-
Contents 2
List of Figures and Tables 3
Abstract 4
1 Introduction 5 1.1 Comparative study between GSM network and
UMTS 6 (3GPP release 99 and 3GPP release 4) 1.1.1 Modulation
Methods and Data rates 6 1.1.2 Types of traffic 7 1.1.3 Network
Architecture 7 2 High Speed Packet Access (HSPA) 11
2.1 High Speed Downlink Packet Access (HSDPA) 11 2.2 High Speed
Uplink Packet Access (HSUPA) 14 2.3 3GPP Release 7 and 8 15 3
Development, Implementation and Architecture of LTE 16
3.0 LTE (Long Term Evolution) Overview 18
3.1 LTE Mobile devices and the LTE Uu interfaces 18
3.2 The e-NODE-B and the S1 and X2 Interfaces 18
3.3 The Mobility Management Entity (MNE) 20
3.4 The Serving Gateway (S-GW) and Gateway to Internet (PDN)
3.4.1 The Serving Gateway (S-GW) 21
3.4.2 The Gateway to the internet (PDN) 21 Conclusion 21
References 22
1
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List of Figures and Tables
Table 1 Data Rates for Mobile Communication Systems 13 Figure 1
GSM Network Architecture 9 Figure 2 UMTS Network Architecture
Release 99 10 Figure 3 UMTS Network Architecture release 4 10
Figure 4 HSDPA Architecture overview 12 Figure 5 HSUPA Architecture
overview 15 Figure 6 LTE Network Architecture overview 17
2
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Abstract This report describes the comparison between Global
System for Mobile Communication (GSM) and Universal Mobile
Telecommunication System (UMTS). High Speed Packet Access (HSPA),
which includes HSDPA (High Speed Downlink Packet Access), HSUPA
(High Speed Uplink Packet Access), and HSUPA+ were evaluated, with
the analysis of its impact to network performance was also
evaluated. And lastly, the development, implementation and overview
of LTE (Long Term Evolution) were reviewed.
3
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1.0 Introduction
Mobile communications systems modernized the way people
communicate, joining together communications and mobility. A lot
has been achieved in a short time in the history of mobile wireless
systems. Evolution of mobile wireless access technologies is about
to reach its Fifth generation (5G). The cellular idea was
introduced in the 1G technologies that made up the large-scale
mobile wireless communication possible; it became available in the
1980s. 1G uses analog cellular technologies for communication and
was later replaced by digital communication technology known as 2G
in the 1990s, which significantly improved the quality of mobile
network. It introduced services such as short messaging service
(SMS) and lower speed data. GSM is generally known as 2G
technologies. In addition to mobile network, Data and voice
communication has been the main focus on 3G technologies and a
converged network for both voice and data communication emerged. 3G
requirements were specified by the ITU as part of the International
Mobile Telephone 2000 (IMT-2000) project, for which digital
networks had to provide 144 kbps of throughput at mobile speeds,
384 kbps at pedestrian speeds, and 2 Mbps in indoor environments.
UMTS-HSPA and CDMA2000 EV-DO are the major 3G technologies.
However, 3G Systems regardless of their enhanced features are still
severely bandwidth-constrained, particularly for handling video
communication traffic (Chakraborty , 2013). The Fourth generation
(4G) which is considered as LTE (Long Term Evolution) provides
access to a wide range of telecommunication services, including
applications like wireless broadband access, Multimedia Messaging
Service (MMS), video chat, mobile TV, HDTV content, Digital Video
Broadcasting (DVB), minimal services like voice and data, and other
services that utilize bandwidth according to the demands in
multiuser environment (Sesia, Toufik and Baker, 2011).
4
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1.1 Comparative Review between GSM and UMTS Network 1.1.1
A. GSM GSM is the most widely used 2G air interfaces worldwide.
Its strength lays in its widespread global penetration, which
enables consumers to use their telephones when they travel. GSM
phones have clip-on Subscriber Identity Module (SIM) cards. These
cards contain a microchip that stores user identity and other
information such as speed-dial lists. The SIM card encrypts voice
and data before they are transmitted. GSM is the digital cellular
standard that was originally decided on by European governments and
was first deployed in 1992. GSM divides channels of 200 KHz
spectrum into eight time slots. Seven of the time slots carry
traffic and the eighth carries control signals. At first GSM was
used exclusively for Voice communication but later, the control
channel but soon it was also used to carry text messages called
Short Message Service (SMS), which is otherwise known as text
messaging. GSM uses a form of Time-Division Multiplexing (TDM). The
GSM uses Gaussian Minimum Shift Keying (GMSK) modulation
method.
B. UMTS Universal Mobile Telecommunications System (UTMS) is
considered to be an effective and efficient 3G mobile communication
systems in which there is an incorporated radio interface system.
Additionally, it has been observed that the radio interface system
is significantly based on Wideband Code Division Multiple Access
(WCDMA). The radio frequencies that have been used in this system
are of the order of 1900-2025 MHz as well as 2110-2200 MHz In this
mobile system, a range of wireless multimedia communications is
possible that are spread across the entire Internet protocol. It
has been observed that this system allows a number of different
mobile Internet users for the purpose of enabling them to access a
variety of multimedia contents. These contents are available across
the entire Internet and they are 5
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considered to be arranged in a seamless fashion with data rates
that are as much as up to 2 Mbps inside and 384 Kbps outside.
1.1.2 Types of Traffic GSM: It basically supports three types of
traffic which includes: 1. Signaling: 16k, 32k, and 64k. 2.
Voice/Fax 3. GSM Data: GPRS, EDGE, and Extended Data. UMTS: It has
basically has four main classes of traffic types which includes: 1.
Conversational class (voice, video telephony, video gaming). 2.
Streaming class (multimedia, video on demand, webcast). 3.
Interactive class (Web browsing, network gaming, database
access).
4. Background class (Email, SMS, and Downloading).
1.1.3 Network Architecture
A. GSM
The GSM architecture can be divided into three categories, which
includes: the Mobile Station (MS), the Base Station Subsystem
(BSS), and the Network Subsystem. The mobile Station (MS): A mobile
may be known as Mobile Equipment (ME), Mobile Terminal (MT) or
Handset. The mobile Station usually contains the Subscriber
Identity module (SIM). And they come in three sizes. Each device
comes with an IMEI (international Mobile equipment Identity) and
also each SIM has Unique Identification number known as IMSI
(international Mobile Subscriber Identity). The Base Station
subsystem (BSS): This consists of the Base Station Controller (BSC)
and the Base Transceiver Station (BTS).
6
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Base Station Controller (BSC): This manages a group of BTSs
which are usually connected together. The major function of the BSC
is call maintenance. Base Transceiver Station (BTS): GSM uses a
series of radio transmitters called BTSs to connect the mobile
stations to the radio network.
The Network Subsystem: The network subsystem consists of: The
mobile Switching Center (MSC), The Home Location Register (HLR),
The Visitor Location Register (VLR), The Authentication center
(AuC), and the Equipment Identity Register (EIR). The Equipment
Identity Register (EIR): The EIR is a database that contains the
list of all valid mobile station equipment within the network. The
Mobile Switching Center (MSC): The MSC is responsible for functions
relating to a mobile subscriber which includes registration,
authentication, location updating, handovers and call routing. The
Home Location Register (HLR): This is a database that is used for
handling and managing mobile subscriber information. It stores the
IMSI, IMEI, and the VLR address. The Visitor Location Register
(VLR): This is database that contains the details of a Mobile
Station such as information about last location, the power usage
and details about other services. The Authentication Center (AUC):
This is a database that holds the secret key used for the
authentication and encryption of a mobile station within a
network.
7
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Figure 1: GSM Network Architecture (Eberspacher et al.,
2009)
B. UMTS As shown from the diagram, the key components of an UMTS
system are: UTRAN (Universal Terrestrial Radio Access network), CN
(Core network), UE (user Equipment), and NMS (Network Management
Station), which is also the only vendor specific component. UTRAN:
This is located between two open interfaces which are Uu and lu. It
is the part that controls and manages the WCDMA radio resources.
And it can also further handle handover. BSs: These are located
between the interface Uu and lub in UTRAN architecture. Their main
task is to establish physical implementation of the Uu and the lub
interfaces by making use of protocol stack. RNC: This is located
between the lub and lu interfaces, it acts as the switching and the
controlling element in the UTRAN. UMTS CN: This is located between
the access networks and the external networks. It is the basic
medium for all communications services provided to the UMTS users.
While the PS and the CS services are the two basic communication
services provided by the Core network.
8
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Figure 2: UMTS Network Architecture Release 99 (Atayero et al.,
2011)
Figure 3: UMTS Network Architecture Release 4 (Holma and
Toskala, 2000).
9
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3GPP Release 99 and 3GPP Release 4 are the same in terms of the
UTRAN (Universal Terrestrial Radio Access Network), with the UE and
NMS. The only differences in 3GPP Release 4 and 3GPP Release 99
were on the CN (Core Network). Especially in 3GPP R4 in which the
CN CS domain, MSC/VLR and GMSC have evolved into (G) MSC server and
MGW. In the whole connection process is controlled by the server
and the MGW acting as a switch. MGW contains the functionality of
performing actual switching and network inter-working. And also in
some instances, few MSC/GMSC servers can control numerous MGWs
(Sauter, 2011; Abdullah et al., 2014). 2.0 High Speed Packet Access
(HSPA) High Speed Packet Access (HSPA) is a broadband access that
is an improvement to the WCDMA networks (FDD, and TDD) which is
used in improving network performance. It is a combination of
HighSpeed Downlink Packet Access or 3GPP Release 5, which was
specified in 2002, and High Speed Uplink Packet Access (HSUPA),
which is 3GPP Release 6, and specified in December 2004. HSPA is
needed to increase the data rates of mobile networks, in comparison
with fixed line broadband services. Therefore, HSPAs can support
high data consuming and low latency applications such as Voice over
Internet Protocol (VOIP). 2.1 High Speed Downlink Packet Access
(HSDPA) HSDPA stands for High Speed Downlink Packet Access. It is
referred to as a mobile telephony protocol. It is a new improved
downlink packet data transfer structure for 3GPP systems. HSDPA is
not just an ordinary transformation to a 3GPP specification, but an
important upgrade that brings clear distinctive improvements and
far higher data speeds than the normal 3G systems. HSDPA offers a
technique by which the downlink capacity was improved within the
current spectrum. With this, HSDPA downlink air interface is
doubled or tripled. The present 3G system can only tolerate few
maximum data rate per users at a particular time before the cell
capacity runs out of downlink
10
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data from the spectrum. A normal mobile user consumes more
downlink that uplink resources (Enan and Mustafa, 2014). Since the
downlink consumes more payload data for most applications compared
to the uplink. The HSDPA aims to expand downlink data capacity, and
thus this possible bottleneck from the entire system. It helps to
upgrade the entire system capacity as a whole by increasing the
data rate allotted to a user (Holma and Toskala , 2006)
.
Figure 4: HSDPA Architecture (Abdullah et al., 2014)
Features of HSDPA
1. The HSDPA differs from the UMTS, which is observed by its
ability to provide higherorder 16QAM modulation mode is used to
improve spectral efficiency. 2. Both code division and time
division are used in scheduling User Equipment (UEs). 3. The
highest maximum transmission rate is the downlink. And also the
rate reaches up to 14.4Mbit/s.
11
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4. The hybrid Automatic Repeat Request (HARQ) and Adaptive
Modulation and Coding (AMC) technologies are applied at the
physical layer. It means the factors such as modulation and a
number of different coding formats have the ability to change
themselves in relation to the differences in the channel
conditions.
Advantages
1. HSDPA uses relatively shorter length of frame thereby
displaying faster response to problems relating to radio channels.
2. HSDPA works best for applications that have unusual changeable
and uneven requirement of bandwidth. 3. Some specific delays tend
to occur in HSDPA, which may in turn assist novel applications such
as interactive networked systems. 4. The HSDPA technology adds
extra wideband downlink shared channel that is optimized for higher
speed data transfer. HSDPA increases only the downlink
throughput.
Table 1. Data Rates for Mobile Communication Systems (Holma
and
Toskala, 2000).
System GSM GPRS EDGE 3G(R99) HSDPA
Typical Max. data rate (Kbit/s)
9.6 50 130 384 2048 (or more)
Theoretical Max. data rate (Kbit/s)
14.4 170 384 2048 14400
12
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2.2 High Speed Uplink Packet Access (HSUPA) High Speed Uplink
Packet Access (HSUPA) is a release 6 Specification in 3GPP systems.
And it is among the High Speed Packet Access (HSPA) family. It is
more often known as technologies of 3.75G or Enhanced Uplink
Dedicated Channel (E-DCH) by the technically mindful people, which
is higher that most of the 3G technologies that are available. The
main target of the HSUPA is to increase the data transfer speed in
UMTS evolution technologies, thereby achieving a data speed of up
to 5.8Mbps in the uplink. High Speed Uplink Packet Access (HSUPA)
has the ability to improve the symmetric data rates such as emails
in the mobile and video and gaming and data applications that vary
from person to person. In addition to this, contrary to HSDPA,
HSUPA has a dedicated channel and also, there is a series of
channel for the purpose of traffic and signal so that all the
uplink capabilities can be significantly improved. HSUPA can also
be used in a number of different applications for the purpose of
improving the DVD quality, live and heavy streaming and the ability
to play real-time games in different modes readily and easily (Enan
and Mustafa, 2014). Furthermore, if HSUPA is compared to the
technology of dedicated channel, it may be found that the former
has the ability to enable a higher user throughput.
Features of HSUPA
Transmission rate of about 5.8 Mbps. BPSK method of modulation.
It supports Soft handover technique and Hybrid ARQ (HARQ). It
supports fast packet scheduling with multicode transmission.
13
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Advantages
1. HSUPA significantly improves the data transmission rates,
which aids in the fast transmission of data and retransmission of
failed data, thereby enhancing the network performance of a system.
2. It supports the utilization of Soft hand over technique. The
user receives control signals related to Node B cell scheduling
from every radio link. After this, the transmission rate signals
are combined together from different cells with the help of user
terminal.
Figure 5: HSUPA Architecture (Abdullah et al., 2014)
2.3 3GPP Release 7 and 8 The Third Generation Partnership
Program (3GPP) specifications has important enhancements in the
downlink data rates and capacity in release 5 (HSDPA) which is also
similar to the increase in uplink data rates and capacity in
release 6 (HSUPA). 3GPP release 7 and release 8 are advancement to
the High Speed Packet Access (HSPA) (3gpp, 2008).The 3GPP release 7
is known as HSPA
14
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evolution or HSPA+. While release 8 is categorized under the LTE
specification. 3GPP release 7 supports the easy breakdown of
network architecture. And the number of network elements is reduced
as compared to release 6. And also the release 8 has further
increased the radio capabilities and data rates thereby reducing
the latency of the entire system as compared to the former
technology releases. The LTE performance aim is to provide 2 to 4
times the performance of the HSPA release 6. 3GPP release 7 and 8
solutions for the HSPA evolution was merged in parallel together
with the LTE development, and some aspects of the LTE work are
reflected on the HSPA evolution as well (3gpp, 2008). .
Features of 3GPP Release 7 and Release 8
The challenges faced in earlier 3GPP specifications from release
99 to release 6 is the continuous reception and transmission when
the mobile device. In former specifications the mobile device keeps
transmitting the physical control channel even if there is no data.
In release 7 and 8, the mobile terminal cuts off the CCT when there
is no data channel transmission, allowing it to shut down the
transmitter completely. In 3GPP release 7 and 8, the VOIP capacity
is enhanced. A number of features have been introduced to 3GPP
release 7 and 8 to improve the efficiency of low-bit rate, delay
critical applications like Voice over IP. 3GPP 7 and 8 has far more
flat and flexible architecture compared to lower 3GPP release. 3GPP
release 6 has four network elements while, release 8 (LTE) has only
two network elements.
3.0 LTE - Overview LTE, which stands for Long Term Evolution, is
Third Generation Partnership Project (3GPP), which was proposed in
November 2004. It is a system, which advanced from the Universal
Mobile Telecommunication System (UMTS) and 15
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also in turn from the Global System for Mobile Communications
(GSM). Related specifications which were formally known as the
evolved UMTS terrestrial radio access (E-UTRA) and evolved UMTS
terrestrial radio access network (E-UTRAN). The First version of
LTE was documented in Release 8 of the 3GPP specifications. The
main aim of LTE is to offer a high data rate, low latency and
packet optimized radio access technology supporting flexible
bandwidth implementation. At the same time its network architecture
has been designed with the aim to support packet-switched traffic
with seamless mobility and great quality of service (Dahlman et
al., 2011).
MME Serving-GW
PDN-GW
HSS
Internet
Mobile Device
eNode-BeNode-B
X2
S6
CP UPS1
S11
CP UP
S5
Figure 6: LTE Network Architecture overview (Sauter, 2011)
16
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3.1 LTE Mobile devices and the LTE Uu interfaces In the LTE,
just like in Universal Mobile Telecommunication Systems (UMTS), the
mobile devices are called User Equipment (UE). In 3GPP Release 8,
five different UE classes was defined and unlike in HSPA where
devices support a wide range of different modulation and coding
schemes because the standard evolved over time, all LTE UEs support
the very fast 64-QAM (Quadrature Amplitude Modulation) in the
downlink direction and antenna diversity. In the uplink direction,
only the support of the slower but more reliable 16-QAM is
required. LTE User Equipments (UEs) are categorized into five
classes, 1-4 and these mobile devices under this category support
MIMO transmission in the downlink direction. With this advanced
transmission scheme, several data streams are transmitted on the
same carrier frequency from multiple antennas from the base station
to multiple antennas in the mobile device. LTE networks and devices
use 2 2 MIMO, that is, two transmit and two receive antennas. In
the future, 4 4 MIMO might be used with category 5 UEs class. Most
LTE mobile devices also support other radio technologies such as
GSM and UMTS. As a result, a typical LTE device today does not only
support more LTE frequency bands but also supports those for the
other radio technologies (Sauter, 2011).
3.2 The E-NODE-B and the S1 and X2 Interfaces In LTE
specification, the Base station is usually known as eNode-B and it
is a complex system. The name, which was gotten from UMTS base
station which was called (Node-B) with the e meaning evolved. This
changes was also done to UTRAN (Universal Mobile Telecommunications
System Terrestrial Radio Access Network) which is now referred to
as eUTRAN in LTE networks. 17
-
The eNode-B in LTE networks consists of three key elements which
includes; The Antennas, radio modules that (modulate and demodulate
all signals transmitted in the air interface and the digital
modules that processes all signals transmitted and received on the
air interface. In LTE networks, the eNode-B is not only responsible
for the air interface but also focuses on management in general and
scheduling air interface resources. The following are some of the
other functions of eNode-B in LTE radio networks: For ensuring QoS
such as ensuring latency and minimum bandwidth requirements for
real-time users and maximum throughput for some applications. For
load balancing between the different simultaneous radio network
users. Mobility management For interference management, that is, to
reduce the impact of its downlink transmissions on neighboring base
stations in cell edge situations. The S1 as defined in LTE radio
network serves two purposes which are: the eNode-B uses the S1
interface for interaction with the core network for its own
purposes, i.e. to make itself known to the network, to send status
and connection keep-alive information and for receiving
configuration information from the core network (Atayero, 2011).
And secondly, the S1 interface is used for transferring signaling
messages that concern the users of the system. And it can also be
used to maintain the connection, to organize a handover of the
connection to another LTE, UMTS or GSM base station, in which user
data packets can be forwarded between the two base stations
involved in a handover process. The X2 interface is in the
communication between two base stations in LTE radio networks. It
has two major functions it performs, which are: The X2 interface
with the core network are used in the
18
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implementation of handovers and secondly, it is used in the
coordination of interferences (Atayero, 2011). .
3.3 The Mobility Management Entity (MNE) Since the eNode-Bs
separately handles users and their radio bearers once they are
established in LTE networks. There is need for a single point over
which data flows between the user and the Internet, a centralized
user database is required, which can be accessed from anywhere in
the home network and also from networks abroad in case the user is
roaming (Sauter, 2011). The network node responsible for all
signaling exchanges between the base stations and the core network
and between the users and the core network is the Mobility
Management Entity (MME). In larger networks, there are usually many
MMEs to manage the amount of signaling. Other functions of MMEs are
stated below: Authentication. When a subscriber first attaches to
the LTE network, the eNode-B communicates with the MME over the S1
interface and helps to exchange authentication information between
the mobile device and the MME. Establishment of bearers. The MME
itself is not directly involved in the exchange of user data
packets between the mobile device and the Internet. It is
responsible for selecting a gateway router to the Internet.
Handover support. In case no X2 interface is available, the MME
helps to forward the handover messages between the two eNode-Bs
involved. Interworking with other radio networks. When a mobile
device reaches the limit of the LTE coverage area, the eNode-B can
decide to hand over the mobile device to a GSM or UMTS network or
instruct it to perform a cell change to suitable cell. MME is
largely in charge of instance and communication with the GSM or
UMTS network components during this operation. 19
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3.4 The Serving Gateway (S-GW) and Gateway to Internet
(PDN).
3.4.1 The Serving Gateway (S-GW) The S-GW is responsible for
managing user data tunnels between the eNode-Bs in the radio
network and the Packet Data Network Gateway (PDN-GW), which is the
gateway router to the Internet. For example, a handover is
performed by the eNode-B under the control of the MME and Serving
Gateway (S-GW).
3.4.2 Gateway to the Internet (PDN) The third LTE core network
node is Gateway to the Internet (PDN. In the LTE network, this node
is the gateway to the Internet and some network operators also use
it to interconnect to intranets of large companies over an
encrypted tunnel to offer employees of those companies direct
access to their private internal networks (Sauter, 2011). PDN also
has the function of assigning IP addresses to LTE mobile devices.
When a mobile device connects to the network after being switched
on, the eNode-B connects to the MME, which then authenticates the
subscriber and requests an IP address from the PDN-GW for the
device (Sauter, 2011).
Conclusion In todays world Mobile communication is getting
faster and speedy and it is the backbone of every business and
day-to-day life. Mobile technologies have played a very vital role
in rapid advancement and growth of technology over the past
half-decade. With the rapid growth of user demands, and the
limitations of some mobile communication technologies, it is
expected that new technologies will eventually hit the market and
are expected to become a platform capable of delivering 20
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increased data rates, greater interoperability across
communication protocols, user-friendly innovative and secure
applications.
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