brings
increment of the delay
l Types
p No Coding
p Convolutional Coding (1/2, 1/3)
p Turbo Coding (1/3)
Code Block of N Bits
No Coding
1/2 Convolutional Coding
1/3 Convolutional Coding
1/3 Turbo Coding
Uncoded N bits
Coded 2N+16 bits
Coded 3N+24 bits
Coded 3N+12 bits
l UTRAN employs two FEC schemes: convolutional codes and turbo
codes. The idea is to add redundancy to the transmitted bit stream,
sO that occasional bit errors can be
corrected in the receiving entity.
l The first is convolution that is used for anti-interference.
Through the technology,
many redundant bits will be inserted in original information.
When error code is caused by interference, the redundant bits can
be used to recover the original
information. Convolutional codes are typically used when the
timing constraints are tight. The coded data must contain enough
redundant information to make it possible
to correct some of the detected errors without asking for
repeats.
l Turbo codes are found to be very efficient because they can
perform close to the
theoretical limit set by the Shannons Law. Their efficiency is
best with high data rate services, but poor on low rate services.
At higher bit rates, turbo coding is more
efficient than convolutional coding.
l In WCDMA network, both Convolution code and Turbo code are
used. Convolution code applies to voice service while Turbo code
applies to high rate data service.
l Note that both block codes and channel codes are used in the
UTRAN. The idea behind this arrangement is that the channel decoder
(either a convolutional or turbo
decoder) tries to correct as many errors as possible, and then
the block decoder (CRC check) offers its judgment on whether the
resulting information is good enough to be
used in the higher layers.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-37
Page37Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Interleaving
l Effect
p Interleaving is used to reduce the probability of consecutive
bits error
p Longer interleaving periods have better data protection with
more delay
11101........................0000100
0 0 1 0 0 0 0 . . . 1 0 1 1 1
11101........................0000100
0 0 0 1 0 1 0 0 1 0 1 1 Inter-column permutation
Output bits
Input bits
Interleaving periods: 20, 40, or 80 ms
l Channel coding works well against random errors, but it is
quite vulnerable to bursts
of errors, which are typical in mobile radio systems. The
especially fast moving UE in
CDMA systems can cause consecutive errors if the power control
is not fast enough to
manage the interference. Most coding schemes perform better on
random data errors
than on blocks of errors. This problem can be eased with
interleaving, which spreads
the erroneous bits over a longer period of time. By
interleaving, no two adjacent bits
are transmitted near to each other, and the data errors are
randomized.
l The longer the interleaving period, the better the protection
provided by the time
diversity. However, longer interleaving increases transmission
delays and a balance
must be found between the error resistance capabilities and the
delay introduced.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-38
Page38Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Processing Procedure of WCDMA System
SourceCoding
Channel Coding& Interleaving
Spreading Modulation
SourceDecoding
Channel Decoding& Deinterleaving
Despreading Demodulation
Transmission
Reception
chipmodulated
signalbitsymbol
ServiceSignal
Radio Channel
ServiceSignal
Receiver
l Source coding can increase the transmitting efficiency.
l Channel coding can make the transmission more reliable.
l Spreading can increase the capability of overcoming
interference.
l Scrambling can make transmission in security.
l Through the modulation, the signals will transfer to radio
signals from digital signals.
l Bit, Symbol, Chip
p Bit : data after source coding
p Symbol: data after channel coding and interleaving
p Chip: data after spreading
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-39
Page39Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Correlation
l Correlation measures similarity between any two arbitrary
signals.
l Identical and Orthogonal signals:
Correlation = 0Orthogonal signals
-1 1 -1 1
-1 1 -1 1
1 1 1 1
+1
-1+1
-1
+1
-1
+1
-1
Correlation = 1Identical signals
-1 1 -1 1
1 1 1 1
-1 1 -1 1
C1
C2+1
+1
C1
C2
l Correlation is used to measure similarity of any two arbitrary
signals. It is computed by
multiplying the two signals and then summing (integrating) the
result over a defined
time windows. The two signals of figure (a) are identical and
therefore their
correlation is 1 or 100 percent. In figure (b) , however, the
two signals are
uncorrelated, and therefore knowing one of them does not provide
any information
on the other.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-40
Page40Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Orthogonal Code Usage - Coding
UE1: 1 1
UE2: 1 1
C1 : 1 1 1 1 1 1 11
C2 : 1 1 1 1 1 1 1 1
UE1c1 1 1 1 1 1 1 11
UE2c2 1 1 1 1 1 1 1 1
UE1c1 UE2c2 2 0 2 0 2 0 2 0
UE1: 1 1
UE2: 1 1
C1 : 1 1 1 1 1 1 11
C2 : 1 1 1 1 1 1 1 1
UE1c1 1 1 1 1 1 1 11
UE2c2 1 1 1 1 1 1 1 1
UE1c1 UE2c2 2 0 2 0 2 0 2 0
l By spreading, each symbol is multiplied with all the chips in
the orthogonal sequence
assigned to the user. The resulting sequence is processed and is
then transmitted over
the physical channel along with other spread symbols. In this
figure, 4-digit codes are
used. The product of the user symbols and the spreading code is
a sequence of digits
that must be transmitted at 4 times the rate of the original
encoded binary signal.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-41
Page41Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Orthogonal Code Usage - Decoding
UE1C1 UE2C2: 2 0 2 0 2 0 2 0
UE1 Dispreading by c1: 1 1 1 1 1 1 11
Dispreading result: 2 0 2 0 2 0 2 0
Integral judgment: 4 (means1) 4 (means1)
UE2 Dispreading by c2: 1 1 1 1 1 1 1 1
Dispreading result: 2 0 2 0 2 0 2 0
Integral judgment: 4 (means1) 4 (means1)
UE1C1 UE2C2: 2 0 2 0 2 0 2 0
UE1 Dispreading by c1: 1 1 1 1 1 1 11
Dispreading result: 2 0 2 0 2 0 2 0
Integral judgment: 4 (means1) 4 (means1)
UE2 Dispreading by c2: 1 1 1 1 1 1 1 1
Dispreading result: 2 0 2 0 2 0 2 0
Integral judgment: 4 (means1) 4 (means1)
l The receiver dispreads the chips by using the same code used
in the transmitter.
Notice that under no-noise conditions, the symbols or digits are
completely recovered
without any error. In reality, the channel is not noise-free,
but CDMA system employ
Forward Error Correction techniques to combat the effects of
noise and enhance the
performance of the system.
l When the wrong code is used for dispreading, the resulting
correlation yields an
average of zero. This is a clear demonstration of the advantage
of the orthogonal
property of the codes. Whether the wrong code is mistakenly used
by the target user
or other users attempting to decode the received signal, the
resulting correlation is
always zero because of the orthogonal property of codes.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-42
Page42Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Spectrum Analysis of Spreading & Dispreading
Spreading code
Spreading code
Signal Combination
Narrowband signalf
P(f)
Broadband signal
P(f)
f
Noise & Other Signal
P(f)
f
Noise+Broadband signal
P(f)
f
Recovered signal P(f)
f
l Traditional radio communication systems transmit data using
the minimum bandwidth
required to carry it as a narrowband signal. CDMA system mix
their input data with a
fast spreading sequence and transmit a wideband signal. The
spreading sequence is
independently regenerated at the receiver and mixed with the
incoming wideband
signal to recover the original data. The dispreading gives
substantial gain proportional
to the bandwidth of the spread-spectrum signal. The gain can be
used to increase
system performance and range, or allow multiple coded users, or
both. A digital bit
stream sent over a radio link requires a definite bandwidth to
be successfully
transmitted and received.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-43
Page43Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Spectrum Analysis of Spreading & Dispreading
Max allowed interference
Eb/No Requirement
Power
Max interference caused by UE and others
Processing Gain
Ebit
Interference from other UE Echip
Eb / No = Ec / No PG
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-44
Page44Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Process Gain
l Process Gain
p Process gain differs for each service.
p If the service bit rate is greater, the process gain is
smaller, UE
needs more power for this service, then the coverage of this
service will be smaller, vice versa.
)rate bitrate chiplog(10Gain ocessPr =
l For common services, the bit rate of voice call is 12.2kbps,
the bit rate of video phone
is 64kbps, and the highest packet service bit rate is
384kbps(R99). After the spreading,
the chip rate of different service all become 3.84Mcps.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-45
Page45Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Spreading Technology
l Spreading consists of 2 steps:
p Channelization operation, which transforms data symbols into
chips
p Scrambling operation is applied to the spreading signal
scramblingchannelization
Data symbol
Chips after spreading
l Spreading means increasing the bandwidth of the signal beyond
the bandwidth
normally required to accommodate the information. The spreading
process in UTRAN
consists of two separate operations: channelization and
scrambling.
l The first operation is the channelization operation, which
transforms every data
symbol into a number of chips, thus increasing the bandwidth of
the signal. The
number of chips per data symbol is called the Spreading Factor
(SF). Channelization
codes are orthogonal codes, meaning that in ideal environment
they do not interfere
each other.
l The second operation is the scrambling operation. Scrambling
is used on top of
spreading, so it does not change the signal bandwidth but only
makes the signals
from different sources separable from each other. As the chip
rate is already achieved
in channelization by the channelization codes, the chip rate is
not affected by the
scrambling.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-46
Page46Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Channelization Code
l OVSF Code (Orthogonal Variable Spreading Factor) is used
as
channelization code
SF = 8SF = 1 SF = 2 SF = 4
Cch,1,0 = (1)
Cch,2,0 = (1,1)
Cch,2,1 = (1, -1)
Cch,4,0 = (1,1,1,1)
Cch,4,1 = (1,1,-1,-1)
Cch,4,2 = (1,-1,1,-1)
Cch,4,3 = (1,-1,-1,1)
Cch,8,0 = (1,1,1,1,1,1,1,1)
Cch,8,1 = (1,1,1,1,-1,-1,-1,-1)
Cch,8,2 = (1,1,-1,-1,1,1,-1,-1)
Cch,8,3 = (1,1,-1,-1,-1,-1,1,1)
Cch,8,4 = (1,-1,1,-1,1,-1,1,-1)
Cch,8,5 = (1,-1,1,-1,-1,1,-1,1)
Cch,8,6 = (1,-1,-1,1,1,-1,-1,1)
Cch,8,7 = (1,-1,-1,1,-1,1,1,-1)
l Orthogonal codes are easily generated by starting with a seed
of 1, repeating the 1
horizontally and vertically, and then complementing the -1
diagonally. This process is
to be continued with the newly generated block until the desired
codes with the
proper length are generated. Sequences created in this way are
referred as Walsh
code.
l Channelization uses OVSF code, for keeping the orthogonality
of different subscriber
physical channels. OVSF can be defined as the code tree
illustrated in the following
diagram.
l Channelization code is defined as Cch SF, k,, where, SF is the
spreading factor of the
code, and k is the sequence of code, 0kSF-1. Each level
definition length of code tree is SF channelization code, and the
left most value of each spreading code
character is corresponding to the chip which is transmitted
earliest.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-47
Page47Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Channelization Code
l SF = chip rate / symbol rate
p High data rates low SF code
p Low data rates high SF code
16Data 128 kbps DL8Data 128 kbps UL
32Data 64 kbps DL16Data 64 kbps UL
8Data 384 kbps DL4Data 384 kbps UL
16Data 144 kbps DL8Data 144 kbps UL
128Speech 12.2 DL64Speech 12.2 UL
SFRadio bearerSFRadio bearer
l The channelization codes are Orthogonal Variable Spreading
Factor (OVSF) codes. They are used to preserve orthogonality
between different physical channels. They also increase the clock
rate to 3.84 Mcps. The OVSF codes are defined using a code
tree.
l In the code tree, the channelization codes are individually
described by Cch,SF,k, where SF is the Spreading Factor of the code
and k the code number, 0 k SF-1.
l A channelization sequence modulates one users bit. Because the
chip rate is constant, the different lengths of codes enable to
have different user data rates. Low SFs are reserved for high rate
services while high SFs are for low rate services.
l The length of an OVSF code is an even number of chips and the
number of codes (for one SF) is equal to the number of chips and to
the SF value.
l The generated codes within the same layer constitute a set of
orthogonal codes. Furthermore, any two codes of different layers
are orthogonal except when one of the two codes is a mother code of
the other. For example C4,3 is not orthogonal with C1,0and C2,1,
but is orthogonal with C2,0.
l SF in uplink is from 4 to 256.
l SF in downlink is from 4 to 512.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-48
Page48Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Purpose of Channelization Code
l Channelization code is used to distinguish different
physical
channels of one transmitter
p For downlink, channelization code ( OVSF code ) is used to
separate different physical channels of one cell
p For uplink, channelization code ( OVSF code ) is used to
separate
different physical channels of one UE
l For voice service (AMR), downlink SF is 128, it means there
are 128 voice services
maximum can be supported in one WCDMA carrier;
l For Video Phone (64k packet data) service, downlink SF is 32,
it means there are 32
voice services maximum can be supported in one WCDMA
carrier.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-49
Page49Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Purpose of Scrambling Code
l Scrambling code is used to distinguish different
transmitters
p For downlink, scrambling code is used to separate different
cells in
one carrier
p For uplink, scrambling code is used to separate different UEs
in
one carrier
l In addition to spreading, part of the process in the
transmitter is the scrambling
operation. This is needed to separate terminals or base stations
from each other.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-50
Page50Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Scrambling Code
l Scrambling code: GOLD sequence.
l There are 224 long uplink scrambling codes which are used
for
scrambling of the uplink signals. Uplink scrambling codes are
assigned
by RNC.
l For downlink, 512 primary scrambling codes are used.
l Different scrambling codes will be planned to different cells
in downlink.
l Different scrambling codes will be allocated to different UEs
in uplink.
l The scrambling code is always applied to one 10 ms frame.
l In UMTS, Gold codes are chosen for their very low peak
cross-correlation.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-51
Page51Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Primary Scrambling Code Group
Primary scrambling codes for downlink physical channels
Group 0
Primary scrambling code 0
Primary scrambling code
8*63
Primary scrambling code
8*63 +7512 primary scrambling
codes
Group 1
Group 63
Primary scrambling code 1
Primary scrambling code 8
64 primary scrambling code
groupsEach group consists of 8 primary scrambling codes
l There are totally 512 primary scrambling codes defined by
3GPP. They are further
divided into 64 primary scrambling code groups. There are 8
primary scrambling codes
in every group. Each cell is allocated with only one primary
scrambling code.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-52
Page52Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Code Multiplexing
l Downlink Transmission on a Cell Level
Scrambling code
Channelization code 1
Channelization code 2
Channelization code 3
User 1 signal
User 2 signal
User 3 signal
NodeB
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-53
Page53Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Code Multiplexing
l Uplink Transmission on a Cell Level
NodeB
Scrambling code 3
User 3 signalChannelization code
Scrambling code 2
User 2 signal
Channelization code
Scrambling code 1
User 1 signal
Channelization code
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-54
Page54Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Processing Procedure of WCDMA System
SourceCoding
Channel Coding& Interleaving
Spreading Modulation
SourceDecoding
Channel Decoding& Deinterleaving
Despreading Demodulation
Transmission
Reception
chipmodulated
signalbitsymbol
ServiceSignal
Radio Channel
ServiceSignal
Receiver
l Source coding can increase the transmitting efficiency.
l Channel coding can make the transmission more reliable.
l Spreading can increase the capability of overcoming
interference.
l Scrambling can make transmission in security.
l Through the modulation, the signals will transfer to radio
signals from digital signals.
l Bit, Symbol, Chip
p Bit : data after source coding
p Symbol: data after channel coding and interleaving
p Chip: data after spreading
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-55
Page55Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Modulation Overview
1 00 1
time
Basic steady radio wave:
carrier = A.cos(2pFt+f)
Amplitude Shift Keying:
A.cos(2pFt+f)
Frequency Shift Keying:
A.cos(2pFt+f)
Phase Shift Keying:A.cos(2pFt+f)
Data to be transmitted:Digital Input
l A data-modulation scheme defines how the data bits are mixed
with the carrier signal,
which is always a sine wave. There are three basic ways to
modulate a carrier signal in
a digital sense: amplitude shift keying (ASK), frequency shift
keying (FSK), and phase
shift keying (PSK).
l In ASK the amplitude of the carrier signal is modified by the
digital signal.
l In FSK the frequency of the carrier signal is modified by the
digital signal.
l The PSK family is the most widely used modulation scheme in
modern cellular systems.
There are many variants in this family, and only a few of them
are mentioned here.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-56
Page56Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Modulation Overview
l Digital Modulation - BPSK
1
t
1 10
1
t-1
NRZ coding
fo
BPSKModulated
BPSK signal
Carrier
Information signal
f=0 f=p f=0
1 102 3 4 9875 6
1 102 3 4 9875 6
Digital Input
High FrequencyCarrier
BPSK Waveform
l In binary phase shift keying (BPSK) modulation, each data bit
is transformed into a
separate data symbol. The mapping rule is 1 > + 1 and 0 >
1. There are only two possible phase shifts in BPSK, 0 and
radians.
l NRZ means none return zero.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-57
Page57Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Modulation Overview
l Digital Modulation - QPSK
-1 -1
1 102 3 4 9875 6
1 102 3 4 9875 6
NRZ Input
I di-Bit Stream
Q di-Bit Stream
IComponent
QComponent
QPSK Waveform
1
1
-1
1
-1
1
1
-1
-1
-1
1 1 -1 1 -1 1 1 -1
l The quadrature phase shift keying (QPSK) modulation has four
phases: 0, /2, , and 3/2 radians. Two data bits are transformed
into one complex data symbol; A symbol is any change (keying) of
the carrier.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-58
Page58Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Modulation Overview
NRZ coding
90o
NRZ coding
QPSK
Q(t)
I(t)
fo
A
A Acos(wot)
Acos(wot + p/2)
f
1 1 p/41 -1 7p/4-1 1 3p/4-1 -1 5p/4
)cos(2: fw +oAQPSK
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-59
Page59Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Demodulation
l QPSK Constellation Diagram
1 102 3 4 9875 6
QPSK Waveform
1,1
-1,-1
-1,1
1,-1
1 -11 -1 1 -1-11-1 1
-1,1
NRZ Output
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-60
Page60Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
WCDMA Modulation
l Different modulation methods corresponding to different
transmitting abilities in air interface
HSDPA: QPSK or 16QAMR99/R4: QPSK
l The UTRAN air interface uses QPSK modulation in the downlink,
although HSDPA may
also employ 16 Quadrature Amplitude Modulation (16QAM). 16QAM
requires good
radio conditions to work well. As seen, with 16QAM also the
amplitude of the signal
matters.
l As explained, in QPSK one symbol carries two data bits; in
16QAM each symbol
includes four bits. Thus, a QPSK system with a chip rate of
3.84Mcps could
theoretically transfer 2 3.84 = 7.68 Mbps, and a 16QAM system
could transfer 4 3.84 Mbps = 15.36 Mbps. In 3GPP also the usage of
64QAM with HSDPA has been
studied.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-61
Page61Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Processing Procedure of WCDMA System
SourceCoding
ChannelCoding
Spreading Modulation
SourceDecoding
ChannelDecoding
Despreading Demodulation
Transmission
Reception
chipmodulated
signalbitsymbol
ServiceSignal
Radio Channel
ServiceSignal
Transmitter
Receiver
l Source coding can increase the transmitting efficiency.
l Channel coding can make the transmission more reliable.
l Spreading can increase the capability of overcoming
interference.
l Scrambling can make transmission in security.
l Through the modulation, the signals will transfer to radio
signals from digital signals.
l Bit, Symbol, Chip
p Bit : data after source coding
p Symbol: data after channel coding and interleaving
p Chip: data after spreading
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-62
Page62Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Wireless Propagation
ReceivedSignal
TransmittedSignal
Transmission Loss:Path Loss + Multi-path Fading
Time
Amplitude
l A mobile communication channel is a multi-path fading channel
and any transmitted
signal reaches a receive end by means of multiple transmission
paths, such as direct
transmission, reflection, scatter, etc.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-63
Page63Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Propagation of Radio SignalSignal at Transmitter
Signal at Receiver
-40
-35
-30
-25
-20
-15
-10
-5
dB
0
0
dBm
-20
-15
-10
-5
5
10
15
20
Fading
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-64
Page64Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Fading Categories
l Fading Categories
p Slow Fading
p Fast Fading
l Furthermore, with the moving of a mobile station, the signal
amplitude, delay and
phase on various transmission paths vary with time and place.
Therefore, the levels of
received signals are fluctuating and unstable and these
multi-path signals, if overlaid,
will lead to fast fading. Fast fading conforms to Rayleigh
distribution. The mid-value
field strength of fast fading has relatively gentle change and
is called slow fading.
Slow fading conforms to lognormal distribution.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-65
Page65Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Diversity Technique
l Diversity technique is used to obtain uncorrelated signals
for
combining
p Reduce the effects of fading
n Fast fading caused by multi-path
n Slow fading caused by shadowing
p Improve the reliability of communication
p Increase the coverage and capacity
l Diversity technology means that after receiving two or more
input signals with
mutually uncorrelated fading at the same time, the system
demodulates these signals
and adds them up. Thus, the system can receive more useful
signals and overcome
fading.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-66
Page66Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Diversity
l Time diversity
p Channel coding, Block interleaving
l Frequency diversity
p The user signal is distributed on the whole bandwidth
frequency
spectrum
l Space diversity
l Polarization diversity
l Diversity technology is an effective way to overcome overlaid
fading. Because it can be
selected in terms of frequency, time and space, diversity
technology includes
frequency diversity, time diversity and space diversity.
l Time diversity: Channel coding
l Frequency diversity: WCDMA is a kind of frequency diversity.
The signal energy is
distributed on the whole bandwidth.
l Space diversity: using two antennas
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-67
Page67Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Principle of RAKE Receiver
Receive set
Correlator 1
Correlator 2
Correlator 3
Searcher correlator Calculate the time delay and signal
strength
CombinerThe combined
signal
tt
s(t) s(t)
RAKE receiver help to overcome on the multi-path fading and
enhance the receive performance of the system
l The RAKE receiver is a technique which uses several baseband
correlators to
individually process multipath signal components. The outputs
from the different
correlators are combined to achieve improved reliability and
performance.
l When WCDMA system is designed for cellular system, the
inherent wide-bandwidth
signals with their orthogonal Walsh functions were natural for
implementing a RAKE
receiver. In WCDMA system, the bandwidth is wider than the
coherence bandwidth of
the cellular. Thus, when the multi-path components are resolved
in the receiver, the
signals from different paths are uncorrelated with each other.
The receiver can then
combine them using some combining schemes. So with RAKE receiver
WCDMA
system can use the multi-path characteristics of the channel to
get signal with better
quality.
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-68
Page68Copyright 2008 Huawei Technologies Co., Ltd. All rights
reserved.
Summary
l In this course, we have discussed basic concepts of WCDMA:
p Spreading / Despreading principle
p UTRAN Voice Coding
p UTRAN Channel Coding
p UTRAN Spreading Code
p UTRAN Scrambling Code
p UTRAN Modulation
p UTRAN Transmission/Receiving
PDF created with pdfFactory Pro trial version
www.pdffactory.com
-
WCDMA RAN Fundamental
Confidential Information of Huawei. No Spreading Without
Permission
N-69
Thank youwww.huawei.com
PDF created with pdfFactory Pro trial version
www.pdffactory.com