9400 lte ran radio principles...

9400 LTE Radio Principles - All Rights Reserved © Alcatel-Lucent 2009

All Rights Reserved © Alcatel-Lucent 2009

9400 LTE RAN Radio PrinciplesDescription

STUDENT GUIDE

TMO18214 D0 SG DEN Issue 4

All rights reserved © Alcatel-Lucent @@YEAR Passing on and copying of this document, use and communication of its

contents not permitted without written authorization from Alcatel-Lucent



9400 LTE RAN Radio Principles Description

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Course Outline

About This CourseCourse outline

Technical support

Course objectives

1. Topic/Section is Positioned HereXxx

Xxx

Xxx

2. Topic/Section is Positioned Here






1. Introduction

1.1 Why the 3G LTE ?

1.2 Standardization

1.3 Key Differentiators

2. OFDMA Principles

2.1 Modulation

2.2 OFDMA Basic Concepts

2.3 OFDMA Transmitter and Receiver

2.4 SC-FDMA in UL

2.5 OFDMA and LTE

3. Air Interface Structure

3.1 Radio Frame Structure

3.2 Protocol Stack

3.3 Radio Channels

4. eUTRAN Scenarios

4.1 RRC Connection Scenarios

4.2 E-RAB and QoS

4.3 Traffic Operation

5. LTE Antenna System

5.1 Introduction

5.2 MIMO and Co

5.3 Beamforming

6. Mobility Management

6.1 Introduction

6.2 Handover

6.3 Idle Mode




6

Course Outline [cont.]






7

Course Objectives


Welcome to 9400 LTE RAN Radio Principles Description

Upon completion of this course, you should be able to:

This course provides a foundation of knowledge to understand the radio principles of the 3G

LTE. This course is designed to enable you to:

* Explain what are the drivers of the LTE and what are the key differentiators of the LTE

standard* Explain what is the principle of the LTE layer 1, the OFDMA.

* Describe the structure of the radio frame and how the channels (logical, transport and

physical) are mapped on to the resources

* List and describe the steps of the RRC connection

* Describe the bearer establishment and all the radio operations required during the traffic

* Describe the different antenna systems available and explain their interest

* Describe the mechanism of mobility with the handover and with the idle mode and the

paging




8

Course Objectives [cont.]






9

About this Student Guide

� Switch to notes view!Conventions used in this guide

Where you can get further information

If you want further information you can refer to the following:

� Technical Practices for the specific product

� Technical support page on the Alcatel website: http://www.alcatel-lucent.com

Note

Provides you with additional information about the topic being discussed.

Although this information is not required knowledge, you might find it useful

or interesting.

Technical Reference (1) 24.348.98 – Points you to the exact section of Alcatel-Lucent Technical

Practices where you can find more information on the topic being discussed.

WarningAlerts you to instances where non-compliance could result in equipment

damage or personal injury.




10

About this Student Guide [cont.]

� Switch to notes view!





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Self-assessment of Objectives

� At the end of each section you will be asked to fill this questionnaire

� Please, return this sheet to the trainer at the end of the training


Instructional objectives Yes (or globally yes)

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Comments

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Tick the corresponding box

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Self-assessment of Objectives [cont.]


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Do not delete this graphic elements in here:


1 Module 1Introduction





9400 LTE RAN Radio Principles DescriptionIntroduction

1 � 2

Blank Page


First editionOlivier Guivarc’h2009-0801

RemarksAuthorDateEdition

Document History




1 � 3

Module Objectives

Upon completion of this module, you should be able to:

� List the drivers of the 3G LTE

� Explain the context of the standardization of the 3G LTE

� Describe the services provided to the End User

� Give an estimation of the performance of the LTE

� List the key differentiators compared to the other Radio Access technologies




1 � 4

Module Objectives [cont.]





1 � 5

Table of Contents

Switch to notes view!Page

1 Why 3G LTE? 71.1 Market Trends 81.2 3G Limitations 101.3 3G LTE Requirements 11

2 Standardization 122.1 What is the 3GPP? 132.2 3GPP Release 152.3 3GPP Performance 162.4 3GPP Web Site 17

3 Key Differentiators 183.1 Key Differentiators 193.2 Architecture 20




1 � 6

Table of Contents [cont.]






1 � 7

1 Why 3G LTE?




1 � 8

1 Why 3G LTE?

1.1 Market Trends

� The trend of the market is an increase and an acceleration of the data mobile traffic in the next years.

� This has been possible thanks to the introduction of:

� EV-DO with CDMA2000

� HSDPA and HSUPA with WCDMA

Mobile Data Traffic Evolution

With the recent introduction of HSDPA and EV-DO Rev A, there has been a significant increase in mobile data

traffic, with some operators quadrupling their Packet Switched traffic in one year. At this growth rate, and

with the proliferation of new applications on the network, cells in hot pots will be quickly saturated and the

network will require densification in these overloaded areas. This can be delivered by using a higher capacity

solution such as LTE. Mobile traffic growth is illustrated on this slide: mobile data traffic (in Gigabits per

year), with a typical operator in a western country with a 60 million population.




1 � 9

1 Why 3G LTE?

1.1 Market Trends [cont.]

� Mobile phone user population is estimated to increase to 4 billion by 2011.

� Fixed Broadband application, massively adopted, can be exported to the mobile environment.

� The millennial generation will spread in the next years their “early adopters” way of life.

� The richer ecosystem of devices allows one to be connected all the time:

� PDA, laptop, mobile phone, USB device

All these trends require some radio access networks able to carry more and more data with stringent

requirements in terms of QoS (minimum bit rate, delay, etc.).




1 � 10

DL: 100Mbps &

UL: 50 Mbps

OFDM & Long symbolDuration

5MHz Spectrum

Highly sensitive to Frequency

Selective Fading

1 Why 3G LTE ?

1.2 3G Limitations and LTE Response

DL: 14.4Mbps DL & UL:5.7Mbps

1.4MHz, 3Mhz, 5MHz, 10MHz,

15MHz and 20 MHz

3G

LTE

Advantages of LTE:

� Reduce the network nodes to 2 instead of 3 as compared to previous technologies (RNC + nodeB

merged into one eNodeB component): lower latency

� Based of OFDM RF transmission technology

� One single Core Network (voice applications moved to packet core network)

� IP-based network

� Scalable system bandwidth offers deployment flexibility




1 � 11

1 Why 3G LTE ?

1.3 3G LTE Requirements

� Spectrum efficiency

� DL : 3-4 times

� UL : 2-3 times

� Frequency Spectrum

� Scalable bandwidth : 1.4, 3, 5, 10, 15, 20MHz

� To cover all frequencies of IMT-2000: 450 MHz to 2.6 GHz

� Peak data rate

� DL : > 100Mb/s for 20MHz spectrum allocation

� UL : > 50Mb/s for 20MHz spectrum allocation

� Latency

� C-plane : < 100ms to establish U-plane

� U-plane : < 10ms from UE to server

� Coverage

� Performance targets up to 5km, slight degradation up to 30km

� Mobility

� LTE is optimized for low speeds 0-15km/h but

� connection maintained for speeds up to 350 or 500km/h

� Handover between 3G & 3G LTE

� Real-time < 300ms

� Non-real-time < 500ms

LTE is aimed at minimizing cost and power consumption while ensuring backward-compatibility and a cost

effective migration from UMTS systems. Enhanced multicast services, enhanced support for end-to-end

Quality of Service (QoS) and minimization of the number of options and redundant features in the

architecture are also being targeted.

The spectral efficiency in the LTE DownLink (DL) will be 3 to 4 times of that of Release 6 HSDPA while in the

UpLink (UL), it will be 2 to 3 times that of Release 6 HSUPA. The handover procedure within LTE is intended

to minimize interruption time to less than that of circuit-switched handovers in 2G networks. Moreover the

handovers to 2G/3G systems from LTE are designed to be seamless.

bsaffach

Note

Bandwidth: Pour definir la capacité de la cellule

bsaffach

Note

Carrier Frequency: Pour définir la couverture de la Cellule




1 � 12

2 Standardization




1 � 13

2 Standardization

2.1 What is the 3GPP?

� 3GPP Specified Radio Interfaces

� 2G radio: GSM, GPRS, EDGE

� 3G radio: WCDMA, HSPA, LTE

� 4G radio: LTE Advanced

� 3GPP Core Network

� 2G/3G: GSM core network

� 3G/4G: Evolved Packet Core (EPC)

� 3GPP Service Layer

� GSM services

� IP Multimedia Subsystem (IMS)

� Multimedia Telephony (MMTEL)

� Support of Messaging and other OMA functionality

� Emergency services and public warning

� Etc.

The 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunication associations, to make a globally applicable third generation 3G mobile phone system specification within the scope of the International Mobile Telecommunication-2000 project of the International Telecommunication Union (ITU). 3GPP specifications are based on evolved Global Systel for Mobile Communication (GSM) specifications. 3GPP standardization encompasses Radio, Core Network and Service architecture.

The groups are the European Telecommunications Standarts Institute, Association of Radio Industries and Businesses/Telecommunication Technology Committee (ARIB/TTC) (Japan), Alliance for Telecommunications Industry Solutions (North America) and (South Korea). The project was established in December 1998.

3GPP should not be confused with 3rd Generation Partnership Project 2 (3GGP2), which specifies standards for another 3G technology based on IS-95 (CDMA), commonly known as CDMA2000.

The 3GPP has specified the following standards:

� GSM

� GPRS

� GERAN

� WCDMA

� HSPA (HSDPA and HSUPA)

3GPP2 was born out of the International Telecommunication Union's (ITU) International Mobile Telecommunications “IMT-2000” initiative, covering high speed, broadband, and Internet Protocol (IP)-based mobile systems featuring:

� network-to-network interconnection,

� feature/service transparency,

� global roaming,

� seamless services independent of location.

IMT-2000 is intended to bring high-quality mobile multimedia telecommunications to a worldwide mass market by achieving the goals of increasing the speed and ease of wireless communications, responding to the problems faced by the increased demand to pass data via telecommunications, and providing "anytime, anywhere" services.

bsaffach

Note

IEEE: standard du Wimax




1 � 14

2 Standardization

2.2 3GPP Release Concept

201120102009200820072006200520042003200220012000

R99 R4 R5 R6 R7 R8 R9 R10

HighSpeed

Accesses

IP CoreNetwork

Services

UM

TS

HS

PA

DL

HS

PA

UL

LTE

LTE

Adv

HS

PA

+

EP

C

Com

mIM

S

IMS

MM

Tel

Each release incorporates hundreds of individual standards documents, each of which may have been through

many revisions 3GPP web site:

� http://www.3gpp.org

All the specifications are free.

� http://www.3gpp.org/ftp/Specs/html-info/36-series.htm

� Series 36 defines 3G LTE.

� TS 36.201

� Evolved Universal Terrestrial Radio Access (E-UTRA); Long Term Evolution (LTE) physical layer ->

General description

� TS 36.300

� Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access

Network (E-UTRAN) -> Overall description

bsaffach

Note

R99: débit => 384Mbps ou 128 Mbps/user Une seule modulation: QPSK

bsaffach

Note

R99: débit => 14,4 Mbps/cellule 2 Modulations: ¨QPSK & 16QUAM

bsaffach

Note

EPC: Evolved Packet Core. Pren la place du SGSN La spec 3GGP pour EPC: série 23




1 � 15

3 Key Differentiators




1 � 16


3.1 Key LTE Features to Overcome Challenges

A common evolution…

OFDM MIMO Flat IP

Robust modulation in dense

environmentsOFDMA (DL) / SC-FDMA (UL)

Increased spectral efficiency. Simplified Rx design cheaper

UE Scalable - go beyond 5 MHz limitation

Increased link capacity

Multiple-input, multiple-output UL& DL.

Collaborative MIMO (UL). Overcome multi-path

interference

Flat, scalableShort TTI: 1 ms (2 ms for HSPA). Backhaul based on IP / MPLS transport. Fits

with IMS, VoIP, SIP

L

T

E

GSM/UMTS

GSM/EDGE

GSM/EDGE

1X/EV-DO RevA

1X/EV-DO RevA

B/A+

HSPA+

UMTS/HSPA+

TD-SCDMA

WIMAX

…introducing highly efficient technologies

4G“3.9G”3G

IMT-Advanced family

Definition in progress by ITU-R

IMT-2000 family

•100 Mbps peak, mobile

•1 Gbps peak, fixedLTE introduces the building blocks of 4G

1.4MHz 3MHz 20MHz10MHz5MHz

LTE bandwidths options

CDMA2000 1X

LTE introduced in Rel 8

� Minor improvements in Rel 9 and Rel 10

Significantly increased data throughput

� Downlink target 3-4 times greater than HSDPA Release 6

� Uplink target 2-3 times greater than HSUPA Release 6

Increased cell edge bit rates

� Downlink: 70% of the values at 5% of the Cumulative Distribution Function (CDF)

� Uplink: same values at 5% of the Cumulative Distribution Function (CDF)

Significantly reduced latency

High mobility

Cell ranges up to 5 km; with best throughput, spectrum efficiency and mobility. Cell ranges up to 30 km;

Mobility with some degradation in throughput and spectrum efficiency permitted. Cell ranges up to 100 km;

Supported; degradations accepted

bsaffach

Note

4G: doit fournir en débit 1Gbps/cellule




1 � 17


3.2 Architecture

EPS = eUTRAN + ePC

� Long Term Evolution (LTE) is the newest 3GPP standard for mobilenetwork technology.

P-GWS-GW

HSS

PDN

MGW

IMS

Transport

PCRF

PSTN

User and control

Control only

LTE

OFDM

SC-FDMA

eUTRAN

ePC

All-IP network carries all types of traffic, including VoIP.

Provides control functions for LTE access networks.

Routes and forwards user data packets to eNodeB.

Connects UE to external packet data networks.

Controls QoS policy for each service data flow that passes through the SGW and PGW.

IMS network provides services, including VoIP.

S1-MME

S1-U S5/S8

Gx

SGi

SGi

S6a

S11

MME

x2

Gxc

� The goal of the System Architecture Evolution (SAE) effort in 3GPP is to develop a framework for the

evolution and migration of current systems to a system which supports the following:

� high data rates

� low latency

� packet-optimized (all IP network)

� provides service continuity across heterogeneous access networks

bsaffach

Note

PCRF: Policy Charging Route Function => assure le PCC: Policy Charging Control

bsaffach

Note

HSS: contient HLR




1 � 18

End of ModuleIntroduction



2All Rights Reserved © Alcatel-Lucent 2009

Module 2OFDMA Principles





9400 LTE RAN Radio Principles DescriptionOFDMA Principles

2 � 2

Blank Page


First editionLast name, first nameYYYY-MM-DD01


Document History




2 � 3

Module Objectives


� Explain the basic concepts of OFDM

� Describe a basic OFDMA transmitter and receiver

� Explain the application of OFDMA in LTE

� Describe the modulation used in 3G LTE




2 � 4






2 � 5

Table of Contents


1 Modulation 71.1 Introduction 81.2 Modulation in LTE 101.3 Constellation 111.4 Link Adaption & Robustness 14

2 OFDMA Basic Concepts 162.1 Carrier and Bandwidth 182.2 OFDMA principles 202.3 Notion of Orthogonality 252.4 LTE Sub-carrier 302.5 Inter-symbol interference 32

3 OFDMA Transmitter and Receiver 363.1 OFDMA Transmitter 373.2 OFDMA Receiver 41

4 SC-FDMA in UL 424.1 Difference between DL and UL 434.2 Benefits 44

5 OFDMA and LTE 455.1 OFDMA parameter for LTE 46




2 � 6







2 � 7

1 Modulation




2 � 8

1 Modulation

1.1 Introduction

� A baseband signal can not be sent directly to an antenna

� The signal is not broadcast over the air interface

� The baseband signal or “message” is carried by a carrier over the air interface

� The carrier is modulated by the baseband signal by the transmitter and demodulated by the receiver

message

transmitted signal

carrier

Modulator Demodulatormessage

Transmitter Receiver

The modulation allows one to mix the message and the carrier

There are 3 ways to modulate the carrier:

� The amplitude: the receiver can identify the bit by analyzing the amplitude

� The frequency

� The phase




2 � 9

1 Modulation

1.2 Modulation in LTE

� The 3G LTE uses 3 Quadrature Amplitude Modulations (QAMs) depending on the radio quality.

� QAM uses both the amplitude and the phase.

� The LTE supports in DL and UL the following modulations:

� QPSK, the most robust but the less efficient

� 16-QAM

� 64-QAM, the less robust but the most efficient

Data bits 0 1 0 0 1

Unmodulated carrier

Amplitude Modulation (AM)

Frequency Modulation (FSK)

(Differential) Phase Modulation (DPSK)

QAM is a modulation method modifying the phase and the amplitude of the carrier signal.

QAM symbols are represented by the carrier signal being transmitted with specific phase / amplitude

(dictated by the message), for finite periods of time.

One symbol is identified by a Q and an I value.

Transmission channels with a limited bandwidth limit the amount of symbols per second (Baud rate) that can

be transmitted.

To increase the bit per sec (bps) capacity of a channel, while keeping the Baud rate at the low values imposed

by the channel bandwidth, the symbols carry (represent) more than one single bit.

Symbols will represent a number of n bits, increasing the channel capacity by a factor of n.

The price paid is the presence of multiple symbols in the channel, increasing the probability of incorrect

symbol identification at the receiver.

bsaffach

Note

Modulation utilisée si le mobile est au centre de la Cellule

bsaffach

Note

Modulation utilisée si le mobile est en bordure de Cellule

bsaffach

Note

Modulation utilisée si le mobile est proche de l'eNB




2 � 10

1 Modulation

1.3 Constellation

� The QPSK is the most robust modulation. It can be represented by a constellation:

� The radius, R, represents the amplitude.

� The angle, φ, represents the phase.

I

Q

R

φ

� There are 1 amplitude but 4 phases to 4 different states.

� 2 bits can be coded with 1 QPSK symbol.

00

0111

10

By analyzing the phase and the amplitude, the receiver

can identify the bits

01 11




2 � 11

1 Modulation

1.3 Constellation [cont.]

� The 16-QAM can modulate 4 bits per symbol.

modulation technique

nu

mb

er o

f sy

mb

ols

nu

mb

er o

f b

its

per

sym

bo

l

bit

rat

e / B

aud

ra

te

number of

amp

litu

des

ph

ases constellation

4QAM (QPSK)

24 2/1 1 4

01 11

00 10

Q

I-1 +1+1

-1

16QAM 416 4/1 3 12

not all combinations are

used

0010 0110 1110 1010

0011 0111 1111 1011

0011 0101 1101 1001

0000 0100 1100 1000

Q

I-1-3 +3+1

+3

+1

-1

-3




2 � 12

000101 001101 011101 010101 110101 111101 101101 100101

000111 001111 011111 010111 110111 111111 101111 100111

000110 001110 011110 010110 110110 111110 101110 100110

000010 001010 011010 010010 110010 111010 101010 100010

000011 001011 011011 010011 110011 111011 101011 100011

000001 001001 011001 010001 110001 111001 101001 100001

000000 001000 011000 010000 110000 111000 101000 100000

000100 001100 011100 010100 110100 111100 101100 100100

Q

I-1-3-5-7 +7+5+3+1

+3

+5

+7

+1

-1

-3

-5

-7

1 Modulation

1.3 Constellation [cont.]

� The 64-QAM can modulate 6 bits per symbol.

modulation technique

nu

mb

er o

f sy

mb

ols

nu

mb

er o

f b

its

per

sym

bo

l

bit

rat

e / B

aud

ra

te

number of

amp

litu

des

ph

ases constellation

64QAM 664 6/1 9 52

not all combinations are

used




2 � 13

1 Modulation

1.4 Link Adaption & Robustness

� In reception, it may be difficult to make the distinction between 2 states, i.e. 2-bit sequence. If the wrong state is selected, there are errors of reception.

000101 001101 011101 010101 110101 111101 101101 100101

000111 001111 011111 010111 110111 111111 101111 100111

000110 001110 011110 010110 110110 111110 101110 100110

000010 001010 011010 010010 110010 111010 101010 100010

000011 001011 011011 010011 110011 111011 101011 100011

000001 001001 011001 010001 110001 111001 101001 100001

000000 001000 011000 010000 110000 111000 101000 100000

000100 001100 011100 010100 110100 111100 101100 100100

Q

I-1-3-5-7 +7+5+3+1

+3

+5

+7

+1

-1

-3

-5

-7

The use of higher-order modulation provides the possibility for higher bandwidth utilization, that is the

possibility to provide higher data rates within a given bandwidth.




2 � 14

1 Modulation

1.4 Link Adaption & Robustness

� Before processing the data (bit stream) to send it on the air interface, the transmitter performs the encoding, to be able to detect or correct errors of reception.

� The amount of parity bits is defined by a rate, called coding rate

10011100

Bit stream

Encoder 1101011111110101

Parity bits

2

1==rofBitTotalNumbe

efulBitNumberOfUsCodingRate

If the coding rate = ½, the number of bits

transmitted on the air interface is multiplied

by 2

The typical coding rates are ½, 2/3, ¾.

The coding methods are:

� Convolutional

� Turbo




2 � 15

1 Modulation

1.4 Link Adaption & Robustness [cont.]

� The combination of the modulation and the channel coding (identified by its rate) forms one of the possible Modulation and Coding Schemes

� The link adaptation is done by the selection of the most adapted modulation to the current radio conditions.

64 QAM

16 QAM

QPSK

Radio Quality

Spectrum efficiency

The 3GPP defines 32 possible MCS

MCS corresponding to the CQI index such that the PDSCH could be received with a transport block error

probability not exceeding 10 %

The best modulation does not always give the best performance. If the radio quality is not good enough, the

receiver is not able to correctly decode the modulation. It may be more efficient to select a less robust

modulation depending on the radio quality.

Coding rate = (transport Block Size + number of CRC bits)/number of bits transmitted on RF interface

bsaffach

Note

MCS: Modulation Coding Scheme. Calculé par l'eNB qui tient compte de la modulation (les condition radio du mobile dans la Cellule) auquel eNB rajoute un coding rate. La 3GPP définit 30 MCS En DL: QPSK 16QAM & 64 QAM En UL: QPSK & 16QAM




2 � 16

2 OFDMA Basic Concepts




2 � 17


2.1 Carrier and Bandwidth

� TDD = Time Division Duplex

� The Uplink and the downlink transmissions are separated by the time.

� Only one bandwidth is used.

� Example: WiMAX

frequency DLtime

UL DL UL

� FDD = Frequency Division Duplex

� The Uplink and the downlink transmissions are separated by the frequency.

� 2 bandwidths are used.

� Example: WCDMA, CDMA2000

frequency

DL

UL DL timeUL

frequency

The LTE PHY is a highly efficient means of conveying both data and control information between an enhanced

base station (eNodeB) and mobile user equipment (UE). The LTE PHY employs some advanced technologies

that are new to cellular applications. These include Orthogonal Frequency Division Multiplexing (OFDM) and

Multiple Input Multiple Output (MIMO) data transmission.

Although the LTE specs describe both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD)

to separate UL and DL traffic, market preferences dictate that the majority of deployed systems will be

FDD.




2 � 18


2.1 Carrier and Bandwidth [cont.]

� The 3GPP specifies that the 3G LTE can be deployed in the existing IMT-2000 frequency bands.

� IMT-2000 bands: from 450 MHz to 2.6 GHz� Including WCDMA/HSPA, CDMA2000/EV-DO, and GSM bands

Band 7 (2,6 Ghz)

DLUL

2500 2570 2620 2690

Frequency(MHz)

� The bandwidth is more flexible than in the previous 3GPP standards.

� Scalable from 1.4, 3, 5, 10, 15, 20MHz

� The capacity of a cell depends strongly on its allocated bandwidth.

Frequency

5 MHz 10 MHz 20 MHz

The FDD frequency bands are paired to allow simultaneous transmission on two frequencies. The bands also

have a sufficient separation to enable the transmitted signals not to unduly impair the receiver performance.

If the signals are too close then the receiver may be "blocked" and the sensitivity impaired. The separation

must be sufficient to enable the roll-off of the antenna filtering to give sufficient attenuation of the

transmitted signal within the receive band.

With the interest in TDD LTE, there are several unpaired frequency allocations that are being prepared for

LTR TDD use. The TDD LTE allocations are unpaired because the uplink and downlink share the same

frequency, being time multiplexed.




2 � 19



� e-UTRAN is designed to operate in the frequency bands defined in the following table:

Spectral efficiency is increased by up to four-fold compared with UTRA, and improvements in architecture and

signalling reduce round-trip latency. Multiple Input / Multiple Output (MIMO) antenna technology should

enable 10 times as many users per cell as 3GPP’s original W CDMA radio access technology.

To suit as many frequency band allocation arrangements as possible, both paired (FDD) and unpaired (TDD)

band operation is supported. LTE can co-exist with earlier 3GPP radio technologies, even in adjacent

channels, and calls can be handed over to and from all 3GPP’s previous radio access technologies

bsaffach

Note

Band 1 : Carrier Frequency of 3G




2 � 20



� The supported carrier depends on the eNodeB hardware

� Bandwidth examples:

2.1 GHz

Frequency(MHz)

700 MHz

900 MHz1800 MHz

1GHz 2GHz

2.6 GHz

f

5 MHz 10 MHz

f

5 MHz 10 MHz

UL Band DL Band




2 � 21


2.2 OFDMA Principles

� There are several ways to transmit over the frequency band and to share the resource between several devices.

FDMA• The users are

separated by the frequency

• The 3G LTE used an improved FDMA called OFDMA

TDMA• The users are

separated by the the time

• Used by the GSM

CDMA• The users are separated

by the codes. They receive data at the same time at the same frequency.

• Used in the CDMAOne, CDMA200 and WCDMA

bsaffach

Note

TDMA: Time Division Multipe Access

bsaffach

Note

CDMA: Code Division Multiple Access

bsaffach

Note

FDMA: Frequency Division Multiple Access OFDMA: Othogonal Frequency Division Multiple Access




2 � 22


2.3 Notion of Orthogonality

� In FDM, the sub-carriers are separated in the frequency domain to avoid interference between the sub-channels

� It results in a loss of spectrum efficiency because the frequency guard band can not be used to send data.

� The OFDM allows one to remove the frequency guard band.

� Benefit: There are more sub-carriers, so more symbols are sent at the same time. The orthogonality brings a better spectrum efficiency.

5 MHz

Frequency guard band

5 MHz

In OFDM, the sub-carrier frequencies are chosen so that the sub-carriers are orthogonal to each other,

meaning that cross-talk between the sub-channels is eliminated and inter-carrier guard bands are not

required. This greatly simplifies the design of both the transmitterand the receiver; unlike conventional FDM a

separate filter for each sub-channel is not required.

The orthogonality requires that the sub-carrier spacing is ∆f = k/(TU) Hertz, where TU seconds is the useful

symbol duration (the receiver side window size), and k is a positive integer, typically equal to 1. Therefore,

with N sub-carriers, the total passband bandwidth will be B ≈ N�∆f (Hz).




2 � 23


2.3 Notion of Orthogonality [cont.]

� That leads to the representation of a sub-carrier.

Temporal domainFrequency domain

1/T2

T2

T1/T

� The duration of the symbol depends on the width of the sub-carrier.

� It is inversely proportional. The shorter the symbol, the wider the sub-carrier and vice-versa.

� The frequency center of the sub-carrier is linked to the frequency of the carrier.




2 � 24


2.3 Notion of Orthogonality [cont.]

� The inter-channel (or inter sub-carrier) interferences are cancelled because they are located in a such way that when there is the peak for a given sub-carrier, the adjacent subcarriers are null.

4 5 6 7 8 9

x 105

-0.2

0

0.2

0.4

0.6

0.8

1

The red and the blue sub-carriers are crossing the zero point when the green

one is at its maximum

� OFDM allows high density of carriers, without generating Inter-Channel Interference (ICI).

BASIC IDEA : The channel bandwidth is divided into multiple subchannels to reduce ISI and frequency-selective

fading.

� A single wideband signal is transformed into multiple narrow band signals transmitted on orthogonal sub-

carriers

� One single stream at high rate

� Each symbol occupies the whole bandwidth

� Very short symbol duration to ensure high rate




2 � 25


2.4 LTE Sub-carrier [cont.]

� There are different kinds of sub-carriers:

� Data sub-carrier

� Pilot Sub-carrier

� DC sub-carrier

� Guard Sub-carrier

DC sub-carrier Pilot Sub-carrierData sub-carriers

Bandwidth from 1.4 to 20 MHz

DC stands for Direct Current and it is a subcarrier that has no information sent on it. This is an important

subcarrier in OFDM based systems. It is used by the mobile device to locate the center of the OFDM frequency

band. So, if LTE does not have a DC subcarrier, it would be a big deal .

bsaffach

Note

Sub-Carrier centrale utilisée lorsque le mobile s'alume pour se caler

bsaffach

Note

Sub-Carrier de référence utilisée pour faire des mesures




2 � 26


2.5 Inter-Symbol Interference

� What is the multipath?

� Due to the signal propagation phenomena, like reflection or diffraction, a receiver can receive several delayed versions of the same signal.

� This creates Inter-Symbol Interference (ISI).

eNode-B

t

Symbol Duration

t

Symbol Duration

Inter-symbol interference

The multi-path impact is an overlapping of 2 symbols, called Inter-Symbol Interference (ISI).

The modulation is based on the amplitude and on the phase, so in case of overlapping there are 2 different

amplitudes and phases.

The receiver is not able to decode the state of the symbol.

bsaffach

Note

MultiPath: chemin multiple que prend le signal lorsqu'il se propage




2 � 27


2.6 Cyclic Prefix

� The problem is fixed by adding a guard time between each symbol to avoid the ISI.

� The ISI is still present but is not disturbing for the receiver.

Principle : add a prefix to absorb channel effect and avoid ISI

� Cyclic prefix permits to facilitate demodulation

� The cyclic prefix transform the classical channel convolution into a cyclic convolution which permits easy

demodulation after FFT




2 � 28


2.5 Inter-Symbol Interference [cont.]

� The guard time is called the Cyclic Prefix (CP). It permits to facilitate demodulation.

� The cyclic prefix transforms the classical channel convolution into a cyclic convolution which permits easy demodulation after FFT.

Symbol Duration

Copy Copy

Useful OFDM symbol




2 � 29

3 OFDMA Transmitter and Receiver




2 � 30


3.1 OFDMA Transmitter

10 01

Bit stream SerialTo

Parallel

Add CPEncoding

Interleaving

11010111With a coding

rate ½

Data protection

Digital Modulation

2 bits per symbol with QPSK

“11” carried by the Sub-Ca #1




Add CP

ODFMA symbol

SerialTo

Parallel&

ChannelMapping

iFFT

Frequency to time domain

In the downlink, OFDM is selected to efficiently meet E-UTRA performance requirements. With OFDM, it is

straightforward to exploit frequency selectivity of the multi-path channel with lowcomplexity

receivers. This allows frequency selective in addition to frequency diverse scheduling and one cell reuse of

available bandwidth.

Furthermore, due to its frequency domain nature, OFDM enables flexible bandwidth operation with low

complexity. Smart antenna technologies are also easier to support with OFDM, since

each sub-carrier becomes flat faded and the antenna weights can be optimized on a per sub-carrier (or block

of sub-carriers) basis.

In addition, OFDM enables broadcast services on a synchronized single frequency network (SFN) with

appropriate cyclic prefix design.

This allows broadcast signals from different cells to combine over the air, thus significantly increasing the

received signal power and supportable data rates for broadcast services.

bsaffach

Note

Inter-leaving: mélanger l'ordre des bits avant la transmission




2 � 31


3.2 OFDMA Receiver

Synchronization Remove CP FFT Sub-Carrier Demapping

Signal in baseband

Demodulation

De-interleavingDecoding1001

Bit stream

Time to frequency domain

bsaffach

Note

Decoding == enlever le coding rate (les bits en plus)




2 � 32

4 SC-FDMA in UL




2 � 33

� OFDMA

� Advantages

� Robust against narrow-band co-channel interference

� Robust against Intersymbol interference (ISI) and fading

� High spectral efficiency

� Efficient implementation using FFT

� Drawbacks

� High Peak-to-Average Power Ratio

4 SC-FDMA in UL

4.1 Difference between DL and UL

The power limitation is more problematic in UL than in DL

Signal with high PAPR will limit the Tx power in UL and reduce coverage




2 � 34

LTE uses in UL a modified form of OFDMA process, called SC-FDMA� SC-FDMA = Single Carrier – Frequency Division Multiple Access

� SC-FDMA improves the peak-to-average power ratio (PAPR) compared to OFDM� Reduced power amplifier cost for mobile

� Reduced power amplifier back-off � improved coverage

eNode-B

DL : OFDMA

UL : SC-FDMA

4 SC-FDMA in UL

4.1 Difference between DL and UL

t

Amplitude

t

Amplitude

t

Amplitudet

Amplitude

+

+

In DL, use OFDM together with some PAPR reduction techniques (“clipping and filtering”, “tones reservation”,

etc…)

In UL, find an alternative to OFDM combining some of OFDM’s advantages, but with a PAPR equivalent to

single carrier’s one: DFT-Spread OFDM (DFT-SOFDM), also known as Single-Carrier FDMA (SC-FDMA)




2 � 35

4 SC-FDMA in UL

4.2 Benefits

� DFT spreading of modulation symbols reduces PAPR

� In OFDM, each modulation symbols “sees” a single 15 kHz subcarrier (flat channel)

� In SC-FD-A, each modulation symbol “sees” a wider bandwidth (i.e. m x 180 KHz)

� Equalization is required in the SC-FDMA receiver

OFDMA Sub-carriers SC-FDMA Sub-carriers

5 or 10 MHz

DFT-spread OFDM (DFTS-OFDM) is a transmission scheme that can combine

the desired properties discussed in the previous sections, i.e.:

• Small variations in the instantaneous power of the transmitted signal (‘singlecarrier’ property).

• Possibility for low-complexity high-quality equalization in the frequency domain.

• Possibility for FDMA with flexible bandwidth assignment.

Due to these properties, DFTS-OFDM has been selected as the uplink transmission scheme for LTE




2 � 36

5 OFDMA and LTE




2 � 37

5 OFDMA and LTE

5.1 OFDMA Parameter for LTE

� The width of a Sub-carrier is 15 kHz whatever the bandwidth

� The bandwidths are: 1.4, 3, 5, 10, 15 and 20 MHz

� Note that in LA1.1, only 5, 10 MHz are implemented

5 MHz 10 MHz

… …

15 kHz Sub-carrier

� The symbol duration is always the same whatever the bandwidth

� There are 2 times more sub-carriers in 10 MHz than in 5 MHz

� 2 times more symbols can be sent or received at the same time.

� The capacity is multiplied by 2

Reduced subcarrier spacing of 7.5 KHz for MBSFN operation also supported

• Center subcarrier (DC subcarrier) not used to allow for direct conversion receiver implementation




2 � 38

5 OFDMA and LTE

5.1 OFDMA Parameter for LTE [cont.]

1200 (1201)900 (901)600 (601)300 (301)180 (181)72 (73)Number of useful sub-carriers

204815361024512256128Number of sub-carriersFFT size

30.72 MHz(8 × 3.84)

23.04 MHz(6 × 3.84)

15.36 MHz(4 × 3.84)

7.68 MHz(2 × 3.84)3.84 MHz

1.92 MHz(1/2 × 3.84)

Sampling frequency

15 kHz Sub-carrier spacing

20 MHz15 MHz10 MHz5 MHz3 MHz1.4 MHzSpectrum allocation

5 MHz7.68 MHz

� For the 5 MHz, there are 512 sub-carriers of 15 kHz. The total band is 7.68 MHz. It is larger than the 5 MHz band!

� But only 301 sub-carriers are used (Pilot, DC, data), the other ones are guard sub-carriers:

� 301 Sub-ca * 15 kHz = 4.515 MHz

Used bandwidth

Flexible bandwidth allocation supported by OFDM

• Still different RF filter will be required

• Frame structure always the same

• Sampling frequency is an transmitter and receiver implementation issue

• Sampling rate is multiple of 3.84 MHz Ł single clock for multi-mode UE with WCDMA

• Smallest bandwidth that is supported was modified recently and needs to be updated




2 � 39

5 OFDMA and LTE

5.1 OFDMA Parameter for LTE [cont.]

�The symbol duration depends on the sub-carrier width.

� 2 Cyclic Prefixes are defined by the 3GPP:

� Long CP: 16.67 micro seconds

� Normal CP: 4.69 micro seconds

� Only the normal CP is supported in LA1.x

� The total duration of a symbol is:

� Useful duration + CP = 66.6 + 4.69

� Total duration = 71.29 µs � With normal CP

#4#3#2#1

User 1

User 1

User 1

User 2

User 2

User 2

User 2

User 3

User 3

User 3User 4User 4

Time

skHzthCarrierWidSub

olDurationUsefulSymb µ6.6615

11 ==−

=

Exercise




2 � 40

Exercise 1

� Let‘s assume the following 2 radio conditions:

� Case 1: Radio conditions -> 16 QAM and coding rate ½

� Case 2: Radio Conditions -> QPSK and coding rate 2/3

� How many symbols are required to transmit 100 bits when radioconditions are similar to:

� case 1?

� case 2?




2 � 41

Exercise 2

� What is the maximum bit rate of a sub-carrier?




2 � 42

Module Summary

� The link adaption is done by the selection on the most suitable MCS (Modulation Coding Scheme) using the QPSK, the 16-QAM and the 64-QAM modulation

� The OFDMA uses multiple Sub-carriers into the bandwidth to send several symbol on the same time and to reach several users

� The width of a sub-carrier, the number of sub-carrier, the bandwidth and the symbol duration are fixed by the 3GPP

� To fix the ISI issue, a guard time called Cyclic prefix, is added on each symbol

� The SC-FDMA is used in UL like it is more efficient than the OFDMA in the point of view of the limited power capacity of the UE




2 � 43

End of ModuleOFDMA Principles




Module 3Air Interface Structure





9400 LTE RAN Radio Principles DescriptionAir Interface Structure

3 � 2

Blank Page




Document History




3 � 3

Module Objectives


� Describe the structure of an LTE radio frame

� List the radio protocols and their functions

� Describe the channels architecture of the air interface




3 � 4






3 � 5

Table of Contents


1 Radio Frame Structure 71.1 Basic Frame Structure 81.2 Resource Block 101.3 Resource Element Group 11

2 Protocol Stack 122.1 Radio Interface Overview 132.2 Terminology 152.3 RRC 162.4 PDCP 192.5 RLC 212.6 MAC 22

3 Radio Channels 263.1 Channel Architecture 273.2 Logical Channel 293.3 Transport Channel 313.4 From the Transport to the Physical Channel 353.5 Physical Channel 37




3 � 6







3 � 7

1 Radio Frame Structure




3 � 8


1.1 Basic Frame Structure

� In FDD, the DL and UL Radio Frames (RFs) are not on the same carrier.

� The RF frame is called Type 1 by the 3GPP.

� The RF length is 10 ms.

RF #3RF #2RF #1 ……

DL Carrier

UL Carrier

� The radio frame is made up of 10 sub-frames of 1 ms.

� Each sub-frame is made up of 2 slots of 0.5ms.

RF #1

10 sub-frames

2 slots

RF #3RF #2RF #1

#9#8#7#6#5#4#3#2#1#0

#2#1

For FDD, 10 subframes are available for downlink transmission and 10 subframes are available for uplink

transmissions in each 10 ms interval. Uplink and downlink transmissions are separated in the frequency

domain.

A Frame structure type 2 is also defined and is applicable to TDD




3 � 9


1.1 Basic Frame Structure [cont.]

� Each slot is made up of:

� 7 symbols in case of normal CP (guard time between symbols)

#9#8#7#6#5#4#3#2#1#0

RF #1

10 sub-frames

Tu= 66.7µs

Tu = Useful Symbol DurationTcp = Cyclic Prefix durationTecp = Extended Cyclic Prefix duration

#7

Tcp = 4.7 µs

#6#5#4#3#2#1

#6#5#4#3#2#1

Tecp = 16.7 µs

#2#1

Since OFDM offers a better flexibility in terms of sub-frame structure and pilot allocation, there is no reason

to consider the same structure as for DFT-SOFDM.




3 � 10

DwPTS GuardPeriod

UpPTS


1.1 Basic Frame Structure [cont.]

� 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 are further split into five sub frames, each 1ms long.

Frame N-1 Frame N+1Frame N

SF0 SF8SF2 SF7SF5 SF9SF3 SF4

10 ms 10 ms10 ms

1ms 1ms

Half Frame Half Frame

1ms DwPTS Guard

PeriodUpPTS

The subframes may be divided into standard subframes of special subframes.

The special subframes consist of three fields:

� DwPTS - Downlink Pilot Time Slot

� GP - Guard Period

� UpPTS - Uplink Pilot Time Stot.

These three fields are also used within TD-SCDMA and they have been carried over into LTE TDD (TD-LTE)

and thereby help the upgrade path. The fields are individually configurable in terms of length, although the

total length of all three together must be 1ms.




3 � 11

1 Type 2 LTE Frame Structure

1.4 LTE TDD Subframe Allocations

� One of the advantages of using LTE TDD is that it is possible to dynamically change the up and downlink balance and characteristics to meet the load conditions.

� In order that this can be achieved in an ordered fashion, a total of seven up / downlink configurations have been set within the LTE standards, in order to make possible

D/ U is a subframe for downlink/ Uplink transmission and S is a "special" subframe used for a guard time.

D

D

D

D

D

D

U

9

U

D

D

D

D

U

U

8

U

D

D

D

U

U

U

7

S

D

D

D

S

S

S

6

D

D

D

D

D

D

D

5

U

D

D

U

D

D

U

4

U

D

U

U

D

U

U

3

U

U

U

U

U

U

U

2

S

S

S

S

S

S

S

1

D

D

D

D

D

D

D

0

SUBFRAME NUMBER

5 ms

10 ms

10 ms

10 ms

5 ms

5 ms

5 ms

Down to Up link Switch periodicity

5

3

1

6

4

2

0

Up/ Down

Link Config

� In the case of the 5ms switch point periodicity, a special subframe exists in both half frames.

� In the case of the 10 ms periodicity, the special subframe exists in the first half frame only.

� It can be seen from the table below that the subframes 0 and 5 as well as DwPTS are always reserved for

the downlink.

� It can also be seen that UpPTS and the subframe immediately following the special subframe are always

reserved for the uplink transmission.




3 � 12

One downlink slot, Tslot

subc

arri

ers

NB

WDL

Resource element

OFDM symbolsOFDM symbols

NB

Wsu

bcar

rier

sR

B

Resource block

RBBW

DLsymb NN ×

resource elements

RBBW

DLsymb NN ×

resource elements


1.2 Resource Block

4324

86Extended cyclic prefix

9712

Normal cyclic prefix

Frame structure type 2

Frame structure type 1

ConfigurationRBBWN

DLsymbN

kHz 15=∆f

kHz 15=∆f

kHz 5.7=∆f

Note*: This system bandwidth is used only for FDD migrationNote**: This system bandwidth is used only for TDD migration

100755025[15] or [16]

76Number of resource

blocks

2015105[3] or [3.2]

1.6**1.4*Operating system bandwidth [MHz]

Multiplex multiple users both in time and frequency, together with pilots and control signals.

The time-frequency plane is divided into chunks=minimum resource allocation unit.

The traffic multiplexing is performed by allocating to each user a certain number of chunks depending on its

data rate/geometry.




3 � 13


1.3 Physical Resource Block

PRB is the minimum unit of allocation in LTE

2 Slots (14 symbols)= 1 ms

Physical Resource Block (PRB) = 14 OFDM symbols(2 slots) x 12 Subcarrier

In OFDMA, users are allocated a specific number of subcarriers for a predetermined amount of time. These are

referred to as physical resource blocks (PRBs) in the LTE specifications. PRBs thus have both a time and

frequency dimension. Allocation of PRBs is handled by a scheduling function at the 3GPP base station

(eNodeB).




3 � 14


1.4 Resource Element Group

�For the control channel, the radio signaling, the Resource Block is not the adapted unit.

�The control channels mapped on the Resource Elements Groups (REGs), which represent less radio resources

�A REG is made up of 4 (or 6 if there are pilot sub-carriers) sub-carriers during 1 symbol.

� The REG are grouped into the CCE (Control Channel Element) Sub-carriers

Symbols1 REG

#12

#11

#10

#9

#8

#7

#6

#5

#4

#3

#2

#1

Exercise

Resource element groups are sued for defining the mapping of control channels to resource elements.




3 � 15

2 Protocol Stack




3 � 16

2 Protocol Stack

2.1 Radio Protocol Stack Overview

eNB

PHY

UE

PHY

MAC

RLC

MAC

MME

RLC

NAS NAS

RRC RRC

PDCP PDCP

User & Control Plane

Control Plane Only

In the C-plane, the NAS functional block is used for network attachment, authentication, setting up bearers,

and mobility management. All NAS messages are ciphered and integrity protected by the MMEand UE.

The radio resource control (RRC) layer in the eNB makes handover decisions based on neighbor cell

measurements reported by the UE, performs paging of the users over the air interface, broadcasts system

information, controls UE measurement and reporting functions such as the periodicity of channel quality

indicator (CQI) reports and further allocates cell-level temporary identifiers to active users. It also executes

transfer of UE context from the serving eNB to the target eNB during handover and performs integrity

protection of RRC messages. The RRC layer is responsible for setting up and maintenance of radio bearers.

In the U-plane, the Packet Data Convergence Protocol (PDCP) layer is responsible for compressing or

decompressing the headers of user-plane IP packets using robust header compression (RoHC) to enable

efficient use of air interface resources . The radio link control (RLC) layer is used to format and transport

traffic between the UE and the eNB .




3 � 17

2 Protocol Stack

2.1 Radio Protocol Stack Overview

eNode-B

Control PlaneUser Plane Control PlaneUser Plane

Logical Channel

Radio Bearer

Transport Channel

Physical Channel

Non-Access StratumSignaling between Core Network and UE

Radio Signaling

PDCP

Physical Layer

MAC Layer

RLC

RRC

NAS

PDCP

Physical Layer

MAC Layer

RLC

RRC

NAS

Layer 2 is split into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC) and

Packet Data Convergence Protocol (PDCP)

Segm.ARQ etc

Multiplexing UE1

Segm.ARQ etc

...

HARQ

Multiplexing UEn

HARQ

BCCH PCCH

Scheduling / Priority Handling

Logical Channels

Transport Channels

MAC

RLC Segm.ARQ etc

Segm.ARQ etc

PDCPROHC ROHC ROHC ROHC

Radio Bearers

Security Security Security Security

...CCCH

bsaffach

Note

Couche PDCP: gère




3 � 18

2 Protocol Stack

2.2 Terminology

� PDU = Protocol Data Unit

� SDU = Service Data Unit

Layer N Layer N

Layer N+1

Layer N receives an SDU from Layer N+1

2 protocols of the same layer exchange PDU

SDU (layer N+1)Header Layer N

PDU (Layer N)




3 � 19

2 Protocol Stack

2.3 RRC

Higher layers

� The Radio Resource Connection (RRC) protocol is implemented in the eNodeB and the UE. In WCDMA, it is implemented in the RNC!

� RRC is the highest protocol in the control plane on the radio side. The RRC protocol allows:

� 2 instances (eNodeB and UE) to exchange signaling messages.

� to forward signaling messages coming from the core network, called NAS signaling.

RRC

RRC

eNode-B

ePC

Radio signaling

NAS signaling

Broadcast of system information related to non-access stratum (NAS),

- Broadcast of system information related to access stratum (AS),

- Paging,

- Establishment, maintenance and release of an RRC connection between the UE and the e-UTRAN including:

� Allocation of temporary identifiers between UE and e-UTRAN,

� Configuration of signalling radio bearer(s) for RRC connection:

� Low priority SRB and high priority SRB,




3 � 20

2 Protocol Stack

2.3 RRC [cont.]

Establishment, maintenance and release of an RRC connection between the UE and E-UTRAN

NAS direct message transfer to/from NAS from/to UE

Broadcast of System Information

UE measurement reporting and control of the reporting

Mobility Management

Paging

RRC Functions

The establishment and maintenance of the RRC connection includes:

� Allocation of temporary identifiers between UE and E-UTRAN.

� Configuration of signaling radio bearer(s) for RRC connection.

� Low priority SRB and high priority SRB.

� Security functions including key management.

� Establishment, configuration, maintenance and release of point to point Radio Bearers

The Mobility management functions includes:

� UE measurement reporting and control of the reporting for inter-cell and inter-RAT mobility.

� Handover.

� UE cell selection and reselection and control of cell selection and reselection.

� Context transfer at handover.




3 � 21

2 Protocol Stack

2.3 RRC [cont.]

� RRC uses the following states:

RRC_Idle:•The UE is not connected. There is no radio link. •The network knows that the UE is present on the network and is able to reach it in case of incoming call.•The UE switches in idle mode when it isconnected and there is no traffic to save radio resources and its battery.

RRC_Idle:•The UE is not connected. There is no radio link. •The network knows that the UE is present on the network and is able to reach it in case of incoming call.•The UE switches in idle mode when it isconnected and there is no traffic to save radio resources and its battery.

RRC_Connected•The UE has an e-UTRAN-RRC connection.•The network can transmit/receive data to/from the UE and knows its location at the cell level.•The network manages the mobility with handover.

RRC_Connected•The UE has an e-UTRAN-RRC connection.•The network can transmit/receive data to/from the UE and knows its location at the cell level.•The network manages the mobility with handover.

The LTE UE could have one of the two following states:

� RRC Connected, when it has a RRC connection with a given eNB

� RRC IDLE when it has no valid RRC link with any eNB.




3 � 22

2 Protocol Stack

2.4 PDCP

� The main services provided by the Packet Data Convergence Protocol (PDCP) are:

PDCP

Physical Layer

MAC Layer

RLC

RRC

NAS

User Plane Control Plane� For the user plane:

� IP header compression and decompression with the Robust Header Compression (ROHC) method only

� Ciphering

� Transfer of user data

� In-sequence delivery of upper layer PDUs at HO in the uplink

� For the control plane:

� Ciphering and Integrity Protection to secure the transmission of core network signaling

� The main services and functions of the PDCP sublayer for the user plane include:

� Header compression and decompression: ROHC only;

� Transfer of user data;

� In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM;

� Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM;

� Retransmission of PDCP SDUs at handover for RLC AM;

� Ciphering and deciphering;

bsaffach

Note

Taille du header = 20 octets avant compression => taille significative pour des paquets voip qui sont petits et nombreux => interessant de compresser ces header




3 � 23

2 Protocol Stack

2.4 PDCP [cont.]

� The header of an IP packet is 20 octets.

� For example, during an FTP transfer, a lot of IP packets are sent over the air interface and the IP headers are almost always the same. They represent a significant amount of data which can be reduced thanks to a compression method.

� The PDCP header is 1 (or 2) octet.

� The Robust Header Compression (ROHC) is a standardized method used to compress IP, UDP, TCP and RTP headers.

� RFC 4995

Payload (http, ftp, rtp for voice …) Header

- Length- Destination IP address- Source IP address- TTL




3 � 24

2 Protocol Stack

2.5 RLC

� The Radio Link Control (RLC) protocol provides the following services:

PDCP

Physical Layer

MAC Layer

RLC

RRC

NAS

User Plane Control Plane� Segmentation of SDU according to the size

� Re-Segmentation of PDU

� Radio Bearer to logical channel mapping

� Transfer of data in 3 modes:

� TM Transparent Mode

Without retransmission. For real-time service.

� UM Unacknowledged Mode

Without retransmission, but error statistics (BLER)

It can be used for the signaling.

� AM Acknowledged Mode

With retransmission. For non real-time services, like internet.

� The main services and functions of the RLC sublayer include:

� Transfer of upper layer PDUs;

� Error Correction through ARQ (only for AM data transfer);

� Concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer);

� Re-segmentation of RLC data PDUs (only for AM data transfer);

� In sequence delivery of upper layer PDUs (only for UM and AM data transfer);

� Protocol error detection and recovery;

� RLC SDU discard (only for UM and AM data transfer);

bsaffach

Note

Le mécanisme de retransmission au niveau RLC s'appelle ARQ




3 � 25

2 Protocol Stack

2.6 MAC

� The MAC protocol provides the following services:

PDCP

Physical Layer

MAC Layer

RLC

RRC

NAS

User Plane Control Plane� Logical Channel to Transport channel mapping

� Scheduling:

There is no dedicated channel allocated to a UE. Time and frequency resources are dynamically shared between the users in DL and UL.

The scheduler is part of the MAC layer and controls the assignment of uplink and downlink resources.

� Multiplexing/Demultiplexing of RLC PDU

� The main services and functions of the MAC sublayer include:

� Mapping between logical channels and transport channels;

� Multiplexing/demultiplexing of MAC SDUs belonging to one or different logical channels into/from

transport blocks (TB) delivered to/from the physical layer on transport channels;

� scheduling information reporting;

� Error correction through HARQ;

� Priority handling between logical channels of one UE;

� Priority handling between UEs by means of dynamic scheduling;

� Transport format selection;

� Padding.




3 � 26

2 Protocol Stack

2.6 MAC [cont.]

eNodeB

DL

UL

Frequency

Time

� The scheduler (in the eNodeB) determines dynamically, each 1 ms, which UEs are supposed to receive data on the DL shared channel and on the UL shared channel and on what resources.

� The basic time-frequency unit is the resource block.

� To select the adapted modulation and coding rate, the scheduler needs measurement reports in DL and UL.

The eNodeB allocates physical layer resources for the uplink and downlink shared channels (UL-SCH and DL-

SCH).

Resources are composed of Physical Resource Blocks (PRB) and Modulation Coding Scheme (MCS). The MCS

determines the bit rate, and thus the capacity, of PRBs.

bsaffach

Note

3 type de scheduler: - Static: pour allouer les données qui utilsent tjrs les memes tailles - Semi-static - Dynamic




3 � 27

2 Protocol Stack

2.6 MAC [cont.]

eNode-B

eNodeB

Scheduler

Buffer

Data

Multiplexing

Modulation, Coding

Transmission

eNodeB

UE

DL channel quality measurement

� In downlink, the scheduler needs the following inputs to schedule data:

� Amount of data

� Nature of the data

� Radio resource available

� Radio Condition in DL

� The UE reports regularly its measurement report, called Channel Quality Indicator (CQI).

bsaffach

Note

la QOS




3 � 28

UE

2 Protocol Stack

2.6 MAC [cont.]

eNode-B

eNodeB

Scheduler

Buffer

Data

Multiplexing

Modulation, Coding

Transmission

eNodeB

UL channel quality measurement

� In uplink, the mechanism is similar but:

� Measurements are made by the eNodeB

� The eNodeB scheduler controls the UE transmission

Request to transmit




3 � 29

3 Radio Channels




3 � 30

Radio Bearer

Logical Channel

Transport Channel

Physical Channel

3 Radio Channels

3.1 Channel Architecture

PDCP

Physical Layer

MAC Layer

RLC

PDCP

Physical Layer

MAC Layer

RLC

eNode-B




3 � 31

3 Radio Channels

3.1 Channel Architecture [cont.]

� A Logical Channel is defined by the type of information it carries. Logical channels are classified into control and traffic channels.

� Answer to the question: what is it being transported?

� A Transport Channel is defined by how and with what characteristics the information is transmitted.

� Answer to the question: how is it being transported?

� A Physical Channel is defined by the physical resources used to transmit the data. At the physical level, a distinction can be made between:

� The physical channel on which are mapped transport channels.

� The physical signal, which does not carry information but is used for synchronization or measurement.

bsaffach

Note

Pour les SIBs => en modulation robuste == QPSK modulation




3 � 32

3 Radio Channels

3.2 Logical Channel

� The following control logical channels have been defined by the 3GPP:

� BCCH, Broadcast Control Channel, used for the transmission of system control information. A UE needs to decode it before requesting a connection.

� PCCH, Paging Control Channel, is a downlink channel that transfers paging information and system information change notifications. This channel is used for paging when the network does not know the location cell of the UE.

� CCCH, Common Control Channel is a channel for transmitting control information between UEs and network. This channel is used for UEs having no RRC connection with the network.

� DCCH, Dedicated Control Channel is a point-to-point bi-directional channel that transmits dedicated control information between a UE and the network. Used by UEshaving an RRC connection.

� MCCH, Multicast Control Channel is a point-to-multipoint downlink channel used for transmitting MBMS control information from the network to the UE, for one or several MTCHs. This channel is only used by UEs that receive MBMS.

bsaffach

Note

Pour les SIBs => en modulation robuste == QPSK modulation

bsaffach

Note

Pour le Paging

bsaffach

Note

Pour le SRB0

bsaffach

Note

Pas implémmenté




3 � 33

3 Radio Channels

3.2 Logical Channel [cont.]

� The following traffic logical channels have been defined by the 3GPP:

� DTCH, Dedicated Traffic Channel, is a point-to-point channel, dedicated to one UE, for the transfer of user information. A DTCH can exist both in uplink and downlink.

� MTCH, Multicast Traffic Channel is a point-to-multipoint downlink channel for transmitting traffic data from the network to the UE. This channel is only used by UEs that receive MBMS.

bsaffach

Note

Pas implémmenté




3 � 34

3 Radio Channels

3.3 Transport Channel

� A transport channel defines how and with what characteristics the information is transmitted.

� Inherited from the WCDMA, data on the transport channel is organized into “Transport Blocks”, TBs.

� A Transport block can be transmitted every TTI = 1 ms

� The “Transport Format”, TF, defines how the blocks can be transmitted:

� Transport block size, it depends on the MCS and the number of PRB allocated

� Allowed modulation scheme

� Antenna mapping

Transport Block

TTI = 1 ms

Transport Block

Note: In case of multi-antenna system, there can be 2 TBs for each TTI.

Each TTI, the scheduler decides which chunk to allocate to which user. The chunks are not standardized.

bsaffach

Note

Le logical channel DTCH va être mappé sur le canal de transport DL-SCH




3 � 35

3 Radio Channels

3.3 Transport Channel [cont.]

� The following transport channels in DL have been defined by the 3GPP:

� Broadcast Channel (BCH) characterized by a fixed, pre-defined transport format with a robust modulation to be broadcast in the entire coverage area of the cell.

� Downlink Shared Channel (DL-SCH) characterized by:� a dynamic link adaptation by varying the modulation, coding and transmit power

� support for H-ARQ (radio retransmission).

� Paging Channel (PCH) characterized by:� Requirement to be broadcast in the entire cell.

� Multicast Channel (MCH) characterized by:� requirement to be broadcast in the entire coverage area of the cell

bsaffach

Note

Pas impléménté




3 � 36

3 Radio Channels


� The following transport channels in UL have been defined by the 3GPP:

� Uplink Shared Channel (UL-SCH) characterized by:� support for dynamic link adaptation by varying the transmit power and potentially modulation and coding

� support for H-ARQ

� support for both dynamic and semi-static resource allocation.

� Random Access Channel (RACH) characterized by:� limited control information

� collision risk

bsaffach

Note

Pour le message de Preamble




3 � 37

MAC Layer

3 Radio Channels


BCCHPCCH CCCH MCCHDCCH DTCH MTCH

BCHPCH DL-SCH MCHUL-SCH

Transport Channel

Logical Channel

bsaffach

Note

Pour les messages de HO & Measurement Report

bsaffach

Note

Pour les messages de SIB & MIB

bsaffach

Note

Pour les messages SRB1 & SRB2

bsaffach

Note

Pour les messages de traffic

bsaffach

Note

Pour les messages de Paging

bsaffach

Note

Pas impléménté




3 � 38

3 Radio Channels

3.4 From the Transport to the Physical Channel

� Transport channels are then mapped on the physical channels which are sent over the air interface

� A CRC is calculated and appended to each TB. It allows the receiver to detect errors. It is used by retransmission mechanisms like H-ARQ

� Depending on the Transport Format and the radio quality, the TB is coded and interleaved.

� The H-ARQ is a process running in the UE and in the eNodeB to allow a fast retransmission in case of errors.

� The resulting bit sequence is modulated and mapped on the sub-carriers of the Resource Block used for the transmission (one or several RBs).

100 bits Transport Block

Physical Layer

Add CRC

TB CRC

Coding, Interleaving

TB CRC Parity bits

H-ARQ If activated

Data Modulation




3 � 39

3 Radio Channels

3.4 From the Transport to the Physical Channel [cont.]

� The data are modulated and mapped on the sub-carriers.

� The basic time-frequency unit is the Resource Block.7 symbols

12 sub-carriersData Modulation

11111111111111111111111

16 QAM Modulation -> 4 bits per symbol48 bits can be sent with the 1st symbol of the RB

1111

1111

1111

1111

1111

1111

1111

1111

1111

1111

1111

1111




3 � 40

3 Radio Channels

3.5 Physical Channel

� A distinction has to made between:� The physical channel

� The physical signal

� Carries information originating from the upper layer

Physical channel

PDCP

Physical Layer

MAC Layer

RLC

Data or signaling

� Does not carry information from the upper layer

� Used for synchronization or measurement

Physical signal

eNode-B

PHY

PHY




3 � 41

3 Radio Channels

3.5 Physical Channel [cont.]

� The DL physical channels are:

� Physical DL Shared Channel (PDSCH)� It is a shared channel used to carry user data, radio & core network, system information (BCH), paging message.

� Physical DL Control Channel (PDCCH)� It is a shared signaling channel to carry the allocation of the resources (PDSCH).

� Physical Broadcast Channel (PBCH)� It is the channel used to broadcast the system information.

� The UL physical channels are:

� Physical Random Access Channel (PRACH)� It is a shared channel used for the access procedure.

� Physical UL Shared Channel (PUSCH)� It is a shared channel used to carry user data, radio & core network,

� Physical UL Control Channel (PUCCH)� It is a shared signaling channel in uplink to allow the UE to request resources on the PUSCH.




3 � 42

3 Radio Channels

3.5 Physical Channel [cont.]

PHY Layer

UL-SCHDL-SCH BCH RACH MCH

PDCCH

PDSCH PUSCH

PUCCH

PBCH

Physical Channel

Transport Channel

PMCHPRACH

PCH

Physical control channel in DL and UL

Exercise

BCCHPCCH CCCH MCCHDCCH DTCH MTCH

Logical Channel

MAC Layer

PCFICH

PHICH

bsaffach

Note

pour la MIB

bsaffach

Note

RACH procedure quand le mobile s'allume + HO

bsaffach

Note

Pour les ACK du HARQ Les CQI en UL en LA3.0

bsaffach

Note

Pour allumer le HARQ

bsaffach

Note

Contient les infos pour coder le PDCCH




3 � 43

Exercise 1

� The aim is to calculate the max theoretical raw bit of a cell.

� This max bit rate is only theoretical and can not be reached on a real network

� Assumptions:

� MIMO 4×4

� That means that are 4 antennas on the eNodeB and 4 antennas on the UE. The eNodeB can transmit 4 independent streams on the same time to the UE.

� Bandwidth: 20 MHz

� The overhead per Resource Block is:

� 6 Resource Elements due to the PDCCH (physical DL control channel)

� 10 Resources Elements due to the Reference signal (for measurements)

� Best Modulation: 64 QAM

� Follow the method on the next slides to calculate the max raw bit rate

30 minutes




3 � 44

Exercise 1

� Step 1: Calculate the number of useful Resource Element in a Resource Block

� Step 2: Calculate the number of Resource Block

� Step 3: Calculate the number of useful Resource Element in the sub-frame

� Step 4: Calculate the max number of bit in the sub frame

� Step 5: Calculate the raw bit rate for 1 antenna

� Step 6: Calculate the max bit rate for MIMO 4×4




3 � 45

Exercise 2

� Match each of the entities listed below to its appropriate location on the diagram (see next page).

� MAC header

� RLC SDU

� CRC

� RLC header

� Transport Block

� PDCP header

� MAC SDU




3 � 46

Exercise 2

Voice sampleRTPUDPIP HTTPTCPIP

PDCP header compression

Voice sampleheaders HTTPheaders

Voice sampleheaders HTTPheaders1 1

RLC Segmentation, Concatenation

2 2

3 3

MAC Multiplexing 54

6 7PHY

1

2

3

4

5

6

7

MAC headerRLC SDUCRCRLC headerTransport BlockPDCP headerMAC SDU

bsaffach

Note

PDCP Header

bsaffach

Note

RLC Header

bsaffach

Note

RLC SDU

bsaffach

Note

MAC Header

bsaffach

Note

MAC SDU

bsaffach

Note

Transport Block

bsaffach

Note

CRC




3 � 47

Module Summary

� The duration of type 1 radio frame is 10 ms. It is made of 10 sub-frame (1 ms)

� A sub-frame is made 2 slots

� A slot is made of 7 symbols

� A Resource Block is made of 12 sub-carriers and 7 symbol (a slot)

� A Resource Element is a 1 Sub-carrier/1 Symbol

� The RRC protocol is the head of the air interface

� The DL and UL scheduler are running in the MAC layer in the eNodeB

� The Radio Bearer is mapped on Logical channel -> Transport Channel -> Physical Channel




3 � 48

End of ModuleAir Interface Structure




Module 4eUTRAN Scenarios





9400 LTE RAN Radio Principles DescriptioneUTRAN Scenarios

4 � 2

Blank Page




Document History




4 � 3

Module Objectives


� Describe the steps and the resources used by a UE to request a connection

� Describe the different traffic operations, i.e. what are the different mechanisms to allow a traffic with a UE

� Describe the bearer establishment scenario

� Describe the measurement report mechanisms

� Describe the radio retransmission mechanisms

� Describe the resources allocation




4 � 4






4 � 5

Table of Contents


1 RRC Connection Scenarios 71.1 Overview 81.2 Synchronization 121.2 Synchronization & BCH for TDD Frame 171.3 Obtain Cell Parameters 181.4 Random Access Procedure 201.5 RRC Connection Establishment 241.6 Attach Setup 25

2 Bearer Management 262.1 EPS Bearer 272.1 EPS Bearer [CONT] 282.2 QoS Parameters 292.2 QoS Parameters [CONT] 302.3 Radio Bearer 31

3 Traffic Operation 353.1 Traffic Operation Overview 363.2 Data Transmission in DL 433.3 Data Transmission in UL 473.4 DCI 513.5 Measurement Report 533.6 Radio Retransmission 573.6.1 H-ARQ Mechanism in DL 59




4 � 6






4 � 7

1 RRC Connection Scenarios




4 � 8


1.1 Overview

eNodeB MME Gateway

ePC

Synchronization

Obtain DL Parameters

RRC Connection

Initial Network Attach

� When the UE is powered up, it has to be RRC connected to be able to exchange data and signaling with the network.

� After the RRC connection, the Initial network attach allows to establish all the bearers to carry the data from the UE to the gateway.

Scanning

bsaffach

Note

UE scans the andwidth of the Cell

bsaffach

Note

UE se synchronise en utilisant les canaux primaires & secondaires

bsaffach

Note

UE recoit les SIB1 & SIB2




4 � 9


1.1 Overview [cont.]

� After the RRC connection, Signaling Radio Bearers (SRBs) are established.

� An SRB is a Radio Bearer that only carries the signaling:

� SRB1 carries the RRC signaling.

� SBR2 carries the NAS signaling, i.e. between the Core Network and the UE.

bsaffach

Note

SRB2 est établi à la fin de la procédure d'ATTACH




4 � 10



� During the Initial Attach:

� An MME is selected.

� The UE is authenticated.

� An IP address is allocated to the UE.

� S-GW and P-GW are selected.

� Bearers are established on the S1-U, S5/S8 and on the air interface.

� The RRC connection is reconfigured to allow user data traffic.

� At the end of the Initial Attach, the UE is able to reach external networks.




4 � 11



� The RRC Connection is basically made up of 2 steps:

� Contention Based Random Access.

� Exchange of Signaling to establish the connection.

� When a UE requests a connection, it has no dedicated resources to reach the eNodeB. It uses an uplink common channel which is able to manage the collision between 2 UEs requesting an access at the same time.

eNodeB




4 � 12


1.2 Synchronization

� After the power on, the UE knows:

� the UE category and capability.

� the preferred PLMN.

� the carriers.

� The UE needs to know:

� The frame synchronization to be able to decode the DL radio frame.

� The cell parameters to be able request a connection.

� The UE can use:

� The PSS: Primary Synchronization Signal.

� The SSS: Secondary Synchronization Signal.

� The BCH, the broadcast channel.




4 � 13


1.2 Synchronization [cont.]

� The synchronization signals provide the cell id to the UE.

� LTE supports 510 different cell identities.

� They are divided into 170 cell id groups and there are 3 cell ids per group.

� Cell id = 3* Cell_Group_id + Cell_id_in_group

0 to 169Provided by the SSS

0 to 2Provided by the PSS

0 1

2

Cell Group #23

Cellid #69 Cellid #70

Cellid #71

0 1

2

Cell Group #100

Cellid #300 Cellid #301

Cellid #302

P-SCH & s-SCH location:

over the 62 central frequencies of the spectrum (regarless of the system bandwidth)

In the fifth and sixth symbol position of slot 0 of subframes 0 & 5




4 � 14



� The Primary Synchronization Signal (PSS):

� is used for the slot synchronization.

� is on the last OFDM symbol of slots 0 & 10 in the 1st & 6th sub-frames of each frame.

� carries one of the 3 cell id in group sequence.

Frame

TS0

SF1

TS1 TS2 TS3

SF0 SF5 SF9

TS10 TS11 TS18 TS19

10ms

1ms

0.5ms

Sb0 Sb1 Sb2Sb

NDL-2

Sb

NDL-1

…….. ……..

…….. ……..

Sb0 Sb1 Sb2Sb

NDL-2

Sb

NDL-1

0.5ms

PSS PSS

P-SCH decoding

P-SCH sequence is encoded according to one of 3 possible CAZAC sequences (identical in subframe 0 & 5)

The UE performs correlation of the known sequence with the received samples over half a frame and keeps the highest

correlation

slot boundary is known and subframe known modulo 5 subframes

Nid2 = 0..2 is retrieved from p-SCH decoded sequence




4 � 15



� The Secondary Synchronization Signal (SSS):

� is used for the frame synchronization.

� is on the same slot as PSS.

� is on the next to last OFDM symbol of slots 0 & 10 in the 1st & 6th sub-frames of each frame.

� carries one of the 170 unique cell group identifiers.

Frame

TS0

SF1

TS1 TS2 TS3

SF0 SF5 SF9

TS10 TS11 TS18 TS19

10ms

1ms

0.5ms

Sb0 Sb1 Sb2SbNDL-2

SbNDL-1

…….. ……..

…….. ……..

Sb0 Sb1 Sb2SbNDL-2

SbNDL-1

0.5ms

Frame

TS0

SF1

TS1 TS2 TS3

SF0 SF5 SF9

TS10 TS11 TS18 TS19

Sb0 Sb1 Sb2SbNDL-2

SbNDL-1

…….. ……..

…….. ……..

Sb0 Sb1 Sb2SbNDL-2

SbNDL-1

SSS SSS SSS SSS

S-SCH decoding

S-SCH sequence is encoded according to one of 168 possible sequences (differing in subframes 0 & 5)

The UE performs correlation of the known sequence with the two possible locations and keeps the highest correlation

Frame boundaries are known

Nid1 = 0..167 is retrieved from s-SCH decoded sequence

Ncellid is derived from these previous computation

Ncellid=3*Nid1+Nid2

Ncellid used as input for all channels encoding

bsaffach

Note

Permet de décoder le PCI




4 � 16



� The PSS, the SSS and the BCH are carried over 6 Resource Blocks (RB) whatever the bandwidth

� 6 RBs = 6 * 12 Sub-ca = 72 Sub-carriers

6 central RBs

� By this way, these signals are independent from the bandwidth and can decode this signal without knowing it.

Bandwidth: from 1.4 to 20 Mhz

P-SCH & s-SCH location:


In the fifth and sixth symbol position of slot 0 of subframes 0 & 5

pBCH location:


In the first four symbol positions of slot 1 of subframes 0 not used by RS signal




4 � 17


1.2 Synchronization & BCH for TDD Frame

� The Primary synchronization signal (PSS): is placed at the third symbol in subframes#1 and #6.

� The secondary synchronization signal (SSS): is placed at the last symbol in subframes#0 and #5.

� The S-RACH is transmitted on the UpPTS within the special frame.

� The Primary Broadcast Channel (P-BCH) and the Dynamic Broadcast Channel (D-BCH): are located as in LTE FDD.

SF0 SF8SF2 SF7SF5 SF9SF3 SF4

SSS

SSS

PSS

PSS

S-RACH/SRS

RACH

S-RACH/SRS

RACHPBCH

DBCH

Mapping of critical control channels to TDD configuration #1

Random access typically uses one of the normal subframes as in FDD, allowing for a relatively long

random-access preamble providing coverage and capacity also in large cells. However, in scenarios

where random-access coverage is not an issue, a short random access preamble in the UpPTS can be

used instead.




4 � 18


1.3 Obtain Cell Parameters

� To provide the most critical information to the UEs, the eNodeB uses the BCH channel

� The information is sent on pre-defined time-frequency resources

� This information is organized into different information blocks:� The MIB, the Master Information Block.

� System Frame Number

� DL System Bandwidth

� Number of Transmit Antennas at eNodeB

� Periodicity: 4 RFs

� SIB1� How other SIBs are scheduled and cell accessibility

� Periodicity: 8 RFs

� SIB2: Access Info

� SIB3: Serving Cell info for Cell reselection

� SIB4: Intra-frequency neighbors

� SIB5: Other e-UTRA frequency

� SIB6: UTRA frequency

� MasterInformationBlock defines the most essential physical layer information of the cell required to

receive further system information;

� SystemInformationBlockType1 contains information relevant when evaluating if a UE is allowed to access

a cell and defines the scheduling of other system information blocks;

� SystemInformationBlockType2 contains common and shared channel information;

� SystemInformationBlockType3 contains cell re-selection information, mainly related to the serving cell;

� SystemInformationBlockType4 contains information about the serving frequency and intra-frequency

neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a

frequency as well as cell specific re-selection parameters);

� SystemInformationBlockType5 contains information about other E-UTRA frequencies and inter-frequency



� SystemInformationBlockType6 contains information about UTRA frequencies and UTRA neighbouring cells

relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as

cell specific re-selection parameters);

� SystemInformationBlockType7 contains information about GERAN frequencies relevant for cell re-selection

(including cell re-selection parameters for each frequency);

� SystemInformationBlockType8 contains information about CDMA2000 frequencies and CDMA2000



� SystemInformationBlockType9 contains a home eNB identifier (HNBID);

� SystemInformationBlockType10 contains an ETWS primary notification;

� SystemInformationBlockType11 contains an ETWS secondary notification.




4 � 19


1.3 Obtain Cell Parameters [cont.]

� The MIB is carried by the BCH channel.

� All the SIBs are carried by the DL-SCH.

BCCH

System Information

BCH DL-SCH

PBCH PDSCH

MIB only Other SIB

System information are broadcast in the whole cell

Transmitted in PDSCH with QPSK modulation and good coding rate

Signaled through PDCCH DCI1A with reserved RNTI value = SI-RNTI (0xffff)

System informations blocks are aggregated in system information (SI):

• systemInformationBlockType1 is a special SI that contains the most basic system informations as well as the

scheduling details of the other SI

• Other SI contain one ore more System information sharing the same transmission periodicity,

• Each SI is transmitted in parallel with other SI and benefits from HARQ repetitions

• Special HARQ processes identified by the SI-RNTI and the SI number (in the example above, 3 HARQ processes are

defined




4 � 20


1.4 Random Access Procedure

� When the UE has obtained system information, it has to request an RRC connection. Like it has no dedicated resources, the UE requests the connection using the Random Access Procedure using common uplinkresources.

� At the end of the procedure, the UE is RRC connected

� UE and eNodeB are able to exchange data using dedicated radio resources

� This procedure is also used in case of:

� Initial access from RRC_IDLE

� RRC Connection Re-establishment procedure

� Handover

RRC_CONNECTED

(active state)

RRC_NULL

(detachedstate)

Traffic / HORRC Connection using Random

Access procedure




4 � 21


1.4 Random Access Procedure [cont.]

� There are 4 steps to allow the UE to exchange signaling messages with the eNodeB

eNodeBRandom Access Preamble (msg1)

On the PRACH/RACH

Random Access Response (msg2)

On the PDCCH

Scheduled Transmission (msg3)

On the UL-SCH/PUSCH

Contention Resolution (msg4)

On the DL-SCH/PDSCH

The UE receives temporary C-RNTI to identify it on the air interface

The message also conveys the RRC Connection Request

Not synchronized with the previous message. The Temporary C-RNTI is promoted C-RNTI

Random Access Response

PDSCH signaled through PDCCH with RNTI = PRACH subframe number

Contains the signature index of the detected RACH preamble (1rst contention resolution step)

Contains the timing alignment command to apply (2 ways transmission time)

Contains a temporary RNTI assigned to the UE

Contains the resource assignment for next PUSCH (acts as DCI0)

bsaffach

Note

C-RNTI: Connection Radio Nativ Temprary Id

bsaffach

Note

RRC Connecxtion REQ: Ce message s'apelle aussi UL Grant

bsaffach

Note

Random Access Procedure is achieved at reception of RRC Conection Setup Complete => SRB1 is established




4 � 22



� The Physical Random Access Channel (PRACH):

� is made up of 6 RBs anywhere in the spectrum.

� occupies between 1 and 3 sub-frames per frame.

� The preamble:

� is generated from the Zadoff-Chu sequence.

� is associated to an RA-RNTI.

� There are 64 preamble sequences available per cell.

eNodeBPreamble

UL

DL

6 RBsfor the PRACH

The random access preambles are generated from Zadoff-Chu sequences with zero correlation zone (ZC-ZCZ)

generated from one or several root Zadoff-Chu sequences.

The random access preamble is 0.9 ms long (i.e. a 0.1 ms guard interval not to overlap in the next subframe)

It is Sent in specific subframes depending on RACH configuration parameter. It Contains an orthogonal

sequence chosen among 64 possible signatures




4 � 23



� The response conveys:

� The RA-RNTI, to match the response with the preamble

� Timing alignment information

� The Temporary C-RNTI

� The initial UL grant, allocation of resources for the temporary C-RNTI.

� The C-RNTI identifies an RRC Connection.

eNodeB

Preamble Associated to an RA-RNTI

Random access response on PDCCH

PUSCH(RRCConnectionRequest)

contains RRC message for RRC connection establishment

NAS identity (S-TMSI) or randomNumber included in RRC message)

PDSCH(RRCConnectionSetup)

PDSCH signaled through PDCCH with RNTI = RNTI previously assigned to the UE

Contains a MAC header ‘contention resolution octet’ which is a repetition of the RRC PDU (2nd contention resolution step)

Contains a RRC message providing with signaling radio bearer configuration + physical configuration

bsaffach

Note

RA-RNTI: Random Access RNTI




4 � 24


1.5 RRC Connection Establishment

� The main steps of the RRC connection establishment are:

eNodeBRRC Connection Request

RRC Connection Setup

RRC Connection setup complete

The request includes:- UE id (like TMSI)- Establishment cause

Radio resources configuration to establish the SRB1

SRB = Signaling Radio Bearer

Id of selected PLMNNAS dedicated information

After an RRC connection, several SRBs are established.

An SRB is a Radio Bearer (RB) used only for the transmission of RRC and NAS messages. More specifically, the

following three SRBs are defined:

� SRB0 is for RRC messages using the CCCH logical channel.

� SRB1 is for RRC messages as well as for NAS messages prior to the establishment of SRB2, all using the DCCH

logical channel.

� SRB2 is for NAS messages, using the DCCH logical channel. SRB2 has a lower priority than SRB1 and is always

configured by e-UTRAN after security activation.

bsaffach

Note

Contient le NAS sur l'ATTACH REQ que le eNB va envoyer au MME




4 � 25


1.6 Attach Setup

� The Attach setup aims at establishing a default EPS bearer for user data between the UE and the P-GW.

� It includes:

� Authentication

� Allocation IP address

� Establishment of Radio bearer, S1 bearer, S5 bearer

PSTN

Internet

eNodeB

eUTRAN

CSCF

SGW

MGCF

MGWIMS

MME

P-GW

ePC

UE

EPS Bearer

S-GW




4 � 26

2 Bearer Management




4 � 27

2 Radio Management

2.1 EPS Bearer

� EPS is a connection-oriented transmission network and, as such, it requires the establishment of a “virtual” connection between two endpoints (e.g. a UE and a PDN-GW)

� This virtual connection is called an “EPS Bearer”

� It provides a “bearer service”, i.e. a transport service with specific QoSattributes.

� The QoS parameters associated to the bearer are: QCI, ARP, GBR and AMBR.

Internet

(PDN)

eNodeB

e-UTRANMME

P-GW

UE

EPS Bearer

S-GW

As a concept, the EPS Bearer corresponds to the “PDP Context” used in GPRS

As the mobile device is already known in the core network the following radio bearers are now established

automatically:

bsaffach

Note

Pour le EPS bearer i.e. the PDP Context




4 � 28

2 Radio Management

2.1 EPS Bearer [CONT]

� A data radio bearer transports the packets of an EPS bearer between a UE and an eNB. � When a data radio bearer exists, there is a one-to-one mapping between this data radio bearer and the EPS bearer/E-RAB.

� An S1 bearer transports the packets of an E-RAB between an eNodeB and a Serving GW.

� An S5/S8 bearer transports the packets of an EPS bearer between a Serving GW and a PDN GW.

� The QoS parameters associated to the bearer are: QCI, ARP, GBR and AMBR.

P-GWS-GW PeerEntity

UE eNB

EPS Bearer

Radio Bearer S1 Bearer

End-to-end Service

External Bearer

Radio S5/S8

Internet

S1

E-UTRAN EPC

Gi

E-RAB S5/S8 Bearer

A low priority signaling (message) bearer (SRB1)

A high priority signaling (message) bearer (SRB2)

A data radio bearer (DRB), i.e. a bearer for IP packets

Part of the bearer establishment procedure are authentication and activation of encryption. The required

data for this process is retrieved by the base station (the eNodeB or eNB in 3GPP talk) from the Access

Gateway (aGW), or more precisely from the Mobility Management Entity (MME). The MME also delivers all

necessary information that is required to configure the data radio bearer, like for example min/max

bandwidth, quality of service, etc.




4 � 29

2 Radio Management

2.2 QoS Parameters

� The QoS Class Identifier (QCI) is a scalar that is used as a reference to access node-specific parameters that control bearer level packet forwarding treatment (e.g. scheduling weights, admission thresholds, queue management thresholds, link layer protocol configuration, etc.).

bsaffach

Note

Eqivalent au Class en UMTS: Conversanional interactive, Background Streaming




4 � 30

2 Radio Management

2.2 QoS Parameters [CONT]

� The Allocation and Retention Priority (ARP) primarily allows one to decide whether a bearer establishment request can be accepted orrejected in case of resource limitations.

� In addition, the ARP can be used by the eNodeB to decide which bearer(s) to drop during exceptional resource limitations (e.g. at handover).

� Each GBR bearer is additionally associated with the following bearer level QoS parameter:

� GBR = Guaranteed Bit Rate, the bit rate that can be expected to be provided by a GBR bearer

� MBR = Maximum Bit rate

� Each non-GBR is additionally associated with the following bearer level QoS parameter:

� UE-AMBR = UE Aggregate Maximum Bit Rate (in UL)

� APN-AMBR = APN Aggregate Maximum Bit Rate (in DL)




4 � 31

2 Radio Management

2.3 Radio Bearer

� There are 2 types of Radio Bearers (RB):

� To carry signaling. There are called the SRB (Signaling Radio Bearer)

� To carry user data. There are associated with an EPS Bearer

� In LA1.X, the maximum number of RB per UE is 4

eNodeBUE

Signaling RB

User data -> RB

S-GW

S1 Bearer




4 � 32

2 Radio Management

2.3 Radio Bearer [cont.]

The following types of Radio Bearer are defined:

� SRB1: RRC signaling with high priority

� SRB2: RRC signaling and NAS signaling (lower priority)

� Best Effort: also defined as the default EPS Bearer

� GBR: Radio Bearer with a guaranteed bit rate

� VoIP: Radio bearer to carry the VoIP

In LA1.X the following combination are supported:

� SRB1

� SRB1+SRB2+Best Effort

� SRB1+SRB2+Best Effort + GBR

� SRB1+SRB2+Best Effort + VoIP

� SRB1+SRB2+Best Effort + Best Effort




4 � 33

2 Radio Management


� At the RRC connection, the eNodeB scheduler creates a context for the UE containing the UEBearerList.

� this list is limited to 4 per user in LA1.X

� Each bearer is identified by the LCID (Logical Channel ID)

� Each bearer is associated with QoS parameters like :

� Max bit rate and guaranteed bit rate

� VoIP or not

� H-ARQ usage

UE

eNodeB

UEBearerList

Bearer1 ->LCID, QoS parameterBearer2 ->LCID, QoS parameterBearer3 ->LCID, QoS parameter




4 � 34

2 Radio Management


� Default Bearer vs Dedicated Bearer

� A default bearer is bearer able to carry all kinds of traffic (no filter) without QoS. It is typically created during the attach procedure

� A dedicated bearer is a bearer to carry a specific data flow, identify by the TFT (Traffic Flow Template), with a given QoS.

� Example: Voice, streaming

� It can be established:

� During the Attach procedure (depending on the user profile)

� After the Attach procedure, on demand

UEeNodeB

Established during the attach procedureSRB 1

SRB2

Default Bearer (Best Effort)

Established after the attach procedure

VoIP

bsaffach

Note

Si plusieurs dedicated bearers, TFT + QoS identifient un bearer particulier




4 � 35

3 Traffic Operation




4 � 36

3 Traffic Operation

3.1 Traffic Operation Overview

eNode-B

UE1

UE2

UE1

1. PUCCH / Reported CQIs

1. PUCCH / Reported CQIs

Scheduler

3. Control Information (PDCCH)

Data transmission (PDSCH)

4. PUCCH / Ack-Nack

2. Scheduling decisionDL Data Transmission

bsaffach

Note

A ce jour c'est sur le canal PUSCH (aperiodic)




4 � 37

3 Traffic Operation

3.1 Traffic Operation Overview [cont.]

eNode-B

UE1

1. PUCCH / Scheduling request

3. PDCCH / Scheduling Grants

Scheduler

4. PUSCH / Control & Data info

5. PHICH / Ack-Nack

2. Scheduling decisionUL Data Transmission

bsaffach

Note

Utilisé par eNB pour ACK/NACK les transmissions ou re-transmission HARQ




4 � 38

3 Traffic Operation


� DL and UL schedulers are running in the eNodeB.

� From the following inputs, the eNodeB schedules the data on the air interface and indicates to the UE how to send (in UL) or receive (in DL) the data.

Scheduler

UE Category

Radio Resources available

Radio Measurement

Associated QoS parameters

Amount of data in the buffer

Scheduled user




4 � 39

3 Traffic Operation


The DL scheduler is spit into 3 functional parts:

� The Static Scheduler:Which assigns a fixed amount of Transport Blocks as well as PDCCH and PDSCH resources for

the BCCH over the DL-SCH Transport Channel.

Those resources are permanently allocated.

� The Semi-static Scheduler:Which assigns Transport Blocks as well as PDCCH and PDSCH resources for PCCH and CCCH

over the PCH and DL PDSCH SCH Transport Channels.

The semi-static scheduler also assigns a regular set of Transport Blocks for all established

VoIP bearers.

� The Dynamic Scheduler:

Which assigns Transport Blocks as well as PDCCH and PDSCH resources for DCCH & DTCH

over the DL-SCH Transport Channels.

The dynamic scheduler is also in charge of sending the MAC Control Timing Advance control

messages in order to keep the UE in the connected mode, synchronized with the network

bsaffach

Note

Toutes les 20ms, le scheduler alloue les resources Pour envoyer les canaux toujours envoyés au meme endroit: PSS SSS & MIB Ce scheduler tourne toutes les ms

bsaffach

Note

Toutes les 20ms, le scheduler alloue les resources Pour envoyer le Paging & les SIBs & pour VOIP Ce scheduler tourne toutes les ms pour le traffic

bsaffach

Note

Toutes les 20ms, le scheduler alloue les resources Ce scheduler tourne toutes les ms




4 � 40

3 Traffic Operation


The LTE DL scheduler is composed of 2 main algorithms:

� A pre-booking stage which reserve resources over the PDSCH for the static and semi-static schedulers.

� A scheduling stage which assign the resources over the PDSCH for effective traffic.

Static schedulerPre-booking

Every 20msInput is the Time Frequency ResBlock Occupancy with available PDSCH resources for L2

Semi-Static schedulerPre-booking

Output is Time Frequency Res Block Occupancy With blocks reserved for static and semi static scheduler.

Every msInput is the TimeFrequencyResBlocOccupancy with blocks reserved for static and semi-static scheduler.

Static schedulerScheduling

Semi-Static schedulerScheduling

Dynamic schedulerscheduling

Output is the interface to L1 for PDSCH& PDCCH

DL Scheduler pre-booking stage

DL Scheduler scheduling stage




4 � 41

3 Traffic Operation


� UE categories

� These UE categories are often referred to as UE classes. The low end UE does not support MIMO but the high end UE will support 4x4 MIMO

� Whatever category a UE belongs to, it has to be capable of receiving transmissions from up to four antenna ports. This is because the system information can be transmitted on up to four antenna ports.

It should be noted that some of the capabilities are outside the UE category info. For example the Inter-RAT

capabilities like the support of EV-DO or GSM, etc is not specified as part of the UE categories. Similarly the

support of duplexing schemes and the support of UE-specific reference signals are outside the scope of this.




4 � 42

3 Traffic Operation


� The channels used to carry high transmission data are:

� The PDSCH in Downlink

� The PUSCH in uplink

� The usage of these channels is packet optimized.

� There are no dedicated resources allocated to a UE.

� The resources, RB and slot, are allocated by the eNodeB scheduler dynamically.

� It takes in account the QoS requirements of each stream.




4 � 43

� The data in DL are sent on the PDSCH

� A minimum of 2 RBs are allocated by the eNodeBs.� A RB is 12 sub-carriers on a slot (7 symbols).

� The eNodeB sends on the PDCCH the required information to allow the UE decode the data on the PDSCH.� On which slot?

� On which Resource blocks?

� How are the data modulated?

eNodeBPDSCH

RF A Slot

PDCCH

You will receive on the PDSCH

f

Resources Blocks

3 Traffic Operation

3.2 Data Transmission in DL




4 � 44

3 Traffic Operation

3.2 Data Transmission in DL [cont.]

� The Physical Downlink Shared Channel (PDSCH) carries:

� User data

� User signaling

� Paging messages

� System information message

� The PDSCH can use all the resources not used by the other channel:

� Synchronization channels

� Reference signal

� PDCCH

� PBCH

� PCFICH




4 � 45

3 Traffic Operation


� The PDCCH, Physical Downlink Control Channel, allocates the DL and UL resources.

� There is one PDCCH per sub-frame.

� It helps the UE retrieve the transport blocks from the PDSCH:

� Allocated RB

� Modulation and Coding Scheme (MCS)

� Multi-antenna transmission

1 sub-frame PDCCH

� PDCCH

� Shared between all UE of the cell

� Each TTI contains an aggregation of PDCCH allowing to address several users simultaneously (UL and/or

DL)

� The CRC of each PDCCH is scrambled (XOR) with the UE RNTI

� Each UE tries to decode PDCCH and compares the resulting RNTI with its own identity (blind decoding)

� PDCCH resource granularity = 1 CCE (Control Channel Element)

� 1 CCE = 36 Resource Element = 72 bits (QPSK modulation only for PDCCH)

� Physical mapping is such that RE of a same CCE are scattered in time and frequency to get the best

diversity

� Physical mapping depends on the physical parameter ncell_id so that CCE of synchronized neigbouring

cells do not collide

bsaffach

Note

Le cfi indique la taille du PDCCH En 5 & 10 MHz, cfi == 3 symbols En 20 MHz, cfi == 2 symbols Le cfi est donné au mobile sur le canal PCFICH (ce canal ne contient d'ailleurs que cette donnée)




4 � 46

3 Traffic Operation


� The reception of the PDCCH is essential for the data transmission.

� Its size and location are not pre-defined since the amount of control data depends on the traffic.

� The Physical Control Format Indication Channel (PCFICH):

� allows the UE to decode the PDCCH.

� is carried on pre-defined time-frequency resources.

� indicates the number of symbols occupied by the PDCCH.




4 � 47

3 Traffic Operation

3.3 Data Transmission in UL

� In UL, the UE has no dedicated resources to transmit directly when new data arrived in the buffer from higher layer.

� It requests resources to transmit them.

� It receives radio resources.

� It transmits them.

eNodeB

MAC Layer

Data (http request)

How to send this packet?

MAC Layer

Scheduling Request

UL Grant

Buffer status & Data transmission

bsaffach

Note

UL Grant est envoyé sur le PDCCH

bsaffach

Note

Le Scheduling REQ est envoyé sur le PUCCH




4 � 48

3 Traffic Operation

3.3 Data Transmission in UL [cont.]

� The scheduling request is sent on the Physical Uplink Control Channel (PUCCH).

� This channel carries radio signaling in uplink:� Scheduling Request to grant resources in UL� Radio measurement report from the UEs� Radio retransmission ack or nack

� The UE can know from the SIB how to use the PUCCH.� The response, the UL grant, is sent on the PDCCH.

eNode-B

MAC Layer

Data (http request)

MAC Layer

Scheduling Request on the PUCCH

UL Grant on the PDCCH




4 � 49

3 Traffic Operation


� The Physical Uplink Share Channel (PUSCH) carries:

� User data

� User Signaling

� The resources are dynamically assigned in time and frequency.

� The PUSCH supports the H-ARQ.




4 � 50

3 Traffic Operation


� When the UE transmits in UL, it transmits also UL reference signals.

� Data demodulation reference signal (DM-RS)� Sent with each packet transmission in order to

demodulate data

� Occupies center SC-FDMA symbol of the slot, only sent over bandwidth allocated for data transmission

� Sounding reference signal (SRS)

� Used to sound uplink channel to support frequency selective scheduling

� SRS parameters are UE specific and configured semi-statically

� 1 symbol in subframe used for SRS

� Periodicity: {2, 5, 10, 20, 40, 80, 160, 320} ms

� Bandwidth: typically transmitted over the entire PUSCH bandwidth (does not include PUCCH region)

� SRS is not sent when there is a scheduling request (SR) or CQI to be sent on PUCCH (to avoid multi-carrier transmission)

UE 1

UE 2

UE 3

Slot = 0.5ms

Slot = 0.5ms

SRS (wideband)

DM-RS UE 1

DM-RS UE 2

DM-RS UE 3

1. Data demodulation reference signal (DM-RS)

� Sent with each packet transmission in order to demodulate data

� Occupies center SC-FDMA symbol of the slot, only sent over bandwidth allocated for data transmission

2. Sounding reference signal (SRS)

� Used to sound uplink channel to support frequency selective scheduling

� Channel sensitive scheduling in both time and frequency

� SRS parameters are UE specific and configured semi-statically

� 1 symbol in subframe used for SRS

� Periodicity: {2, 5, 10, 20, 40, 80, 160, 320} ms

� Bandwidth: typically transmitted over the entire PUSCH bandwidth (does not include PUCCH region)

� SRS is not sent when there is a scheduling request (SR) or CQI to be sent on PUCCH (to avoid multi-

carrier transmission)

� ALU implementation configures a wideband SRS with a period of 5ms




4 � 51

3 Traffic Operation

3.4 DCI

� The PDCCH carries Downlink Control Information or DCI to indicate the resource assignment in UL or DL for one RNTI.

� A DCI can conveys various pieces of information, but the useful content depends on the specific case of system deployment or operations.� If the MIMO is not used during the transmission , there is no need to transmit the MIMO parameter in the DCI

� There are several format of DCI defined by the 3GPP for each need

eNodeB

PDCCH

DCIDCI

RB AssignmentMSC

H-ARQ infoPower Control

PUSCH

Data transmission

� UE feed backs the network with CQI (Channel Quality Indication) giving an estimation of the channel

quality

� The network adapts downlink transmission accordingly by changing:

� The coding rate (amount of information bits over number of transmitted bits)

� The modulation (QPSK, 16QAM, 64QAM)

� Radio resources are shared among users: a trade-off is needed between maximizing the bitrate and using

the smallest amount of resource blocks

� For MIMO configuration, the RI and PMI are also reported




4 � 52

3 Traffic Operation

3.4 DCI [cont.]

� The main DCI formats are:

� Format 0

� For scheduling of the PUSCH (UL Grant)

� Format 1A

� Used during the Random Access Procedure

� Format 1

� For the scheduling of the PDSCH (DL Grant)

� In case of TxDiv

� Format 2A

� For the scheduling of the PDSCH (DL Grant)

� In case of Open Loop SU- MIMO

� Format 2

� For the scheduling of the PDSCH (DL Grant)� In case of Closed Loop SU- MIMO

� Downlink Control Information (DCI) used to grant UL/DL traffic

� DCI0 for uplink grant of PUSCH

� DCI1 and DCI1A for downlink grant of PDSCH with one single codeword

� DCI2 for downlink grant of PDSCH with one or two codewords (closed-loop MIMO)

� DCI2A for downlink grant of PDSCH with one or two codewords (open-loop MIMO)

� DCI carried in PDCCH transport channel




4 � 53

3 Traffic Operation

3.5 Measurement Report

� The UE reports its measurements to the eNodeB.

� It is a key mechanism for:

� The Link adaptation, the selection of the modulation and coding rate.

� The e-UTRA mobility, in case of mobility in the e-UTRA coverage.

� The Inter-RAT mobility, if the UE is leaving the LTE coverage.

� The UE is able to measure:

� The serving cell

� The e-UTRA neighbors

� The UTRAN cell

� The GERAN cell

� The CDMA2000 cell eNodeB

To be able to optimize downlink transmissions by adapting the modulation and coding scheme (MCS), the

mobile device has to send channel quality indications (CQI) on the PUCCH and the PUSCH). In addition, the

mobile also collects measurements on neighboring cells and reports them to the base station whenever a

threshold is crossed (e.g. a neighboring cell is received better than the current cell).




4 � 54

3 Traffic Operation

3.5 Measurement Report [cont.]

� The UE measures the Reference Signal which is a cell specific signal.� It depends on the Cell ID and so is different in 2 adjacent cells.

� It is sent every sub-frame

� Here is the mapping of this signal on a sub-frame:

12 sub-Ca = 1 RB

14 symbols = 2 slots = 1 Sub-frame

Cell-specific reference signals shall be transmitted in all downlink sub-frames in a cell supporting non-MBSFN

transmission. In case the sub-frame is used for transmission with MBSFN, only the first two OFDM symbols in a

sub-frame can be used for transmission of cell-specific reference symbols.

The measurement quantities on the RS are:

� The Reference Signal Received Power (RSRP)

� It is defined as the linear average over the power contributions of the resource elements that

carry cell-specific reference signals within the considered measurement frequency bandwidth.

� The Reference Signal Received Quality (RSRQ)

� It is defined as the ratio N×RSRP/(e-UTRA carrier RSSI), where N is the number of RBs of the E-

UTRA carrier RSSI measurement bandwidth. The measurements in the numerator and denominator

shall be made over the same set of resource blocks.

� The Received Signal Strength Indicator (RSSI)

� It comprises the linear average of the total received power observed only in OFDM symbols

containing reference symbols, in the measurement bandwidth, over N number of resource blocks

by the UE from all sources, including co-channel serving and non-serving cells, adjacent channel

interference, thermal noise etc.

bsaffach

Note

Reference signal est présent ans tous les PRB & toutes les sub-frames UE va mesurer: Reference Reference Signal & Signal Received Received Power Quality UE calcule le RSRQ avec le RSSI: RSRQ = RSRP/RSSI A partir de ces mesures (RSRP & RSRQ) le mobile calcule le CQI et l'envoit sur le PUSCH NB: le UE mesure le CQI par wideBand (groupe de bande): WB CQI & par sub Band SB CQI Quand eNB recoit les CQI il calcule le SINR (Signal Interference Node Ratio en Db) pour en déduire la table des MCS




4 � 55

3 Traffic Operation


� The UE reports the Channel Quality Indicator (CQI) about its serving cell.

� The CQI is used by the scheduler to select the most adapted MCS.

5.554794864QAM15

5.115287364QAM14

4.523477264QAM13

3.902366664QAM12

3.322356764QAM11

2.730546664QAM10

2.406361616QAM9

1.914149016QAM8

1.476637816QAM7

1.1758602QPSK6

0.8770449QPSK5

0.6016308QPSK4

0.3770193QPSK3

0.2344120QPSK2

0.152378QPSK1

out of range0

efficiencycode rate x 1024modulationCQI index




4 � 56

3 Traffic Operation


� The CQI is reported:

� periodically by the PUCCH.

� aperiodically by the PUSCH.

� In case multiple antennas are used, the UE can also report by means of the following channels:

� Precoding Matrix Indicator (PMI).

� Rank Indicator (RI).

eNodeB

PUCCH: periodic report

PUSCH: aperiodic report




4 � 57

3 Traffic Operation

3.6 Radio Retransmission

� The radio retransmission mechanism is called Hybrid Automatic Request (H-ARQ).

� H-ARQ allows to retransmit fastly erroneous blocks between the eNodeBand the UE.

� It avoids long retransmission between 2 TCP layers.

Internet

e-UTRANMME

P-GW

ePC

UE

EPS Bearer

S-GW

Web server

TCP retransmission

bsaffach

Note

Le mécanisme de retransmission H-ARQ est au niveau MAC Il existe aussi un mécanisme de retransmission ARQ au niveau RLC RLC Un block erronné est jeté MAC Un block erronné est reconstruit et ré-émis




4 � 58

3 Traffic Operation

3.6 Radio Retransmission [cont.]

� The H-ARQ process runs in the eNodeB and in the UE.

� The H-ARQ is based on ACK/NACK messages carried by PUCCH or PUSCH.

� The LA1.X implementation is a hard HARQ technique:

� It reserves the same RB resources & MCS used for the initial transmission.

CombiningRx packets

Packet transmission

H-ARQ Re-Tx

H-ARQ NACK

H-ARQ ACK

eNode-B UE

Using information that was sent in the previous transmissions of the same block to increase the probability of

decoding

If data block not received correctly, soft values are stored in order to reuse them after the retransmission of

the block

When data is retransmitted, a different puncturing scheme is used so that the transmitted bit do not carry the

same information as the first time

If puncturing schemes are disjoint between two transmission, number of coded bits transmitted after the

second transmission is twice as high, thus coding rate has been divided by 2. After the third transmission,

coding rate has been divided by 3. Probability to decode the block is increased after each transmission.

If puncturing schemes are not disjoint, soft values corresponding to the samed bits are added. Decisions’

average reliability increases




4 � 59


3.6.1 H-ARQ Mechanism in DL

Transport Block#1

PDCCH

PDSCH

1

Soft buffer

TB #1

TB #1

2

Nack

PUCCH3

1. The Transport block is transmitted to the UE on the PDSCH.

2. The UE receives it but it is erroneous. The TB is stored in a buffer.

3. The UE transmits directly a NACK concerning the erroneous block on the PUCCH.

One HARQ entity in the UE and the e-UTRAN

Made of 8 HARQ processes in each direction (extended to 16 in DL MIMO)

Each process handles STOP and WAIT HARQ protocol

Each process is responsible for generating ACK or NACK indicating delivery status of PDSCH/PUSCH

bsaffach

Note

8 processes HARQ per UE




4 � 60


3.6.1 H-ARQ Mechanism in DL [cont.]

Transport Block#1

PDCCH

PDSCH 1 Retransmission

Transportblock #1

TB #1 TB #1

Soft buffer

2 Combination

Ack

PUCCH

3 Acknowledgement

1. On reception of the NACK, the eNodeB retransmits the TB.

2. The UE receives it. Even if the retransmitted TB (Transport Block) is erroneous, the UE can try to

recombine the 2 TB to have a correct one.

3. The UE send a ACK on the PUCCH




4 � 61


3.6.2 H-ARQ Mechanism in UL [cont.]

Transport Block

PUSCH

1

TB #1

Soft buffer

TB #1

2

PHICH

NACK

3

In UL, it is the same principle, but the eNodeB send the ACK/NACK on a channel dedicated to the H-ARQ

called the PHICH.

bsaffach

Note

PHICH: Physical HARQ Indicator Chanel Utilisé pour les acquittements de ce qui a été transmis en UL




4 � 62

Answer the Questions 1

� Which ID is assigned by the eNodeB to the UE during the Random Access Procedure ?

A. The GUTI

B. The TMSI

C. The C-RTNI

D. The IP address

bsaffach

Note

GUTI: Global Unique Identity Mobile Donné par le MME quand le Mobile s'attache Permet quand le UE est en mode idle et veut se reconnecter de dire au MME qui il est sans redéclancher la procedure d'identification




4 � 63


� After the RRC connection, the UE can download a file by ftp ?

A. TRUE

B. FALSE

bsaffach

Note

B false




4 � 64


� The CQI is:

A. Class identifier to attribute QoS parameters to EPS Bearer

B. Measurement feedback

C. Format of information on the PDCCH to assigned resources on the PDSCH

D. Name of a transport channel




4 � 65


� To receive data on the PDSCH, the UE decodes:

A. The PBCH channel

B. The PDCCH channel

C. The PCFICH channel

D. The PUCCH channel




4 � 66

Exercise 1

� Could you match each task with the appropriate channel?

� A task can require several channels.

Transmit user data in UL

Send a CQI

Reference signal

PUCCH

PUSCH

PDCCH

Identify the cell ID

Measure the quality of an adjacent cell

Receive user data in DL

PSS & SSS

PDSCH

PBCH




4 � 67

Module Summary

� Thanks to the PSS, the SSS and the BCH, the UE can be synchronized and can obtain the System parameters

� The Random Access procedure allows a UE to contact the eNodeB using preamble on the PRACH

� During the RRC connection, a Signaling Radio Bearer (SRB) is established to exchange signaling between the UE and the eNodeB

� The attach procedure between the UE and the ePC is made of the authentication, the allocation of an IP address and the establishment of radio bearer depending on the user profile

� During data transfer, the UE measurement report allows the eNodeB to adapt the transmission




4 � 68

End of ModuleeUTRAN Scenarios

� Page 1




Module 5LTE Antenna System



� Page 2



9400 LTE RAN Radio Principles DescriptionLTE Antenna System

5 � 2

Blank Page




Document History

� Page 3




5 � 3

Module Objectives


� Explain what is the Rx Diversity

� Explain what is the Tx Diversity

� Describe the different types of MIMO

� Explain what is the Beamforming

� Page 4




5 � 4



� Page 5




5 � 5

Table of Contents


1 Terminology 71.1 Introduction 81.2 Single Antenna 91.3 Transmit Diversity 101.4 Receive Diversity 111.5 MIMO 121.5 MIMO Single User 141.6 MIMO Multi User 171.7 MIMO & Cell Traffic 18

� Page 6




5 � 6




� Page 7




5 � 7

1 Terminology

� Page 8




5 � 8

1 Terminology

1.1 Introduction

� The multiple-antenna technique is not a synonym of MIMO.

� The main techniques are:

� MIMO

� Beamforming

� Diversity

� The principle is to use several antennas in transmission and/or reception to improve signal robustness and consequently system capacity or coverage.

eNodeB

� Page 9




5 � 9

1 Terminology

1.2 Single Antenna

� SISO = Single Input Single Output

� It is the most basic radio channel access mode.

� Only one transmit antenna and one receive antenna are used.

� This is the form of communications that has been the default one since radio has begun. SISO is the baseline against which all the multiple antenna techniques are compared.

eNodeB

Using the 1 antenna in transmission and 1 antenna in reception is the standard configuration since the

beginning of the telecom.

� Page 10




5 � 10

1 Terminology

1.3 Transmit Diversity

� MISO = Multiple Input Single Output� Principle

� More complex than SISO.

� 2 or more transmitters and one receiver.

� MISO is more commonly referred to as transmit diversity.

� The same data is sent on both transmitting antennas but coded in such a way that the receiver can identify each transmitter.

� Benefits� Transmit diversity increases the robustness of the signal to fading and can increase performance in low Signal-to-Noise Ratio (SNR) conditions.

� It does not increase data rates as such, but rather supports the same data rates using less power.

eNodeB

When the eNodeB uses 2 antennas in DL to transmit twice the same data, it is the diversity in transmission,

also called the TxDiv. It improve the quality and the coverage at the cell edge.

bsaffach

Note

En LTE utilisé pour transmettre la MIB

� Page 11




5 � 11

1 Terminology

1.4 Receive Diversity

� SIMO = Single Input Multiple Output

� Principle

� It uses one transmitter and 2 or more receivers.

� It is often referred to as receive diversity.

� Benefits

� It is particularly well suited for low SNR conditions in which a theoretical gain of 3 dB is possible when two receivers are used.

� No change in the data rate since only one data stream is transmitted, but coverage at the cell edge is improved due to the lowering of the usable SNR.

eNodeB

The UE in UL can transmit only one stream, but with 2 antennas in reception, the eNodeB can receive twice

the signal. So it can combine them to improve the reception quality.

� Page 12




5 � 12

1 Terminology

1.5 MIMO

� MIMO = Multiple Input Multiple Output

� 2 or more transmitters and 2 or more receivers.

� MIMO transmits several streams whereas SIMO or MISO transmits only one stream.

� If there are N streams, there will be at least N antennas (here only 2).

� By spatially separating N streams across at least N antennas, N receivers

will be able to fully reconstruct the original data streams

eNodeB

MIMO requires N antennas in transmitter and receiver and by this way it can transmit N streams in the same

radio resources on the same time. Currently, N=2 and there are 2 2 antennas on the eNodeB and 2 antennas

on the UE.

It allows to transmit 2 TB (Transport Block) on the same subframe for a given UE and by this it boosts the radio

performance.

� Page 13




5 � 13

1 Terminology

1.5 MIMO [cont.]

� The transmissions from each antenna must be uniquely identifiable so that each receiver can determine what combination of transmissions has been received. This identification is usually done with pilot signals, which use orthogonal patterns for each antenna.

� There are several MIMO methods.

� The stream are sent on the same time, on the same frequency

Each antenna on the receiver receives the 2 TB (the red and the blue one). There are able after to separate

them.

The 2 TB are same on the same time and on the same frequencies (PRB). The receiver can separate them

because it knows the characteristics of transmission for each antennas in real time. There are a lot of RE

use for the reference signal of each antenna to allow the UE to distinguish them.

If the UE is not able to separate the 2 TB (because the 2 transmission paths are not enough different or the

radio condition are bad) the transmitter send the same TB on the 2 antennas.

bsaffach

Note

Le MIMO est utilisé quand les conditions radio permettent de le faire: Le UE envoit le RI: si ==2 il voit bien les 2 antennes => MIMO est possible. Sinon UE envoit un RI == 1 => TxDiv

� Page 14




5 � 14

1 Terminology

1.6 MIMO Single User

� SU-MIMO = Single User MIMO

� It is the most common form of MIMO.

� Each user is served by only one BS and it occupies the resource exclusively, including time, frequency.

� It can be applied in the uplink or downlink.

� But it is generally applied only in DL. The UE can easily have 2 antennas in reception but only 1 antenna can transmit

eNodeB

The Single User MIMO is used in DL and means that the 2 TB send by the 2 antennas using the same radio

resources are for the same UE.

In UL, it is not possible to use this MIMO.

� Page 15




5 � 15

1 Terminology

1.6 MIMO Single User

eNodeB

2 antennas on UE

2 antennas on eNodeB

ePC

� There are two operation modes in SU-MIMO spatial multiplexing:

� the closed-loop spatial multiplexing mode

� The UE reports the CQI, the RI (Rank Indicator) and the PMI (Precoding Matrix indicator)

� the open-loop spatial multiplexing mode

� The reports only the CQI and the RI

� The RI (Rank Indicator) indicates the number of spatial layers (data streams) that can be supported by the current channel experienced at the UE

� The PMI (Precoding Matrix Indicator) is the UE feedback

RI, PMI

The required UE feedback for the MIMO are:

- RI, Rank Indicator. By this one the UE can indicate if it is able to separate 2 TB. If Yes the eNodeB can use

the MIMO. If not it uses the TxDiv

- PMI, Precoding Matrix indicator. It is used only for the Closed Loop MIMO. The UE indicates the eNodeB how

to map the data on the 2 antennas to optimize the reception.

� Page 16




5 � 16

1 Terminology

1.7 MIMO Multi User

� MIMO-MU = Multi user

� It is used only in Uplink.

� MIMO-MU does not increase the individual user’s data rate but it does offer cell capacity gains that are similar to, or better than, those provided by MIMO-SU.

� The UE does not require the expense and power drain of two transmitters, yet the cell still benefits from increased capacity.

� The UE must be well aligned in time and power as received at the eNB.

eNode-B

In UL, the UE can not transmit 2 different signal like it has only 1 amplifier. So to take benefit of the MIMO

capabilities, the eNodeB can allocates the same radio resources to 2 UEs (PRB and sub-frame). By this way,

he eNodeB boosts the capacity in UL.

� Page 17




5 � 17

1 Terminology

1.8 MIMO & Cell Traffic

� The Tx Div can be applied on all the physical channels:

� Physical DL Shared Channel (PDSCH)

� Physical Broadcast Channel (PBCH)

� Physical Control Format Indicator Channel (PCFICH)

� Physical Downlink Control Channel (PDCCH)

� The other MIMO schemes are only applicable to the PDSCH

Like the MIMO required a UE-specific feedback (RI and PMI), it is not possible to use it for all the channel.

Only the PSDCH supports the MIMO and only for UE specific data.

For example, the SIB2 is transmitted on the PDSCH but it is received by all the UE, so TxDiv. The HO command

is transmitted only to a given UE, so MIMO can be used if criterion are fullfilled.

� Page 18




5 � 18

1 Terminology

1.8 MIMO & Cell Traffic

� The 3 possible transmission mode are:

� TxDiV only

� MIMO-SU Open Loop

� MIMO-SU Closed Loop

� Depending on the selected mode, some specific CQI report modes can be configured and some specific DCI can be used

� Page 19




5 � 19

Module Summary

� The TxDiv is the fact to transmit twice the same data stream in DL to improve the quality of the transmission

� The RxDiv is the fact to receive the signal with 2 antennas (in UL) to improve the quality of the transmission

� The MIMO uses multiple antennas on the receiver on the transmitter to send several streams on the same time and on the same sub-carrier

� In DL, it is the SU-MIMO (Single User)

� In UL, it is the MU-MIMO (Multi-User)

� Page 20




5 � 20

End of ModuleLTE Antenna System




LTE � 9400 LTE Radio PrinciplesMobility Management

6 � 2

Blank Page




Document History





6 � 3

Module Objectives


� Describe the mobility mechanism when the UE is RRC connected, i.e. the handover

� Describe the mobility mechanism when the UE is in idle mode, i.e. the paging, the TAU and cell reselection





6 � 4







6 � 5

Table of Contents


1 Introduction 71.1 Mobility Management 8

2 Handover 122.1 Types of Handover 132.2 Intra E-UTRAN Handover 142.3 Process 152.4 Measurements 17

3 Idle Mode 183.1 Principles 193.2 Paging 203.3 Tracking Area 233.4 Cell reselection 24





6 � 6








6 � 7

1 Introduction





6 � 8

1 Introduction

1.1 Mobility Management

� The mobility management of a UE depends on its state.

� Depending on its state, there are different mechanisms to manage the mobility:

� Handover intra e-UTRA

� Handover Inter-RAT

� Cell reselection

� Idle mode and paging mechanisms

eNodeB

ePC

MME





6 � 9

1 Introduction

1.1 Mobility Management [cont.]

� There are 2 EMM states

� EMM-DEREGISTERED

� The UE is not reachable by the MME.

� Some UE context is kept by the MME.

� EMM-REGISTERED

� The MME assigns this state to UE up on successful Attach.

� UE location is known by the MME at least with an accuracy of the tracking area list allocated to the UE.

� The UE, MME, S-GW and P-GW, all keep the UE context.

� Changing states

� The MME changes the UE state from EMM-REGISTERED to EMM-DERGISTERED for events like Attach Reject, TAU reject, Detach (for example, when the UE powers

off).

� EMM = EPS Mobility Management

Attach

Detach

EMM-DEREGISTERED EMM-REGISTERED





6 � 10

1 Introduction


� There are 2 ECM states:

� ECM-Idle

� No Non-Access Stratum (NAS) signaling connection between UE and MME.

� The UE continues to take cell measurements for cell selection or reselection.

� ECM-Connected

� A UE has NAS signaling connection with the MME.

� UE location is known by the MME with an accuracy of the serving eNB.

� Mobility is handled by handover procedures.

� Changing states

� Transition to the ECM-Connected state is initiated by Attach, TAU, and service requests (for example, the UE clicks a button to read email).

� ECM -> EPS Connection Management

Signaling Connection

Established

Signaling Connection

Released

ECM-IDLE ECM-CONNECTED





6 � 11

1 Introduction


No Mobility Management

EMM-DEREGISTERED EMM-REGISTERED

The UE is RRC_idle. It is known at the Tracking Area level• paging & TA update

ECM-IDLE

The UE is RRC Connected. It is known at the eNodeBlevel• Handover

ECM-CONNECTED





6 � 12

2 Handover





6 � 13

2 Handover

2.1 Types of Handover

WCDMA cell

CDMA2000 cell

� The Handover is the process of transferring an ongoing call or data session from one cell connected to the core network to another

� It is transparent for the end user

� It is network controlled and UE assisted

� The 3GPP defines handover:� Intra e-UTRAN

� Inter RAT with 3GPP technologies (GSM, WCDMA)

� Inter RAT with non-3GPP technologies (CDMA2000, HRPD)

ePC

MME

eNodeB

eNodeB

HO intra e-UTRAN

HO inter-RAT

HO inter-RAT with non-3GPP standard





6 � 14

2 Handover

2.2 Intra E-UTRAN Handover

� The UE is RRC connected.

� During the HO:

� The radio link is released from the eNodeB 1 and re-established on the eNodeB 2

� The Control plane is switched to the eNodeB 2 and the MME

� The User plane is switched to the eNodeB 2 and the S-GW

eNodeB 1

MME

Serving GW

eNodeB 2

x2

S1-MME

S1-U

S11

User data

The Intra-e-UTRAN-Access Mobility Support for UEs in ECM-CONNECTED handles all necessary steps for

relocation/handover procedures, like processes that precede the final HO decision on the source network side

(control and evaluation of UE and eNB measurements taking into account certain UE specific area restrictions),

preparation of resources on the target network side, commanding the UE to the new radio resources and

finally releasing resources on the (old) source network side. It contains mechanisms to transfer context data

between evolved nodes, and to update node relations on C-plane and U-plane.





6 � 15

2 Handover

2.3 Process

Source eNB Target eNB MME S-GW

Measurements

HO Decision

HO Request

Admission Control

HO ResponseRRC Reconfig

HO command

Detach from old cellSynchro with new cell

RRC Reconfig

SRB and RB re-establishment

The source eNB issues a HANDOVER REQUEST message to the target eNB passing the necessary information to

prepare the HO on target side (UE X2 signaling context reference at source eNB, UE S1 EPC signaling context

reference, target cell ID, KeNB*, RRC context including the C-RNTI of the UE in the source eNB, AS-

configuration, E-RAB context and physical layer ID of the source cell + MAC for possible RLF recovery). UE X2 /

UE S1 signaling references enable the target eNB to address the source eNB and the EPC. The E-RAB context

includes necessary RNL and TNL addressing information, and QoS profiles of the E-RABs.

Admission Control may be performed by the target eNB dependent on the received E-RAB QoS information to

increase the likelihood of a successful HO, if the resources can be granted by the target eNB. The target eNB

configures the required resources according to the received E-RAB QoS information and reserves a C-RNTI and

optionally an RACH preamble.

The target eNB prepares HO with L1/L2 and sends the HANDOVER REQUEST ACKNOWLEDGE to the source eNB.

The HANDOVER REQUEST ACKNOWLEDGE message includes a transparent container to be sent to the UE as an

RRC message to perform the handover. The container:

� includes a new C-RNTI, target eNB security algorithm identifiers for the selected security algorithms,

� may include a dedicated RACH preamble, and possibly some other parameters i.e. access parameters, SIBs,

etc.





6 � 16

2 Handover

2.3 Process [cont.]

Source eNB Target eNB MME S-GW

Path switch

RequestUser plane update

Request

User plane update

ResponsePath switch

AckUE context

Release

Release Resources





6 � 17

2 Handover

2.4 Measurements

� Measurements to be performed by a UE for intra/inter-frequency mobility are controlled by e-UTRAN, using broadcast or dedicated control.

� If the frequency center of the measured cell is the same

� No measurement gaps are required

� If the frequency center of the measured cell is not the same

� Measurement gaps are required

Source eNB

Measurement Control

Data Transfer and Measurements

Measurement Report

In RRC_CONNECTED state, a UE shall follow the measurement configurations specified by RRC directed from

the e-UTRAN (e.g. as in UTRAN MEASUREMENT_CONTROL).





6 � 18

3 Idle Mode





6 � 19

3 Idle Mode

3.1 Principles

� When there is no traffic during a given time, the radio link can be released to save resources. The RRC state is switched to RRC_Idle

� The UE is still attached to the network and the radio link can be re-established fastly in case of incoming traffic.

RRC Connected• UE has an e-UTRAN-RRC connection;• e-UTRAN knows the cell which the UE

belongs to• Network can transmit and/or receive

data to/from UE• Network controlled mobility (handover);• Neighbor cell measurements

RRC Idle• Broadcast of system information

• Paging

• Cell reselection mobility

• No RRC context stored in the eNB

Traffic

Traffic





6 � 20

3 Idle Mode

3.2 Paging

� The idle UE is reachable in case of incoming traffic thanks to the paging mechanisms

MME

ePC

e-UTRAN

S-GW

P-GW

Incoming data

1

Paging message

2

Paging message over the air interface

3

Paging receivedIt requests a connection4

S-GW

When the UE is in idle mode, the Radio bearer and the S1 bearer are released. But the S5 bearer is still

maintains. By this way, when there are incoming data, the PGW is able to forward them to the SGW.

The SGW knows that the UE is attached but not connected. So it requests to the MME to wake up the UE by

paging.

bsaffach

Note

At rececption of the Paging msg from MME, UE sends a SERVICE REQUEST (corresponding to the ATTACH REQUEST) asking the resources allocation





6 � 21

3 Idle Mode

3.2 Paging [cont.]

� The UE is inactive but monitors periodically the paging messages sent on the PDSCH.

� The DRX cycle is configurable.

� There is one paging occasion per cycle:

� It is negative if there is no DL incoming traffic.

� It is positive if there is an incoming packet.

� Rules known by the UE and the eNodeB allows to synchronize the paging occasion.

PCCH

PCH

PDCSH

Radio Frame

DRX cycle

Paging message





6 � 22

3 Idle Mode

3.2 Paging [cont.]

� At the reception of a paging message, the UE requests the re-establishment of its context including SRB and RB for user traffic.

� The UE context is stored in the MME.

UE eNB MME

S1- AP: INITIAL CONTEXT SETUP COMPLETE+ eNB UE signalling connection ID+ Bearer Setup Confirm (eNB TEID)

S1-AP: INITIAL UE MESSAGE (FFS)+ NAS: Service Request+ eNB UE signalling connection ID

S1-AP: INITIAL CONTEXT SETUP REQUEST+ (NAS message)+ MME UE signalling connection ID+ Security Context+ UE Capability Information (FFS)+ Bearer Setup (Serving SAE-GW TEID, QoS profile)

RRC: Radio Bearer Setup(NAS Message)

RRC: Radio Bearer Setup Complete

Random Access Procedure

NAS: Service Request

PagingPaging





6 � 23

3 Idle Mode

3.3 Tracking Area

� In idle mode, the network knows the location of the UE at the Tracking Area level.

� The Tracking Area is a group of cells. The Tracking Area Identifier (TAI) is sent over the Broadcast Channel.

� A paging message is sent on the UE tracking area and not on the whole network.

TAI 1

TAI 1

TAI 1

TAI 1

TAI 1

TAI 2

TAI 2

TAI 2

TAI 2

TAI 2

TAI 2

TAI 3

TAI 3

TAI 3

TAI 3

Tracking Area 1

Tracking Area 2Tracking Area 3





6 � 24

3 Idle Mode

3.4 Cell Reselection

� Cell Reselection

� The UE in idle mode measures regularly the selected cell and the adjacent cells to always select the best cell.

� When the UE reselects a cell, it checks the TAI.

� It is not the same TAI as in the previous cell. So it performs a Tracking Area Update (TAU) to update its location.

TAI 1

TAI 1

TAI 1

BCCH

TAI 1

TAI 1

TAI 2

TAI 2

TAI 2

TAI 2

TAI 2

TAI 2

TAI 3

TAI 3

TAI 3

TAI 3

Tracking Area 1

Tracking Area 2Tracking Area 3





6 � 25

Module Summary

� When a UE is EMM-REGISTERED, its context is known by the MME, the S-GW and the P-GW but it can be RRC connected or not (idle mode)

� The Handover is controlled by the eNodeB based on the UE measurement.

� If there is not enough traffic, the UE switches in Idle mode. It is not connected but still active to reselect always the best cell and to monitor the paging message

� In Idle mode, its location is known at the Tracking Area level (group of cell). There is a Tracking Area Update (TAU) when the UE reselect a cell which belongs to the current TA.





6 � 26

End of ModuleMobility Management




Module 7Abbreviations





9400 LTE RAN Radio Principles DescriptionAbbreviations

6 � 2

Abbreviations and Acronyms


3G third Generation 3GPP third Generation Partnership Project

A

AAA Authentication, Authorization and Accounting AM Acknowledgement Mode AM Amplitude Modulation AMBR Aggregated Maximum Bit Rate ARP Allocation and Retention Priotity AS Access Stratum B

BCCH Broadcast Control Channel BCH Broadcast Channel

C

CCCH Common Control CHannel (GPRS) CDMA Code Division Multiple Access CP Cyclic Prefix CQI Channel Quality Indicator CRC Cyclic Redundancy Cycle C-RNTI Cell – Radio Network Temporary Identifier CS Coding Scheme CSCF Call Session Control Function

D

DCCH Dedicated Control Channel DL DownLink DL-SCH Downlink – Shared Channel DPSK Differential Phase Shift Keying DRX Discontinuous Reception DTCH Dedicated Traffic Channel E

ECM EPS Connection Management EDGE Enhanced Data rates for GSM Evolution EMM EPS Mobility Management eNB enhanced Node B ePC evolved Packet Core EPS evolved Packet Switch e-RAB evolved RAB e-UTRA evolved UTRA e-UTRAN evolved UTRAN EV-DO Evolution Data Optimized F FDD Frequency Division Duplex FDM Frequency Division Multiplexing FDMA Frequency Division Multiple Access FTT Fast Fourier Transformation FSK Frequency Shift Keying FT Fourier Transform G GBR Guaranteed Bit Rate GERAN GSM EDGE Radio Access Network GPRS General Packet Radio Service GSM Global System for Mobile communications

H

H-ARQ Hybrid Automatic Request HO Handover HRPD High Rate Packet Data HSDPA High-Speed Downlink Packet Access HSPA High-Speed Packet Access HSS Home Subscriber Server HSUPA High-Speed Uplink Packet Access HTTP HyperText Transfer Protocol

I ICI Inter-Channel Interference iFFT inverse Fast Fourier Transformation IMS IP Multimedia Subsystem IP Internet Protocol ISI Inter-Symbol Interference ITU International Telecommunications Union

L

LTE Long-Term Evolution M MAC Medium Access Control (GPRS) MBMR Multiband Multimode Radio MBMS Multimedia Broadcast/Multicast Service MBR Maximum Bit Rate MBSFN MBMS Single Frequancy Network MCCH MBMS point-to-multipoint Control Channel MCH Multicast Channel MCS Modulation Coding Scheme MGCF Media Gateway Control Function MGW Media Gateway MIB Management Information Base MIMO Multiple Input Multiple Output MIMO-MU MIMO-Multi User MIMO-SM MIMO-Spatial Multiplexing MIMO-STBC MIMO-Spatial Time Block Coding MIMO-SU MIMO-Single User MISO Multiple Input Single Output MME Mobility Management Entity MTCH MBMS point-to-multipoint Traffic Channel

N NAS Non-Access Stratum

O

OFDM Orthogonal Frequency Division Multiplexing OFDMA Orthogonal Frequency Division Multiplex

Access




6 � 3

Abbreviations and Acronyms [cont.]


P PBCH Packet Broadcast Control Channel PCCCH Packet Common Control Channel PCFICH Physical Control Format Indication

Channel PCH Paging Channel PCRF Policy and Charging Rule Function PDA Personal Digital Assistant PDCCH Physical Downlink Control Channel PDCP Packet Data Convergence Protocol PDN Packet Data Network PDSCH Physical Downlink Shared Channel PDU Packet Data Unit P-GW PDN Gateway PLMN Public Land Mobile Network PMI Precoding Matrix Indicator PRACH Packet Random Access Channel P-SCH Primary SCH PSDSCH Physical Downlink Shared Channel PSTN Public Switched Telephone Network PUCCH Physical Uplink Control Channel PUSCH Physical Uplink Shared Channel Q QAM Quadrature Amplitude Modulation QCI QoS Class Identifier QoS Quality of Service QPSK Quadrature Phase Shift Keying R RAB Radio Access Bearer RACH Random Access Channel RA-RNTI Random Access – Radio Network

Temporary Identifier RAT Radio Access Technology RB Radio Bearer RB Resource Block REG Resource Element Group RF Radio Frame RFC Request For Comments RI Rank Indicator RLC Radio Link Control ROHC Robust Header Compression RRC Radio Resource Connection RSRP Reference Signal Received Power RSRQ Reference Signal Receive Quality RSSI Received Signal Strength Indicator RTP Real-Time Protocol Rx Reception

S

SC-FDMA Single Carrier - Frequency Division Multiple Access

SDU Service Data Unit S-GW Serving Gateway SIB Service Independent Building Block SIMO Single Input Multiple Output SISO Single Input Single Output SNR Signal-to-Noise Ratio SRB Signaling Radio Bearer

S-SCH Secondary Synchronization Channel

T

TA Tracking Area TAI Tracking Area Identifier TAU Tracking Area Update TB Transport Block TCP Transport Control Protocol TDD Time Division Duplex TF Transport Format TM Transport Mode TMSI Temporary Mobile Subscriber Identity TTI Transmission Time Interval TTL Time To Live Tx Transmission

U UDP User Data Packet UE User Equipment UL UpLink UL-SCH Uplink Shared Channel UM Unacknowledge Mode UMA Unlicensed Mobile Access UMTS Universal Mobile Telecommunications System UTRA Universal Terrestrial Radio Access UTRAN Universal Terrestrial Radio Access Network V VoIP Voice over IP W

WCDMA Wideband Code Division Multiple Access WiMAX Worldwide interoperability for Microwave Access Z

ZC-ZCZ Zadoff-Chu sequences with Zero Correlation Zone




6 � 4

End of Module

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