LTE Fundamentals

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Course documentation

December 2010

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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 3GPPLTE ... 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 LTERADIO ... 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

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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 LTEBUSINESS 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

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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.

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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.

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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.

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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 (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.

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

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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 Integrating different standards

Bandwidth used (Theoretical) Used 30 KHz AMPS Using D-AMPS uses 30 KHz and 200 KHz GSM Using 5 MHz WCDMA Speeds up to 2 Mbps Scalable band widths. Speeds up 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 Voice and data (SMS, MMS,

internet narrow band)

Voice and 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

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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

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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

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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.

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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.

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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 MHz frequency 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

100-200 users > 200 users to 5MHz

> 400 users for higher bandwidth

Spectral efficiency 3.75 (bps / Hz) 5 (bps / Hz)

Handover Hard Handover Soft handovers

MIMO:

DL 2Tx * 2RX 4Tx * 4RX

UL 1Tx * NRX 2Tx * 2RX

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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.

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3 Third-generation networks as the basis for

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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.

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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).

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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

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BSS Abis

Interface - - A Interface - - A

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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).

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• 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;

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• 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

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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.

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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.

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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.

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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).

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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

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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.