Citation
Wireless ubiquitous communications model using femtocells

Material Information

Title:
Wireless ubiquitous communications model using femtocells
Creator:
Kurup, Sumesh Sukumaran
Place of Publication:
Denver, Colo.
Publisher:
University of Colorado Denver
Publication Date:
Language:
English
Physical Description:
89 leaves : ; 28 cm

Thesis/Dissertation Information

Degree:
Master's ( Master of Science)
Degree Grantor:
University of Colorado Denver
Degree Divisions:
Department of Electrical Engineering, CU Denver
Degree Disciplines:
Electrical Engineering
Committee Chair:
Beaini, Joseph
Committee Members:
Radenkovic, Miloje
Grabbe, Robert

Subjects

Subjects / Keywords:
Femtocells ( lcsh )
Multivariate analysis ( lcsh )
Principal components analysis ( lcsh )
Computer input-output equipment ( lcsh )
Algorithms ( lcsh )
Algorithms ( fast )
Computer input-output equipment ( fast )
Femtocells ( fast )
Multivariate analysis ( fast )
Principal components analysis ( fast )
Genre:
bibliography ( marcgt )
theses ( marcgt )
non-fiction ( marcgt )

Notes

General Note:
Department of Electrical Engineering
Statement of Responsibility:
by Sumesh Sukumaran Kurup.

Record Information

Source Institution:
University of Colorado Denver
Holding Location:
Auraria Library
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
317586884 ( OCLC )
ocn317586884
Classification:
LD1193.E54 2008m K88 ( lcc )

Full Text
Wireless Ubiquitous Communications Model
USING FEMTOCELLS
by
Sumesh Sukumaran Kurup
B.E. Electronics Engineering, University of Pune, India, 2003
A thesis submitted to the
University of Colorado Denver
in partial fulfillment
of the requirements for the degree of
Master of Science in Electrical Engineering
2008


This thesis for the Master of Science
degree by
Sumesh Sukumaran Kurup
has been approved
by
Dr. Miloje Radenkovic
12/02/2008


Sumesh Sukumaran Kurup (M.S., "Electrical Engineering)
Wireless Ubiquitous Communications Model using Femtocells
Thesis directed by Associate Professor Joseph Beaini
ABSTRACT
Femtocell is a portable device which acts as a small cellular base station which incorporates the
features of a typical base station but is typically designed to serve the residential or small office
environments. It serves the purpose of better coverage for the end user by connecting the 3G
handsets to a standard DSL or cable service and provides high speed voice and data coverage to
the end user by deriving the benefits provided by the 3G UMTS technology. By converging the
advantages provided by both the 3G mobile network and the high speed cable lines, it is set to
provide better coverage to the end users typically in an environment where the mobile access
would have be limited and unavailable.
The purpose of this thesis is to study the performance of the femtocell system in a simulated
environment using the upcoming UMTS technology where the core architecture of a femtocell
network would be implemented with a UMTS network and an IP backbone would be used to route
the call and the data traffic to the end user with the help of the femtocell device. The simulation
environment would be implemented with the help of the UMTS Module in OPNET simulating a
real time scenario of a call process.
This abstract accurately represents the content of the candidates thesis. I recommend its
publication.
Signed
Joseph Beaini


DEDICATION
To my wife,
Nilima, my
parents and my
sister.
For their great love and endless support
Sumesh Sukumaran Kurup


ACKNOWLEDGEMENT
First and foremost, I would like to take thank the Great Lord, Ruler of the Heavens, for His
support in mysterious ways. May His blessings be upon us all.
I would like to express my deep esteem and sincere thanks to Prof. Joseph Beaini, at University
of Colorado Denver, U.S.A. It is true without his guidance, endless help, proper remarks and
continuous availability; the present work would have been by no means the same.
I am deeply indebted to my family and my wife, Nilima, for their incredible support and
encouragement from starting line to kickoff, my family never failed to show. Also special thanks
goes out to my very good friend Tischiel Balachandra for his valuable insight and constant
guidance without which it would have been almost impossible to complete this thesis.
Thanks to my friends who have seen my best and worst- you know who you are.
Finally I would like to thank the OPNET for providing me the help and support for granting the
use of Modeler tool for the thesis.


TABLE OF CONTENTS
Figures.........................................................................vi
Tables........................................................................viii
Chapter
1. Introduction..................................................................1
1.1 Benefits offered by Femtocells..............................................3
2. Communication System........................................................5
2.1 Modern Communications Systems............................................. 5
2.2 Cellular Communications Concepts............................................5
2.3 Mobile Cellular Environment.................................................8
2.4 Evolution of Mobile Cellular Systems.......................................9
2.4.1 First Generation (1G) Cellular Systems.....................................9
2.4.2 Second Generation (2G) Cellular Systems...................................9
2.4.3 Third Generation (3G) Cellular Systems....................................10
2.4.3 Ubiquitous Mobile Communication Architecture for Next-
Generation Heterogeneous Wireless Systems.................................11
3. UMTS Overview................................................................15
3.1 Background in the standardization of UMTS..................................15
3.2 Migration path to UMTS.....................................................18
3.3 UMTS Basics................................................................19
3.4 WCDMA Air Interface........................................................20
3.4.1 Spreading and Despreading.................................................21
3.5 WCDMA Uplink Spreading, Scrambling, and Modulation.........................25
3.6 WCDMA Downlink Spreading, Scrambling, and Modulation.......................27
3.7 WCDMA Uplink Dedicated Channel Format......................................29


3.8 WCDMA Downlink Dedicated Channel Format
31
3.9 Overview of the UMTS General Architecture.......................................32
3.10 UTRAN Architecture..............................................................33
3.10.1 The Radio Network Controller...................................................34
3.10.1.1 Logical Role of RNC.........................................................35
3.10.2 The Node B (Base Station).....................................................36
3.11 UTRAN Interfaces and Protocols................................................37
3.11.1 lu-CS Interface............................................................. 39
3.11.2 lu-PS Interface................................................................41
3.11.3 lub Interface..................................................................43
3.11.4 lur Interface................................................................. 45
3.12 UMTS Core Network Architecture and Evolution....................................45
3.12.1 Release 99 Core Network Elements..............................................46
3.12.2 Release 5 Core Network and IP Multimedia Sub-Systems..........................48
4 Femtocell.......................................................................50
4.1 Femtocell Architecture (Home NodeB Architecture)................................50
4.2 Protocol Stack for lu-h.........................................................52
4.3 Mechanism for 3G HNB-GW Discovery...............................................55
4.3.1 HNB-GW Discovery Procedure......................................................56
4 .4 Data transfer between lu-h and the core network...................................60
4 4.1 Data transfer on lu-PS Interface..............................................60
4.4 .2 Data transfer on lu-CS Interface.............................................62
4.5 Femtocell Deployment Configurations...........................................64


5 Simulation of the Femtocell environment........................................68
5.1 Overview of Simulation Model...............................................68
5.2 Simulation Results and Graphs..............................................71
5.2.1 Simulation Results for Voice and HTTP traffic simulation...................75
5.2.2 UMTS Simulation Results.................................................67
5.2.2.1 UMTS GPRS Mobility Management (GMM) Simulation Results...............79
5.2.2.2 UMTS RNC Simulation Statistics..........................................81
5.2.3. ATM Simulation Statistics..................................................82
A. Appendix......................................................................83
B. Abbreviations.................................................................85
Bibliography......................................................................89


1. Introduction
The demand for higher data rates in wireless networks is unrelenting and has triggered the
design and development of new data-minded cellular standards such as WiMAX (802.16e),
the 3GPPs High Speed Packet Access (HSPA) and LTE standards and 3GPPs EVDO and
UMB standards. In parallel, Wi-FI mesh networks are also being developed to provide
nomadic high-rate data services in a more distributed manner. Although the Wi-Fi network
will not be able to support the same level of mobility and coverage as the cellular standards,
to be competitive for home and office use, cellular data systems will need to provide service
roughly comparable to that offered by Wi-Fi networks.
The wireless capacity has increased manifold since 1957. Breaking down the gains shows a
25X improvement from wider spectrum, a 5X improvement by dividing the spectrum into
smaller slices, a 5X improvement by designing better modulation schemes and a whopping
1600X gain through reduced cell sizes and transmit distance. The enormous gains reaped
from smaller cellular sizes arise from efficient spatial reuse of spectrum or, alternatively,
higher area spectral efficiency.
The main problem in this continued microization of cellular networks is that the network
infrastructure for doing so is expensive. A recent development is femtocells, also called as
home base stations (BSs), which are small, extremely low power, cellular base station
designed to be located inside a home and using a DSL/Cable connection to backhaul traffic.
In other words, femtocells are home base stations deployed in high volume for residential
use, connected to the core network via broadband. They are connected to the general


cellular network only through the IP core network, which they use as the main backhaul
method. They can typically accommodate between four and six users, and they radiate very
low power (< 10 mW). The high receive sensitivity of current 3G handsets lends itself to this.
Figure 1.1 Concept of a Femtocell
2


Femtocell devices use licensed radio spectrum, so must be operated and controlled by a
mobile phone company. Thus it will work with only one mobile phone operator, and thus
encourages all users in a household to switch to the same network operator.
A femtocell allows service providers to extend service coverage indoors, especially where
access would otherwise be limited or unavailable. The femtocell incorporates the
functionality of a typical base station but extends it to allow a simpler, self contained
deployment; for example, a UMTS femtocell containing a Node B, RNC and GSN with
Ethernet for backhaul. Although much attention is focused on UMTS, the concept is
applicable to all standards, including GSM,CDMA-2000, TD-SCDMA and WiMAX solutions.
While conventional approaches require dual-mode handsets to deliver both in-home and
mobile services, an in-home femtocell deployment promises fixed mobile convergence with
existing handsets. Compared to the other techniques for increasing system capacity, such
as distributed antenna systems and microcells, the key advantage of femtocells is that there
is very little upfront cost to the service provider.
1.1 Benefits offered by Femtocells
According to some estimates, the proportion of calls originating from residences is in the
range of 30% to 60%, and has an upward trend, as wireless calling becomes more
affordable, and often a replacement for landline calls. At the same time, percentage of
homes with a broadband Internet connection is also rapidly increasing.
Under these circumstances, femtocells have the following benefits:
3


Improvement of Coverage and Capacity: Cellular operators can improve indoor coverage
of wireless services, and enhance performance and QoS of wireless data services delivered
in the home or in the office. Due to their short transmit-receive distance, femtocells can
greatly lower transmit power, prolong handset battery, and achieve a higher signal-to-
interference-plus-noise ratio (SINR). This translate to improved reception so called five-bar
coverage and higher capacity. Because of the reduced interference, more users can be
packed into a given area in the same region of spectrum, thus increasing the area spectral
efficiency or equivalently, the total number of users per Hertz per unit area.
Backhaul: Wireless operators can take advantage of existing home broadband connectivity
for backhauling traffic whenever the subscriber is in the vicinity of a femtocell (e.g. at home).
New Service Offering: Femtocells offer the operator a possibility to develop new service
offerings at home, e.g., home zone subscription plan.
Acceleration of Fixed/Mobile Convergence: Unlike in the case of WiFi use for fixed
installation, femtocells do not require dual mode handsets. By enabling any wireless
handset to use femtocells, fixed and mobile service convergence would occur at an
accelerated pace.
Other Operational Efficiency: Femtocells can additionally help reduce churn and can be
used as a platform on which operators can effectively deliver triple- and quadruple-play
services (Internet, TV, fixed/mobile telephony).
4


2. Communication Systems
2.1 Modern Communication Systems
Advancement in communication and information processing technologies creates more new
applications and products. In particular, the demand for wireless communication services
has increased rapidly and the trend is expected to continue. There are already numerous
modern wireless systems, as: mobile telephones transmitting to a base station, ground
stations communicating with a satellite, local area networks, packet-radio networks,
interactive cable television networks, etc, and the area is in complete growth always
promising new and exciting services to the end-user. Therefore, stringent requirements on
the capacity of communication systems are needed in terms of the number of users a
system can serve simultaneously. In other or more appropriate words, as much information
as possible should be transferred.
2.2 Cellular Communications Concepts
In the early mobile radio systems a large coverage was attained by placing an antenna with
a high-power transmitter in one of the highest point of the coverage area for instance, on top
of a hill or a high building. Nevertheless, it meant that only a small number of users could be
allocated in a large area due to the few available radio frequencies. So any attempt to reuse
the same frequencies throughout the system would result in interference. Thus, the need of
5


higher capacity with limited radio channel brought into the cellular concept. A cellular mobile
communications system uses a large number of low-power wireless transmitters to create
cells which are the basic geographic service area of a wireless communications system.
Figure 2.1 illustrates the structure of a cellular comrrtunication system. Each cell consists of
a base station (BS) transmitting over a small geographic area usually depicted as an
hexagon (the true shape of a cell is not a perfect hexagon due to constraints impose by the
terrain). According to the density and demand of mobile users (Mobile Station) within a
certain region, the cell size is determined. The base stations in turn are connected to a
central called the mobile switching centre (Mobile Switching Center) which provides
connectivity between the public switched telephone network (PSTN) and the base stations.
Thus a global communication network is formed with PTSNs which connects the
conventional telephone switching centers with MSCs all over the world.
An obstacle in the cellular network arises when a mobile user travel from one cell to another
during a call. To ensure that mutual interferences between users remain low, adjacent cells
do not use the same radio frequency channel, then when a user moves out from a cell the
call has to be transferred to another stronger frequency channel (which becomes the new
cell where the user is moving in). This process is known as hand-off or hand-over, changing
a call from one cell to another without being notice by the users. Another important concept
inside the established cellular systems is the frequency planning or frequency reuse. Due to
the reduce number of radio frequency channels available for mobile systems, a reuse of the
frequency channels had to be implemented into the cellular concept.
6


PSTN
MSC

BS4
Figure 2.1 Structure of cellular communication system
This reuse process means that the radio frequency channels used in one cell can also be
reused in another cell some distance away. Usually clusters of cells (no frequency channels
are reused in a cluster) are reused in a regular pattern during the entire coverage area as it
shown in Figure 2.2. Hence, the frequency reuse factor in a system is determined by the
available frequency channels, i.e. for the particular case depicted in Figure 2.2 the frequency
reuse factor of the system is 1/7.
Figure 2.2 Frequency reuse pattern in cellular system
7


2.3 Mobile cellular environment
A cellular communication system provides with a full duplex communication between the
mobile user and the base stations to carry through a normal conversation talk (back and
forth). To achieve this type of radio transmission the mobile users and the base station both
need circuitry to transmit on one frequency while receiving on another. The radio link from
the base station to the mobile phone (BS-MS) is usually referred as downlink (or forward
link) and the inverse process (MS-BS) is called uplink (or reverse link), see Figure 2.3. In the
downlink, all the users signals are transmitted by the same single source, base station;
therefore the signals received at each mobile terminal are synchronous. On the other hand,
in the uplink the signals received in the base station are asynchronous as now the
transmissions are yielded by several uncoordinated and geographical separated sources
(mobile users).
Uplink
/ /
/' /
/ "
/
/ Downlink
Q C
OCOi
; ocGj
MS

l

Figure 2.3 Radio channels used in the transmission of information
8


2.4 Evolution of Mobile Cellular Systems
2.4.1 First Generation (1g) Cellular Systems
The cellular concept was developed in Bell Laboratories in 1947. Instead of transmitting
signals from one location with high power, the system capacity could be dramatically
increased by limiting the range of the transmission, which enables the same frequencies to
be reused at much shorter distances. However, the concept was not implemented until 1979.
It was not until that time that the technological developments such as integrated circuits,
microprocessors, frequency synthesizers, etc. have made it possible. Soon after this came
the first generation of commercial cellular radio systems, such as The Nippon Telephone
and Telegraph (NTT) system in 1979, the Nordic Mobile Telephone (NMT) system in 1981,
the Advanced Mobile Phone Service (AMPS) in 1983 and the British Total Access
Communications System (TACS) in 1985 (a modified version of AMPS). TACS is also used
in Japan, where the system is called JTACS. These systems are/were analog, and where
designed for wireless speech service.
2.4.2 Second Generation (2g) Cellular Systems
The developments of digital signal processing methods along with the rapid development of
integrated circuits and microprocessors led to the replacement of the analog 1G cellular
system by the digital 2G cellular systems. The first of these, the Global System for Mobile
Communication (GSM), was realized in 1992 in Europe. It operates in 900 MHz band, and is
based on FDMA/TDMA. Variants of GSM have been developed for higher frequency bands,
9


such as the Cellular System 1800 (DCS 1800) in Europe and PCS 1900 in North America.
The GSM system became a huge success. As of December 2004, there were 626 GSM
networks on air in 198 countries or territories around the world.
The major improvements offered by the digital transmission of the 2G systems over 1G
systems were better speech quality, increased capacity, global roaming, and data services
like the Short Message Service (SMS), which gained tremendous popularity in the 1990s.
Major improvements in the data services were also the introduction of packet switched
services such as the General Packet Radio Services (GPRS) and higher data rate circuit
switched services such as the High Speed Circuit Switched Data Service (HSCSD).
2.4.3 Third Generation (3g) Cellular Systems
Although the 2G systems could already provide some basic data services, the possible data
rates were still relatively low, and could not satisfy the needs of future services like mobile
web browsing, file transfer, real-time video, digital TV etc. The 3G cellular systems are
known with the name International Mobile Communications for the year 2000 (IMT-2000),
and are being implemented in many countries around the world. The 3G systems introduce
wireless wideband packet-switched data services for wireless access to the internet with
speeds up to 2 Mb/s. The 2G systems have been ( and still are) evolving towards the next
generation with the introduction of new technology enhancements, such as GPRS and
HSCSD in GSM, Cellular Digital Packet Data (CDPD, that operates over AMPS, and High
Speed Data (HSD) in IS-95. A step further towards the 3G networks is the Enhanced Data
10


Rates for GSM Evolution (EDGE) technology, which enables three times higher data rates
than those possible with the ordinary GSM/GPRS network.
Several standardization bodies joined their forces in 1998 in the 3rd Generation Partnership
Project (3GPP) agreement with the joint goal of producing globally applicable technical
specifications and technical reports for a 3rd generation mobile system. It has a sister
project, the 3rd Generation Partnership Project 2 (3GPP2), which compromises North
America and Asian interests developing the 3G mobile systems. The 3GPP projects
produces the radio interference standard for the 3G networks, wideband CDMA (WCDMA),
which is the main 3rd generation air interface in the world and will be deployed in Europe
and Asia, including Japan and Korea. The 3G systems within the scope of 3GPP are
generally known with the name Universal Mobile Telecommunication Services (UMTS), and
WCDMA is called Universal Terrestrial Radio Access (UTRA) Frequency Division Duplex
(FDD) and Time Division Duplex (TDD), the name WCDMA being used to cover both FDD
and TDD operation.
UMTS stands for Universal Mobile Telecommunications System. UMTS is one of the
emerging mobile phone technologies known as third-generation, or 3G. Third-generation
systems are designed to include such traditional phone tasks as calls, voice mail, and
paging, but also new technology tasks such as Internet access, video, and SMS, or text
messaging.
One of the main benefits of UMTS is its speed. Current rates of transfer for broadband
information are 2 Mbits per second. This speed makes possible the kind of streaming video


that can support movie downloads and video conferencing. In a sense, UMTS makes it
possible for you to enjoy all of the functionality of your home computer while you are
roaming. By combining wireless and satellite cellular technologies, UMTS takes advantage
of all existing options to result in the Holy Grail of 3G presentation: seamless transitions
between WiFi and satellite.
UMTS is based on the Global System for Mobile (GSM) standard, which is the gold standard
in Europe and more than 120 countries worldwide. In fact, UMTS is sometimes referred to as
3GSM. The two systems are not compatible, however. UMTS is incompatible with GSM.
Some phones are dual GSM/UMTS phones, but unless that exciting new mobile phone or
handset that you can't wait to get your hands on has that kind of duality built in, you will only
be able to utilize one mode, the one that came with the device.
2.4.4 Ubiquitous Mobile Communication Architecture for Next-
Generation Heterogeneous Wireless Systems
Mobile users are demanding anywhere and anytime access to high-speed data real- and
non-real time multimedia services from next-generation wireless systems (NGWS). These
services have different requirements in terms of latency, bandwidth, and error rate.
Currently, there exist disparate wireless networks, such as Bluetooth for personal areas,
wireless LANs (WLANs) for local areas, Universal Mobile Telecommunications System
(UMTS) for wide areas, and satellite networks for global networking. These networks are
designed for specific service needs and vary widely in terms of bandwidth, latency, area of
12


coverage, cost, and quality of service (QoS) provisioning. For example, satellite networks
can provide global coverage, but are limited by high cost and long propagation delays (from
20-25 ms for low Earth orbit [LEO] satellites to 250-280 ms for geostationary Earth orbit
[GEO] satellites). Third-generation (3G) wireless systems like UMTS can deliver a maximum
data rate of 2 Mb/s at lower cost and have wide areas of coverage. WLANs support
bandwidth up to 54 Mb/s at extremely low cost. It may be noted that the future generation of
WLANs are expected to provide data rates in excess of 100 Mb/s. However, WLANs can
support only low- mobility users and have small coverage areas. Therefore, none of the
existing wireless systems can simultaneously satisfy the low latency, high bandwidth, and
ubiquitous coverage needs of mobile users at low cost. This necessitates a new direction in
the design of NGWS.
There can be two possible approaches in designing NGWS:
Develop a new wireless system with radio interfaces and technologies that can satisfy the
requirements of the services demanded by future mobile users.
Intelligently integrate the existing wireless systems so that users may receive their services
via the best available wireless system.
The first approach is expensive and needs more time for development and deployment;
hence, it is not practical. Therefore, we advocate the use of the second approach, which is a
more feasible option. Following the second approach, heterogeneous wireless systems,
each optimized for some specific service demands and coverage area, will cooperate with
13


each other to provide ubiquitous always best connection to mobile users. In this integrated
heterogeneous network architecture, each user is always connected to the best available
network or networks.
The integrated NGWS keeps the best features of the individual networks: the global
coverage of satellite networks, the wide mobility support of 3G systems, and the high speed
and low cost of WLANs. At the same time, it eliminates the weaknesses of the individual
systems. For example, the low-datarate limitation of 3G systems can be overcome when
WLAN coverage is available through handover of the user to the WLAN. When the user
moves out of a WLAN coverage area, it can be handed over to the overlaid 3G system.
Similarly, a satellite network can be used when neither a 3G system nor a WLAN is
available. The basic idea is to use the best available network at any time.
The integrated NGWS must have the following characteristics:
Support for the best network selection based on users service needs
Mechanisms to ensure high-quality security and privacy
Protocols to guarantee seamless intersystem mobility
Moreover, the architecture should be scalable; that is, able to integrate any number of
wireless systems of different service providers who may not have direct service level
agreements (SLAs) among them.
14


3. UMTS Overview
This chapter presents an overview of Universal Mobile Telecommunications System (UMTS)
Release 5, including a short description of the evolution of mobile cellular systems that led to
creation of third generation systems and UMTS in particular. It intends to provide an insight
into UMTS and 3G technology in general, in order to better understand the importance of the
goals of this thesis and obtained research results.
3.1 Background in the standardization of UMTS
The rapid increase in the demand for data services, primarily IP, has been thrust upon the
wireless industry. Over the years, since first mobile cellular systems appeared, there has
been much anticipation of the onslaught of data services, but the radio access platforms
have been the major bottleneck for the real time implementation of it. Third generation is a
term that has received and continues to receive much attention as the enabler for high
speed data for the wireless mobility market. 3G and all it is meant to be are defined in the
ITU specification International Mobile Telecommunications-2000 (IMT-2000). IMT-2000 is a
radio and network access specification, defining several recommended methods and
technology platforms that meet the overall goals of the specification. It provides a framework
for worldwide wireless access by linking the diverse systems of terrestrial and/or satellite
based networks and intends to exploit the potential synergy between digital mobile
telecommunications technologies and systems for fixed and mobile wireless access
systems. ITU activities on IMT-2000 comprise international standardization, including
15


frequency spectrum and technical specifications for radio and network components, tariffs
and billing, technical assistance and studies on regulatory and policy aspects. Some of the
main IMT-2000 requirements for the third generation of mobile cellular systems are listed
below:
Global standard
Compatibility of service within the IMT-2000 family of standards
High quality of service
Worldwide or at least regional common frequency bands
Small terminals for worldwide use
Worldwide roaming capability
Support for multimedia services, applications and terminals
Improved spectrum efficiency
Flexibility for evolution to the next generation of wireless networks
High speed packet data rates, at least:
o 2 Mbps for fixed environment
o 384 kbps for pedestrian speeds
o 144 kbps for vehicular speeds
The selected family of technology platforms that comprise the IMT-2000 is listed below; ITU-
R mapping of these platforms to TDMA and CDMA-based groups is illustrated in Figure 3.1
below.
16


3.84 Mcps 3.6864 Mcps 3 84 McPs 1
1.28 Mcps
Figure 3.1 ITU-RIMT-2000 technology grouping
IMT-DS (Direct Spread) UTRA FDD/WCDMA (Universal Terrestrial Radio
Access Frequency Division Duplex / Wideband Code Division Multiple Access)
IMT-MC (Multi-Carrier) CDMA2000 (Code Division Multiple Access 2000)
IMT-TC (Time-Code) -UTRA TDD & TD-SCDMA (Universal Terrestrial Radio
Access Time Division Duplex & Time Division Synchronous Code Division
Multiple Access)
IMT-FT (Frequency-Time) DECT (Digital European Cordless
Telecommunications)
IMT-SC (Single Carrier) UWC-136 (Universal Wireless Communications 136)
17


3.2 Migration path to UMTS
The radio access for UMTS is known as Universal Terrestrial Radio Access (UTRA). This is
a WCDMA-based radio solution, which includes both FDD and TDD modes. The radio
access network (RAN) is known as UTRAN. It takes more than an air interface or an access
network to make a complete system, however. The core network must also be considered.
Because of the widespread deployment and success of Global System for Mobile
communications (GSM), it is appropriate to base the UMTS core network upon an evolution
of the GSM core network.
The first release of specifications from 3GPP is known as 3GPP Release 1999. The release
includes not only new specifications for the support of a UTRAN access, but also enhanced
versions of existing GSM specifications (such as for the support of EDGE). The 3GPP
Release 1999 specifications were completed in March of 2000. The next release of 3GPP
specifications was originally termed 3GPP Release 2000. This included major changes to
the core network. The changes were so significant, however, that they could not all be
handled in a single step. Thus, Release 2000 was divided into two releases: Release 4 and
Release 5. 3GPP Release 1999 focuses mainly on the access network (including a totally
new air interface) and the changes needed to the core network to support that access
network. Release 4 focuses more on changes to the architecture of the core network.
Release 5 introduces a new call model, which means changes to user terminals, changes to
the core network, and some changes to the access network (although the fundamentals of
the air interface remain the same).
18


3.3 UMTS Basics
UMTS includes two of the air interfaces proposed in the IMT-2000 recommendation. These
both use Direct Sequence CDMA (DS-CDMA). One solution uses Frequency Division
Duplex (FDD) and the other uses Time Division Duplex (TDD).ln the FDD option, paired 4.4-
5 MHz carriers are used in the uplink and downlink. Frequency bands between 1920 MHz
and 1980 MHz are used in uplink, and bands between 2110 MHz and 2170 MHz are used in
downlink. Thus, for the FDD mode of operation, a separation of exists between uplink and
downlink. For TDD, the availability of spectrum varies: in Europe it is expected that 25 MHz
will be available for licensed TDD use in the 1900-1920 MHz and 2020-2025 MHz bands.
The rest of the unpaired spectrum is expected to be used for unlicensed TDD applications in
the 2010-2020 MHz band. In TDD systems a given carrier is used in both directions so that
no separation exists.
In Wideband Code Division Multiple Access (WCDMA), which is the UMTS air interface, user
data is spread to a far greater bandwidth than the user rate by the application of a spreading
codes, which are unique sequences of bits known as chips. The transmission from each
user (generally) is spread by a different spreading code, and all users transmit at the same
frequency at the same time. At the receiving end, signals from different users are separated
by dispreading the set of received signals using the spreading codes applicable to those
users. The chip rate in WCDMA is 3.84 Mcps (megachips per second)
3.4 WCDMA Air Interface


WCDMA is a wideband Direct-Sequence Code Division Multiple Access (DS-CDMA) system,
i.e. user information bits are spread over a wide bandwidth by multiplying the user data with
quasi-random bits (called chips) derived from CDMA spreading codes. In order to support
high data rates, the use of a variable spreading factor and multicode connections (i.e.
connections using several parallel codes) are supported. The chip rate of 3.84 Mcps leads to
a carrier bandwidth of approximately 5 MHz DS-CDMA systems with a bandwidth of about 1
MHz, such as IS-95, is commonly referred to as narrowband CDMA, as opposed to
WCDMA. The inherently wide carrier bandwidth of WCDMA supports high user data rates
and also has certain performance benefits, such as increased multipath diversity. Subject to
the operating license, the network operator can deploy multiple 5 MHz carriers to increase
capacity, possibly in the form of hierarchical cell layers. The actual carrier spacing can be
selected on a 200 kHz grid between approximately 4.4 and 5 MHz, depending on
interference between the carriers.The table 3.1 below gives us a brief overview of the main
system design parameters that characterize WCDMA.
Multiple access method DS-WCDMA
Duplex method FDD/TDD
Base station synchronization Asynchronous operation
Chip rate 3.84 Mcps
Frame length 10 ms
Service multiplexing Services with different QoS requirements are multiplexed on one connection
Multirate concept Variable spreading factor and multicode
Detection L Coherent using pilot symbols or common pilot
Table 3.1 WCDMA Parameters
20



WCDMA uses two basic modes of operation: FDD and TDD, as already described in section
3.2. In the FDD mode, separate 5 MHz carrier frequencies are used for the uplink and
downlink, whereas in TDD only one 5 MHz carrier is time-shared between the two directions.
The operation of asynchronous base stations is supported, so that there is no need for a
global time reference such as Global Positioning System (GPS) signal. Deployment of indoor
and micro base stations is easier when no GPS signal needs to be received. WCDMA also
employs coherent detection on uplink and downlink based on the use of pilot symbols or
common pilot.
3.4.1 Spreading and Despreading
Figure 3.2 depicts the basic operations of spreading and despreading for a DS-CDMA
system User data is assumed to be a bit sequence of rate R, the user data bits are
assumed to have the values of +1 and -1. The spreading operation is the multiplication of
each user data bit with a spreading code, which is a sequence of n code bits, called chips.
The resulting spread data is at a rate of n*R and has the same random (pseudo-noise-like)
appearance as the spreading code. It can be said that a spreading factor of n has been
used.
During despreading, the spread data is multiplied again with the same n-bit user spreading
code. The original user bit sequence can be recovered correctly, provided there is (as shown
In Figure 3.2) good synchronization between the spread user signal and the spreading and
despreading codes. The increase of the actual bit rate by a factor of n corresponds to a
21


widening (by factor of n) of the occupied spectrum of the spread user data signal. Due to this
virtue, CDMA systems are more generally called spread spectrum systems.
The despreading operation is applied also to interfering CDMA signals of other users which
are assumed to have been spread with a different spreading code. The result of multiplying
the interfering signal with the own code and integrating the resulting product leads to
interfering signal values lingering around 0. Therefore, in the process of integrating the
product, the amplitude of the own signal increases on average by a factor of n relative to that
of the other user, i.e. the correlation detection process raises the desired user signal by the
spreading factor of n from the interference present in the system. This effect is termed
processing gain and is a fundamental aspect of CDMA systems. Processing gain is what
gives CDMA systems the robustness against self-interference that is necessary in order to
reuse the same carrier frequencies over geographically close distances. The processing
gain is always higher for lower user bit rates than for high bit rates, for any given chip rate.
Spreading and despreading by themselves do not provide any signal enhancements.
Indeed, the processing gain comes at the price of an increased transmission bandwidth (by
the amount of the spreading factor). However, processing gain allows theoretical frequency
reuse of 1 between different cells, i.e. a frequency may be reused in every cell/sector. This
feature can be used to obtain high spectral efficiency, but in requires tight power control to
avoid too much interference.
22


Table 3.2 presents total channel bit rates and approximate maximum throughput achieved at
the physical layer assuming Vi-rate channel coding for different spreading factors. High
spreading factors provide more robust communication, but slower data rates.
Spreading factor Channel bit rate Approx, physical throughput (assuming /2-rate coding)
256 15 kbps 7.5 kbps
128 30 kbps 15 kbps
64 60 kbps 30 kbps
32 120 kbps 60 kbps
16 240 kbps 120 kbps
8 480 kbps 240 kbps
4 960 kbps 480 kbps
4, with 6 parallel codes 5740 kbps 2.8 Mbps
Table 3.2 Spreading factor, channel bit rate and approximate physical throughput
23


Data
+

Spreading
rtmjuin^jL
rir^_ri_m_Lnn_
Spreading Code
Spread Data = Data X Spreading Code
| transmission


Transmitted Data
fU LTLTU LTUU LTL
Despreading
Data =
spread data x
spreading code
Fig 3.2 Spreading and despreading in WCDMA
24


3.5 WCDMA Uplink Spreading, Scrambling, and Modulation
A number of different physical channels are used in the uplink, with a given type of channel
selected according to what the user equipment (UE) is attempting to dosuch as simply
request access to the network, send just a single burst of data, or send a stream of data. For
now, let us focus on the situation where a user is transmitting a stream of data, which would
happen in a voice conversation. In such a situation, the terminal will normally use at least
two physical channelsa Dedicated Physical Data Channel (DPDCH) and a Dedicated
Physical Control Channel (DPCCH). The DPDCH carries the user data and the DPCCH
carries control information. Depending on the amount of data to be sent, a single user can
use just a single DPDCH, which will support up to 480 Kbps of user data or as many as six
DPDCHs, which will support up to 2.3 Mbps of user data.
A DPDCH can have a variable spreading factor. The spreading factor for a DPDCH can be
4, 8, 16, 32, 64, 128, or 256. These correspond to DPDCH bit rates of 15 Kbps (3.84 X
106/256 =15 X103) and up to 960 Kbps (3.84 X 106/4 = 960 X 103). Of course, these are not
the actual user data rates, because a significant amount of coding overhead is included in
the DPDCH to support forward error correction. In general, the user data rate
is approximately half (or less) of the DPDCH rate. Thus, for example, a DPDCH operating at
a spreading rate of 4 will carry data at a rate of 960 Kbps. Of this, however, only about 480
Kbps will correspond to usable data. The rest is consumed by additional coding required for
error correction. If a single user wants to transmit user data at a rate greater than 480 Kbps,
then multiple DPDCHs can be used (up to a maximum of 6).
25


Figure 3.3 shows how multiple DPDCHs are handled. Also shown is the DPCCH, which is
also sent whenever one or more DPDCHs are sent. The channelization codes (C d,i to Cd,2)
represent the channelization codes applied to each of the six DPDCHs. The channelization
code applied to the DPCCH is represented as Cc. Each of the DPDCHs is spread to the
chip rate by a channelization code. DPDCHs 1,3, and 5 are channelized and weighted by a
gain factor bd. These DPDCHs are on the so-called I (in-phase) branch. DPDCHs 2, 4, and
6 plus the DPCCH are on the so-called Q (quadrature) branch. These are also channelized.
These spread DPDCHs are also weighted by the gain factor bd, whereas the spread DPCCH
is weighted by the gain factor bc.
Mathematically, the spread signals on the Q branch are treated as a stream of imaginary
bits. These are summed with the stream of real bits on the I branch to provide a stream of
complex-valued chips at the chip rate. This stream of complex-valued chips is then
subjected to a complex-valued scrambling code, which is aligned with the beginning of a
radio frame.
WCDMA uses Quadrature Phase Shift Keying (QPSK) modulation in the uplink. This
technique is depicted in Figure 3.4. The stream of spread and scrambled signals, such as
the output shown in Figure 3.3, forms the complex-valued input stream of chips. The real
and imaginary parts are separated, with the real part of a given complex chip forming the in-
phase (I) branch and the imaginary part forming the quadrature phase (Q) branch in the
modulator.
26


Fig 3.3 Uplink Channelization and Scrambling
Fig 3.4 Uplink Modulation (QPSK)
27


3.6 WCDMA Downlink Spreading, Scrambling, and Modulation
As is the case for the uplink, a number of channels are used in the downlink. In fact, more
channels are defined for the downlink than for the uplink. That is because the downlink
includes pilot channels, synchronization channels, channels used for the broadcast of
system information, channels used for the paging of subscribers, and so on.
With the exception of the synchronization channels (SCHs), the downlink channels are
spread to the chip rate and scrambled, as shown in Figure 6-6. Each channel to be spread is
split into two streamsthe I branch and the Q branch. The even symbols are mapped to the
I branch and the odd symbols are mapped to the Q branch. The I branch is treated as a
stream of real-valued bits, whereas the Q branch is treated as a stream of imaginary bits.
Each of the two streams is spread by the same channelization code. The spreading
code/channelization code to be used is taken from the same code tree as used in the
uplinkthat is, OVSF codes that are chosen to maintain the orthogonality between different
channels transmitted from the same base station. The spreading rate for a given channel
depends on the channel in question.
The I and Q streams are then combined such that each I and Q pair of chips is treated as a
single complex value, such that the result of combining them is a stream of complex-valued
chips. This stream of chips is then subjected to a complex downlink scrambling code,
identified as Sdi n in Figure 3.5.
28


The downlink modulation is similar to what you have in the uplink modulation. So the same
figure 3.4 can be referred for the downlink modulation.
Fig 3.5 Downlink Channelization and Scrambling
3.7 WCDMA Uplink Dedicated Channel Format
Figure 3.6 shows the structure of the uplink DPCCH as used with the uplink DPDCH. The
DPCCH is transmitted in parallel with the DPDCH and the information in a given DPCCH
frame relates to the corresponding DPDCH frame. The DPCCH always uses a spreading
factor of 256.Thus, each slot (2,560 chips) corresponds to 10 bits of DPCCH information.
These 10 bits are divided into pilot bits, Transport Format Combination Indicator (TFCI) bits,
Feedback Indicator (FBI) bits, and Transmit Power Control (TPC) bits.
29


The pilot information bits are used for channel estimation purposes and include specific bit
patterns for frame synchronization. The TFCI bits indicate the bit rate and channel coding for
the DPDCH. A single DPDCH can carry multiple DCH transport channels. The FBI bits are
used in conjunction with transmit diversity at the base station. WCDMA supports downlink
transmit diversity, whereby two antennas can be used for downlink transmission. When
transmit diversity is used, it is possible for the power and/or phase on one transmit antenna
to differ from that on the other. The FBI bits are used in the uplink to instruct the base station
to change the power or phase differences associated with transmit diversity. Finally, the TPC
bits are used to command the base station to change the transmit power when necessary.
DPDCH
DPDCH Data (N bits)
-2,560 chips, 10x2kbits
K = 0 to 6 depending on spreading factor
DPCCH
Pilot Bits TFCI bits FBI bits TPC bits
2,560 chips, 10 bits
Slot 0 Slot 1 Slot 2 Sloti Slot 14

1 radio frame = 10ms
Fig 3.6 Uplink DPDCH and DPCCH Frame and Slot
Structure.
30


3.8 WCDMA Downlink Dedicated Channel Format
Figure 3.7 shows the structure of the downlink DPDCH and DPCCH. The most notable
characteristic is that the DPCCH is time-multiplexed with the DPDCH rather than being
transmitted separately. In each slot on the downlink, two fields contain DPDCH user data,
while three other fields maintain information on the pilot bits, the TFCI, and the TPC. As is
the case for the uplink, a number of slot formats can be applied to the downlink
DPDCH/DPCCH.
SlotO Slot 1 Slot 2 Sloti Slot 14
M-
1 radio frame = 10 ms
Fig 3.7 Downlink DPDCH and DPCCH Frame and Slot
Structure.
31


3.9 Overview of the UMTS General Architecture
Fig 3.2 shows a simplified UMTS architecture with the external reference points and
interfaces to the UTRAN.
UE
UTRAN UMTS Terrestrial Radio Access Network
CN Core Network
UE User Equipment
Fig 3.8 UMTS High Level System Architecture
Radio Access Network (RAN) that handles all radio-related functionality; the main UMTS
RAN is UMTS Terrestrial RAN (UTRAN).
Core Network (CN) which is responsible for switching and routing calls and data
connections to external networks.
User Equipment (UE) that interfaces with the user.
32


3.10 UTRAN Architecture
UTRAN consists of one or more Radio Network Sub-systems (RNS). An RNS is a
subnetwork within UTRAN and consists of one Radio Network Controller (RNC) and one or
more Node Bs. RNCs may be connected to each other via an lur interface. RNCs and Node
Bs are connected with an lub interface.
The UTRAN comprises two types of nodesthe Radio Network Controller (RNC) and the
Node B, which is the base station. The RNC is analogous to the GSM Base Station
Controller (BSC). The RNC is responsible for the control of the radio resources within the
network. It interfaces with one or more base stations, known as Node Bs. The interface
between the RNC and the Node B is the lub interface. Unlike the equivalent Abis interface in
GSM, the lub interface is open, which means that a network operator could acquire Node Bs
from one vendor and RNCs from another vendor. Together an RNC and the set of
Nodes Bs that it supports are known as a Radio Network Subsystem (RNS).
Unlike in GSM where BSCs are not connected to each other, UTRAN contains an interface
between NCs. This is known as the lur interface. The primary purpose of the lur interface is
to support inter-RNC mobility and a soft handover between Node Bs connected to different
RNCs.
The user device is the UE. It comprises the Mobile Equipment (ME) and the UTMTS
Subscriber Identity Module (USIM). UTRAN communicates with the UE over the Uu
interface. The Uu interface is none other than the WCDMA air interface.
33


UTRAN ;
Fig 3.9 UTRAN Architecture
UTRAN communicates with the core network over the lu interface. The lu interface has two
componentsthe lu-CS interface, which supports circuit-switched services, and the lu-PS
interface, which supports packet-switched services. The lu-CS interface connects the RNC
to an MSC and is similar to the GSM A-interface. The lu-PS interface connects the RNC to
an SGSN and is analogous to the GPRS Gb interface.
3.10.1 The Radio Network Controller
The RNC (Radio Network Controller) is the network element responsible for the control of
the radio resources of UTRAN. It interfaces the CN (normally to one MSC and one SGSN)
and also terminates the RRC (Radio Resource Control) protocol that defines the messages
and procedures between the mobile and UTRAN. It logically corresponds to the GSM
BSC.
34


3.10.1.1 Logical role of RNC
The RNC controlling one Node B (i.e. terminating the lub interface towards the Node B) is
indicated as the Controlling RNC (CRNC) of the Node B. The Controlling RNC is responsible
for the load and congestion control of its own cells, and also executes the admission control
and code allocation for new radio links to be established in those cells.
In case one mobile-UTRAN connection uses resources from more than one RNS (see
Figure 3.5), the RNCs involved have two separate logical roles (with respect to this mobile-
UTRAN connection):
Fig 3.10 Logical role of the RNC for one UE UTRAN connection. The left-hand scenario shows
one UE in inter-RNC soft handover (combining is performed in the SRNC). The right-hand
scenario represents one UE using resources from one Node B only, controlled by the DRNC
35


Serving RNC
The SRNC for one mobile is the RNC that terminates both the lu link for the transport of user
data and the corresponding RANAP signalling to/from the core network (this connection is
referred to as the RANAP connection). The SRNC also terminates the Radio Resource
Control Signalling, which is the signalling protocol between the UE and UTRAN. It performs
the L2 processing of the data to/from the radio interface. Basic Radio Resource
Management operations, such as the mapping of Radio Access Bearer parameters into air
interface transport channel parameters, the handover decision, and outer loop power control,
are executed in the SRNC. The SRNC may also (but not always) be the CRNC of some
Node B used by the mobile for connection with UTRAN. One UE connected to UTRAN has
one and only one SRNC.
. Drift RNC
The DRNC is any RNC, other than the SRNC, that controls cells used by the mobile. If
needed, the DRNC may perform macro diversity combining and splitting. The DRNC does
not perform L2 processing of the user plane data, but routes the data transparently between
the lub and lur interfaces, except when the UE is using a common or shared transport
channel. One UE may have zero, one or more DRNCs.
3.10.2 The Node B (Base Station)
The main function of the Node B is to perform the air interface L1 processing (channel
coding and interleaving, rate adaptation, spreading, etc.). It also performs some basic Radio
36


Resource Management operations such as the inner loop power control. It logically
corresponds to the GSM Base Station. The enigmatic term Node B was initially adopted as
a temporary term during the standardization process, but then never changed.
3.11 UTRAN Interfaces and Protocols
Looking at Figure 3.5 in the vertical direction, we see three planesthe control plane, the
user plane, and the transport network user plane. The control plane is used by UMTS-
related control signaling. It includes the application protocol used on the interface in
question. The control plane is responsible for the establishment of the bearers that transport
user data, but the user data itself is not carried on the control plane. As seen from control
plane, the user bearers established by the application protocol are generic bearers and are
independent of the transport technology being used. If the application protocol were to view
the bearers in terms of a specific transport technology, then it would not be possible to
cleanly separate the radio network layer from the transport network layer. In other words, the
application protocol would have to be designed to suit a particular transport technology. The
signaling bearers that carry the application signaling are established by O&M actions. These
signaling bearers are analogous, for example, to the SS7 signaling links that are used
between a BSC and a MSC in GSM.
37


Radio
Network
Laver
Control plane
Application
protocol
------Z------
User plane
Data
streams
Transport
Network
Layer
Transport network
user plane
Signaling
bearers
Transport network
control plane
ALCAP
Signaling
bearers
-----?-----
___________
Physical layer
Transpor user ' network jlane r
Data bearers
i

Fig 3.11 General Protocol model for UTRAN Interfaces
The user plane is what carries the actual user data. This data could, for example, be data
packets being sent or received by the UE as part of a data session. Each data stream
carried in the user plane will have its own framing structure.
The transport network control plane contains functionality that is specific to the transport
technology being used and is not visible to the radio network layer. If standard pre-
configured bearers are to be used by the user plane and these are known to the control
plane, then the transport network control plane is not needed. Otherwise, the transport
network control plane is used. It involves the use of an Access Link Control Application Part
(ALCAP). This is a generic term that describes a protocol or set of protocols used to set up a
38


transport bearer. The ALCAP to be used is dependent on the user plane transport
technology.
3.11.1 lu-CS Interface
If we apply this generic structure to the lu-CS interface (RNC to MSC), then it appears as
shown in Figure 3.5. The application protocol in the control plane is the Radio Access
Network Application Part (RANAP). This provides functionality similar to that provided by
BSSAP in GSM. Among the many functions supported by RANAP are the establishment of
radio access bearers (RABs), paging, the direct transfer of signaling messages between the
UE and core network, and SRNS relocation.
RANAP is carried over an ATM-based SS7 signaling bearer. This signaling bearer for the
control plane is comprised of the ATM Adaptation Layer 5 (AAL5), the service-specific
connection-oriented protocol (SSCOP), the service-specific coordination function at the
network node interface (SSCF NNI), the layer 3 broadband message transfer part (MTP3b),
and the Signaling Connection Control Part (SCCP). Different AAL layers may reside above
the ATM layer depending on the type of service that needs to use ATM. In the case of
signaling, it is normal to use AAL5, which supports variable bit rate services. SSCOP
provides mechanisms for the establishment and release of signaling connections. It also
offers the reliable exchange of signaling information, including functions such as sequence
integrity, error detection and message retransmission, and flow control. SSCF-NNI maps the
39


requirements of the upper layer to the layer below. Together SSCOP and SSCF are known
as the signaling ATM adaptation layer (S-AAL).
MTP3b is similar to standard MTP3, as used in standard SS7 networks, with some
modifications to enable it to take advantage of the broadband transport that ATM can use.
SCCP is the same SCCP as used in standard SS7 networks.
The same signaling stack is used for the transport network control plane broadband SS7.
Instead of SCCP, however, we find the Broadband ISDN ATM Adaptation Layer Signaling
Transport Converter for the MTP3b (Q.2150.1). Above Q.2150.1, we have the ALCAP, which
is AAL2 Signaling Protocol Capability Set 1 (Q.2630.1).
On the user side, things are much less complicated. We simply have the ATM Adaptation
Layer 2 (AAL2) as the user data bearer. This is an AAL specifically designed for the
transport of short-length packets, such as those we find with packetized voice. One
advantage of AAL2 is that it enables multiple user packets to be multiplexed within one cell
to minimize ATM overhead. At the radio network layer, we have the User Plane Protocol.
This is a simple protocol that provides either transparent or supported service. In transparent
mode, data is simply passed onwards. In supported mode, the protocol takes care of
functions such as data framing, time alignment, and rate control. Speech is an example of a
service that would use supported mode.
40


Fig 3.12 lu-CS Protocol Structure
3.11.2 lu-PS Interface
The protocol architecture for the lu-PS interface is shown in Figure 6-20.We first notice that
no transport network control protocol is involved. It is not needed because of the protocol
that is used in the user plane. Specifically, in the user plane, we find that the GPRS
Tunneling Protocol (GTP) tunnel extends to the RNC. This is different than standard GPRS
where the tunnel ends at the SGSN and a special Gb interface is used from SGSN to BSC.
41


The fact that the tunnel extends to the RNC means that only a tunnel identifier and IP
addresses for each end are required for establishment of the bearer. These are included in
the application messages used for establishment of the bearer, which means that no
intermediate ALCAP is needed.
As mentioned, the user plane uses the GTP (GTP-U indicates a GTP user plane). This
protocol uses the User Datagram Protocol (UDP) over IP.AAL5 over ATM is used as the
transport. For a packet data transfer, the identification of individual user packets is supported
within the GTP-U protocol. Consequently, it is not necessary to structure these user packets
according to ATM cell boundaries. This means that multiple user packets can be multiplexed
on a given ATM cell, thereby reducing ATM overhead.
In the control plane, we again find RANAP at the application layer. We have a choice of
signaling bearer, however. One option is to use the standard ATM SS7 stack, as described
previously, for the lu-CS interface. Another option is to use SCCP over IP-based SS7
transport over ATM. For IP-based SS7 transport, we use the MTP3 User Adaptation (M3UA)
protocol over the Stream Control Transmission Protocol (SCTP).
42


Fig 3.13 lu-PS Protocol Structure
3.11.3 lub Interface
The protocol architecture for the lub interface is shown in Figure 3.7. This is the interface
between an RNC and the Node B that it controls. In the protocol architecture, we again find
the transport network control plane as was seen for the lu-CS interface. In the control plane,
we find the Node B Application Part (NBAP) as the application protocol. In the user plane,
we find a number of frame protocols related to various types of transport channels. Basically,
43


a specific framing protocol is applicable to each of the transport channels. Note that Figure
3.7 indicates the Uplink Shared Channel (USCH). This is a transport channel defined for
TDD-mode only.
Fig 3.14 lub Protocol Structure
44


3.11.4 lur Interface
The interface between RNCs is the lur interface. The primary purpose of this interface is to
support inter-RNC mobility (SRNS relocation) and a soft handover between Node Bs
connected to different RNCs. The protocol architecture for the lur interface is shown in Fig-
ure 3.8. The controlling application protocol is known as the Radio Network System
Application Part (RNSAP). Signaling between RNCs is SS7-based, whereby RNSAP uses
the services of SCCP. As is the case for the lu-PS interface, the signaling can be
transported on a standard ATM SS7 transport or can use an IP-based transport over ATM.
The same applies for the transport network control plane.
The user plane contains two frame protocols, one related to dedicated transport channels,
the DCH FP, and one related to common transport channels, the CCH FP. These user
protocols carry the actual user data and signaling between the SRNC and DRNC.
3.12 UMTS Core Network Architecture and Evolution
While the UMTS radio interface, WCDMA, represented a bigger step in the radio access
evolution from GSM networks, the UMTS core network did not experience major changes in
the 3GPP Release 99 specification. The Release 99 structure was inherited from the GSM
core network and, as stated earlier, both UTRAN and GERAN based radio access network
connect to the same core network.
45


Fig 3.15 lur Protocol Structure
3.12.1 Release 99 Core Network Elements
The Release 99 core network has two domains: Circuit Switched (CS) domain and Packet
Switched (PS) domain, to cover the need for different traffic types. The division comes from
the different requirements for the data, depending on whether it is real time (circuit switched)
or non-real time (packet data). The following sections present the functional split in the core
46


network side, however, it should be understood that several functionalities can be
implemented in a single physical entity and all entities do not necessarily exist as separate
physical units in real networks. Figure 5.9 illustrates the Release 99 core network structure
with both CS and PS domains shown. The Figure also contains registers, as well as
the Service Control Point (SCP), to indicate the link for providing a particular service to the
end user.
Data and control
Control
pstWisdn
IP networks
Fig 3.16 Release 99 UMTS core network structure
The CS domain has the following elements:
Mobile Switching Centre (MSC), including Visitor Location Register (VLR);
47


Gateway MSC (GMSC).
The PS domain has the following elements:
Serving GPRS Support Node (SGSN), which covers similar functions as the MSC for the
packet data, including VLR type functionality.
Gateway GPRS Support Node (GGSN) connects PS core network to other networks, for
example to the Internet.
in addition to the two domains, the network needs various registers for proper operation:
Home Location Register (HLR)
Equipment Identity Register (EIR) contains the information related to the terminal equipment
and can be used to, e.g., prevents a specific terminal from accessing the network.
3.12.2 Release 5 Core Network and IP Multimedia Sub-system
The Release 5 core network has many additions compared to Release '99 core networks.
Release 4 already included the change in core network CS domain when the MSC was
divided into MSC server and Media Gateway (MGW). Also, the GMSC was divided into
GMSC server and MGW. Release 5 contains the first phase of IP Multimedia Sub-system
(IMS), which will enable a standardized approach for IP-based service provision via PS
domain. The capabilities of the IMS will be further enhanced in Release 6. Release 6 IMS
will allow the provision of services similar to CS domain services from the PS domain. The
following sections summarize the elements in Release 5 based architecture, added to
Release '99 and Release 4 architecture. The Release 5 architecture is presented in Figure
48


3.10, with the simplification that the registers, now part of Home Subscriber Server (HSS),
are shown only as an independent item without all the connections to the other elements
shown.
Services and applications^ Control
Data and control
i
UTRAN
MSC
/ server
t
lu-cs / I
/
! ^ MGW
lu-cs
_ GMSC
server
i
i
s
MGW
HSS
PSTN/ISDN
Eg \
v IP Networks
Fig 3.17 Release 5 UMTS core network structure
From a protocols perspective, the key protocol between the terminal and the IMS is the
Session Initiation Protocol (SIP), which is the basis for IMS-related signaling.
The following elements have experienced changes in the CS-domain for Release 4.
49


The MSC or GMSC server takes care of the control functionality as MSC or GMSC
respectively, but the user data goes via the Media Gateway (MGW). One MSC/GMCS server
can control multiple MGWs, which allows better scalability of the network when, e.g., the
data rates increase with new data services. In that case, only the number of MGWs needs to
be increased.
MGW performs the actual switching for user data and network interworking processing, e.g.,
echo cancellation or speech decoding/encoding.
In the PS-domain, the SGSN and GGSN are as in Release 99 with some enhancements,
but for the IP-based service delivery, the IMS has now the following key elements included:
Media Resource Function (MRF) which, e.g., controls media stream resources or can mix
different media streams. The standard defines further the detailed functional split for MRF.
Call Session Control Function (CSCF), which acts as the first contact point to the terminal in
the IMS (as a proxy). The CSCF covers several functionalities from handling of the session
states to being a contact point for all IMS connections intended for a single user and acting
as a firewall towards other operator's networks.
Media Gateway Control Function (MGCF), to handle protocol conversions. This may
also control a service coming via the CS domain and perform processing in an MGW,
e.g. for echo cancellation.
50


4. Femtocell
4.1 Femtocell Architecture (Home NodeB Architecture)
lull Interface Iu Interface
Fig 4.1 Iu-based 3G HNB Architecture
The figure 4.1 shows the proposed 3GPP lu-based 3G Home NodeB Architecture. The
Home NodeB is the most vital part of the femtocell network implementation. The HNB and
HNB GW implement the whole legacy UTRAN functionality together. Additionally, HNB is a
brand new RAN node, which is deployed by user itself, so some new HNB specific functions
including HNB discovery, HNB Registration etc. should be added to guarantee HNBs
operation
51


The 3G HNB implements the same legacy NodeB functionality as designed for the UTRAN
i.e all the functionality of the NodeB of UMTS is being implemented in the 3G HNB
architecture itself. The 3G HNB also implements the legacy RNC functionality without some
special functions in order to reduce the HNBs cost and to make it more simplified, i.e NNSF
(NAS Node Selection Functionality), ATM transfer function, etc. It also implements some
HNB specific functionalities to support Home Nodes Bs deployment, i.e.: HNB
Authentication, HNB-GW Discovery, HNB Registration, and UE access control. To increase
the security of the 3G HNB, IPsec tunnel is mandatory for signalling and data transport
between HNB and HNB GW.
The 3G Home NodeB Gateway (3G HNB GW) handles specific HNB functions such as HNB-
GW Discovery and HNB registration. It also handles some transaction mechanism of
RANAP and some RNC functionality which is not implemented in HNB. It handles data
forwarding of the lu user plane. As mentioned for the 3G HNB, here also IPsec tunnel is
mandatory for signalling and data transport between HNB and HNB GW.
For luh interface, IP transport is the exclusive option. But for lu interface, HNB GW should
support both IP and ATM option to connect to different CN nodes.
4.2 Protocol Stack for lu-h
Shown in the fig 4.2 is the lu-h stack. As seen it is very much similar to the lu stack defined
earlier but there are some difference between both the stack. As the Home NodeB
communicates with the HNB gateway through the internet, security is a very important issue
in here. As HNB (Home NodeB) is an unsafe node in the operators network, it utilizes the
IPSec protocol when the HNB communicates with the HNB gateway.
52


Fig 4.2 Protocol Stack of the Iu-h interface
For the deployment of 3G HNBs, SCTP is defined as the transport network user plane layer
for the signalling bearer. For connection-oriented procedures as defined to be supported by
53


RANAP, an adaptation layer i.e. RANAP User Adaptation (RUA) is introduced to denote a
dedicated lu signalling connection. The RUA contains information necessary for UE
connection management at the 3G HNB and 3G HNB GW as well as the necessary
information to support NNSF (NAS Node Selection Function) functionality.
Fig 4.3 Protocol Stack of the HNB GW Discovery Procedure
54


HND GW discovery procedure is a part of HNBAP, and provides the means for a designated
Provisioning HNB GW" to provide the address for the Serving 3G HNB GW for the 3G HNB.
HNB should complete this procedure as soon as possible to reduce HNBs boot time. And
for HNBs amount is very large, the resource consuming in discovery procedure should be
as little as possible to reduce the burden of the provisioning HNB GW If the same transport
method is used in this procedure, HNB spends much resource on SCTP connection, and
wastes a lot of time on the connection establish and release. So it recommends a simple
protocol stack based on UDP for HNB GW discovery between HNB and the provisioning
HNB GW. This UDP based protocol stack for HNB GW discovery costs less resource, and
doesnt waste time on connection establishment and release. The reliability of procedure can
be guaranteed by the application layer (HNBAP).
4.3 Mechanism for 3G HNB-GW Discovery
With the rapid growth of the registered HNBs, its necessary to execute network planning
and keep the balance of network distribution. Its beneficial to introduce load balancing
mechanism in the early fist step, i.e. HNB-GW discovery and HNB registration procedure,
which can improve the efficiency and QoS of HNB network.
This section describes the mechanism of the HNB GW discovery and HNB registration by
taking into account network load and access control requirements. A brief architecture of
HNB network is figured below.
55


HNB Home Node B
HNB GW Home Node B Gateway
SeGW Security Gateway
CPE Customer Premise Equipment
Fig 4.4 Architecture of the HNB Network
As per the 3GPP proposal, two lists are defined to facilitate the HNB gateway discovery.
LLS (the List of Load Status)
Precondition: HNB-GWs report their load information (including throughput, amount of
registered HNBs, hardware/software handling load, and their preset thresholds, etc) to
Configuration Server (CS).
CS collects the load information of HNB-GWs, and forms a list of the HNB-GWs represent
access priority according to their load status, which is called LLS (the List of Load Status).
Then CS hands out the LLS list to the HNB-GWs for future purpose.
56


LAC (the List of Access Control)
When user subscribes at network, the operator can define the list of access-permitted HNB-
GWs for the HNB owned by separate user. The operator could save this list called LAC (the
List of Access Control) in CS for future purpose.
Note: LLS and LAC can be defined and used independently according to the operators
requirements.
4.3.1 HNB-GW Discovery Procedure
When at first time (without stored information) a HNB tries to connect to the network, it
requests DNS (Domain Name Server) for the address of CS. Then it achieves the address of
default HNB GW from CS. CS suggests default HNB GW to HNB based on LAC and/or LLS.
Then the HNB tries to register on default HNB GW, the HNB-GW can decide whether it can
register or not, according to LAC (HNB-GW can query CS for LAC when HNB request to
register), and with the reference of its own load. If this registration is rejected, the HNB-GW
will redirect the HNB to another HNB-GW based on the LLS and/or LAC information.
HNB-GW Discovery Procedure lists as below:
HNB-GW Reports load status(throughput, amount of registered HNB, hardware/software
handling load, and their preset threshold, etc)to Configuration Server (CS).
57


2. CS collects the load information of HNB-GWs, and forms LLS (the List of Load Status). Then
CS hands out the LLS list to the HNB-GWs for future purpose.
3. 3G HNB requests DNS (Domain Name Server) for the address of CS.
4. DNS responses with the address of CS.
5. Establish a Secure Tunnel between 3G HNB and SeGW.
6. The HNB sends a Discovery Request with registration information to CS.
7. CS decides whether the HNB is authorized or not. If the connection is permitted, CS selects
default HNB-GW according to LLS and/or LAC for the HNB and sends the address of default
HNB-GW and HMS to the HNB.
8. The HNB sends a Configuration Request with registration information to HMS.
9. HMS decides whether the HNB is authorized or not. If the connection is permitted, HMS
responses with initial setup and configuration Information.
10 The HNB sends a Registration Request with registration information to default HNB-GW.
11. The HNB-GW decides whether the HNB is authorized or not. If the connection is permitted,
the HNB-GW queries CS for LAC of the HNB.
12 CS responses with LAC of the HNB.
13 The HNB-GW checks its load status (including throughput, amount of registered HNBs,
hardware/software handling load, etc), and compares its load status to its preset thresholds.
Then the HNB-GW make the decision whether the HNB can register or not (considering LAC
58


and load). If the registration is not permitted, the HNB-GW redirects HNB to another HNB-
GW according to LLS and/or LAC.
14. If Registration Request is accepted, the HNB-GW sends Registration accept Response to
the HNB.
15. If Registration Request is rejected, the HNB-GW sends Registration Reject to the HNB and
redirects it to another HNB-GW.
16. If Registration Request is rejected, the Secure Tunnel between 3G HNB and SeGW is
released.
Shown in the figure 4.5 is the HNB GW discovery procedure. It shows all the steps
described in the procedure steps above.
59


3G HNB DNS SeGW CS HMS HNB-GW
1 DNS request
I DNS response
I Report load status(lhroughpul
registered HNB, hard
load, and their prje;
, amoum of
.vare/software handling
rset threshold, etc)
Fonn LLS represent
access priority according j
to HNB-GW load status I
r
5 Establish Secure Tunnel
6 Discovery Request
(Registration Information)
7 Discovery Response
(addresses of default HNB GW and
HMS)
8 Cbi
(Re|i
9Ccn
(Setup and
2 Response
vith LLS
Assign default HNB-GW
according to LLS and/or LAC
n figuration Request
stration Infortnation)
^figuration Response
configuration Information!)
10 Registration Re (Registration Inform;
[uest
ation)
)1 LAC Rec uest for HNB
12 Respons^ with LAC
14 Registration accept Response
15 legislation reject, redirect
13 Make decision whether HNB can
register or not(considering LAC and load).
If not permitted, redirect HNB to another
HNB-GW according to LLS and/or LAC
HNB to another HNB
-gIv
16 Release Secure Tunnel
Fig 4.5 HNB GW Discovery Procedure
60


4.4 Data transfer between lu-h and the core network
4.4.1 Data transfer on lu-PS Interface
In figure 4.6, SGSN doesnt need know the address of HNBs, and HNBs dont need know
the address of SGSN, either; HNB GW is responsible for forwarding PS data from CN/HNB
to HNB/CN. HNB GW will map the right destination address if needed.
Of cause, HNB can communicate with SGSN directly without HNB GW, but there are several
problems:
Security issues. HNB is a user self-deployment node which is unsafe to operators work, this
may need CN nodes to modify its security module to support HNB. The impaction on CN
nodes is acceptable.
Evolution problem. HNB system including HNB and HNB GW cant evolve its transport
layers individually without impaction on CN nodes, vice versa.
Protocol adaptation. In current lu-PS user plane (IP Transport Option), IPv6 is mandatory,
and IPv4 is an option, but IPv4 is widely used in public internet, luh may be based on IPv4.
So SGSN cant communicate with HNB directly.
QoS guarantee. Dedicated line is used between HNB GW and CN, public line is used
between HNB and HNB GW, the two parts have different transport conditions. To guarantee
the QoS more efficiently, it recommends that all the transport layers are terminated on HNB
GW.
61


From the former discussion, it recommends that all the PS transport layers are terminated on
HNB GW.
HNB
luh
HNB GW
SGSN
Fig 4.6 luh User Plane on PS domain
4.4.2 Data transfer on lu-CS Interface
There are two possible data transport options on current lu CS data transfer: one is based
on ATM, which is widely used in current operators system; the other one is based IP. The
following two figures show the two options using in HNB system.
There are several characters in figure 4.7 below:
Standard III UP is terminated in HNB and CN Nodes, HNB GW will just relay it transparently.
CN nodes can control the data rate directly by lu UP protocol.
62


Different transport option are used in HNB side and CN side, RTP should be terminated in
HNB GW and HNB. HNB GW is responsible for the mapping between AAL address and IP
address.
HNB HNB GW lu" CN(MGW)
Note 1: RTCP is optional.
Fig 4.7 luh User Plane on CS domain (ATM Option)
The figure 4.7 below shows the data transfer from the luh interface to the lu-CS place
implemented with an IP option. As the same situation in PS data transfer, all the transport
layers should be terminated in HNB GW. And standard IU UP is terminated in HNB and CN
Nodes, HNB GW will just relay it transparently. CN nodes can control the data rate directly
by lu UP protocol.
63


HNB HNBGW CS CN(MGW)
Note 1: RTCP is optional.
Fig 4.8 Iuh User Plane on CS domain (IP Option)
4.5 Femtocell Deployment Configurations
A number of different deployment configurations have been considered for Home NodeB.
The aspects which define these are as follows:
Open access or CSG (Closed Subscriber Group)
o Open access HNBs can serve any UE in the same way as a normal NodeB
o CSG HNBs only serve UEs which are a member of a particular Closed
Subscriber Group
Dedicated channel or co-channel
o Whether HNBs operate in their own separate channel, or whether they
share a channel with an existing (e)UTRAN network
64


Fixed or adaptive (DL) maximum transmit power
o Fixed: HNBs have a set fixed maximum transmit power
o Adaptive: HNBs sense interference to existing networks, and adjust
maximum transmit power accordingly
The following configurations are considered and are described in more detail in the following
sections.
A. CSG, Dedicated channel, Fixed Power
B. CSG, Dedicated channel, Adaptive Power
C. CSG, Co-channel, Adaptive Power
D. Partial Co-Channel
E. Open Access, dedicated or co-channel
Configuration A: CSG, Dedicated Channel, Fixed Power
HNB is configured as a Closed Subscriber Group. Access to HNB is controlled through an
arrangement between the HNB owner and by the network operator. Access is restricted to a
very limited number of UE; the majority of UE do not have access to the HNB. Therefore, a
CSG covers the partially open system.
The HNB is deployed on a dedicated channel; i.e. a channel that is not used within the
macro layer. The worst case dedicated channel deployment is the adjacent channel. The
worst case adjacent channel deployment is when the adjacent channel is owned by a
different operator.
65


Although the HNB is deployed on the dedicated frequency with respect to the macro
network, a co-channel interference scenario remains between HNBs. HNBs must share the
same frequency; hence co-channel coexistence must be analyzed within a dense population
of HNB.
In this configuration, the Home NodeBs maximum transmit power could potentially be fixed
by the operator to be lower than the Maximum Transmit power capability. The reduced
power limit ensures the dominance of the HNB with respect to a macro cell is appropriately
bounded. Therefore, the HNB cell size is limited with respect to a weak macro signal.
Consequently, the HNB can operate with a fixed maximum power level even at the edge of a
macro cell.
Configuration B: CSG, Dedicated Channel, Adaptive Power
HNB is configured as a Closed Subscriber Group. The HNB is deployed on a dedicated
channel. Maximum transmit power may be set as high as the maximum capability of the
HNB class of base station. However, higher maximum power level than the acceptable
fixed maximum power for dedicated channel deployment shall only be used when
appropriate for the deployed environment, and when the resulting interference is acceptable.
Configuration C: CSG Co-channel, Adaptive Power
HNB is configured as a Closed Subscriber Group. The HNB is deployed on the same
channel as the macro network. This is considered the worst case interference scenario;
66


consequently this is the highest risk deployment. Power levels used by the Home Node B
and all attached UEs must be set as appropriate for the deployed environment.
The fixed maximum transmit power limit is not considered feasible for co-channel
deployment and has been removed from further analysis.
Configuration D. Partial Co-Channel
Partial co-channel is proposed for CSG operation for HNBs. This works by limiting
frequencies which are shared by the macro layer and the HNB, as shown in 4.7. The
macro layer uses the all available frequencies, whereas the home NodeB only uses a subset
- the shared part. Macro UEs can operate on any frequency. Macro UEs in the shared part
experiencing "pathological" interference from home NodeBs can move to the clear part.
Whist this configuration is indented as a solution for CSG operation, it may also be
applicable to open access in order to limit the influence of the HNB in the overall network
and allow more control over mobility.
shared part clear part
frequency
Fig 4.9 Spectrum arrangement for Macro and Home Node Bs
67


Figure 4.8 shows how this could be implemented in UTRAN. Two channels are needed, one
for Macro+HNB, the other for Macro only. Macro-only UEs experiencing HNB interference in
channel 1 would handover to channel 2.
Macro
Macro
Home Node Bs
channel 1
channel 2

Fig 4.10 Spectrum arrangement for UTRAN
Providing UEs hand over to the clear channel when experiencing HNB interference, the
performance of this configuration should be similar to that of configuration A (dedicated
channel, fixed power).
Configuration E: Open Access, dedicated or co-channel
Open access Home NodeBs serve all UEs, in the same way as other NodeBs do.
68


5. Simulation of the Femtocell environment
5.1 Simulation of the Indoor Path Loss Model for HNB propagation in
Matlab
The path loss between an UE located inside the building and a HNB is calculated as:
/
jmtoar ~ 38.46 + 20 logl0 {diD m )+ p Lw + 0.7 d2D m + L, n
n+2
where p is the number of heavier walls (walls separating the apartments) between the
transmitter and the receiver and Lw is the additional loss introduced by one such wall,
assumed to be equal to 5 dB. When calculating the 3-dimensional distance (d3D) between
the UE and the HNB, an assumption is made that the height of each floor is 4 m. Finally, the
value for Lf is assumed to be equal to 18.3 dB. A log-normal fading value is also added,
assuming a standard deviation equal to 10 dB and including some amount of correlation
(0.5) between the different HNBs. Finally, a check is made that the obtained path loss is not
smaller than the corresponding free space loss.
Figure 5.1 presents the resulting indoor path loss as a function of distance, assuming a
single apartment (p = 0) and a single floor (n = 0) in Matlab.
The code for the simulation is given below.
Code starts here
d2d=0:10e-6:15;
height=0:2*10e-7:3;
d3d=sqrt(d2d.A2 + height.*2);
Lhjndoor = 38.46 + 20*log10(d3d) + 0.7*d2d
69


plot(d3d,Lh_lndoor,'r',,LineWidth',2)
set(gca,'XTick',0:5:15)
setfgca.'XTickLaber.fOVSVIOVIS'})
set(gca,Ytick', 30:10:90)
setteca/YtickLabel'.pOVAO','50760770780','90'})
xlabel('Distance[m]')
ylabel('Path Loss[dB]')
title(Plot of Path Loss[dB] as a function of distance')
Code ends
Plot 3f Patti Lossl^j as a Kmctton i distatv:e
Fig 5.1 Simulation for the Indoor Pathloss Propagation Model
70


5.2 Overview of the Simulation Model in Opnet
The simulation of the femtocell environment was carried out with the help of the Opnet
14 5.A Modeler. In this modeler UMTS network was used as a framework to build the
femtocell network. The network which was used to simulate was as shown in the figure 5.1
below.
Fig 5.2 Architecture of the Implemented Femtocell
Network
71


As shown in the figure 5.1 above the interfaces between the Mobile User Equipment (UE)
and the Home NodeB is the WCDMA interface. The interface between the Home NodeB and
the IP router would be an Ethernet cable (10BaseT cable). Again an Ethernet Cable (10
BaseT cable) is used to connect the IP Cloud and the IP router. A Home NodeB (HNB)
Gateway is used to interconnect the RNC (Radio Network Controller) and the IP Cloud. The
interface between the RNC and the HNB is a SLIP interface. The RNC is connected to the
Serving GPRS Support Node (SGSN) through the ATM Interface. And finally the SGSN is
connected to the Gateway GPRS Support Node (GGSN) again through a Ethernet interface.
The figure 5.2 below shows the actual implementation of the network in OPNET Modeler. As
shown in the screens hot below we have implemented the femtocell scenario of a typical
residential scenario. The femtocell is supposed to support up to 4 simultaneous connections
according to 3GPP Standards. The four connections are the four mobile nodes implemented
in OPNET. Also there are two Application Definition and Profile Definition nodes. One of
the Application and Profile Definition node used to simulate an HTTP connection between
Mobile Node 2 (Source) and Mobile Node 1 (Destination). The other Application and Profile
Definition node simulates voice call traffic between Mobile Node 3 (Source) and Mobile
Node 0 (Destination). Thus there are two simultaneous transmissions going on at the same
time. The simulation was conducted for a period of 2 hours during which both the HTTP and
the Voice traffic were simulated between the mobile nodes.
72


Network: Testingl23-Test_123_Case 3 [Subnet: top.Office Network
4t H
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n>de 9
Apptl
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5y|2fU Definition j
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ateklt nde 1 oJ_2
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mobfe_no tscaa mum
ggj-gi
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nd*_l nd< 6
OipvrijH (a) 2001 Paalafa Oorrati4, Troy, Aavyork. I# 19a rtadaftd *i*9 >rorni4tl;
'*farHKM iv Coiyrigat (e) 2001 Stafaa Ha Wan *w.wor Id-^aaanaar.eoe.
Fig 5.3 Implementation of Femtocell
Network in OPNET
73


The figure 5.3 below shows the simulation speed (events/ sec) for the above simulation
which is nothing but number of events (voice and http transfer) per second.
S,iialw Speed |-*e SrV:[ Hwwy Utagej Meaege^ Irwcatwij
(urtrt Sniftfi Saeii {ertfta/jattnd)
i Avw & bnteor 'jpwd (tventt/ttoyd)
1^,00

i ...............................


125,000
aim
* -...............................................................
i
i
i
SC,000 j- ................- .........................................
i i................~i.....................r~............i.................... f............................i r................i
C 1,000 2,000 3,000 4,000 5,000 6^)00 7,000 8,000
SMatedTiM (seconds)
Fig 5.4 Simulation Speed (events /seconds)
74


5.2 Simulation Results and Graphs
5.2.1 Simulation Results for Voice and HTTP traffic simulation
Statistic Average Maximum Minimum
Voice Packet Delay Variation 0.002195 0.096362 0.000227
Voice Packet End-to-End Delay (sec) 0.21079 0.26568 0.20804
Voice Traffic Received (bytes/sec) 1,145.5 1,414.4 0.0
Voice Traffic Sent (bytes/sec) i 1,224.7 1,512.5 0.0
Table 5.2.1 Voice Statistics
The table 5.2.1 shows the voice statistics for the voice traffic routed between Mobile Node 0
to Mobile Node 3 as shown in figure 5.2. The statistics for the voice traffic is given in the
table which displays the stats for the Voice Packet Delay Variation, Voice Packet End-to-End
Delay between the two nodes, Mobile Node 0 and Mobile Node 3. It also displays the overall
voice traffic generated between the two mobile nodes in the Voice Traffic Received table and
the Voice Traffic Sent table in bytes/sec. The figure 5.2.1.1 below shows the graphical
representation of the statistical data in the table 5.2.1.
75


Fig 5.5 Graphical Representation of Voice Statistics
As seen from the graphs above we can conclude that the overall voice traffic at the
generated at the origination (Mobile Node 0 and Mobile Node 3) and destination (Mobile
Node 0 and Mobile Node 3) are almost the same as the voice packets are being received
almost in the same pattern as it is being transmitted.
76


Statistic Average Maximum I Minimum
HTTP Object Response Time (seconds) 0.7386 1.4533 0.6143
HTTP Page Response Time (seconds) 2.0230 4.9836 1.4380
HTTP Traffic Received (bytes/sec) 394.17 836.43 0.00
HTTP Traffic Sent (bytes/sec) ; 418.5 1,014.7 0.0
Fig 5.2.1.2 HTTP Statistics
The table above shows the HTTP statistics for the HTTP traffic between Mobile Node 2 and
Mobile Node 1. The table above shows the Object Response Time, Page Response Time,
Traffic Received and the Traffic Sent between the two mobile nodes. The Object and the
Page Response time is represented in seconds and the HTTP Traffic is represented in
bytes/sec.The figure 5.2.1.2 shows the graphical representation for the HTTP traffic
generated between the two nodes (Mobile Node 2 and Mobile Node 1). In this case Mobile
Node 2 is the client requesting HTTP traffic from Mobile Node 1.
77


Fig 5.6 Graphical Representation of HTTP Statistics


5.2.2 UMTS Simulation Results
5.2.2.1 UMTS GPRS Mobility Management (GMM) Simulation Results
Statistic i Average Maximum j Minimum
UMTS GMM GPRS Attach Delay (sec) ; 0.77402 0.91388 0.76846
UMTS GMM PDP Context Activation Delay (sec) i 1.3996 1.4002 0.5444
UMTS GMM Service Activation Delay (sec) ! 0.31523 0.63149 , 0.14074
Table 5.2.2 UMTS GPRS Mobility Management (GMM)
Statistics
As shown in the table above we have the stats for the UMTS GMM. The UMTS GMM GRPS
Attach Delay, the time taken to make the terminal itself known by the UMTS, and at the
same time establish a GPRS Mobility Management (GMM) context, which has an average
around 0.77402 seconds. The UMTS GMM PDP Context Activation Delay, time taken by the
MS activate PDP contexts via "Activation Procedures", has an average around 1.3996 secs.
The UMTS Service Activation delay, time taken to establish a RAB, has an average delay of
about 0.31523 seconds
79


UMTS GMM GFKS Attach Delay (sec)
?t ft .ft ft .ft .ft .ft .ft .ft .ft
v s',^v <:? <; v <*,y s*v >*<* \*;r
' xY .> tV-/ ff A0/ vf/ ^ .X*'5; a'f'i*' >P i '
\ \ 'j ' rt ' f fi' ' ' ry ' rff ' piC
UMTS GMMJDP Cortex! Activated Delay (sec)
ft ft ft ft ft ft ft ft ft

4* 4v 4t
4*4*
JA chip ,sfc*> $$ < 1?
4* 4* 4
Fig 5.7 UMTS GMM Statistics
80


5.2.2.2 UMTS RNC Simulation Statistics
Fig 5.8 UMTS RNC Traffic Graphical Representation
The figure 5.2.2.2 shows the traffic statistics for the UMTS RNC obtained during the
simulation. This shows traffic (voice and web packets) handled by the RNC during the
simulation. Also we have the statistics sorted out by the average and the peak which is given
below:
Sort By Sorted By Sorted By Sort By Sorted By Sorted By
Node Average Peak Node Average Peak
node 4 18,812 (bits/s) 23,605 (bits/s) node_4 18,740 (bits/s) 23,406 (bits/s)
Table 5.2.3 UMTS RNC Traffic Statistics
81


5.2.3 ATM Simulation Statistics
Statistic
ATM Call Setup Time (sec)
A TM CBR Cell Delay (sec)
Average Maximum Minimum
0.0000012294j 0.0000012294 [ 0.0000012294
0.0000007553 \ 0.0000009180 0.0000006342
Table 5.2.4 ATM Statistics
As shown in the table above the ATM Call Setup Time for the voice call between Mobile
Node 0 and Mobile Node 3 is around 0.0000012294 seconds. Also the ATM CBR (Constant
Bit Rate) Delay for the voice call has an average value of 0.0000007553 seconds which is
depicted in the graphs in figure 5.2.3.1 below
;coocois
cjxaon
ogooooi:
JfirO
5 'mm
c :okoc*
f'ttCijM
bUKoe
Fig 5.9 ATM Statistics
ATM.Cal Setup Time (sec)
82


APPENDIX A
A. Definitions:
Home Node B: Logical node in the 3G HNB ANS responsible for the control of the use and
integrity of the radio resources and for the radio transmission / reception in one or more
UTRA cells. Each cell may be configured as a CSG cell or an unrestricted cell. The 3G HNB
is a Customer Premise Equipment terminating the luh interface towards the 3G HNB-GW.
3G Home Node B Access Network Subsystem: 3G HNB ANS can be either a full UTRAN
or only a part of a UTRAN. A 3G HNB ANS offers the allocation and release of specific radio
resources to establish means of connection between an UE and the UTRAN. A 3G HNB
ANS contains one 3G HNB-GW and is responsible for the resources and
transmission/reception in a set of cells controlled by 3G HNBs.
3G Home Node B Gateway: Logical node in the 3G HNB ANS responsible for the control of
the connection between the 3G HNB and the operator network. The 3G HNB GW provides
concentration function for the control plane and for the user plane.
ALCAP: Generic name for the transport signalling protocols used to set-up and tear-down
transport bearers.
lu: Interface between an RNC [3G HNB or 3G HNB-GW] and an MSC, SGSN or CBC,
providing an interconnection point between the RNS and the Core Network. It is also
considered as a reference point.
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lub: Interface between the RNC and the Node B.
3G HNB luh: interface between the 3G HNB-GW and the 3G HNB.
lur. logical interface between two RNCs.
Node B: Logical node in the RNS responsible for radio transmission / reception in one or
more cells to/from the UE. The logical node terminates the lub interface towards the RNC.
Controlling RNC: Role an RNC can take with respect to a specific set of Node B's
There is only one Controlling RNC for any Node B. The Controlling RNC has the overall
control of the logical resources of its node Bs.
Serving RNS: Role an RNS can take with respect to a specific connection between an UE
and UTRAN There is one Serving RNS for each UE that has a connection to UTRAN. The
Serving RNS is in charge of the radio connection between a UE and the UTRAN. The
Serving RNS terminates the lu for this UE.
Universal Terrestrial Radio Access Network: UTRAN is a conceptual term identifying that
part of the network which consists of RNCs and Node Bs between lu an Uu
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B. Abbreviations
3G HNB 3G Home Node B
3G HNB-GW 3G HNB Gateway
AAL ATM Adaptation Layer
A A 1.2 ATM Adaptation Layer 2
ALCAP Access Link Control Application Part
ANS Access Network Subsystem
APN Access Point Name
ATM Asynchronous Transfer Mode
BC Broadcast
BM-IWF Broadcast Multicast Interworking Function
BMC Broadcast/Multicast Control
BSS Base Station Subsystem
CBC Cell Broadcast Centre
CBS Cell Broadcast Service
CN Core Network
C'RNC Controlling Radio Network Controller
CSG Closed Subscriber Group
DCH Dedicated Channel
DL Downlink
DRNS Drift RNS
E-DCI1 Enhanced UL DCH
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EDGE Enhanced Data rates for Global Evolution
FACII Forward Access Channel
FFS For Further Study
GERAN GSM EDGE Radio Access Network
GSM Global System for Mobile Communications
GIT GPRS Tunnelling Protocol
GWGN GateWay Core Network
UN BAP Home Node B Application Part
HPLMN Home PLMN
IPv4 Internet Protocol, version 4
IPv6 Internet Protocol, version 6
LA Location Area
MAC Medium Access Control
.MB MS Multimedia Broadcast Multicast Service
MCCH MBMS point-to-multipoint Control Channel
MOCN Multi Operator Core Network
MSCH MBMS point-to-multipoint Scheduling Channel
MTCH MBMS point-to-multipoint Traffic Channel
NAC'C Network Assisted Cell Change
NAS Non Access Stratum
NBAP Node B Application Part
NNSF NAS Node Selection Fuction
NSAP Network Service Access Point
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pen Paging Channel
PLMN Public Land Mobile Network
PTM Point To Multipoint
PIP Point To Point
QoS Quality of Service
RAB Radio Access Bearer
RACH Random Access Channel
RANAP Radio Access Network Application Part
RET Remote Electrical Tilting
RIM RAN Information Management
RNC Radio Network Controller
RNL Radio Network Layer
RNS Radio Network Subsystem
RNSAP Radio Network Subsystem Application Part
RNTI Radio Network Temporary Identity
RL'A RANAP User Adaptation
SAB Service Area Broadcast
SABP SAB Protocol
SAS Stand-Alone SMLC
SMI.C Serving Mobile Location Centre
SNA Shared Network Area
SRNC Serving Radio Network Controller
SRNS Serving RNS
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TMA Tower Mounted Amplifier
TE1D Tunnel Endpoint Identifier
TMGI Temporary Mobile Group Identity
TNI Transport Network Layer
TTI Transmission Time Interval
UDP User Datagram Protocol
IIE User Equipment
UL Uplink
UM'IS Universal Mobile Telecommunication System
ura UTRAN Registration Area
USIM UMTS Subscriber Identity Module
UTRAN Universal Terrestrial Radio Access Network
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BIBLIOGRAPHY
1. WCDMS For UMTS, Third Ed., Edited By Harri Holma and Antti Toskala, Nokia Finland,
2004.
2. Radio Network Planning and Optimization for UMTS, Second Ed., Edited by Jaana Laiho and
Achim Wacher, Nokia Group, Finland and Tomas Novosad, Nokia Group USA.
3. Theodore S. Rappaport, Wireless Communications, Principle and Practice, Second edition.2002.
4. 3G Wireless Networks, Clint Smith and Daniel Collins, Published by McGraw-Hill Professional,
2002.
5. 3GPP TS 23.101: "General UMTS Architecture".
6. 3GPP TS 25.410: UTRAN Iu Interface: general aspects and principles.
7. R3-081166, lu-based 3G HNB Architecture, Huawei.
8. R3-0815S8, Support of 3G HNB, RAN3#60.
9. R3-081652, 3G HNB Architecture, Huawei,Samsung.
10. R3-081653, Data Transfer on Iuh, Huawei.
! 1. R3-081658, UE Registration and Access Control for UTRA HNBs, Qualcomm Europe.
12. R3-081638, Access Control in 3G HNB Network, ZTE.
13. R3-081639 Mechanism for 3G HNB-GW Discovery, ZTE.
14. 3GPP TR 25.820: 3G Home NodcB Study Item Technical Report, (Release 8)
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