Aircom K025 LTE Technology for Engineers Asset_2

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LTE Technology for EngineersTraining Guide

K025

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The information in this document is subject to change without notice and describesonly the product defined in the introduction of this documentation. This document isintended for the use of AIRCOM International's customers only for the purposes ofthe agreement under which the document is submitted, and no part of it may be

reproduced or transmitted in any form or means without the prior written permissionof AIRCOM International. The document has been prepared to be used byprofessional and properly trained personnel, and the customer assumes fullresponsibility when using it. AIRCOM International welcomes customer comments aspart of the process of continuous development and improvement of thedocumentation.

The information or statements given in this document concerning the suitability,capacity, or performance of the mentioned hardware or software products cannot beconsidered binding but shall be defined in the agreement made between AIRCOMInternational and the customer. However, AIRCOM International has made allreasonable efforts to ensure that the instructions contained in the document areadequate and free of material errors and omissions. AIRCOM International will, ifnecessary, explain issues, which may not be covered by the document.

AIRCOM International's liability for any errors in the document is limited to thedocumentary correction of errors. AIRCOM International WILL NOT BERESPONSIBLE IN ANY EVENT FOR ERRORS IN THIS DOCUMENT OR FOR ANYDAMAGES, INCIDENTAL OR CONSEQUENTIAL (INCLUDING MONETARYLOSSES), that might arise from the use of this document or the information in it.

This document and the product it describes are considered protected by copyrightaccording to the applicable laws.

ASSET is a registered trademark of AIRCOM International.Other product names mentioned in this document may be trademarks of theirrespective companies, and they are mentioned for identification purposes only.

Copyright © AIRCOM International 2010. All rights reserved.


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K025 LTE Technology for Engineers Page 5Contents

Contents

1

Introduction to LTE 9

1.1 Where are we? 9

1.2 Release 99 11

1.3 UTRAN 15

1.4 3G Services and QoS Classes 21

1.5 HS-PDSCH 22

1.6 HSDPA 23

1.7

HSUPA 24

1.8

HSPA+ Error! Bookmark not defined.

1.9 Upgrade Paths to LTE 28

1.10 R8 LTE 29

1.11 Scalability of Bandwidth 33

1.12 LTE Key Features 34

2 IP Core Network Overview 41

2.1 The TCP/IP Layers 41

2.2

Transport Layer Protocols 43

2.3 Application Layer Services 47

2.4 TCP/IP Inter-networks 52

2.5

IP Datagram Format 53

2.6

Maximum Transfer Unit (MTU) 55

2.7 Fragmentation 56

2.8 Time To Live (TTL) 57

2.9 IP Addresses 59

2.10

Dotted Decimal Notation 60

2.11 Address Classes 61

2.12 Special IP Addresses 62

2.13

Realtime Transport Protocol (RTP) 63

2.14

Base Header Format 66

2.15 The Need for QoS 72

2.16 IP Precedence 73

2.17 Type of Service 75


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Page 6 K025 LTE Technology for EngineersContents

2.18 Differentiated Services 81

2.18.1 Assured Forwarding 86 2.18.2 Weighted Fair Queing 88 2.18.3

RNC Scheduling 89

2.19

Questions 90

3 Layer 2 Switching 91

3.1 Introduction 91

3.2 Spectral Efficiency 93

3.3 The TCP/IP Layers 95

3.4 Message Switching 97

3.5

Frames 98

3.6

Hardware Addresses 101

3.7 Store & Forward 102

3.7.1 Cut Through Switching 103 3.7.2 Modified Cut-Through 104

3.8

Switches and VLAN’s 105

3.9

Link Aggregation 109

3.10

Carrier Ethernet Overview 114

3.11 The Three Essential Functions of Connection-Oriented Ethernet 118

3.12 Colour Marking 124

3.13

Traffic Policing and Shaping 125

3.14 MEF Bandwidth Profiles 126

3.15

Mapping at the UNIs 128

3.16

Class of Service (CoS) 130

3.17

IEEE 802.1Q — Virtual LANS (VLANS) 131

3.18 Carrier Ethernet Services 132

3.19 Questions 136

4

LTE Basic Air Interface 137

4.1

New Air Interface 137

4.2 OFDMA 138

4.3 Advanced Antenna Techniques 139

4.4 Cyclic Delay Diversity 143

4.5 FDD/TDD 144

4.5.1 FDD 145 4.5.2 TDD 146 4.5.3

LTE TDD / TD-LTE Subframe Allocations 149

4.5.4

Flexible Carrier Bandwidths 150

4.6

Slot Structure and Physical Resources 152

4.6.1 Transmission Bandwidths 155


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K025 LTE Technology for Engineers Page 7Contents

4.7 Orthagonality 156

4.7.1 Single-Frequency Network Multicast Services 158 4.7.2 Single Carrier Frequency Division Multiple Access (SC-FDMA) 160

4.8

Cyclic Prefix 162

4.9

Delay Spread 163

4.10 Slot Structure and Physical Resources 166

4.11 Scheduler 167

4.12 ASSET - LTE 172

4.13 Downlink Data Transmission 173

4.14 Modulation and Subcarriers 175

4.15

Downlink Reference Signal Structure 177

4.15.1

Configuration of Carrier 178

4.16

Reference Signal Received Power (RSRP) 181

4.17

Channel Quality Indicator Reporting 183

4.18

Downlink Shared Channel (DL-SCH) 187

4.18.1 Physical Cell Identity (PCI) 188 4.18.2

Physical Downlink Control Channel 189

4.19 Questions 190

5 LTE Network Architecture and Protocols 191

5.1 LTE Architecture 192

5.2

Roaming Architecture 195

5.3 Bearer Establishment Procedure 199

5.4

KPI-RAB Success 204

5.5

KPI –Dropped Call Ratio ? 205

5.6

The Home Subscriber Service 210

5.7 PDN Gateway 212

5.8 Network Sharing 217

5.9 Session Initiation Protocol Architecture 219

5.10

LTE Functional Nodes 224

5.11 Physical Channels, Transport Channels & Logical Channels 227

5.11.1

Logical Channels 228

5.11.2 Transport Channels 231 5.11.3 Physical Channels 235

5.12

Modulation and Coding 238

5.12.1 PDSCH 239 5.12.2

PUSCH 241

5.13 Functional Nodes 242

5.13.1 Functional Nodes - UE 243 5.13.2 Functional Nodes - eNodeB 244

5.14

RLC Modes 245

5.14.1 RLC Modes - Qos 246


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Page 8 K025 LTE Technology for EngineersContents

5.15 Medium Access Control (MAC) 247

5.16 Physical Control Channel 251

5.16.1 Physical Downlink Control Channel 252

5.17 Multimedia Broadcast/Multicast Service (MBMS) 257

5.18 Reference Signal Received Power (RSRP) 264

5.19 Quality Channel Indicator Reporting 266

6 Mobility Management 271

6.1 UE States 271

6.2 UE Power-up 273

6.2.1 EPS Mobility Management 275 6.2.2 Tracking Area Update 277

6.3

LTE Functional Modes - MME 279

6.4 RRC States 282

6.5 Reference Signal Received Power (RSRP) 295

6.6 Cell Re-selection 299

6.7 Handover – RRC Connected 302

6.7.1

LTE Reference Signal Received Quality (RSRQ) 306

6.7.2 Received Signal Strength Indicator (RSSI) 307 6.7.3 Reference Signal Received Power (RSRP) 308 6.7.4

Handover 309

6.7.5 Automatic Neighbour Relations 315 6.7.6 Measurement Configuration 322

6.8

Questions 324


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K025 LTE Technology for Engineers Page 9Introduction to LTE

1 Introduction to LTE

1.1 Where are we?

C H A P T E R 1


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1.2 Release 99

UMTS/W-CDMA was initially conceived as a circuit switched based system and wasnot well-suited to IP packet based data traffic. Once the basic UMTS system wasreleased and deployed, the need for better packet data capability became clear,especially with the rapidly increasing trend towards Internet style packet dataservices which are particularly bursty in nature. It supports Cell-DCH and typicalspeeds 384kb/s.

Release 5: This release included the core of HSDPA itself. It provided for downlinkpacket support, reduced delays, a raw data rate (i.e. including payload, protocols,error correction, etc.) of 14 Mbps and gave an overall increase of around three times

over the 3GPP UMTS Release 99 standard.Release 6: This included the core of HSUPA with an enhanced uplink with improvedpacket data support. This provided reduced delays, an uplink raw data rate of 5.74Mbps and it gave an increased capacity of around twice that offered by the originalRelease 99 UMTS standard. Also included within this release was the MultimediaBroadcast Multicast Services (MBMS), providing improved broadcast services such asMobile TV.

Release 7: This release of the 3GPP standard included downlink MIMO operation aswell as support for higher order modulation up to 64 QAM in the uplink and 16 QAMin the downlink. However, it only allows for either MIMO or higher order

modulation. It also introduced protocol enhancements to allow support forContinuous Packet Connectivity (CPC).


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Page 12 K025 LTE Technology for EngineersIntroduction to LTE

Release 8: This release of the standard defines dual carrier operation as well asallowing simultaneous operation of the high order modulation schemes and MIMO.Further to this, latency is improved to keep it in line with the requirements for manynew applications being used.


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Rb_phy includes DPDCH (User data + L3 control) + Error protection + DPCCH (L1control)

DPCCH = Dedicated Physical Control Channel In UL, symbol rate=ch bit rate.

The DPDCH channel bit rate is less than channel bit rate because the latter containsboth DPDCH and DPCCH ch bit rates. The exact DPDCH bit rate depends on the slotformat. DPDCH is shared by logical/transport channels (DCCH/DCH +DTCH/DCH).

The exact DTCH bit rate depends on the selected channel configuration or transportformat, for example with AMR 12.2, the DTCH is 12.2 kbit/s and DCCH is 3.7 kbit/sby default (SF = 128).

For the channel coding, three options are supported: convolutional coding, turbocoding, or no channel coding. Channel coding selection is indicated by upper layers.

For example, with single DPDCH in UL:

– 960kbps can be obtained with SF=4, no coding

– 400-500 kbps with coding

With 3 codes, up to 5740 kbps uncoded or 2Mbps (or even more) with coding.

Error Correction Coding Parameters

Transport channel type Coding scheme Coding rate

BCH, PCH, RACH Convolutional code 1/2

CPCH, DCH, DSCH, FACH Convolutional code 1/3, 1/2

CPCH, DCH, DSCH, FACH Turbo code 1/3

CPCH, DCH, DSCH, FACH No coding -


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1.3 UTRAN

In UMTS, the UTRAN is formed from RNCs, Node Bs and their defined interfaces. AnRNC is the UMTS equivalent of a GSM BSC, but has greater functionality. One of themain differences between UMTS (Release 99) and GSM (Release 99) is that there is anIur interface interconnecting multiple RNCs. This additional interface permits theRNCs to communicate with each other, allowing soft handover (not present in GSM).

Another difference between GSM and UMTS is that some of the MobilityManagement (MM) has been moved to the RNC from the Core Network, allowingUTRAN initiated paging. The RNC has greater control over a group of cells and thefunctionality allows soft handover.


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Core Network

The Core Network is divided in circuit switched and packet switched domains. Someof the circuit switched elements are Mobile services Switching Centre (MSC), Visitorlocation register (VLR) and Gateway MSC. Packet switched elements are Serving

GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN). Somenetwork elements, like EIR, HLR, VLR and AUC are shared by both domains.

The functions of RNC are:

Radio Resource Control

Admission Control

Channel Allocation

Load Control

Handover Control

Macro Diversity

Ciphering

Segmentation / Reassembly

Broadcast Signalling

Open Loop Power Control


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Co-existence with legacy standards and systems: LTE users should be able to makevoice calls from their terminal and have access to basic data services even when they

are in areas without LTE coverage. LTE therefore allows smooth, seamless servicehandover in areas of HSPA, WCDMA or GSM/GPRS/EDGE coverage. Furthermore,LTE/SAE supports not only intra-system and intersystem handovers, but inter-domain handovers between packet switched and circuit switched sessions.


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1.4 3G Services and QoS Classes

In UMTS, four Quality of Service classes have been defined:

Conversational class is the QoS class for delay-sensitive real time services such asspeech telephony.

Streaming class is also regarded as a real-time QoS class. It is also sensitive to delays; itcarries traffic, which looks real time to a human user. An application for streamingclass QoS is audio streaming, where music files are downloaded to the receiver. Theremay be an interruption in the transmission, which is not relevant for the user of theapplication, as long as there is still enough data left in the buffer of the receivingequipment for seamless application provision.

Interactive class is a non-real time QoS class. It is used for applications with limiteddelay-sensitivity (so-called interactive applications). But many applications on theinternet still have timing constraints, such as http, ftp, telnet, and smtp. A response toa request is expected within a specific period of time. This is the QoS offered by theinteractive class.

Background class is a non-real time QoS class for background applications, which arenot delay sensitive. Example applications are email and file downloading.


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1.5 HS-PDSCH


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1.6 HSDPA


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1.7 HSUPA


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[CL] From one phase to another, the main limitation is the product development -which resources you can offer to the user.

TTI - 2 ms (HS-DSCH), 10 ms, 20 ms, 40 ms, and 80 ms

TTI is length of transmission on the radio link


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1.8 Upgrade Paths to LTE

Who Needs LTE?

Less than a decade on from the launch of the first 3G/UMTS networks, why is thecellular industry considering additional investments in its radio access and corenetwork infrastructures?

The answer lies in a changing market landscape, where user expectations areconstantly increasing. In the fixed world, broadband connectivity is now ubiquitouswith multi-megabit speeds available at reasonable cost to customers and businessusers via DSL and cable connections.


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1.9 R8 LTE

The result of these radio interface features is significantly improved radioperformance, yielding up to five times the average throughput of HSPA. Downlinkpeak data rates are extended up to a theoretical maximum of 300 Mbit/s per 20 MHzof spectrum. Similarly, LTE theoretical uplink rates can reach 75 Mbit/s per 20 MHzof spectrum, with theoretical support for at least 200 active users per cell in 5 MHz.

Reduced latency: By reducing round-trip times to 10ms or even less (compared with40–50ms for HSPA), LTE delivers a more responsive user experience. This permitsinteractive, real-time services such as high-quality audio/videoconferencing andmulti-player gaming.


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1.10 Scalability of Bandwidth


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1.11 LTE Key Features

Urban areas:

Most likely LTE will be deployed.

Stepwise deployment in UMTS 2.1 bands will be possible at a later stage.

Rural areas:

Option 1: deploy UMTS in 900 MHz band.

Advantage: rollout can start now

Disadvantage: a block of 5 MHz need to be taken out of the GSM band. Not a lot of

operators can affort to take out this much spectrum due to heavy usage in this bandOption 2: Introduce LTE in 900 MHz band

Advantages: reuse of GSM 900 Sites; step by step introduction of LTE with smallergranularity (1.4 / 3 / 5 /…MHz).


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K025 LTE Technology for Engineers Page 41IP Core Network Overview

2 IP Core NetworkOverview

2.1 The TCP/IP Layers

TCP/IP can be represented by the US DoD Model. This model describes therelationship between the main protocols used by TCP/IP.

C H A P T E R 2


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Page 42 K025 LTE Technology for EngineersIP Core Network Overview

Prior to the development of this model most network protocols were vendordependent. The architecture behind TCP/IP is different in the sense that the sameprotocol model can be run on a multitude of different computer systems withoutmodification of the operating system or hardware architecture. TCP/IP is designed to

run as an application.The protocol was primarily used to support application-orientated functions andprocess-to-process communications between hosts. Specific applications to providebasic network services for users were written to run with TCP/IP. The objective of thelower protocols was to provide support for the network layer application services.


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2.2 Transport Layer Protocols

Transport layer protocols provide two basic functions to the application layer services- quality of service and application multiplexing through port numbers. TCP/IP hastwo main transport layer protocols – TCP and UDP.

UDP provides a simple datagram delivery service adding application multiplexingand a checksum to the underlying IP layer. It therefore provides the same unreliable,connectionless delivery service as IP. It does not use acknowledgements to confirmthat messages have arrived, it does not provide any flow control mechanisms, and itdoes no sequencing - UDP messages can be duplicated, arrive out of order or not atall. UDP works well on LANs where error rates are low and delays small, but on

WANs it behaves poorly, especially for large data transfers.TCP provides a reliable, connection-oriented, stream based delivery system by addingacknowledgements, sequencing and flow control to IP. This makes TCP much moreefficient on WANs and for large data transfers, but it has a large protocol overheadwhich makes it slower and less efficient than UDP in certain applications.

Most applications tend to use TCP because it provides reliable delivery, but time-sensitive, transactional and broadcast based applications need to use UDP.


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2.3 Application Layer Services

The power behind TCP/IP is not the sophisticated and powerful nature of theprotocol architecture, but rather it is the absolute simplicity of the protocol. This isequally true of the application-level services which are designed to provide networkservices for users.

TCP/IP provides a consistent application front end to users regardless of theoperating system, platform, or network architecture which is used. Many of theapplication level services retain the look and feel of simple character-orientedapplications. Even today, with TCP/IP providing GUI, once the superficial GUI isremoved, the same basic element of code is used to provide the network service.

The Transport layer protocols (TCP/UDP) use Port Numbers to uniquely identifyeach application level service. The client usually generates a port number above 1,023to identify the process and the server always uses a well known port number.


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2.4 TCP/IP Inter-networks

The term internetworking is used to describe a number of discrete physical networksthat are connected together to form an internet. A characteristic of such an internet isthat the underlying physical network structure should be invisible to network users.Internetworking is defined as a combination of interconnection and interoperation(the ability to physically exchange data and make some sense from it).


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2.5 IP Datagram Format

VERS Protocol version (currently 4)

HLEN Length of header in 32 bit words (normally 5)

Service Type Sets a precedence and Type of Service for the packet (normally 0)

Total Length Length of IP datagram in octets including header & data -Maximum of 65535

Identification Unique ID for each datagram, used for fragmentation

Flags Controls fragmentation (DF - don't fragment and MF - morefragments)

Fragment Offset Position of data in this fragment compared to original datagram -units of 8 octets

Time To Live Specifies how long (in router hops) the datagram is to remain in theinternet.

Protocol ID of transport protocol - UDP, TCP, (ICMP) etc.

Checksum Checksum of the header only

Source IP Address 32 bit IP address of source

Destination IP Address 32 bit IP address of destination

IP Options Option type and data for additional facilities - networkmanagement and debugging


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Padding Padding to extend options data to multiple of 4 octets

DATA The higher level Protocol Data Unit (PDU)


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2.6 Maximum Transfer Unit (MTU)

Each physical network has a defined limit on the size of protocol which it cansupport. This is known as the Maximum Transfer Unit (MTU) and is generallyconsidered a hard limit of the network which cannot be increased. The MTU is themaximum size of software protocol which can be sent, and not the maximum size offrame which can be supported. If hardware control information (such as physicaladdresses) is added to the MTU, the maximum frame size can be derived.

Ethernet limits transfers to 1500 bytes of data, which FDDI permits approximately4470 bytes of data per frame. MTUs vary considerably in size. Local area networks,which generally use high bandwidth, low bit error rate media have relatively large

MTUs, while wide area networks have much smaller MTUs. Limiting datagram sizeto fit the smallest possible MTU in the internet makes transfers inefficient when thosedatagrams pass across a network which can carry larger size frames. However,allowing datagrams to be larger than the minimum network MTU in an internetmeans that a datagram may not always fit into a single network frame.

Instead of making IP datagrams adhere to the constraints of physical networks,TCP/IP software chooses a convenient initial datagram size and arranges a way todivide large datagrams into smaller pieces when the datagram needs to traverse anetwork that has a small MTU. The small pieces into which a datagram is divided arecalled fragments, and the process of dividing a datagram is known as fragmentation.


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2.7 Fragmentation

Hosts can choose to send datagrams up to the supported MTU of their own network.Routers interconnect different physical networks with varying MTUs. Routers canfragment datagrams if desired to permit transport across networks which havesmaller MTUs.

The IP protocol does not limit datagram size nor does it guarantee that the datagramwill be delivered without fragmentation. The source can choose any datagram size itthinks appropriate; fragmentation and reassembly occur automatically, withouttaking action. The IP specification states that routers must accept datagrams up to themaximum of the MTUs of the networks to which they are attached.

Once a datagram has been fragmented, the fragments travel all the way to the finaldestination, where they reassembled. This has a number of disadvantages - smallfragments must be carried by networks which could support larger MTUs, andreassembling the datagrams at the destination can lead to inefficiency, particularly iffragments are lost. If fragments are lost, the original datagram cannot be reassembled.

The receiving machine starts a reassembly timer when it receives an initial fragment.If the timer expires before all fragments arrive, the receiving machine discards thesurviving pieces without processing the datagram. Performing reassembly at theultimate destination works well, and permits each fragment to be routedindependently as well as sparing resources on routers.


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2.8 Time To Live (TTL)

The TIME To LIVE specifies how long, in seconds, the datagram is permitted toremain in the internet. Whenever a host injects a datagram into the internet, it sets amaximum time that the datagram should survive. Router and hosts that processdatagrams must decrement the TIME To LIVE field as time passes and remove thedatagram from the internet when the value in this field reaches zero.

Estimating exact time is difficult because routers do not usually know the transit timeof physical networks. A few rules simplify processing and make it easy to handledatagrams without synchronise clocks. First, each router along the path from sourceto destination is required to decrement the TIME To LIVE field when the datagram

header is processed. Furthermore, to handle cases of overloaded routers thatintroduce long delays, each router records the local time when the datagram arrivesand decrements the TIME To LIVE by the number of seconds that the datagramremained inside the router waiting for service.


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2.9 IP Addresses

TCP/IP uses a 32-bit binary address to uniquely identify a device on a TCP/IPinternetwork. The binary address string is a network layer logical address which mustbe configured by the network manager. The address is used to identify the device in avirtual network.

The 32-bit address structure is divided into a single-level hierarchy where the leadingbits in the address are used to describe a network in logical terms and the remainingbits are used to describe the host on the logical network. The number of bits which areused in each case varies, and will be covered later. The leading bits which make upthe logical network address are used to provide a routing (packet forwarding)

mechanism between logical networks. This allows for far more efficient routing than aflat address space.


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2.10 Dotted Decimal Notation

Binary address strings are very difficult to work with. To overcome this problem andmake logical addressing easier to comprehend, the 32-bit address string is dividedinto 8-bit bytes and then converted into the corresponding decimal notation. It is thisdotted decimal notation which is used to configure hosts on a TCP/IP network.

However, it should be noted that decimal addresses are a human and humaneinterface to TCP/IP. As far as the host is concerned, the address appears and is usedas a binary string. This is the cause of much confusion.


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2.11 Address Classes

There are five main classes of IP addresses but only three are directly usable: A, B andC.

For a Class A address, 8-bits are used to logically identify the network. For Class B,16-bits are used, and for Class C, 24-bits are used. In each case, once the network bitshave been allocated, the remaining bits are used to logically identify the node.

Class E addresses are reserved for testing and development by the IETF and cannot beassigned to any device. Class D addresses are software multicast addresses andreserved for the use of routing protocols such as OSPF, RIPv2 and so on.

The address categorisation is derived from the high bit order rule of the first byte. Thehigh bit order rule is interrupted by every TCP/IP stack as soon as an address isentered. This rule is also used to define the decimal ranges in the first byte of eachaddress.


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2.12 Special IP Addresses

Some binary bit patterns are reserved for management reasons and cannot beallocated to devices on a TCP/IP network.

Although the Internet Protocol has been stable for a considerable number of years, theway IP addresses are used and interpreted has changed over the years.

In general, 1’s indicate "All" and 0’s indicate "Any" - the local broadcast address is anobvious exception; a broadcast to all hosts on all networks (on the Internet) wouldcause chaos!


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2.13 Realtime Transport Protocol (RTP)


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2.14 Base Header Format

Although the IPv6 header must accommodate larger addresses, an IPv6 base headercontains less information than an IPv4 header. Options and some of the fixed fieldsthat appear in an IPv4 header have been moved to extension headers. Changes in thedatagram header reflect changes in the protocol:

Alignment has been changed from 32-bit multiple to 64-bit multiples.

The header length field has been eliminated, and the datagram length field hasbeen replaced by a Payload

Length field.

The size of the source and destination address fields has been increased to 16 byteseach.

Fragmentation information has been moved out of fixed fields in the base headerinto an extension header.

The Time-to-Live field has been replaced by a Hop Limit field.

The Service Type field has been replaced by a Flow Label field.

The Protocol field has been replaced by a field that specifies the type of the nextheader.


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IPv6 handles packet length specification in a new way. Firstly, because the size of thebase header is fixed at 40 bytes, the header does not include a field for the headerlength. Secondly, IPv6 replaces IPv4 packet length field with a 16-bit Payload Lengthfield that specifies the number of octets carried in the packet excluding the header. An

IPv6 packet can contain 64k bytes of data.


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The fixed header occupies the first 40 octets (320 bits) of the IPv6 packet. It containsthe source and destination addresses, traffic classification options, a hop counter, and

a pointer for extension headers if any. The Next Header field, present in each extensionas well, points to the next element in the chain of extensions


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2.16 IP Precedence

IP Precedence was designed in IPv4 by the IETF.

It uses 3 bits of the 8-bit Type of Service (TOS) field of an IP header. There are 8classes of services in IP Precedence. The classification range is 0-7 where 0 (zero) is thelowest and 7 is the highest priority.

The original intention of the TOS field was for a sending host to specify a preferencefor how the datagram would be handled as it made its way through an internet. Forinstance, one host could set its IPv4 datagrams' TOS field value to prefer low delay,while another might prefer high reliability.


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IP Precedence provides the ability to classify network packets at Layer 3. With IPPrecedence configured, network packets traverse IP Precedence devices according to

the priority you set. Priority traffic is always serviced before traditional traffic.


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2.17 Type of Service

The Type of Service field in the IP header was originally defined in RFC 791.

It defined a mechanism for assigning a priority to each IP packet as well as amechanism to request specific treatment such as high throughput, high reliability orlow latency.

Differentiated Services Code Point

In RFC 2474 the definition of this entire field was changed. It is now called the "DS"(Differentiated Services) field and the upper 6 bits contain a value called the "DSCP"(Differentiated Services Code Point). Since RFC 3168, the remaining two bits (the twoleast significant bits) are used for Explicit Congestion Notification.


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In theory, a network could have up to 64 (i.e. 26) different traffic classes usingdifferent markings in the DSCP. The DiffServ RFCs recommend, but do not require,

certain encodings. This gives a network operator great flexibility in defining trafficclasses. In practice, however, most networks use the following commonly-definedPer-Hop Behaviors:

Default PHB—which is typically best-effort traffic

Expedited Forwarding (EF) PHB—dedicated to low-loss, low-latency traffic

Assured Forwarding (AF) PHB— which gives assurance of delivery underconditions

Class Selector PHBs—which are defined to maintain backward compatibility withthe IP Precedence field


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Because the CE indication can only be handled effectively by an upper layer protocolthat supports it, ECN is only used in conjunction with upper layer protocols (for

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2.18 Differentiated Services


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2.19 Assured Forwarding

There are four assured forwarding (AF) classes, AF1x through AF4x. The first numbercorresponds to the AF class and the second number (x) refers to the level of droppreference within each AF class. There are three drop probabilities, ranging from 1(low drop) through 3 (high drop). Depending on a network policy, packets can beselected for a PHB based on required throughput, delay, jitter, loss, or according tothe priority of access to network services


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2.20 Weighted Fair Queing


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2.20.1 RNC Scheduling


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2.21 Questions


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K025 LTE Technology for Engineers Page 91Layer 2 Switching

3 Layer 2 Switching

3.1 Introduction

C H A P T E R 3


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Page 92 K025 LTE Technology for EngineersLayer 2 Switching

With the introduction of 4G systems, wireless networks are evolving to next-generation packet architectures capable of supporting enhanced broadbandconnections. Simple text messaging and slow email downloads are being replaced byhigh-speed connections that support true mobile office applications, real time video,

streaming music, and other rich multimedia applications. 4G wireless networks willapproach the broadband speeds and user experience now provided by traditionalDSL and cable modem wireline service.

From the wireless operator’s perspective, 4G systems are vastly more efficient atusing valuable wireless spectrum. These spectral efficiency improvements supportnew high-speed services, as well as larger numbers of users. The additional speedsand capacity provided by 4G wireless networks put additional strains on mobilebackhaul networks and the carriers providing these backhaul services. Not only arethe transport requirements much higher, but there is also a fundamental shift fromTDM transport in 2G and 3G networks to packet transport in 4G networks.Understanding the impact of 4G on mobile backhaul transport is critical to deployingefficient, cost-effective transport solutions that meet wireless carrier expectations forperformance, reliability and cost.


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3.2 Spectral Efficiency

The amount of bandwidth on a wireless network is ultimately constrained by twofactors: the spectral efficiency of the wireless interface and the amount of licensedspectrum a carrier owns. Spectral efficiency is a fancy way of saying how muchinformation can be transmitted over a given radio channel (i.e., Hz). Spectralefficiency is measured as the amount of data (bps) that can be transmitted for everyHz of spectrum; the higher the number (bps/Hz), the better. Newer technologies,such as LTE, use advanced modulation schemes (OFDM) that support higher spectralefficiencies and higher data rates than 2G and 3G wireless networks.


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3.3 TCP/IP Layers

TCP/IP can be represented by the US DoD Model. This model describes therelationship between the main protocols used by TCP/IP.

Prior to the development of this model most network protocols were vendor-dependent. The architecture behind TCP/IP is different in the sense that the sameprotocol model can be run on a multitude of different computer systems withoutmodification of the operating system or hardware architecture. TCP/IP is designed torun as an application.

The protocol was primarily used to support application-orientated functions andprocess-to-process communications between hosts. Specific applications to provide

basic network services for users were written to run with TCP/IP. The objective of thelower protocols was to provide support for the network layer application services.


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3.4 Message Switching

Message switching moves the entire message from connecting point to connectingpoint, one step at a time. This method is sometimes referred to as ‘store & forward’.

Message switching creates a virtual or dedicated connection to the next switchingstation. The entire message is transmitted and then the connection is terminated. Thereceiving station must buffer the entire message and then create a connection to thenext switching station and forward the entire message. The message is forwarded onestep at time until it is received at the final destination.

The best example of message switching is E-mail servers.


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3.5 Frames

A frame is the fundamental unit of data transfer used on LANs. It has specificnetwork characteristics which relate to the type of network it originated on. All IEEEcompliant frames have a similar structure and start with a preamble which isfollowed by hardware addresses for source and destination stations. Some networkframes (Token Ring) have some special fields for specific MAC control. After thesource MAC address, the LLC protocol data unit follows. Generally, LLC is threebytes in size followed by the network layer protocol. The maximum and minimumsize of the protocol which follows LLC is dependent on the type of network. Theframe is finished by a four-byte trailer used for error checking.


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3.6 Hardware Addresses

A universal address is assigned to a Network Interface Card (NIC) on manufacture.The address is stored in an EPROM and, as the device is initialised, the address iscopied into RAM where it can be used by software. The address is 48 bits in size,divided into six eight-bit fields. The first byte of the address (left hand side) is byte 0and the last byte (right hand side) is byte 5. The first three bytes of the address (0, 1and 2) indicate the vendor, and are unique to that vendor. The last three bytes of theaddress (3, 4 and 5) can be assigned by the vendor (approx. 16M addresses perVendor Code).

For IEEE addressing, two other bits are important in the address. The least significant

bit of the first byte (byte 0) indicates an Individual/Group address. A value of 0indicates a unicast address and 1 indicates a multicast. The second bit of this byteindicates a universally assigned address or locally managed (where the address hasbeen changed by software). Locally managed addresses are supported by differentLAN technologies, but caution must be used when setting locally managed addresses.It is the Network Manager’s responsibility to ensure that the assigned addresses areunique.

Hardware addresses are Data Link characteristics of the OSI protocol stack. They areseparate from software protocol addresses, which are Network layer addresses.


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3.7 Store & Forward

A store and forward switching hub stores the full incoming frame in a buffer. Thisenables the switch to perform a CRC check to see if the frame contains any errors. Ifthe frame is error-free, the switch uses an address lookup table to obtain a destinationport. Once the address is obtained, the switch performs a cross-connect operation andforwards the frame to the destination.

Since the frame must be buffered in shared RAM, this results in greater latency thanthat provided by cut through switching. A key advantage of store and forwardswitches, results from the buffering of the frames in the switch. Since they are placedin memory, this enables frame processing functions to be added to the switch,

permitting vendors to support a variety of filtering operations and the gathering ofstatistics for management reports.


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3.7.1 Cut Through Switching

A cut through switch examines the destination address of each frame entering theport. It then searches a table of addresses associated with ports to obtain a portdestination. Once the port destination is determined, the switch initiates the cross-connection between incoming and outgoing port.

Cut through switching minimises the delay or latency associated with placing a framereceived on one port onto another port. Since the switching decision is made once thedestination address is read, this means that the full frame is not examined. Thus theswitch cannot perform error checking on a frame. This limitation does not present aproblem on most LANs, due to the extremely low error rates. However, whenerroneous frames are encountered, they are passed from one network segment toanother. This results in an unnecessary increase in network utilisation on thedestination segment, as a store and forward switch would discard the framescontaining one or more bit errors.


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3.7.2 Modified Cut-Through

Modified cut-through switches attempt to offer the best of both worlds by holding anincoming Ethernet frame until the first 64 bytes have been received. If the frame isbad, it is nearly always detected within the first 64 bytes, so a trade-off between

switch latency and error-checking is achieved. In effect, modified cut-though switchesact as store and forward switches for short frames. For large frames they act like cut-through switches.


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3.8 Switches and VLAN’s


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3.9 Link Aggregation


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3.10 Carrier Ethernet Overview

The Metro Ethernet Forum (MEF) has led the industry in propagating CarrierEthernet and has identified five key attributes that distinguish Carrier Ethernet fromtraditional LAN based Ethernet. These are:

Standardised services

Scalability

Service manageability

Quality of service

Reliability

Making Ethernet Connection-Oriented

Historically, Ethernet has been a connectionless technology by design. In classic LANenvironments, the connectionless capabilities of Ethernet MAC bridging andCSMA/CD provided considerable flexibility, simplicity, and economy in networkinglatency-insensitive traffic within a single, well-bounded administrative domain.


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3.12 Colour Marking

Packet classification is the processes of identifying to which EVCs the incomingframes belong. The Ingress equipment can examine a variety of Ethernet and IP layerinformation to make this decision. Once the incoming frame is classified, policing isthen applied to ensure that all frames coming into the network conform to the trafficcontract, known as the bandwidth profile, agreed to upon connection setup. Two-level, three-colour marking allows incoming frames that conform to the CIR to beadmitted to the network. Frames that exceed even the EIR are discarded immediately,and frames that exceed the CIR, but not the EIR, are marked for possible discard later,should the network become congested. An EVC can be subject to a single such policerif the bandwidth profile is applied to the entire EVC. EVCs can also includebandwidth profiles for each of many CoS classes within the EVC. In this case, a singleEVC can be subject to multiple policers.


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3.13 Traffic Policing and Shaping


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3.14 MEF Bandwidth Profiles


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3.15 Mapping at the UNIs


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3.16 Class of Service (CoS)


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Based on the Metro Ethernet Forum’s (MEF) definitions, there are two broadcategories of Carrier Ethernet services: point-to-point, referred to as E-Line services;

and multipoint, referred to as E-LAN services. Both E-line and E-LAN services areoften provided with multiple classes of service (CoS); where a single Ethernet virtualconnection (EVC) can carry traffic with one or more CoS. Service providers desire tobuild networks that offer all services simultaneously on a single convergedinfrastructure.


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3.19 Questions


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K025 LTE Technology for Engineers Page 137LTE Basic Air Interface

4 LTE Basic Air Interface

4.1 New Air Interface

C H A P T E R 4


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Page 138 K025 LTE Technology for EngineersLTE Basic Air Interface

4.2 OFDMA

The downlink transmission scheme for E-UTRA FDD and TDD modes is based onconventional OFDM. In an OFDM system, the available spectrum is divided intomultiple carriers, called subcarriers. Each of these subcarriers is independentlymodulated by a low rate data stream. OFDM is used as well in WLAN, WiMAX andbroadcast technologies like DVB. OFDM has several benefits including its robustnessagainst multipath fading and its efficient receiver architecture.


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4.3 Advanced Antenna Techniques

LTE uses advanced antenna techniques and wider spectrum allocations to providehigher data rates throughout the cell area. LTE supports MIMO, SDMA andbeamforming . These techniques are complementary and can be used to trade offbetween higher sector capacity, higher user data rates, or higher cell-edge rates, andthus enable operators to have finer control over the end-user experience.

DL MIMO—LTE supports up to 4x4 MIMO in the DL, which uses four transmitantennas at the Node B to transmit orthogonal (parallel) data streams to the fourreceive antennas at the user equipment (UE). Using additional antennas and signalprocessing at the receiver and transmitter, MIMO increases the system capacity and

user data rates without using additional transmit power or bandwidth. To be mosteffective, MIMO needs a high signal-to-noise ratio (SNR) at the UE and a richscattering environment. High SNR ensures that the UE is able to decode the incomingsignal, and a rich scattering environment ensures the orthogonality of the multipledata streams. The MIMO benefit is therefore maximised in a dense urbanenvironment, where there is enough scattering and the small cell sizes provide anenvironment of high SNRs at the UE.


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SU-MIMO

Similarly, on the UL, SDMA enables two users in the cell to simultaneously send datato the eNode B, using the same time-frequency resource. Even though the

transmissions are simultaneous, the spatial separation ensures that the two datastreams do not interfere with each other. Allowing these concurrent transmissionsincreases the cell capacity in both the DL and the UL. LTE does not supportsimultaneous MIMO and SDMA operation to a user; hence, there is a tradeoffbetween higher user data rates and higher system capacity in the DL.


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Beamforming

Beamforming increases the user data rates by focusing the transmit power in the

direction of the user, effectively increasing the received signal strength at the UE.Beamforming provides the most benefits to users in weaker-signal-strength areas, likethe edge of the cell coverage. Beamforming ensures that cell-edge rates are high, andenables the operator to deploy high-bandwidth services without concern for servicedegradation at the cell edge.


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4.4 Cyclic Delay Diversity


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4.5.1 FDD

Two frame structure types are defined for E-UTRA: frame structure type 1 for FDDmode, and frame structure type 2 for TDD mode.

For the frame structure type 1, the 10 ms radio frame is divided into 20 equally sizedslots of 0.5ms. A sub-frame consists of two consecutive slots, so one radio framecontains ten sub-frames.


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4.5.2 TDD

The frame structure for the type 2 frames used on LTE TDD is somewhat different.The 10 ms frame comprises two half frames, each 5 ms long. The LTE half-frames arefurther split into five sub-frames, each 1ms long.

With TDD the transmission in uplink and downlink is discontinuous within the samefrequency band. As an example, if the time split between down- and uplink is 1/1, theuplink is used half of the time. The average power for each link is then also half of thepeak power. As peak power is limited by regulatory requirements, the result is thatfor the same peak power, TDD will offer less coverage than FDD.


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The special subframes consist of the three fields:

DwPTS (Downlink Pilot Timeslot)

GP (Guard Period)

UpPTS (Uplink Pilot Timeslot).

The special frames replace what would be a normal sub-frame.


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The DL to UL switching method ensures that the high power downlink transmissionsfrom the eNodeB from other neighbour cells do not interfere when the eNodeB UL

reception is going in the current cell.


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4.5.3 LTE TDD / TD-LTE Subframe Allocations

One of the advantages of using LTE TDD is that it is possible to dynamically changethe up and downlink balance and characteristics to meet the load conditions. In orderthat this can be achieved in an ordered fashion, a number of standard configurationshave been set within the LTE standards.

A total of seven up/downlink configurations have been set, and these use either 5 msor 10 ms switch periodicities. In the case of the 5ms switch point periodicity, a specialsub-frame exists in both half frames. In the case of the 10 ms periodicity, the specialsubframe exists in the first half frame only. It can be seen from the table above that thesub-frames 0 and 5 as well as DwPTS are always reserved for the downlink. It canalso be seen that UpPTS and the sub-frame immediately following the specialsubframe are always reserved for the uplink transmission.


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4.5.4 Flexible Carrier Bandwidths

LTE is defined to support flexible carrier bandwidths from below 1.4MHz up to20MHz, in many spectrum bands and for both FDD and TDD deployments. Thismeans that an operator can introduce LTE in both new and existing bands.


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LTE supports a range of bandwidths up to 20 MHz, as depicted above. LTE alsosupports devices that can work on various system-bandwidth combinations, therefore

reducing the need to tailor specific device profiles to each combination. This allows anoperator to deploy LTE in 10 or 20 MHz combinations, without worrying aboutdevice-compatibility issues. LTE devices are mandated to support 20 MHz bandwidthin the DL and the UL. The available peak rates and average user rates for anindividual user, however, scale with the deployment bandwidth.

LTE supports both FDD and TDD modes, allowing operators to address all availablespectrum resources.


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4.6 Slot Structure and Physical Resources

The subcarriers in LTE have a constant spacing of f = 15 kHz. In the frequencydomain, 12 subcarriers form one resource block. The resource block size is the same forall bandwidths.

To each OFDM symbol, a cyclic prefix (CP) is appended as guard time. One downlinkslot consists of 6 or 7 OFDM symbols, depending on whether extended or normal cyclicprefix is configured respectively. The extended cyclic prefix is able to cover larger cellsizes with higher delay spread of the radio channel.


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Data symbols are independently modulated and transmitted over a high number ofclosely spaced orthogonal subcarriers. In E-UTRA, downlink modulation schemes

QPSK, 16QAM, and 64QAM are available.


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4.6.1 Transmission Bandwidths

LTE must support the international wireless market and regional spectrumregulations and spectrum availability. To this end the specifications include variablechannel bandwidths selectable from 1.4 to 20 MHz, with subcarrier spacing of 15 kHz.If the new LTE eMBMS is used, a subcarrier spacing of 7.5 kHz is also possible.Subcarrier spacing is constant regardless of the channel bandwidth.

3GPP has defined the LTE air interface to be "bandwidth agnostic," which allows theair interface to adapt to different channel bandwidths with minimal impact on systemoperation. The smallest amount of resource that can be allocated in the uplink ordownlink is called a resource block (RB). An RB is 180 kHz wide and lasts for one 0.5ms timeslot. For standard LTE, an RB comprises 12 subcarriers at a 15 kHz spacing,and for eMBMS with the optional 7.5 kHz subcarrier spacing an RB comprises 24subcarriers for 0.5 ms. The maximum number of RBs supported by each transmissionbandwidth is given above.


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4.7 Orthagonality

Depending on the required data rate, each UE can be assigned one or more resourceblocks in each transmission time interval of 1 ms. The scheduling decision is made inthe base station (eNodeB).


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For standard LTE, an RB comprises 12 subcarriers at a 15 kHz spacing, and foreMBMS with the optional 7.5 kHz subcarrier spacing an RB comprises 24 subcarriers

for 0.5 ms.


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4.7.1 Single-Frequency Network Multicast Services

LTE specifies a high-capacity multicast and broadcast service, using a single-frequency network (also called multicast-broadcast single-frequency network orMBSFN). As depicted above, all cells in the network (or a geographical area) transmittime-synchronized, identical DL signals. At the user terminal, these multiple time-synchronized transmissions appear as a single transmission with high signal strength,and thus can be easily decoded. In addition to the benefits of time-synchronisedtransmissions, the robustness of OFDM to multipath propagation ensures that theinter-cell interference is reduced.

The capacity benefits of the single-frequency network are highest when the samecontent is transmitted in all cells of the macro network.


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4.7.2 Single Carrier Frequency Division Multiple Access (SC-FDMA)

LTE has ambitious requirements for data rate, capacity, spectrum efficiency, andlatency. In order to fulfill these requirements, LTE is based on new technicalprinciples. LTE uses new multiple access schemes on the air interface: OFDMA(Orthogonal Frequency Division Multiple Access) in downlink and SC-FDMA (SingleCarrier Frequency Division Multiple Access) in uplink.

While OFDMA is seen optimum to fulfil the LTE requirements in downlink, OFDMAproperties are less favourable for the uplink. This is mainly due to weaker peak-to-average power ratio (PAPR) properties of an OFDMA signal, resulting in worse

uplink coverage.Thus, the LTE uplink transmission scheme for FDD and TDD mode is based on SC-FDMA (Single Carrier Frequency Division Multiple Access) with cyclic prefix. SC-FDMAsignals have better PAPR properties compared to an OFDMA signal. This was one ofthe main reasons for selecting SCFDMA as LTE uplink access scheme. The PAPRcharacteristics are important for cost-effective design of UE power amplifiers.


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4.8 Cyclic Prefix

In the time domain, a guard interval may be added to each symbol to combat inter-OFDM-symbol-interference due to channel delay spread. In EUTRA, the guardinterval is a cyclic prefix which is inserted prior to each OFDM symbol.

Delay spread is a type of distortion that is caused when an identical signal arrives atdifferent times at its destination. The signal usually arrives via multiple paths andwith different angles of arrival. The time difference between the arrival moment of thefirst multipath component (typically the Line of sight component) and the last one, iscalled delay spread.


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4.9 Delay Spread

The data to be transmitted on an OFDM signal is spread across the carriers of thesignal, each carrier taking part of the payload. This reduces the data rate taken byeach carrier. The lower data rate has the advantage that interference from reflectionsis much less critical. This is achieved by adding a guard band time or guard intervalinto the system. This ensures that the data is only sampled when the signal is stableand no new delayed signals arrive that would alter the timing and phase of the signal.

The distribution of the data across a large number of carriers in the OFDM signal hassome further advantages. Nulls caused by multi-path effects or interference on agiven frequency only affect a small number of the carriers, the remaining ones being

received correctly. By using error-coding techniques, which does mean adding furtherdata to the transmitted signal, it enables many or all of the corrupted data to bereconstructed within the receiver. This can be done because the error correction codeis transmitted in a different part of the signal. It is this error coding which is referredto in the "Coded" word in the title of COFDM which is often seen.


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To each OFDM symbol, a cyclic prefix (CP) is appended as guard time. One downlinkslot consists of 6 or 7 OFDM symbols, depending on whether extended or normal

cyclic prefix is configured, respectively. The extended cyclic prefix is able to coverlarger cell sizes with higher delay spread of the radio channel.


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4.10 Slot Structure and Physical Resources

Data is allocated to the UEs in terms of resource blocks, i.e. one UE can be allocatedinteger multiples of one resource block in the frequency domain. These resourceblocks do not have to be adjacent to each other. In the time domain, the schedulingdecision can be modified every transmission time interval of 1 ms. The schedulingdecision is done in the base station (eNodeB). The scheduling algorithm has to takeinto account the radio link quality situation of different users, the overall interferencesituation, Quality of Service requirements, service priorities, and so on.


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4.11 Scheduler

Scheduler in eNB (base station) allocates resource blocks (which are the smallestelements of resource allocation) to users for predetermined amount of time. Slotsconsist of either 6 (for long cyclic prefix) or 7 (for short cyclic prefix) OFDM symbolsLonger cyclic prefixes are desired to address longer fading. The number of availablesubcarriers changes depending on transmission bandwidth (but subcarrier spacing isfixed).


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Round Robin

The aim of this scheduler is to share the available/unused resources equally amongthe RT terminals (i.e. the terminals requesting RT services) in order to satisfy their RT-MBR demand.

This is a recursive algorithm and continues to share resources equally among RTterminals, until all RT-MBR demands have been met or there are no more resourcesleft to allocate

Proportional Fair

The aim of this Scheduler is to allocate the available/unused resources as fairly aspossible in such a way that, on average, each terminal gets the highest possiblethroughput achievable under the channel conditions.

This is a recursive algorithm. The remaining resources are shared between the RTterminals in proportion to their bearer data rates. Terminals with higher data rates geta larger share of the available resources. Each terminal gets either the resources itneeds to satisfy its RT-MBR demand, or its weighted portion of the available/unusedresources, whichever is smaller. This recursive allocation process continues until allRT-MBR demands have been met or there are no more resources left to allocate.


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Proportional Demand

The aim of this scheduler is to allocate the remaining unused resources to RT

terminals in proportion to their additional resource demands. This is a non-recursiveallocation process and results in either satisfying the RT-MBR demands of allterminals or the consumption of all of the resources.


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Max SINR

The aim of this Scheduler is to maximise the terminal throughput and, in turn, theaverage cell throughput. This is a non-recursive resource allocation process, whereterminals with higher bearer rates (and consequently higher SINR) are preferred overterminals with lower bearer rates (and consequently lower SINR). This means thatresources are allocated first to those terminals with better SINR/channel conditions,thereby maximising the throughput.


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4.12 ASSET - LTE


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4.13 Downlink Data Transmission

Data is allocated to the UEs in terms of resource blocks. A physical resource blockconsists of 12 (24) consecutive sub-carriers in the frequency domain for the Nf=15 kHz(Nf=7.5 kHz) case. In the time domain, a physical resource block consists of DLNsymb consecutive OFDM symbols, DL Nsymb is equal to the number of OFDMsymbols in a slot.

Depending on the required data rate, each UE can be assigned one or more resourceblocks in each transmission time interval of 1 ms. The scheduling decision is done inthe base station (eNodeB).


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The user data is carried on the Physical Downlink Shared Channel (PDSCH).


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4.14 Modulation and Subcarriers


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4.15 Downlink Reference Signal Structure


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4.15.1 Configuration of Carrier


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4.16 Reference Signal Received Power (RSRP)

Reference Signal Received Power (RSRP), is determined for a considered cell as thelinear average over the power contributions (in [W]) of the resource elements thatcarry cell-specific reference signals within the considered measurement frequencybandwidth. For RSRP determination, the cell-specific reference signals R0 and, ifavailable, R1

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