247164027-LTE-Fundamentals-Course-Documentation-2010.pdf

LTE Fundamentals
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LTE Fundamentals
Course documentation
December 2010

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© 2010 PontoTech
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LTE Fundamentals
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COURSE CONTENTS
LTE FUNDAMENTALS ......................................................................................................................................3
1 EVOLUTION AND TRENDS OF MOBILE TELEPHONY.......................................................................................7
1.1 Introduction.........................................................................................................................................8
1.2 Importance of mobility in telecommunications....................................................................................9
1.3 Increased demand for mobile data services ........................................................................................9
1.3.1 Evolution of mobile terminals to the increased demand for data....................................................................10
1.3.2 The phenomenon of Smartphone....................................................................................................................11
1.4 Evolution of communications to mobile broadband.......................................................................... 12
1.4.1 NGN as a principle to evolve towards broadband...........................................................................................13
1.5 Evolution generation mobile networks .............................................................................................. 15
1.6 Towards the Fourth Generation (4G)................................................................................................ 16
1.6.1 Fourth Generation Technologies.....................................................................................................................18
1.7 Global demand for mobile access...................................................................................................... 19
2 COMPARISON BETWEEN WIMAX AND LTE............................................................................................... 23
2.1 WiMAX Technology Overview........................................................................................................... 24
2.2 LTE Overview.................................................................................................................................... 24
2.3 LTE-Advanced for IMT-Advanced..................................................................................................... 25
2.4 Technical comparison between LTE and Mobile WiMAX................................................................. 28
2.5 Interoperability between the two technologies .................................................................................. 29
2.6 Tendency for operators to implement LTE ........................................................................................ 30
3 THIRD-GENERATION NETWORKS AS THE BASIS FOR THE EVOLUTION TO LTE............................................. 31
3.1 Evolution of a UMTS network to LTE ............................................................................................... 32
3.2 UMTS Network Structure .................................................................................................................. 34
3.2.1 UTRAN ..........................................................................................................................................................34
3.2.2 Core network ..................................................................................................................................................38
4 STANDARDIZATION AND TECHNICAL REQUIREMENTS ACCORDING TO 3GPP LTE...................................... 43
4.1 Reason for the evolution of the system architecture .......................................................................... 44
4.2 Working groups and the definition of technical specifications for LTE ............................................ 44
4.3 3GPP requirements for LTE.............................................................................................................. 46
4.3.1 Requirements related to the ability .................................................................................................................46
4.3.2 Requirements related to performance .............................................................................................................47
4.3.3 Requirements related to network deployment.................................................................................................48
4.3.4 Requirements for E-UTRAN architecture ......................................................................................................49
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4.3.5 Requirements for radio resource management ............................................................................................... 49
4.3.6 Requirements related to the complexity of the systems.................................................................................. 49
4.3.7 Protocols and services requirements .............................................................................................................. 50
4.3.8 Specifications for interoperability with legacy networks ............................................................................... 50
4.4 Standardization beyond Release 8.....................................................................................................52
4.5 Architecture Overview of LTE / SAE .................................................................................................52
4.6 General elements of architecture.......................................................................................................54
4.7 Particular elements of the architecture .............................................................................................56
4.7.1 The eNodeB ................................................................................................................................................... 56
4.7.2 Entity Mobility Management (MME, Mobile Management Entity)............................................................... 58
4.7.3 SAE GW ........................................................................................................................................................ 60
4.7.4 Gateway service (S-GW, Serving Gateway) .................................................................................................. 60
4.7.5 Gateway Packet Data Network (P-GW, Packet Data Network Gateway) ...................................................... 62
4.7.6 Feature Collection Policy and Resources (PCRF, Policies and Charging Resource Function) ...................... 64
4.7.7 Local subscriber server (HSS, Home Subscriber Server)............................................................................... 65
4.8 Interfaces and protocols in the setting of the basic system architecture............................................66
4.8.1 Interface LTE-Uu........................................................................................................................................... 67
4.8.2 S1-MME interface.......................................................................................................................................... 69
4.8.3 S11 interface .................................................................................................................................................. 70
4.8.4 S5/S8 Interface............................................................................................................................................... 72
4.8.5 GTP S5/S8 Interface ...................................................................................................................................... 72
4.8.6 PMIP S5/S8 Interface..................................................................................................................................... 74
4.8.7 Interface X2.................................................................................................................................................... 75
4.8.8 SGI interface .................................................................................................................................................. 76
4.8.9 S6a/S6d Interface ........................................................................................................................................... 78
4.8.10 Rx Interface ............................................................................................................................................... 80
4.9 System Architecture and E-UTRAN access networks legacy.............................................................82
4.9.1 Interconnection infrastructure architecture Bequeathed LTE 3GPP............................................................... 82
4.9.2 Interfacing with legacy infrastructure 3GPP CS ............................................................................................ 85
4.10 Interconnection Architecture LTE infrastructure Bequeathed No - 3GPP........................................86
4.10.1 User Equipment ......................................................................................................................................... 87
4.10.2 Evolved Packet Core (EPC)....................................................................................................................... 88
4.10.3 Non-3GPP access network reliable............................................................................................................ 89
4.10.4 Access networks unreliable non-3GPP ...................................................................................................... 89
4.10.5 Main elements of the Interconnection System ........................................................................................... 90
4.10.6 Interfaces and protocols for the interconnection of the 3GPP networks .................................................... 90
5 ASPECTS OF LTE RADIO.............................................................................................................................93
5.1 Definition of the radio interface ........................................................................................................94
5.1.1 Access Technologies...................................................................................................................................... 94
5.1.2 MIMO (Multiple Input Multiple Output)..................................................................................................... 100
5.1.3 Element and resource block ......................................................................................................................... 102
5.1.4 Downlink transmission................................................................................................................................. 102
5.1.5 LTE OFDM cyclic prefix, CP ...................................................................................................................... 104
5.1.6 Uplink transmission technique..................................................................................................................... 105
5.2 Access modes and frequency bands LTE. ........................................................................................106
5.2.1 Access Modes .............................................................................................................................................. 106
5.2.2 Supported frequency bands. ......................................................................................................................... 108
5.2.3 Bandwidth of transmission........................................................................................................................... 108
5.3 Radio layers and protocols used in LTE..........................................................................................110
5.3.1 Radio Link Control (RLC) ........................................................................................................................... 112
5.3.2 Media Access Control (MAC) ..................................................................................................................... 113
5.3.3 Logical channels and transport channels...................................................................................................... 114
5.3.4 Physical Layer.............................................................................................................................................. 116
5.4 Frame structure ...............................................................................................................................121
5.5 Modulation.......................................................................................................................................123
5.6 Data Flow........................................................................................................................................124
5.7 EU states and zone concepts............................................................................................................125
5.8 Rates of end user data, EU capabilities...........................................................................................126
6 CONSIDERATIONS FOR LTE RADIO SPECTRUM.........................................................................................129
6.1 Overview of Radio Spectrum ...........................................................................................................130
6.2 Actors involved in spectrum management .......................................................................................131
6.3 LTE spectral efficiency ....................................................................................................................132

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6.4 Spectrum bands allocated for LTE .................................................................................................. 133
6.4.1 Frequency bands currently used for LTE......................................................................................................133
6.4.2 Aspects to consider when choosing the frequency of implementation .........................................................134
6.4.3 The choice of refarming as an alternative implementation ...........................................................................137
6.5 Amount of spectrum required for LTE deployment.......................................................................... 138
7 OTHER CONSIDERATIONS ON A MIGRATION TO LTE................................................................................. 139
7.1 Special considerations must take into account an operator ............................................................ 142
7.1.1 Considerations for network planning............................................................................................................142
7.1.2 Initiation stage ..............................................................................................................................................143
7.1.3 Stage details..................................................................................................................................................143
7.1.4 Optimization stage........................................................................................................................................143
7.1.5 Deploying services over LTE .......................................................................................................................144
7.1.6 Voice over LTE ............................................................................................................................................150
7.1.7 Circuit switch fallback (CS fallback)............................................................................................................150
7.1.8 Solution VoLGA...........................................................................................................................................152
7.2 Offer LTE-capable terminals to allow for QoE............................................................................... 155
7.2.1 Election of the terminal (UE)........................................................................................................................155
7.2.2 Multimode terminals.....................................................................................................................................156
7.2.3 Multiband terminals......................................................................................................................................156
7.3 Quality of Service (QoS).................................................................................................................. 157
7.3.1 EPS architecture and quality of service ........................................................................................................157
7.3.2 EPS Carrier...................................................................................................................................................158
7.3.3 QoS parameters.............................................................................................................................................160
7.3.4 Packet Filters ................................................................................................................................................162
7.3.5 Mapping the QoS parameters for UMTS and EPS .......................................................................................162
7.4 Implementing a solution SON (Self Optimizing Network) to support efficiency.............................. 164
7.5 Reuse of access equipment .............................................................................................................. 164
7.6 Reuse and improvement of network backbone and backhaul transport .......................................... 166
7.6.1 Evolution LTE backhaul...............................................................................................................................168
7.6.2 Transport backhaul technologies LTE..........................................................................................................170
7.7 Summary of proposed technical requirements for deploying LTE .................................................. 172
7.7.1 Frequency bands for equipment....................................................................................................................172
7.7.2 Modifications to the data network ................................................................................................................173
7.7.3 Technical Requirements multistandard base stations (UMTS/ HSPA +/ LTE) ............................................174
7.7.4 Technical requirements of the Radio Network Controller (RNC) ................................................................176
7.7.5 Technical characteristics of the packet core..................................................................................................178
7.7.6 Technical characteristics of interfaces ..........................................................................................................179
7.7.7 Core Specifications SAE / LTE....................................................................................................................180
7.7.8 MME techniques features.............................................................................................................................180
7.7.9 Technical specifications of SAE Gateway....................................................................................................181
7.7.10 Technical management of the system.......................................................................................................183
8 LTE BUSINESS PERSPECTIVES.................................................................................................................. 185
8.1 Global trend in demand for data ..................................................................................................... 186
8.2 LTE as a data access solution ......................................................................................................... 190
8.3 Operators Initiatives........................................................................................................................ 192
8.3.1 Operators in Asia..........................................................................................................................................195
8.3.2 Operators in Europe......................................................................................................................................195
8.3.3 Operators in Latin America and the United States........................................................................................196
8.4 Initiatives manufacturers................................................................................................................. 198
8.4.1 Network Equipment......................................................................................................................................198
8.4.2 User terminals...............................................................................................................................................206
8.4.3 Expectations and needs of end users.............................................................................................................213
8.4.4 New services can be provided with LTE ......................................................................................................214
8.4.5 The LTE Ecosystem .....................................................................................................................................218
8.4.6 For TeliaSonera ............................................................................................................................................220
8.5 Conclusions ..................................................................................................................................... 222
9 ACRONYMS .............................................................................................................................................. 225

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1 Evolution and trends of Mobile Telephony

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1.1 Introduction
Traditionally, broadband service has been provided by means of fixed access
technologies because they offer greater accessibility, in comparison with mobile
access technologies.
Following this, in recent years, telecom operators have boosted the deployment of
wireless telecommunications networks, due to the possibility that the end user to use
higher-capacity systems, while allowing flexibility in terms of mobility. Because of this,
research groups around the world have and are devising new standards for wireless
access in order to implement systems that offer greater capacity for bandwidth in the
access, and that in turn make efficient use of the spectrum.
For this reason, mobile phone networks have evolved to provide higher bandwidth
using technologies such as HSPA + and LTE. The latter emerges as an initiative of
the 3GPP, in order to meet new technological needs that today's end users are
demanding. This envisages the delivery of new voice and data applications, as well
as improved speed of access to information. Also, LTE grows on a scalable flat
network design, which seeks to improve the services offered by second generation
networks and existing third-generation.
Among other things, the evolution of mobile systems have meant that today there are
standard technology solutions for the benefit of operators and manufacturers. The
first mobile communication systems (analog systems) were different for each country,
so that economies of scale were achieved worldwide. However, after the introduction
of Global System for Communications (GSM, Global System for Mobile
Communications) begins to speak of a single common solution worldwide in regard to
mobile telephony. Despite its success, factors such as lack of services and the need
for new connectivity solutions have led to the study and development of new mobile
technologies Third and Fourth Generation.
Because of this, this chapter outlines the technological and market reasons that
justify the emergence of new mobile technologies.

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1.2 Importance of mobility in telecommunications
The possibility that a user can communicate at any time and from anywhere using a
single device, has always been one of the main challenges facing the
telecommunications system.
As part of the mobility in question, the mobile phone user must have the following
facilities:
1. Roaming: Allows a user to access the different telecommunications services
from any country that is, if there are prior agreements between the operator
who is subscribed and existing operators in different countries around the
world. Usually, for you may enjoy this feature, you must (apart from
subscribing to the service) have mobile terminals, allowing them to enjoy their
voice and data services contract to move to other countries.
2. Handover or transfer: The process that allows users to carry a mobile terminal
to maintain the connection and voice and data sessions, when they move
between different areas of coverage.
Based on the above, then discussed the trend toward mobile phone technology, for
which demand will respond to the needs of mobility, ubiquity and new services
1.3 Increased demand for mobile data services
The evolution of mobile communications networks, rather than by technological
necessity, is caused by the need to provide new telecommunications services. Using
the concept of service, have adopted new technologies and changing the approach
to providing basic voice services, to a model where the telecommunications operator
looking to offer new data services, with the aim of improving the user experience, and
increased revenues. Besides this, it seeks to enrich the ubiquitous mobile feature that
allows end users to access broadband and a portfolio of related services from their
mobile device at anytime, anywhere. Thus messaging services like MMS, SMS and
new services such as instant messaging, electronic commerce, and social networks
are contributing significantly to the income received by the telecommunications
operators.

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1.3.1 Evolution of mobile terminals to the increased
demand for data
Today's mobile devices or terminals are becoming crucial to meet the communication
needs of individuals.
Aware of this, in recent years, handset manufacturers and telecom operators have
felt the need to adapt the devices to access the lifestyle of people, providing a tool for
them to have access to a diverse set of new services and applications.
Because of this, the mobile phone remains the main device of choice as well as
allowing voice communication, is becoming an important means for the user can
access entertainment services (example games and television), news and
advertising. In turn, being used as an ideal tool for starting content, such as, audio /
video and photographs, as well as to interact through social networks, which also
allow the creation, distribution and consumption of content.

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Today, in the market it can be found terminals with basic services like voice and
sending text messaging to more advanced terminals (type Smartphone) which have a
wide range of data services and in turn are characterized by smaller, lighter and
aesthetically adopted by many users.
It should be noted also that a factor in the expansion of mobile services, will be the
price of the terminals. For this reason, today, many telecom operators, in addition to
its range of services, are subsidizing the cost of 3G handsets as an incentive to
motivate its users to use new applications and services offered today in the market,
which in turn will help drive growth in mobile subscribers in the future. This excessive
increase that may arise should be complemented with more robust networks, namely
higher capacity, both during transport and access.
1.3.2 The phenomenon of Smartphone
As mentioned earlier, one of the fastest growing devices is the Smartphone. It is
estimated that smart phones will occupy 24.2% of the market for 2011, and this
number is expected to exceed 30% by 2012. In turn, as part of the e statistics support
this trend, the Kelsey Group and findings made a consumer survey of users of U.S.
mobile phones and reported that 18.9% of mobile consumers now use a
Smartphone.
Currently there are several types of smart phones such as RIM Blackberry, the Nokia
E61, the 6650, the HTC G1, the Sony Ericsson Xperia X1, the LG Incite, the HTC
FUZE, Apple iPhone and Palm Treo.

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1.4 Evolution of communications to mobile
broadband
Today's users demand higher speeds and quality of access to telecommunications
services and new value-added services, which require higher bandwidth for proper
performance. For this reason, the pursuit of meeting the needs of consumers, based
on the need for high capacity Internet access from their mobile devices (known as
mobile broadband), is one of the main reasons motivating the development.
As in Figure 1 an estimate on the number of broadband subscribers around the world
will be about 3400 million in 2014. For this year it is estimated that about 80% of
these consumers use mobile broadband.
Figure 1 - Estimated global growth of broadband subscribers

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1.4.1 NGN as a principle to evolve towards
broadband
Access networks are a key element because of its influence on the supply and quality
of services. Today in particular, networks of broadband access play an important role
in the development and provision of new services supported on Internet.
As part of the need for users to enjoy higher bandwidth, born the concept of Next
Generation Networks (NGN New Generation Network) which defines the evolution of
telecommunications networks in the future. NGNs are based on Internet protocol (IP,
Internet Protocol) that allow the delivery of services through the use of multiple
access technologies, able to guarantee quality of service, and in which service-
related functions are independent of the underlying technologies associated with
transport. Two of the elements that characterize the NGN are the end-to-end IP
connectivity and separation of the service platforms of the network infrastructure.
Figure 2 shows architecture similar to what in reality would be a next generation
network.
Figure 2 - General diagram of a next generation network (NGN)

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The demand for higher bandwidth requires the transformation of both backbone
networks and in terms of access, the latter being the one that requires greater
investment and effort from those involved. It uses the concept of Next Generation
Access (NGA, New Generation Access) to define the deployment of NGN access
networks.
For the foregoing reasons, it is estimated that in the future all the networks evolve
towards an NGN architecture model and the demand for higher bandwidth will drive
the deployment of new access technologies. And is also important to note that the
relevant element is not so much the technology or the type of network deployment,
but the services and bandwidth that may be provided by the evolution of existing
networks. Despite this, LTE is a technology that today is seeking to be implemented
by several operators around the world due to the capabilities in terms of new services
and applications that technology offers.

LTE Fundamentals
1.5 Evolution generation mobile networks
The evolution of mobile telephony has been marked by several generations. Each of
them has special characteristics that differ markedly from one another.
Between the late 70s and early 80s, appears the first generation (1G), which was
characterized as analog type. The same, using the technique called Access: Access
Frequency Division Multiple (FDMA, Frequency Division Multiple Access). Given its
limited bandwidth, the services were voice-only 1G. Moreover, given the limited
number of channels were blocked calls regularly. In turn, the unavailability of the
network and offering little security were the main complaints from users.
In the 90s, the cell phone industry has evolved into a second generation (2G).This
was characterized as the digital type, appearing also new services such as Caller ID,
Three Way Calling, low data transfer speed as well as sending short messages
(SMS, Short Message Service).The second generation evolved from TDMA / GSM to
GPRS, EDGE (Enhanced Data Rates for GSM Evolution).
In Europe, for example, adopted the TDMA-based 2G technology known as GSM
(Global System for Mobile Communications), which was implemented in many other
countries around the world.
Subsequently, new services and applications, were sued by the users, prompted him
to give rise to third generation (3G). Using the mobile technology Wireless for third
generation known as Wideband Code Division Multiple Access (WCDMA), which
increases data transmission rates of the systems GSM using interface CDMA air
instead of TDMA and therefore provides data rates much higher on mobile and
portable wireless devices than are offered by GSM for example. As an initial
improvement in the standard evolution and 3G / UMTS, joined the technology known
as High Speed Packet Access (HSPA). HSPA is continually evolving thanks to the
work of standardization 3GPP consortium, which regularly publishes Releases,
updated technical specifications that improve the standard. This evolutionary
improvement is commonly known as 3.5G and is considered the first step before the
fourth generation (4G).

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1.6 Towards the Fourth Generation (4G)
Today, as we think about the next step in evolution of mobile telecommunications,
which is known as fourth-generation networks (4G). Its development is directed to a
mobile network based entirely on IP, allowing the user to have higher access speeds
and a greater convergence of technologies. This means, that this generation is
designed to provide end users the possibility to enjoy a wireless connection
anywhere, anytime, with speeds of access to information much higher than those
offered by previous generations.
In this regard, ITU-R (corresponding to the radio division of the ITU) drafted a
document known as 4G/IMT, which establishes minimum requirements for mobile
access technologies must meet to be called 4G.
The following summarizes the key points of the document 4G/IMT defined for the
fourth generation:
• Create a network to enable interoperability between different wireless
communication standards. This indicates that it will support various access
technologies, which will integrate seamlessly into a network layer based on IP
protocol. This means that the network must use only packet switching, which
is required for IPv6 is deployed instead of the IPv4 standard currently in use.
• Using an access system that makes efficient use of spectrum. This will require
use base band modulation technologies such as OFDM (Orthogonal
Frequency Division Multiplexing), allowing the orthogonality of the carriers,
which is a multicarrier modulation scheme highly efficient.
• Another technique to use is accessible MIMO (Multiple-Input and Multiple-
Output), which is a radio technology that uses a multi-antenna system on the
side of the transmitter and receiver. Because of the multiple antennas, the
spatial dimension can be exploited to improve the performance of the wireless
link, making the signal stronger, more reliable and helps increase the speed of
access provided to end users.
• In turn, 4G networks must meet high quality of service and security end to end,
and able to offer any service at any time, anywhere. This means you must
provide transparency in access to services, regardless of the access network
the user to use.
• As one of the requirements that have been established, is to offer access
speeds of 100 Mbps and 1 Gbps, in outdoor environments (mobile) and
internal (fixed), respectively, which represents a high target to be achieved by
technology mobile.

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Figure 3 shows an overview of the process that has marked the evolution of mobile
telephony into the fourth generation:
Figure 3 - Evolution of mobile access technologies

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The table on the next figure describes and compares the different generations of
mobile systems mentioned above:
Comparison between mobile telecommunications networks
Generation mobile telephony 1st generation (1G) 2nd Generation (2G)
3rd generation
(3G)
4th generation
(4G)
Use life 1970's-1980's 1990's-2020 2001 to date
In 2010 begins with
LTE
System used
NMT, AMPS ... GSM, D-AMPS, PDC ...
IMT-2000 (UMTS,
CDMA2000)
IMT-Advanced
(LTE)
Standards Owners Standards Closed standards Open Standards
Integratingdifferent
standards
Bandwidth used (Theoretical) Used 30 KHz AMPS
UsingD-AMPS uses 30 KHz
and 200 KHz GSM
Using5 MHz WCDMA
Speedsup to 2 Mbps
Scalableband
widths.
Speedsup to 1Gbps.
Analog / Digital Analog Digital Digital Digital
Packet Switched (PS) / circuit
switching (CS)
CS CS CS and PS PS ("All IP")
Roaming National International
Global(With same
technology)
Global(Other
technologies)
Services Voice
Voiceand data (SMS, MMS,
internetnarrow band)
Voiceand data (SMS,
MMS, internet
broadband)
IP Multiservice
Figure 4 - Comparison between mobile telecommunications networks
1.6.1 Fourth Generation Technologies
The Radio communication Sector (ITU-R) officially defined the Fourth Generation
wireless systems (4G) called IMT-Advanced. 3GPP addressed the requirements of
IMT-Advanced version of LTE (Release 10), called LTE-Advanced. Other
technologies such as mobile WiMAX (Mobile WiMAX, Mobile Worldwide
Interoperability for Microwave Access), specified in the IEEE 802.16m, and ultra
mobile ultra-wideband (3GPP2 UMB, Ultra Mobile Broadband) are presented as
candidates for 4G.
Of these three, mobile WiMAX and LTE are aimed to be the dominant standards that
give the initial basis for this emerging generation telecommunications technology in
the fourth generation.

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1.7 Global demand for mobile access
Currently GSM is positioned as the technology most widely deployed worldwide,
representing more than eighty percent of mobile phone subscriptions.
The following figure shows the breakdown in terms of number of subscribers existing
technology.
Worldwide subscriptions by technology (December 2009)
Technology Subscribers (thousands) Relative share
GSM 3.449.011,00
80.06%
WCDMA 255.773,00
5.94%
WCDMA / HSDPA 132.079,00
3.07%
TDMA 753,00
0.02%
TD-SCDMA 825,00
0.02%
CDMA 2000 1X 309.508,00
7.18%
CDMA 2000 1X EV-DO 121.822,00
2.83%
CDMA 2000 1X EV-DO REV A 13.912,00
0.32%
PDC 2.752,00
0.06%
iDEN 21.362,00
0.50%
4 307 797,00
Figure 5 - Comparison between mobile telecommunications networks

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To see a bigger picture, the organization 3G Americas unites telecommunications
operators and vendors are located throughout the Americas, published a study
estimating the number of global mobile subscriptions. The following figure shows the
behavior of global demand for distributed mobile technology:
Global volume of subscribers by technology (million)
TECHNOLOGY
YEAR:
2009 2010 2011 2012 2013 2014
UMTS-HSPA
438 649 957 1400 2000 2700
GSM
3700 3900 4000 3800 3400 2700
CDMA 459 521 583 645 707 769
WIMAX
2,80 7,50 16,70 37,10 82,10 0
LTE
0 0,50 3,50 13,10 44,50 131,50
TOTAL
4600 5078 5560 5895 6233 6300
Figure 6 - Worldwide subscriptions by technology (Year 2009)

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To complement the information previously shown, Figure 7 display graphically the
behavior described in Figure 6.
0
1000
2000
3000
4000
5000
6000
7000
2009 2010 2011 2012 2013 2014
459 521 583 645
707 769
3700
3900
4000 3800 3400
2700
438
649
957
1400 2000
2700
S us criptores ( millones)
YEAR
Subscribers by global wireless technology
( 2009 - 2014)
LTE WIMAX CDMA GSM UMTS -HSPA
4600
5078
5560
5895
6233 6300
Figure 7 - Expected growth in mobile subscribers worldwide
From the information presented above, it is expected that 3G technology is the
technology that will take an higher stake on the 2G technology swap. It is further
noted that the growth of adoption of LTE technology will begin to gradually increase
from the year 2010, taking the year 2014 demand of approximately 131.5 million
subscribers.

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For its part, based on the trend presented above, it is estimated that LTE will start to
grow significantly in demand since 2015, causing subscribers to gradually abandon
legacy technologies such as 2G and 3G. The above is shown in Figure 8.
Figure 8 - LTE demand trend
Despite this trend so strong to move towards LTE, one must remember that mobile
WiMAX technology today is also considered as a candidate to evolve into the Fourth
Generation, which is why later on this book a brief comparison between technologies
will be presented.

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2 Comparison between WiMAX and LTE
The mobile WiMAX and LTE are emerging as key technologies for the evolution to
4G. The selection of any of these technologies by telecom operators will depend on
various factors including the availability of spectrum and their own business
strategies.

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2.1 WiMAX Technology Overview
World Interoperability for Microwave Access Worldwide (WiMAX) is a wireless
broadband technology. Is designated as the IEEE 802.16 working group IEEE
organization specializing in the access point to multipoint broadband using WiMAX
technology.
This technology is based primarily on the two substandard IEEE 802.16d for fixed
access, and 802.16e for mobile access. Presenting two different standards for
WiMAX operators has enabled the scalability of their networks according to different
requirements to support last-mile services.
Fixed WiMAX is particularly interesting in providing last-mile access to rural areas
without access to wired network infrastructure or other wireless infrastructure.
Primarily focuses on residential-type users without access to broadband services,
located in remote areas where it has so far been too expensive to access by
traditional broadband infrastructure.
Subsequently, given the need for users to maintain these services in mobile
environment, there is the standard known as IEEE 802.16m WiMAX version 2.0 or
Mobile WiMAX. This standard is an enhanced version of IEEE 802.16e standard and
has been proposed as a fourth-generation technology.
2.2 LTE Overview
As part of the standards that want to implement for the Fourth Generation, appears
LTE preliminary proposal, on which there has been significant investment in research
and development by stakeholders in the telecommunications industry as will be
shown forward.
However, to meet the requirements established by the ITU 4G, the highest governing
body for telecommunications in the world, the Group 3GPP (3rd Generation
Partnership Group) has been given the task of setting a new radio access technology
that has called LTE.

LTE Fundamentals
This has been done with the aim of working on the development and improvement of
the communication standard Third Generation WCDMA based UMTS system. This
path of evolution, born since the 3GPP, in late 1999, developed the first version of
WCDMA. By way of overview, the main versions or Releases that mark the
evolutionary path listed below:
• Release 99: first version of WCDMA developed in late 1999 and was part of
IMT-2000 standards.
• Release 5: This version developed in 2002, introduced speed improvements in
communications from the network to the user (downlink) creating the data
access protocol called HSDPA.
• Release 6: This version completed in late 2004, introduced speed
improvements in communications from the user to the network (uplink)
creating the data access protocol called HSUPA.
• Releases 7 to 10: versions are generally looking for in the stage of access of a
mobile network have higher bandwidth, lower latency and higher capacity to
meet demand in urban areas. In Release 7 defines the protocol HSPA +.The
Release’s 8 and 9 correspond to the LTE standard and Version 10 is the
standard LTE-Advanced, which, unlike LTE, if it is accepted as standard
Fourth Generation.
2.3 LTE-Advanced for IMT-Advanced
Parallel to the work on LTE and future enhancements in Release 9, the 3GPP is
working on creating specifications that qualify in the process of IMT-Advanced in ITU-
R. ITU-R is developing a framework for next generation wireless networks. The
following are the requirements that the ITU-R has been defined for IMT-Advanced.
• Support for speeds up to 1 Gbps in low mobility scenarios (nomad) and 100
Mbps for high mobility.
• Support for large bandwidths.
• Minimum requirements for spectral efficiency in different operating scenarios.
Besides the above, the 3GPP has an own set of requirements among which is
backwards compatibility with LTE (Release 8). This requirement is set so that a
device can access a network LTE LTE-Advanced (Release 10) and similarly a device
to LTE-Advanced LTE access network, in addition to any network or device that

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meets specifications Release 9. For its part is also due to mobility between LTE-
Advanced and other radio access technologies such as GSM / EDGE, WCDMA and
CDMA2000. Ie, LTE Advanced is HSPA + and LTE, HSUPA, HSDPA is a UMTS, ie
they are extensions but do not cause incompatibility.
It is expected that the specifications of ITU-R was completed in early 2011, which
requires 3GPP prepare its first set of specifications for the end of 2010. Among the
improvements are under investigation and is expected to be part of these
specifications are:
• It is hoped to extend coverage by allowing the user equipment further away
from a base station, send your information via relay nodes for better
communication.
• Scalable bandwidth up to potentially around 100 MHz: It is expected that this
capacity is reached mainly based on the solutions that are expected to be
deployed in LTE, although not yet defined as to undertake this expansion.
• Network mobility solutions and nomad / local area.
• Flexible use of spectrum.
• Configuration and network operating independently (Self Organizing Network).
• Coordinated multipoint transmission and reception that relates to the use of
MIMO transmissions coordinated by different transmitters.
Although all the above items are under study, does not necessarily mean that they
will be included in the specifications of 3GPP Release 10. It may be that the decision
to include some aspects within the Release 9 and can also reach the conclusion that
its complexity is too high or the benefits are few to be considered within the
specifications for LTE-Advanced. It is hoped that this research is completed by the
end of 2010 in preparation for the start of the specification to be included in Release
10.
It is noteworthy that LTE will not only be evaluated by the ITU-R for IMT-Advanced
process, but so will other radio access technologies and if they meet the minimum
requirements will become part of the family of IMT -Advanced.

LTE Fundamentals
The following figure presents the most important dates in the process of specification
of LTE-Advanced. You can see that this proposal is already in an advanced stage
and is expected to be completed no later than 2011.
Important Dates specification of LTE - Advanced
Progress made Response
Review article on LTE - Advanced adopted by 3GPP March 2008
Requirements for LTE - Advanced (TR 36913) approved by 3GPP June 2008
Prior submission of LTE - Advanced made to ITU-R September 2008
Preview LTE - Advanced made to ITU-R June 2009
Final presentation of LTE - Advanced made to ITU-R October 2009
Completion of Advanced LTE specifications made by the 3GPP 2010 -2011
Figure 9 - LTE specification schedule - Advanced
Moreover, given that the standard LTE-Advanced is not yet finalized and because
today, as indicated below, some operators are considering the benefits of deploying
LTE networks, then performing a comparison between the LTE and mobile WiMAX
standard, proposed as evolutionary paths to the Fourth Generation.

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2.4 Technical comparison between LTE and Mobile
WiMAX
Some of the key features that define the two technologies are presented in the next
figure.
Comparison between LTE and Mobile WiMAX
Feature Mobile WiMAX 3GPP-LTE
Core Network All IP Network All IP Network
Access Technology.
Downlink (DL) OFDMA OFDMA
Uplink (UL) OFDMA SC-FDMA
Frequency band 2.3-2.4GHz,2.496-2 0.67 GHz, 3.3-3.8 GHz 70,850,1800,2100,2500 MHzfrequency bands
Bit rate:
DL 75 Mbps 100Mbps
UL 25Mbps 50Mbps
Bandwidth of the channel 5, 8.75, 10MHz 1.25-20MHz
Cell Radio 2-7km 5km
Cell Capacity
100-200users > 200 users to 5MHz
> 400 users for higher bandwidth
Spectral efficiency 3.75 (bps/ Hz) 5 (bps / Hz)
Handover HardHandover Soft handovers
MIMO:
DL 2Tx * 2RX 4Tx * 4RX
UL 1Tx * NRX 2Tx * 2RX
Figure 10 - Comparison between LTE and mobile WiMAX

LTE Fundamentals
Based on the above, are the following similarities:
• Mobile version of WiMAX will reach performance capabilities similar to LTE,
and both take advantage of multi antenna techniques (MIMO), which
dramatically improves the communication channels that will achieve better
data transmission rates.
• Both WiMAX and LTE benefit from IP architecture that simplifies data
transmission, since it is optimized for that protocol.
• The most important similarity between LTE and WiMAX OFDM is the
substantially improvement in the use of radio spectrum.
Despite these similarities, LTE appears to offer better performance because it offers
faster speeds and enhanced capabilities for cell about Wimax technology. LTE also
provides greater spectral efficiency, allowing you to make better use of radio
spectrum, a factor which is of utmost importance when choosing an access
technology.
2.5 Interoperability between the two technologies
There is an aspect that suggests that LTE is supplemented in some areas with
networks WIMAX . This is because there are remote places where there is no 2G and
3G coverage, but there WIMAX coverage plans.
Anticipating such a scenario of convergence, able to make a user can access mobile
broadband services using the same terminal, some manufacturers have focused their
efforts on the manufacture of electronic devices that can operate both technologies,
such is the case of chip maker Beceem who announced the first chip called BCS500,
which combines LTE and WiMAX. This is how this chip supports WiMAX 16e
standards and 16m and LTE Release 8 download capabilities allowing up to 150
Mbps perform handover between the two technologies. Beceem expects the chip is
ready to be marketed in the second quarter of 2011.
The actual technical aspect of the way it carries out the interconnectivity between
WiMAX and LTE, will be discussed in Section 5.11 of this job.

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2.6 Tendency for operators to implement LTE
Currently WiMAX has an advantage in their favor on LTE, this advantage is the
anticipation that WiMAX was created with respect to LTE. This means that by the
time the new LTE networks are deployed, consolidated WiMAX networks already
exist in many markets around the world. Despite this, WiMAX technology has not
been as successful as hoped in the beginning and the prevision is that LTE will
surpass WIMAX in 2012.
For example, although since 2007 were initiated implementations of Wimax
technology, three years after the operator TeliaSonera has deployed, the first
commercial networks with LTE technology in the countries of Sweden and Norway.
This is the first step could lose the momentum operators to deploy WiMAX, a
situation well known manufacturers and operators, so that they are in a stage of
analysis to define future technology and initiate deployment their networks as quickly
as possible. Today, some of the biggest in the market as Nokia and Motorola have
turned to the development of LTE without even thinking about a side project with
WiMAX technology. In addition operators like AT & T, like T-Mobile and Verizon
Wireless have opted for the adoption of LTE and plan to carry out large deployments
with this technology. Another reason why many have decided on LTE is the aspect of
compatibility with legacy networks.
For its part, the compatibility issues that have arisen between the various versions of
IEEE 802.16 put many operators to reflect on the true capacity of these systems in
terms of their support back. LTE implies an evolution of the 3GPP legacy systems, so
you will live in the same network simultaneously 2G and 3G technologies, and future
4G LTE-Advanced.
But beyond seeing both as competing technologies, we can conclude that in reality
there is no rivalry. Today it is envisioned that both WiMAX and LTE will become real
technology fourth generation wireless. Still, if we consider that the vast majority of
operators who currently have 2G and 3G networks have decided to LTE, will spend a
few years to produce real growth and maturity of the LTE technology throughout the
world.

LTE Fundamentals
3 Third-generation networks as the basis for
the evolution to LTE

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3.1 Evolution of a UMTS network to LTE
The third generation UMTS system based on access technology W-CDMA has been
developed in many parts of the world. To ensure that this system has to remain
competitive future, in November 2004 3GPP started a project to define a long-term
evolution of the cellular system called UMTS. Its main focus is to improve or evolve
the UTRAN network to LTE.
The specifications related to this effort is formally known as Access Evolved UMTS
Terrestrial Radio (E-UTRA, Evolved UMTS Terrestrial Radio Access) and Enhanced
Terrestrial Radio Access UMTS evolved (E-UTRAN, Evolved UMTS Terrestrial Radio
Access Network) but are commonly referred to as the LTE project. This first version
of LTE is documented in the specifications of 3GPP Release 8.
A side project called Evolution of System Architecture (SAE, System Architecture
Evolution) defines an all-IP architecture composed of a core packet switching
network called evolved packet core (EPC Evolved Packet Core).
The SAE network architecture is an evolution of the core network and has the
following characteristics:
• Simplified architecture directed towards all-IP network.
• Support for multiple systems such as GPRS.
• Mobility between different radio access networks.

LTE Fundamentals
The combination of EPC and define E-UTRAN evolved packet system (EPS, Evolved
Packet System). In this way the whole system is called the LTE / SAE or simply LTE.
When LTE solution for the 3GPP standard, is proposed as a future scenario, the
interoperability of this technology with existing networks 3G/WCDMA 2G/GSM is
garanteed.
For the foregoing reasons, the following is an overview of the number of third-
generation networks, specifically UMTS type, in order to know its architecture and its
basic features, which serve as reference for further understanding and proposing a
series of general recommendations on a technical level, to move towards LTE from
these mobile networks.
It is recalled that a telecommunications network 2G and 3G, is composed of three
main elements: a core network (CN, Core Network), a Radio Access Network (RAN,
Radio Access Network) and equipment (UE, User Equipment).

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3.2 UMTS Network Structure
3.2.1 UTRAN
The group designed specifically for UMTS 3GPP access network called Terrestrial
Radio Access Network UMTS (UTRAN, Terrestrial UMTS Radio Access Network),
which is described below. This network is composed of Radio Network Controllers
(RNC, Radio Network Controller) and base stations known as Node B, together make
up a Radio Network Subsystem (RNS Radio Network Subsystem).
Figure 11 - Radio Access Network UMTS.

LTE Fundamentals
The following is a brief description of the elements of the UTRAN:
• RNC: controls one or more nodes B. The interface between different RNC is a
logical interface, so there is not necessarily a direct physical connection
between them. The RNC is comparable to the base station controller (BSC,
Base Station Controller) in GSM networks.
• Node B: Node is the liaison between the RNC and the mobile terminals.
Contains the physical layer radio interface so that performs the functions of
modulation and demodulation, error detection, time synchronization and
frequency, among others.
Given that there should be interoperability between the networks of 2G and 3G
access, it is important to mention that GSM access network consists of Base Station
Subsystem (BSS, Base Station Subsystem). Each subsystem consists of a Base
Station Controller (BSC, Base Station Controller) and one or more base transceiver
stations (BTS, Base Transceiver Station). The BSC controls the functionality of the
BTS with an air interface (A-bis). The following is a brief description of the elements
of the BSS:
• BSC, in charge of the functions of radio resource management, power control
and handovers between cells, among others.
• BTS: consists of one or more transceivers (TRX). BTS can be omni type with
one cell or sectorized with multiple cells, typically three.

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BSS
Abis
BSS
Abis
Interface - - A
Interface - - A
Figure 12 - Radio Access Network GSM

LTE Fundamentals
The next figure shows the UMTS network architecture coexisting with a GSM access
network.
USIM
A
Gb
IuCS
IuCS
IuPS
IuPS
Gs
Gn Gl
Gf
Gr Gc
F
D
PSTN
PSTN
C
H
E
G
B
B
Uu
Um
Cu
BSS
Abis
RNS
Iub
RNS
Iub
Figure 13 - UMTS network architecture coexisting with GSM
It is noteworthy that the interface "Uu" between the UE and UTRAN, and the interface
"Iu" between UTRAN and core network (CN, Core Network), are open-standard
interfaces, allowing you to connect terminals and equipment provided different
manufacturers.

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3.2.2 Core network
The core network is divided into two domains: the domain of packet switching and
circuit switching. The circuit switched domain provides the main element Switching
Center Mobile Services (MSC, Mobile Switching Center), while the packet domain
covers the main elements of the Service Support Node GPRS (SGSN, Serving
GPRS Support Node) Node Server and Service Support GPRS (SGSN).
The following describes these and other elements that make up the core network:
• Switching Center Mobile Services (MSC) is the central element of the Core
Circuit Switched (CS-CN, Circuit Switching Core Network). The MSC of the
GSM network to 3G can be used that allows updates to comply with the
requirements of 3G. This element is connected to access networks of GSM
and UMTS, with the Public Switched Telephone Network (PSTN, Public
Switched Telephone Network), as well as with other MSC, SGSN and the
various registers of the core of the network (HLR, EIR), among others.
• Visitor Location Register (VLR, Visitor Location Register): This is a temporary
database that contains all information from users who are present at any given
time in the location area controlled by the VLR. Overall MSC and VLR are
physically combined. Among its main features are, allow authentication of the
mobile and also connects to other VLR and HLR through the network signaling
system.
• Local Location Register (HLR, Home Location Register) contains a permanent
record of subscriber data. While the records are temporary VLR in the HLR
are permanent, although they handle almost the same information.
• Equipment Identification Register (EIR, Equipment Identify Register): Stores
Identities international Mobile Station Equipment (IMEI, International Mobile
Equipment Identities). Usually contains three lists to indicate the status of
equipment: IMEI of computers that are authorized to operate normally (white
list), stolen equipment and therefore are prevented from connecting to the
network (black list) and finally the gray list are registered with any equipment
malfunctions occur.
• Authentication Center (AuC, Authentication Center) is associated with the
HLR. Authentication keys stored subscriber and International Mobile
Subscriber Identity (IMSI).
• Gateway MSC (GMSC, Gateway MSC) is an MSC that is located between the
PSTN and other MSC located on the network. Its function is to achieve routing
incoming calls to the appropriate MSC.

LTE Fundamentals
• Server Node Service Support GPRS (SGSN) is the principal element in the
packet switching network, which contains subscription information and user
location.
• Support Node Gateway GPRS (GGSN, Gateway GPRS Support Node):
Makes the interface between the packet core with external data networks,
such as the Internet.
The 3GPP Release 5 brings significant changes to the core architecture of the
network. The next figure shows the network architecture, Release 5:
Figure 14 - 3GPP Release 5 architecture
In this new architecture incorporates a control architecture known as IMS. At the
same time as bringing new elements such as Base subscriber server (HSS, Home
Subscriber Server), which functions as an HLR evolved, and is also the element of
connection between IMS and the packet switched domain.
For its part, this new architecture the MSC is divided into two entities, the media
gateway (MGW) and a MSC server. The control logic is performed by the MSC, while
the switching is done MGW. This separation allows the network to make use of more
efficient routes for the transmission of high-speed data, while control messages may
follow other routes.

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For his part, Release 5 incorporates an all-IP network, which means that all traffic,
including voice, is carried as IP packets.
The next figure shows the IMS architecture:
Figure 15 - Architecture of the IMS domain
In the domain of IMS data traffic is transported through SGSN and GGSN. For his
part, HSS combines and performs the functions that make the HLR and AuC. On the
other hand comes a function element called Call Session Control (CSCF Call
Session Control Function), which is the central element in IMS. There are three types
of CSCF:
• Servant CSCF (S-CSCF): Provides the session control services for the
computer terminal. These include the decision of routing and session
establishment, maintenance and release of multimedia sessions. It also
generates information charges for the billing system;
• Proxy CSCF (P-CSCF) is the first entity of IMS is contacted by the user's
computer when you log into the network. The P-CSCF passes the control of
the session towards the S-CSCF located in the home network;

LTE Fundamentals
• Interrogating CSCF (I-CSCF) is the point of contact within the operator's
network for all connections destined for that network subscribers or
subscribers are roaming.
Finally, other elements within the domain of IMS are:
• Disengage Control Function in Gateway (BGCF, Breakout Gateway Control
Function): selects the network in which the domain interoperability and circuit-
switched PSTN is going to happen. If given in the same network BGCF select
a MGCF responsible for such interoperability. If another network with BGCF
redirects the session signaling to another BGCF in the net.
• Function Control Media Gateway (MGCF, Media Gateway Control Function)
is an entity that is responsible for interoperability. Perform conversion of
protocols between the PSTN and IMS protocols call.
• Processor Media Resource Function (MRFP, Multimedia Resource Function
Processor): handles the bearer channels and can handle different flows of
information.
• Controller Media Resource Function (MRFC, Multimedia Resource Function
Controller) controls the flow of information resources in the MRFP, a task
accomplished by interpreting information that comes from application servers,
S-CSCF and the MRFP.
• Media Gateway Intermediate (IM-MGW, Intermediate Media Gateway):
terminates bearer channels from a circuit network and information flows in a
packet network. MGFC interacts with resource control, in addition to owning
and managing other resources such as echo cancellers.
• Subscriber Locator Function (SLF Subscription Locator Function): it is only
necessary when there are plenty of HSS bodies on a network.
• Application Server (AS, Application Server) offers value-added services and
can reside either on the local network or in a third location.

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LTE Fundamentals
4 Standardization and technical requirements
according to 3GPP LTE
Based on the above shown in the following chapter provides the key technical
requirements and standardization proposed to move towards LTE.

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4.1 Reason for the evolution of the system
architecture
The target for the development of system architecture to improve aspects such as
speed of access and transport as well as quality of service, using this a fully
converged network based on packet switching and ability to support mobility and
service continuity between heterogeneous access networks.
According to the technical report TR 23.882 were identified a number of high-level
requirements for an architecture based on SAE, among which we highlight a few:
• Must support 3GPP and non 3GPP systems.
• You must provide a scalable architecture without compromising the ability of
the system, separating the control plane and transport plane.
• Must be based on IP connectivity with improved quality of service.
• Mobility with other systems and even non-3GPP. 3GPP must support real time
applications as well as applications and services that are not real time.
• Should enable interoperability between terminals, servers and systems with
IPv4 and IPv6 connectivity.
• You must ensure at least the same level of security of Subscriber which is in
the current 3GPP networks.
• Must support the IP Multimedia Subsystem (IMS, IP Multimedia Subsystem)
as well as systems in the domain of circuit switching.
4.2 Working groups and the definition of technical
specifications for LTE
The work focused on the decision of the radio technology as well as the system
architecture. It concluded that needed something new and not just an extension of
the WCDMA system as a result of a complex set of requirements to cover different
bandwidths and a certain amount of data transfer rates.
Within 3GPP Technical Specification Group of the Radio Access Network (3GPP
TSG RAN, 3GPP Technical Specification Group Radio Access Network) is
responsible for the development of LTE specifications for what is the access network.
This job specification is covered by the various working groups (WG, Working

LTE Fundamentals
Groups) which are listed under each group of technical specifications (TSG,
Technical Specifications Group). This distribution is shown in the next figure.
Figure 16 - Work structure of the 3GPP
As part of the main specifications for the access network, it was decided to use
technology Multiple Access Orthogonal Frequency Division (OFDMA, Orthogonal
Frequency Division Multiple Access) as technology in the downlink. To access uplink
technology was chosen Division Multiple Access Single Carrier Frequency (SC-
FDMA Single Carrier Frequency Division Multiple Access) as the most favorable, a
decision that was supported by manufacturers and operators in general. A significant
improvement over WCDMA is the technology that both Frequency Division Duplexing
(FDD, Frequency Division Duplexing) such as Time Division Duplexing (TDD, Time
Division Duplexing) have the same solution for multiple access, ie that an adjustment
is made to minimize the differences in their modes of operation. This decision by the
multiple access was made official in 2005 and after that the work was focused on the
technologies chosen for LTE.
Also, it was decided that it should have a radio access network (RAN, Radio Access
Network) of a single node, which is achieved by putting all the functionality of the
radio base station (Node B). The name of this new element is eNodeB, representing
the letter "e", evolved. The main difference in relation to this aspect is that it removes
the element RNC delegating its functions to the eNodeBs.
The specifications for the evolved packet core (EPC Evolved Packet Core) are
covered by the technical specification group core network and terminals (TSG CT,
Technical Specification Group Core and Terminals) and also by the group of

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technical specifications services and systems (TSG SA, Technical Specification
Group Services and System Aspects). The group of technical specifications of the
radio access network GSM / EDGE (GERAN TSG, Technical Specification Group
GSM / EDGE Radio Access Network) is responsible for changes in GSM / EDGE
introduced in Release 8 to facilitate interoperability between LTE and GERAN. For its
part the group of technical specifications of the radio access network WCDMA (TSG
RAN, Technical Specification Group Radio Access Network) is responsible for the
changes introduced in WCDMA Release 8 to facilitate interoperability between LTE
and WCDMA.
4.3 3GPP requirements for LTE
In November 2004, began work related to the evolution of the access network known
as UTRAN. In this work were present operators, manufacturers and research
institutes with a large number of proposals and views.
Then, in early 2005 began work on the specification of 3GPP LTE, which published
its technical report TR 25.913, Requirements for Evolved UTRA (E-UTRA) and
Evolved UTRAN (E-UTRAN). After that recent versions have been published with
improvements and fixes, version 9.0.0 being the last one.
Key elements of this technical report are described below.
4.3.1 Requirements related to the ability
• Data transfer rates: E-UTRA should support significant increases in data
transfer rates, which must be consistent with the spectrum allocation and
terminal configuration. For example, a terminal to be able to support maximum
speeds of 100 Mbps in the downlink (DL, downlink) and 50 Mbps in the uplink
(UL, uplink), each with an allocation of 20 MHz spectrum.
• Latency: In the control plane must have a latency equal to or less than 50
milliseconds (ms) between active and inactive states. For the user plane must
have a latency no greater than 5ms for a one-way transmission from the
transmitted packet is available at the IP layer at the edge of the border UE /
RAN until it becomes available in the IP layer the other border RAN / EU.
However, this latter requirement should be revised, mainly because you need
to specify clearly the terms of latency for this case.

LTE Fundamentals
4.3.2 Requirements related to performance
• Transfer Rate: Transfer rate (throughput) in the downlink (DL) should be for
the average user, 3 to 4 times compared to the specifications assigned to
HSDPA Release 6, using more than two transmission antennas in the base
station and two receive antennas in the terminal device. Besides the transfer
fee should be scalable in line with the allocation of spectrum. For the uplink
(UL) should have a transfer rate per user on average 2 to 3 times as specified
in Release 6, in this case using a transmitting antenna in the terminal and two
receiving antennas at the base station. It should get a higher data rate using
multiple transmit antennas in the terminal device.
• Spectral Efficiency: Spectral efficiency (bps / Hz / site) in the downlink (DL)
should be 3 to 4 times that obtained with a system based on Release 6
HSDPA, using two transmission antennas in the base station and two
reception terminal. In the uplink (UL) should be 2 to 3 times Release 6 HSDPA
obtained and E-UTRA using a transmitting antenna in the terminal and two
reception at the base station.
• Mobility: Must be optimal for the user transfer rates in the range of 0 km / h 15
km / h. For speeds of 15 km / h and 120 km / h mobility must be supported
with high performance. For its part, the mobility across the cellular network
must be maintained at speeds of 120 km / h 350 km / h, or 500 km / h
depending on the frequency band used (An example of this scenario would be
within high speed train). Services real-time voice and supported in the domain
of circuit-switched network UTRAN (Release 6) should be borne by the E-
UTRAN in the packet switched domain to a higher quality or at least equal.
• Coverage: coverage up to 5 km in the range of cells must meet the
requirements of transfer rate (throughput), spectral efficiency and mobility
above. In a range of up to 30 km degradations accepted transfer rates and
spectrum efficiency, but must comply fully with the requirements of mobility.
For greater ranges requirements have not been defined.
• Enhanced MBMS (Multimedia Broadcast and Multicast Service), MBMS
service is a feature you are looking for an efficient way to deliver broadcast
and multicast services over the network core. E-UTRA should support
enhanced modes of UTRA MBMS in comparison with less downtime, provided
they are caused by the E-UTRAN network.
• Network Synchronization: It is expected that the requirements described in
the technical report TR 25.913 are made in the deployment of the network
without the use of synchronization between sites.

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4.3.3 Requirements related to network deployment
• Deployment scenarios: There is a wide range of deployment scenarios that
can be considered, however at a high level, E-UTRAN should be able to
support basically two different scenarios. The first is the deployment of E-
UTRAN network as an independent network, where the operator deploys the
network without the existence of other networks in the area or there are other
networks UTRAN / GERAN, or where there is no need for interoperability
between them. The second deployment scenario corresponds to a UTRAN
network integration and / or networks of GSM EDGE Radio Access (GERAN,
GSM EDGE Radio Access Network). In this case the network operator has to
totally cover the same geographical area. The deployment and the associated
requirements will be defined by demand for mobile services and the
environment of competition between operators.
• Spectral Flexibility: Must support spectrum allocations of different sizes, which
means you should be able to operate in a bandwidth of 1.4 MHz, 3 MHz, 5
MHz, 10 MHz, 15 MHz and 20 MHz for uplink and in the downward. It should
also be flexible enough to support transmissions in both directions (DL & UL)
making optimal use of available spectrum.
• Deployment in the radio spectrum: E-UTRA should be capable of withstanding
the following scenarios.
o GERAN/3G coexistence with adjacent channel
o Coexistence between operators on adjacent channels
o Coexisting with spectrum sharing and / or adjacent to the borders of
countries
o Operating as an independent network, ie without other networks
operating in the same geographic area
• Coexistence and interoperability with other radio access technologies 3GPP
(3GPP RAT Radio Access Technology): Terminals UTRAN LTE will also
support and / or GERAN should be able to perform handovers to and from E-
UTRAN networks. Disruption of services in real time during a handover
between E-UTRAN network and a UTRAN should be less than 300 ms and for
services that are not in real time should not exceed 500ms. For handovers
between E-UTRAN and GERAN should meet the same requirements of time
in both cases.

LTE Fundamentals
4.3.4 Requirements for E-UTRAN architecture
E-UTRAN should have a single architecture based on packet switching, not ceasing
to be capable of supporting real-time services based on circuit switched domain. It
should also support quality of service (QoS, Quality of Service) point to point, taking
into consideration the different types of traffic. Finally, the E-UTRAN should be
designed so as to minimize delay variations (jitter) for packet TCP / IP.
4.3.5 Requirements for radio resource management
• Improved support for quality of service point to point: E-UTRAN should be able
to support improved control over the quality of service, providing a better
matching of service requirements, protocols and applications with the
resources and network features access.
• Efficient transmission of higher layers: You must provide mechanisms for the
transmission and operation of higher layer protocols on the radio interface.
• Support of load sharing and policy management across different radio access
technologies (RAT): This aims to reduce latency and ensure quality of service
point to point, when there are different body handovers radio access
technologies.
4.3.6 Requirements related to the complexity of the
systems
• Complexity of the system in general: Significantly reduce the complexity of the
system to stabilize the interoperability in early stages and further reduce costs
in terminals and the network itself.
• Complexity of terminal: The requirements of E-UTRA and E-UTRAN should be
possible to reduce the complexity of terminal equipment in terms of size,
weight and battery life among others, always consistent with the advanced
network services.

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4.3.7 Protocols and services requirements
The architecture should enable optimization of communication protocols in addition to
reducing the cost of future network deployments. On the other hand all the interfaces
should be open to ensure interoperability among equipment manufacturers.
E-UTRA should efficiently support various types of services such as web browsing,
video streaming or voice over IP (VoIP) and more advanced services such as real
time video. The VoIP service should be supported with at least the same features as
the voice service over UMTS networks based on circuit switching.
4.3.8 Specifications for interoperability with legacy
networks
One of the requirements of the new system is to ensure interoperability with 3GPP
systems Rel.6, ie SAE expected to coexist with the 3GPP mobile communication
networks today. In this way, users can establish a data session in a LTE area where
coverage is insufficient, and continuing it in a transparent manner with UMTS,
minimizing packet loss and downtime.
Another notable design premise of this new architecture is that not only must ensure
interoperability with 3GPP legacy systems of second and third generation, but also
must provide seamless mobility and continuity of user session between 3GPP
accesses and not "3GPP”, such as WiFi or WiMAX.
To handle mobility between 3GPP access and non-3GPP has chosen to use mobility
skills defined by the IETF (Internet Engineering Task Force), such as Mobile-IP and
Proxy Mobile-IP in the SAE GW acts as an anchor point. This involves defining a new
interface between the SAE GW S2 and non-3GPP accesses and the requirement
that interfaces S5 and S8 (discussed below) support simultaneous GTP protocol
(3GPP accesses) and IETF-based protocols (non-3GPP access) depending on the
type of access.
Therefore, it was proposed an evolution of the architecture according to the 3GPP
standard deliveries (next figure).

LTE Fundamentals
Figure 17 - Evolution of 3GPP was a flatter architecture

LTE Fundamentals
© 2010 PontoTech
52
4.4 Standardization beyond Release 8
The specification work after the Release 8 has already started, including a series of
points that were defined for the Release 8 which was completed in 2009, as well as
specifications for LTE-Advanced which is expected to be published in the 3GPP
Release 10. Here are the key elements that are being defined in future specifications.
• LTE MBMS, which is expected to support the operation with a dedicated
MBMS carrier or carrier shared. It can then sends a signal based on OFDMA
from different base stations (with the same content) and then be combined in
the device. This principle is used for example in digital video broadcasting for
personal devices, DVB-H (Digital Video Broadcasting for Handhelds), which is
also based on OFDMA.
• Improved auto tunable networks (SON, Self Optimizing Networks) whose
specification continues in Release 9
• Improved support for LTE VoIP, including the maximum number of users
supported simultaneously.
• The requirements for base stations operating at different bandwidths and
different radio access technologies. The aim is to define the requirements for
the same frequency can transmit radio signals eg GSM or LTE and LTE and
WCDMA.
4.5 Architecture Overview of LTE / SAE
Evolved System Architecture (SAE, System Architecture Evolution) is the name given
to the Fourth Generation Network Evolved proposed by 3GPP for LTE .
This advanced network is made up primarily of two main components:
• Network Access Evolved Universal Terrestrial (eutrophi, Evolved Universal
Terrestrial Radio Access Network)
• The Packet Core Network Evolved (EPC, Paquet Evolved Core), also known
as evolved packet system (EPS).

LTE Fundamentals
As mentioned above, the idea to E-UTRAN, is that many of the features currently
present in the Third Generation Network (3G) to pass the eNode B (known as Node
B base stations evolved or developed). That is, the existing RNC would be
eliminated. This simplification will mean among other things, a redefinition of
signaling procedures, as well as reducing the number of nodes involved compared to
the current UTRAN architecture.
This e-NodeB will be able to interconnect with each other and the EPC. The eNodeB
will then be responsible for providing nodes termination of user plane protocols and
control plane to the user equipment (UE, User Equipment).
For its part, the main functions of the E-UTRAN will be the radio resource
management (control of radio carriers, radio admission control, dynamic resource
allocation in uplink and downlink to the UEs, header compression, encryption or
protection of user plane data and routing traffic to the EPC.
For his part to the EPC, also known as Core SAE, is considered as the main
component of the SAE Architecture. EPC is expected to be an optimized package
with a higher data rate, which supports multiple access technologies and also allow
new services to support voice and data.

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© 2010 PontoTech
54
4.6 General elements of architecture
The following figure shows the network elements of LTE/SAE architecture. Logical
nodes and connections shown in this figure represent the basic configuration of the
system architecture. It also points to its four main elements:
• User Equipment (UE, User Equipment)
• Evolved UTRAN (E-UTRAN)
• Evolved Packet Core (EPC Evolved Packet Core)
• The service layer.
Figure 18 - Main elements of the network LTE / SAE

LTE Fundamentals
EU Areas, E-UTRAN and EPC, together, represent the connectivity layer Internet
Protocol (IP, Internet Protocol). This set is what is known as Evolved Packet System
(EPS, Evolved Packet System).
The main function of this layer is to provide IP-based connectivity, and optimized
solely for that purpose. All services are offered via IP, and therefore the circuit
switching nodes and interfaces present in previous 3GPP architectures are not
present in E-UTRAN and the EPC.
For its part, the EU is the device or the end user terminal used for communication.
Normally this is a handheld device like a Smartphone or data card (Data card) which
are incorporated into a computer.

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© 2010 PontoTech
56
4.7 Particular elements of the architecture
4.7.1 The eNodeB
As mentioned earlier, E-UTRAN consists of nodes called eNodeB which are
distributed throughout the area of network coverage. That is, E-UTRAN is a mesh of
eNodeBs connected via X2 interface. All radio functions are concentrated in them
and they represent termination points for all related protocols.
In addition, the eNodeB has an important role in mobility management (MM, Mobility
Management), as monitors and analyzes the measurements of the radio signal
carried out by the EU and himself, and based on that perform decisions handover
between cells. It must be remembered that the eNodeB may be serving multiple EU
in its coverage area, but each UE is connected to a single eNodeB at a time. The
eNodeB had to be connected to the neighboring eNodeBs the transfer can take
place. This includes the exchange of signaling transfer between other eNodeBs and
the MME.
ENodeB functionally acts as a bridge to Layer 2 (data link layer) between the EU and
the EPC, being the focal point, using the radio protocols, to the EU, allowing the
transmission of data between the EU and EPC, with the latter based on IP
connectivity. The eNodeB also performs encryption / decryption of data, data security
and compression / decompression IP header, which means avoid repeatedly sending
the same data stream in the IP header.
The following figure shows the connections that eNodeB to neighboring nodes and
summarizes the main features of these interfaces. The eNodeB connections are
peer-to-point and point to multipoint.

LTE Fundamentals
Figure 19 - ENodeB connections with other logical nodes and their primary functions

LTE Fundamentals
© 2010 PontoTech
58
4.7.2 Entity Mobility Management (MME, Mobile
Management Entity)
Mobility Management (MME Mobility Management Entity) is the main element of
control in the EPC. The MME also has a direct logical connection to the EU and this
connection is used as the main control channel between the UE and the network.
The following are the main functions of the MME in a basic configuration of the
system architecture:
• Authentication and security: When the UE is registered on the network for the
first time, the MME initiates authentication by doing the following: seeking
permanent identity of the EU in any of the previously visited network, or at the
EU, claims that the Home Subscription Server (HSS), the vectors of local
network authentication request containing the authentication, sends the
request to the EU and EU response compared to those received by the local
network. This function is necessary to ensure that the EU is the one who
claims to be. The MME also assigns each a unique identity temporary EU
Global (Global Unique Temporary Identity, GUTI), so the need to send the
permanent identity EU - International Mobile Subscriber Identity (IMSI) - on the
radio interface is minimized.
• Mobility Management: The MME tracks the location of all EU in its service
area. When a UE makes its entry to the network, the MME will create an entry
for the UE, and sends the location to the HSS of the network which is the EU.
It also asks the right resources in the eNodeB, as well as the S-GW to be
selected for the EU. In turn, the MME handles the creation and release of
resources based on changes in activity of the EU. The MME is also involved in
controlling the handover of the EU between eNodeBs, S-GW or MMEs. MME
is involved in each change of eNodeB, as there is a separate Radio Network
Controller to monitor these events.
• Subscription Management and Service Profile of Connectivity: The MME
retrieves the subscription profile in the local network and stores this
information for the period in which the EU is in service. This profile determines
which network connection data packets should be allocated to the UE in the
network. The MME automatically configures the default carrier, which gives
the EU the basic IP connectivity. This includes signage eNodeB the CP and e
S-GW. The figure bellow shows the MME with logical connections to
surrounding nodes, and summarizes the main functions of these interfaces.

LTE Fundamentals
Figure 20 - MME connections to other logical nodes and their main functions.

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4.7.3 SAE GW
The EPC is composed of an element called SAE GW, which is the combination of the
two gateways, the Service Gateway (S-GW, Serving-Gateway) and Gateway Packet
Data (P-GW, Packet Data Network Gateway) defined for traffic management in the
EPC. Its implementation as a single node SAE GW represents one possible scenario,
however, the standards define the interface between them, and all operations have
been specified for when they are separated. It is important to note that the basic
architecture of the system configuration and functionality are documented in 3GPP
TS 23.401.This document shows the operation when the S5/S8 interface uses the
GTP protocol. However, when the interface protocol used PMIP S5/S8, the
functionality of these interfaces is slightly different, and GXC interface is also needed
between the Appeal and Collection Policy Functions (PCRF, Resource Policy and
Charging Function) and the S-GW. The appropriate places are clearly marked and
additional functions are described in detail in 3GPP TS 23.402.The following sections
describe the functions together for some cases involving E-UTRAN.
4.7.4 Gateway service (S-GW, Serving Gateway)
The S-GW is part of network infrastructure facilities located in the operator. When
S5/S8 interface is based on the GTP, S-GW GTP tunnels will in all User interfaces
Plane. The mapping between IP services and the GTP tunnels on P-GW, and S-GW
does not need to be connected to the PCRF. All control is related to the tunnel is of
GTP, and comes from any MME and P-GW. On the other hand, when using the
PMIP S5/S8 interface, the S-GW perform the mapping between IP services and the
GTP tunnels in the S1-U interface, and connect to the PCRF to receive mapping
information.
The S-GW has a minor role in the control functions. Only responsible for their own
resources, and maps based on requests from MME, P-GW and the PCRF, which in
turn act on the need to create, modify or delete resources for the EU.
During the mobility of the EU among eNodeB, the S-GW acts as a local mobility
anchor. The MME tells the S-GW to change the tunnel of a eNodeB to another.
During the handover thr MME may request the S-GW tunnels to provide resources to
relay information eNodeB source to eNodeB target. Mobility scenarios also include
changes to a S-GW to another, and the MME handles this change as a result, by
eliminating the tunnels of the old S-GW and put in a new S-GW.
For all data flows belonging to the EU in connection mode, the S-GW forwards the
data between eNodeB and P-GW. However, when the UE is in idle mode, eNodeB
resources are freed, and the data path ends in the S-GW. If the S-GW receives data
packets from the P-GW in any tunnel, you should ask the MME start EU location,
forcing it to connect to the network and when the tunnels are reconnected, the
packets are sent to the EU. The S-GW data tracks in tunnels, and may also collect

LTE Fundamentals
data necessary for accounting and charging the user. The next figure shows how the
S-GW is connected to other logical nodes, and lists the main functions of these
interfaces.
Figure 21 - GW connections with other logical nodes and their primary functions
All these interfaces must be configured in a point-to-multipoint, because the S-GW
can only serve a specific geographical area, with a limited set of eNodeBs, and there
is also a limited set of MMES that controls that area. The S-GW should be able to
connect to any P-GW in the entire network, since the P-GW is not going to change,
while the S-GW if you can change when you move the EU.
In the above figure also shows the case of indirect data forwarding between
eNodeBs through the S-GW. It is clear, yet there are no specifications for the
interface name associated between the S-GWs, as the format is exactly the same as
in the S1-U interface and S-GWs involved may consider that they are communicating
directly with a eNodeB.

LTE Fundamentals
© 2010 PontoTech
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4.7.5 Gateway Packet Data Network (P-GW, Packet
Data Network Gateway)
The P-GW, also often abbreviated as PDN-GW is the router boundary between the
EPS and external data networks. It is the anchor of the highest level of mobility in the
system, given that if a UE moves from an S-GW to another, the P-GW will receive a
prompt to change to the new S-GW. In addition, usually acting as the EU IP
connection.
The P-GW also performs traffic gate functions and filtering as required by the service.
Like the S-GW, the P-GW is maintained in a centralized location in the operator's
premises.
Normally, the P-GW IP address is assigned by the EU and the EU is used to
communicate with other hosts on external networks like the Internet. It is also
possible that the external PDN the UE is connected to assign the address to use the
EU and P-GW tunnels direct all traffic to that network. The P-GW IP performs this
assignment by the Dynamic Host Configuration Protocol (DHCP), or query to an
external DHCP server, and provides direction to the EU. The P-GW can be
configured for IPv4, IPv6 or both protocols as needed.
The P-GW performs the synchronization and filtering functions as required by the
policies established by the EU and the service. The P-GW also has features for
monitoring the data flow for statistical purposes, or for lawful interception.
The following figure shows the logical connections to nodes surrounding the P-GW,
and lists the main functions of these interfaces. Each P-GW can be connected to one
or more PCRF, S-GW and external networks.

LTE Fundamentals
Figure 22 - P-GW connections to neighboring nodes, with per-interface features

LTE Fundamentals
© 2010 PontoTech
64
4.7.6 Feature Collection Policy and Resources
(PCRF, Policies and Charging Resource
Function)
Is the network element that is responsible for the Policy and Charging Control (PCC).
Make decisions about how to manage services in terms of quality of service.
The PCRF is a server that is normally found with other switching elements. The
information provided by the PCRF to the P-GW is known as the PCC rules. The
PCRF sends these PCC rules every time a new subscriber is configured. The PCRF
PCC may establish rules based on a request from the P-GW and the S-GW in case
PMIP and also based on the request of the application function (FA). Each PCRF
may be associated with one or more AF, P-GW and S-GW.
The connections between the PCRF and the other nodes shown on the next figure.
Figure 23 - PCRF connections with logical nodes and their primary functions

LTE Fundamentals
4.7.7 Local subscriber server (HSS, Home
Subscriber Server)
This server represents the subscription database for all users. It also records the
user's location in the visited node level control network, such as the MME.
The HSS stores information about the subscriber profile, contains information about
the services that are applicable to you, including information on PDN connections
allowed, and whether or not to allow roaming to a visited network in particular. To
encourage mobility between non 3GPP access networks, the HSS also stores the
identity of the P-GW in use. The permanent key is used to calculate the
authentication vectors are sent to a host network for user authentication and obtain
the following keys for encryption and integrity protection, is stored in the
Authentication Center (AUC), which is usually part of the HSS.
HSS interacts with the MME, ie must be able to contact all MME throughout the
network, where the EU in question are allowed to move. For each UE, the HSS
records will point to a single MME in use at once and as soon as a new MME informs
serve the EU, the HSS will leave the location of the previous MME.

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© 2010 PontoTech
66
4.8 Interfaces and protocols in the setting of the
basic system architecture
The following figure shows the protocols in the control plane (CP, Control Plane)
related to a connection from the EU to a PDN. The interfaces are shown in two parts,
one on E-UTRAN protocols (LTE-Uu) and the EU, and other protocols to gateways
(S1-MME).
The protocols are shown in white are developed by the 3GPP, while light gray
background protocols are developed by the IETF, and represent the standard
Internet technologies used for transport in the EPS. 3GPP has defined only ways of
how to use these protocols.
Figure 24 - Interfaces Protocols LTE-Uu, S1-MME at the EPS control.

LTE Fundamentals
4.8.1 Interface LTE-Uu
LTE-Uu interface is the radio interface between the terminal and the eNodeB. The
top layer of the CP is the NAS (Non-Access Stratum), which consists of two protocols
(EMM and ESM), which performed in the signaling transport directly between the EU
and the MME.
The contents of the NAS layer protocols is not visible to the eNodeB, and eNodeB
not involved in these operations than the transportation of messages, and provide
some guidance on the transport layer. Here are the protocols for LTE-Uu interface.
4.8.1.1 Protocol EPS Mobility Management (EMM, EPS Mobility
Management)
EMM protocol is responsible for managing mobility within the EU. It includes features
to connect and disconnect the EU's network and performs the update of its location in
the middle. This is called a Tracking Area Update (TAU, Tracking Area Updating),
and occurs in idle mode. Authentication and identity protection EU, ie the allocation
of GUTI (Global Unique Temporary Identity) to the EU, are also part of the EMM layer
and control layer encryption and integrity protection.
4.8.1.2 EPS Protocol Session Management (ESM, EPS Session
Management)
This protocol can be used to handle the management within the limits of coverage
between the UE and MME and is used in conjunction with the management of E-
UTRAN limits. The ESM has procedures for the application of resources (IP
connectivity to a PDN or resources dedicated to the carrier) by the EU.
4.8.1.3 Protocol Radio Resource Control (RRC, Radio Resource
Control)

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