alcatel - lucent 9400 lte la2.0 radio algorithms and parameters description

9400 LTE LA2.0 Radio Algorithms and Parameters Description - All Rights Reserved © Alcatel-Lucent 2010

All Rights Reserved © Alcatel-Lucent 2010

LTE9400 LTE LA2.0 Radio

Algorithms and Parameters Description

STUDENT GUIDE

TMO18315 D0 SG DEN Issue 3

All rights reserved © Alcatel-Lucent 2010 Passing on and copying of this document, use and communication of its

contents not permitted without written authorization from Alcatel-Lucent



9400 LTE LA2.0 Radio Algorithms and Parameters DescriptionLTE

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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






Module 1. eUTRAN Parameter Description1 Configuration Management Overview

2 eUTRAN Parameters

Module 2. Radio Resources Management1 Introduction

2 MIMO and Transmission Mode

3 Measurement Management

4 Schedulers

5 Physical Channel Configuration

6 Link Adaptation

7 H-ARQ

Module 3. Session Management1 Introduction

2 System Broadcast

3 Random Access Procedure

4 RRC Connection

5 eUTRAN in the Attach

6 RRC Connection Re-Establishment

7 Admission Control

8 Paging

Module 4. Mobility Management1 Cell Reselection in Idle Mode

2 Handover

3 Measurement Configuration

4 ANR feature




6

Course Outline [cont.]






7

Course Objectives


Welcome to 9400 LTE LA2.0 Radio Algorithms and Parameters Description

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

� Describe the eNodeB configuration model

� Describe the main radio resources management mechanisms and their parameters

• Describe the various transmission modes and how they can be used in the cell, list

the associated parameters and explain their impacts on the network

• Describe the management of the measurement, list the associated parameters and

explain their impacts on the network

• Describe the function of the schedulers, list the associated parameters and explain

their impacts on the network

• Describe the physical channels, list the associated parameters and explain their

impacts on the network

• Describe the link adaptation principles, list the associated parameters and explain

their impacts on the network

• Describe the H-ARQ mechanism, list the associated parameters and explain their

impacts on the network

� Describe the main radio procedures:

• Describe the system information broadcast and the associated parameters

• Describe the Random Access procedure and the associated parameters

• Describe the RRC Connection procedure and the associated parameters

• Describe the Attach and the associated parameters

• Describe the Admission control and the associated parameters

• Describe the paging mechanism and the associated parameters

� Describe the main mobility management mechanisms:

• Describe the Cell Reselection mechanism and list the associated parameters

• Describe the Handover mechanism and list the associated parameters

• Describe the measurement configuration and list the associated parameters




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!


Module 1 � Page 1


TMO 18315 D0 SG DEN Issue 3

Do not delete this graphic elements in here:

1All Rights Reserved © Alcatel-Lucent 2010

Module 1eUTRAN Parameter Description

LTE9400 LTE LA2.0 Radio Algorithms and Parameters Description


Module 1 � Page 2




9400 LTE LA2.0 Radio Algorithms and Parameters DescriptioneUTRAN Parameter Description

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RemarksAuthorDateEdition

Document History

Module 1 � Page 3





1 � 3

Module Objectives

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

� Describe the eNodeB configuration model

� Describe the parameter properties

Module 1 � Page 4





1 � 4

Module Objectives [cont.]


Module 1 � Page 5





1 � 5

Table of Contents

Switch to notes view! Page

1 Configuration Management Overview 71.1 Main Components 81.2 Configuration Model 91.2.1 Example 10

2 eUTRAN Parameters 112.1 Parameter Properties 12

Module 1 � Page 6





1 � 6

Table of Contents [cont.]



Module 1 � Page 7





1 � 7

1 Configuration Management Overview


Module 1 � Page 8





1 � 8


1.1 Main Components

� The main configuration management physical components are:

� XMS

� WPS

� NEM

� The eUTRAN configuration files, called workorders, are created from WPS.

� They are activated on the network with XMS.

eXtended Management System (XMS)

XMS is a system used to:

� manage the deployed eNodeBs, sending updates of configuration data,

� support the capture of configuration change requests,

� manage faults.

Wireless Provisioning System (WPS)

WPS is a system that supports the capture of NE configuration data, and is used by the operations team for off-line preparation of configuration changes.

Network Element Manager (NEM)

NEM is an application that can be run on a laptop and that allows to create and load an object/parameter file into the eNodeB.

IP Networks – Used to transport data among the OAM Configuration Management components.

eNodeB – The radio base station provides the radio cells, terminates the air interface associations with the User Equipment (UEs), supports backhaul to the evolved Packet Core Network. The eNodeB also accepts configuration information from the XMS and provides other OAM services.

The configuration management snapshots of the eUTRAN can be imported from XMS into the WPS system. Configuration changes can be indicated in the WPS system, and then a configuration management work order file can be exported from WPS to the XMS system. Configuration changes are then sent from XMS to the affected eNodeBs.

Module 1 � Page 9





1 � 9


1.2 Configuration Model

� The LTE eNB Configuration Model (CM) is object oriented and is used to complement the LTE software architecture.

� The model consists of objects that have associated parameters and may contain other objects.

Module 1 � Page 10





1 � 10

1.2 Configuration Model

1.2.1 Example

� Data Model for object Enb

For example, here above is the data model for the LA2.0. Objects like ActivationService, in grey, are

associated with a set of parameters (attributes). Other objects like RrmServices, in white, contain other

objects and are also linked to a set of parameters (attributes).






1 � 11

2 eUTRAN Parameters






1 � 12

2 eUTRAN Parameters

2.1 Parameter Properties

� The parameter properties are summarized in a table as follows:

� Starting in LTE Release LA2.0, each parameter is assigned to a class according to the impact that results when the parameter value ismodified (or created/deleted for an associated object).

The O.D. value means Operator Dependent (depends on the operator’s network-specific configuration.

For example, addressing parameters).






1 � 13

2 eUTRAN Parameters

2.1 Parameter Properties [cont.]

� Each class corresponds to a parameter update rule:

� Class A� The modification/creation/deletion of these parameters requires a full eNodeB reset before the change take effect. The eNB OA&M interfaces are unavailable during the reset.

� Class B� The modification/creation/deletion requires internal resource unavailability in the eNB, which leads to service impact. The eNB OA&M interfaces remain available. The precise service impact can vary between parameters. In general for Class B changes, the object whose parameter value is to be changed must be locked before the parameter value is changed, and then unlocked after the change is downloaded to the eNB.

� Class C� (online reconfiguration). The modification/creation/deletion is taken into account by the eNB without any impact on services.






1 � 14

2 eUTRAN Parameters

2.1 Parameter Properties [cont.]

� The category of a given parameter will be indicated to be one of the following:

� Fixed - the value of the parameter is fixed, meaning that the value should not change from cell to cell.

� Optimization - Tuning: The values of these parameters generally change from cell to cell. These parameters require a fine tuning and are generally performance-impacting parameters and their tuning may involve a tradeoff.

� Optimization - Selection: The values of these parameters generally change from cell to cell (based on the size and the topology of the cell). The value of these parameters is selected from a set of a few possible values. These parameters are generally performance-impacting parameters.

Two other points are worth mentioning for optimization parameters (both categories):

� Even though a “default recommended” value may be provided by ALU, the parameters must be set by

the customer.

� The value may sometimes be the same for all cells with the same radio environment (for example:

hotspot, dense urban, urban, suburban, rural, isolated). In this case, the value changes from one radio

environment to another (i.e. there is no systematic change from cell to cell).






1 � 15

End of ModuleeUTRAN Parameter Description

Module 2 � Page 1





Module 2Radio Resources Management



Module 2 � Page 2




9400 LTE LA2.0 Radio Algorithms and Parameters DescriptionRadio Resources Management

1 � 2 � 2

Blank Page



Document History

Module 2 � Page 3





1 � 2 � 3

Module Objectives


� Describe the various transmission modes and how they can be used in the cell, list the associated parameters and explain their impacts on the network

� Describe the management of the measurement, list the associated parameters and explain their impacts on the network

� Describe the function of the schedulers, list the associated parameters and explain their impacts on the network

� Describe the physical channels, list the associated parameters and explain their impacts on the network

� Describe the link adaptation principles, list the associated parameters and explain their impacts on the network

� Describe the H-ARQ mechanism, list the associated parameters and explain their impacts on the network

Module 2 � Page 4





1 � 2 � 4



Module 2 � Page 5





1 � 2 � 5

Table of Contents


1 Introduction 71.1 Principle 8

2 MIMO and Transmission Mode 112.1 Introduction 122.2 TM3 142.3 TM4 172.3.1 CL-MIMO/TXDIV MIXED MODE 202.3.2 FULL CL-MIMO MODE 21

2.4 Configuration 222.4.1 mIMOMode Parameter 23

3 Measurement Management 253.1 Introduction 263.2 CQI Definition 273.3 CQI processing 293.3.1 Sub-Band CQI 30

3.4 Measurement Reporting 313.4.1 Reporting Mode 323.4.2 Averaging Coefficient 33

4 Schedulers 354.1 DL and UL Schedulers Location 364.2 Schedulers Principles 374.2.1 TimeFrequencyResBlockOccupancy Matrix 384.2.2 Pre-booking and Scheduling stages 394.2.3 DL Static Scheduler 404.2.4 Semi-Static Scheduler 41

4.3 UL Semi-Static Scheduler 424.4 Dynamic Scheduler 434.4.1 Fairness Factor 44

4.5 PRB Allocation 454.6 Scheduler Grants: DCI 464.6.1 DCI format 47

5 Physical Channel Configuration 495.1 Resources Unit Definition 505.2 PCFICH 515.3.1 PHICH 52

5.4 PDCCH 545.4.1 Search Space 55

5.5 DL Power Setting 585.5.1 DL Channel Configuration 595.5.2 Synchronization Signals 605.5.3 PBCH Power Setting 625.5.4 PCFICH Power Setting 635.5.5 PDCCH Power Setting 645.5.6 PDSCH Power Setting 665.5.7 PHICH Power Setting 675.5.8 Cell Power Budget 68

6 Link Adaptation 706.1 Link Adaptation Principles 716.2 PDSCH Link Adaptation 726.2.1 dlMCSTransitionTable 736.2.2 BLER Control Loop 74

6.3 PUSCH Link Adaptation 756.3.1 SRS Signal 76

6.4 PUSCH Power Control 796.4.1 Principle 80

Module 2 � Page 6





1 � 2 � 6



6.4.2 TPC Command 826.4.3 Fractional power control 85

7 H-ARQ 887.1 Principles 897.2 H-ARQ Process 907.3 H-ARQ Timing 917.4 H-ARQ Parameters 92

Module 2 � Page 7





1 � 2 � 7

1 Introduction

Module 2 � Page 8





1 � 2 � 8

1 Introduction

1.1 Principle

� The Radio Resources Management (RRM) mechanisms manage:

� The allocation of the radio resources in UL and DL by the schedulers

� The transmission mode, i.e the MIMO usage

� The configuration of the DL and UL channels

� Dynamic Resources Allocation & Packet Scheduling (DRA&PS)

UE

Transmission mode

DL and UL Schedulersallocate dynamically

radio resources

DL

UL

Frequency

Time

DL and UL Channels

One task of Dynamic Resource Allocation & Packet Scheduling (DRA&PS) Downlink Scheduler is to

allocate radio resources to user and control plane packets. DRA involves several sub-tasks, including

the selection of radio bearers whose packets are to be scheduled and managing the necessary

resources (e.g. the power levels or the specific resource blocks used). PS typically takes into account

the QoS requirements associated with the radio bearers, the channel quality information for UEs,

buffer status, etc.

Other tasks of the DRA&PS are to define the algorithms put in place in order to efficiently manage the

radio resources of the LTE system, and the MAC protocol used for that purpose.

The DRA&PS manages all the “MAC” part.

Module 2 � Page 9





1 � 2 � 9

1 Introduction

1.1 Introduction [cont.]

DL SchedulerDL Scheduler

UL SchedulerUL Scheduler

Cell Config

Power SettingRRM (Radio Resource

Management Algorithm)

MME

P-GW S-GW

Radio Bearer configQoS parameterRLC, CAC

UE feedbackUE radio conditionInterference Level

Scheduled UEsPRB Assignment per UE

MIMO SchemeMCS

Exercise

To schedule UEs every 1 ms, schedulers need inputs about:

� the Radio Bearer QoS parameters (CallP, RLC, CAC),

� the radio conditions of each UE (L1),

� the configuration of the cell (Cell RRM and Power setting),

� the interference level (ICIC).

From these inputs, schedulers (DL and UL) can allocate PRB, Transmission Mode (TM) and Modulation

Coding Scheme (MCS) to UEs.






1 � 2 � 10

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1 � 2 � 11







1 � 2 � 12


2.1 Introduction

� The Transmission Mode (TM) refers to the way the antenna system is used.

� The following modes are supported:

� TM2: In this mode, only TxDiv is supported (1 codeword and no possible switching to 2 codewords).

� TM3: In this mode, 2-layer Open-Loop MIMO (OL-MIMO) is possible. It is

also possible to switch to TxDiv.

� TM4: In this mode, 2-layer Closed-Loop MIMO (CL-MIMO) is possible. It is

also possible to switch to TxDiv or 1-layer CL-MIMO.

� The following parameters selects the mode:

It is well known that MIMO systems perform best in rich scattering environments. Choosing a specific

transmissionMode is thus strongly influenced by the particular morphology of the cell. Transmit

diversity has its value in a number of scenarios, including low SNR, low mobility (no time diversity), or

for applications with low delay tolerance. Diversity schemes are also desirable for channels for which

no uplink feedback signaling is available (e.g. Multimedia Broadcast/Multicast Services (MBMS).

Nevertheless, both tm3 (3), tm4 (4) perform TxDiv transmission for special propagation conditions,

thus choosing tm2(2) should be a carefully thought decision based on specific cell morphology. Usually

OL MIMO or CL MIMO (tm3, tm4) is applied in networks txDIV is used in case of low SNR or high speed ,

the condition of switching to txDiv depends on several parameter setting that is subjectible to

optimization according to the site conditions

For test purposes, it is possible to disable the second antenna of the eNodeB in the DL direction. This mode is called “fake SIMO”.

The list of the transmission modes defined by the 3GPP is:

� Single-antenna port; port 0

� Transmit diversity

� Open-loop spatial multiplexing

� Closed-loop spatial multiplexing

� Multi-user MIMO

� Closed-loop Rank=1 precoding

� Single-antenna port; port 5






1 � 2 � 13



� Transmissions from each antenna must be uniquely identifiable so that each receiver can determine what combination of transmissions has been received.

� The UE needs to know the spatial signature of each transmission path� This identification is usually done with pilot signals, which use orthogonal patterns for each antenna.

DL

freq

time

H

Streams are sent on the same time, on the same frequency.

Note that if the UE is not able to make the distinction between the transmission of each antenna due

to the radio condition, the same transport block is transmitted.






1 � 2 � 14


2.2 TM3

� TM3 = Open-Loop MIMO (OL-MIMO)

eNodeB

2 antennas on UE

� The UE reports only the Channel Quality Indicator (CQI) and the Rank Indicator (RI)

� 2 codewords are transmitted on the same radio resources.

� The rank indicator is a metric reported by the UE. It indicates the number of freedom degrees measured by the receiver, which represents the maximum capacity of the Tx/Rx channel in terms of independent streams.

CQI & RI

UE #1

s1s2s3s4

s2 s4

s3s1

The UE reports the CQI for its radio conditions and the Rank Indicator (RI) to indicate if it is able to

distinguish the transmission of each antenna. From this feedback, the eNodeB can transmit 2 different

transport blocks on each antenna using the same time-frequency resources. The pre-coding (blue box)

matrix is pre-defined in Open-Loop MIMO. This is the way the data are mapped on each antenna.

The transmitter only knows the channel statistics of H but not its realization (hence “open-loop”).

The transmitter transmits equal power (P/M) from each antenna.

The receiver perfectly knows H.

Capacity grows linearly with the number of antennas.






1 � 2 � 15


2.3 TM3 [cont.]

� If the Rank is equal to 1, only one stream can be transmitted and Transmit Diversity is used.

� If the Rank is equal to 2, Open-Loop MIMO becomes possible with a throughput higher than Transmit Diversity for high SINR values.

eNodeB

OL-MIMO

TxDiv

UE1

UE2

The eNodeB can use the Open-Loop MIMO to transmit data to UE1 and on the same time TxDiv for UE2,

since they don’t report the same Rank Indicator (RI).

For UE1, it can change. If radio condition changes, it will report RI=1 and will receive data in TxDiv

mode.






1 � 2 � 16


2.2 TM3 [cont.]

� When the RI is equal to 2, this parameter selects when the OL-MIMO is used depending on the radio quality.

� Higher values will reduce DL data rate otherwise achievable in the higher SINR regime.

� Lower values would allow OL-MIMO too soon, resulting in H-ARQ retransmission rates and BLERs higher than achievable with Tx Diversity and consequently the use of an MCS with a lower DL data rate/throughput.

The current default value for this parameter is 15.0.






1 � 2 � 17


2.3 TM4

� TM4 = Closed-Loop MIMO (CL-MIMO)

eNodeB

2 antennas on UE

CQI & RI & PMI

s1s2s3s4

s2 s4

s3s1

� The UE also reports the Precoding Matrix Indicator (PMI) for TM4.

� PMI indicates the codebook (pre-agreed parameters) the eNB should use for data transmission over multiple antennas based on the evaluation of the received reference signal.

codewords

With the TM4, the precoding matrix is not pre-defined and the UE can report to the eNodeB which

matrix is the best one in the current condition.






1 � 2 � 18


2.3 TM4 [cont.]

� What is a codebook?

� The mapping between the codebook and the precoding matrix is given in the table below:

� In OL-MIMO, a fixed codebook is used:

A codebook contains a lookup table for coding and decoding. Each word or phrase has one or more

strings which replace it. To decipher messages written in code, corresponding copies of the codebook

must be available at either end.






1 � 2 � 19


2.3 TM4 [cont.]

� There are 2 CL-MIMO modes.

� If the dlFullCLMimoMode parameter is:

� Disabled then the eNB uses Transmit Diversity when RANK 1 is reported.

� It is the CL-MIMO/TXDIV MIXED MODE

� Enabled then the eNB uses 1-layer CL-MIMO when RANK 1 is reported.

� It is the FULL CL-MIMO MODE






1 � 2 � 20

2.3 TM4

2.3.1 CL-MIMO/TXDIV MIXED MODE

� The CL-MIMO/TxDiv mode is selected with the following parameter:






1 � 2 � 21

2.3 TM4

2.3.2 FULL CL-MIMO MODE

� The 1-layer or 2-layer CL-MIMO mode is selected with the following parameter:






1 � 2 � 22


2.4 Configuration

� The transmission scheme used depends not only on the transmission mode configured by the transmissionMode parameter but also on:

� The reported rank indicator.

� The dlFullCLMimoMode parameter.

� The dlSinrThresholdBetweenOLMimoAndTxDiv parameter.

� The dlSinrThresholdBetweenCLMimoAndTxDiv parameter.

� The dlSinrThresholdBetweenCLMimoTwoLayersAndOneLayer parameter.

� The mIMOMode parameter, which optionally forces the transmission scheme (over PDSCH) to TxDiv or CL-MIMO.






1 � 2 � 23

2.4 Configuration

2.4.1 mIMOMode Parameter

� mIMOMode can force the usage of a given Transmission Mode depending on the type of the bearer.

� The different types of radio bearer are:

� SRB0, SRB1 and SRB2 for signaling

� nGBR5, nGBR6, nGBR7, nGBR8 and nGBR9 for non-guaranteed bearer

� GBR1, GBR2, GBR3 and GBR4 for guaranteed bearer (including VoIP)

Note that the value clMimoOnly is not supported.






1 � 2 � 24

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1 � 2 � 25







1 � 2 � 26


3.1 Introduction

� The UE reports:

� The Channel Quality Indicator (CQI) used for TM mode and MCS selection, PRB allocation

� RI

� PMI in case of CL-MIMO

� The reporting mode is configured by the eNodeB

� UE performs aperiodic CQI, PMI and RI reporting using the PUSCH channel.

eNodeBPUSCH

CQI, RI and PMI

The CQI, PMI and RI reports follow a fixed 20ms pattern aligned with the UL semi-static VoIP

scheduler.

Single and Multiple PMI

(one per SubBand)

SinglePMI Feedback

WideBand and UE

selected SubBand

WideBand and UE

selected SubBand

CQI Feedback

Sent togetherSent in separate sub-

frame

RI feedback

Indication in scheduling

Grant

NoneTrigger for Report

PUSCHPUCCHPhysical Channel for

Report

Aperiodic ReportingPeriodic Reporting






1 � 2 � 27


3.2 CQI Definition

� The UE measures the Reference Signal (RS)

� It is transmitted by the 2 antennas on every slot on the wideband

All downlink RS common pilots and availible for all users.The DL RS signal is used for cell search and

initial acquization, DL Channel estimation, and downlink channel-quality estimation.

It is transmitted on one or several antenna ports. There is one Downlink Reference Signal transmitted

per downlink antenna port. Scattered pilot pattern -spacing in frequency domain is 6 subcarriers

Note that the RS pattern depends on the Cell ID. By this way, 2 cells using the same frequency center

can be distinguished by the UE.

RS overhead

•4.8% for 1 Tx

•9.5% for 2 Tx

•14.3% for 4 Tx






1 � 2 � 28


3.2 CQI Definition [cont.]

� There are not only one CQI but several CQIs.

� The WideBand CQI (WB CQI) is measured over the entire band (5 MHz or 10 MHz)

� There are 2 WB CQIs for each antenna:

� WB CQI CW1

� WB CQI CW2

� Sub-Band CQI (SB CQI):

� The RBs are grouped into “Sub-band”.

� The UE can report a CQI per sub-band.

� There are several SB CQIs per antenna.

The number of RB per sub-band depends on the bandwidth.

With 5 MHz, there are 7 sub-bands and 4 RB per sub-band. Except for the last sub-band (only one RB)

With 10 MHz, there are 9 sub-bands and 6 RB per sub-band. Except for the last sub-band (only 2 RB)

With 20 MHz, there are 13 sub-bands and 8 RB per sub-band. Except for the last sub-band (only 4 RB)






1 � 2 � 29


3.3 CQI processing

� The eNodeB converts the CQIs into SINR for the scheduler:

� For link adaptation or TM mode selection, the scheduler needs the SINR value (unit: dB) and not the CQI.

� The WB SINR is a float value between -10 and 30, with 0.25 dB step.

WB CQI CW1WB CQI CW2

SB CQI x

Inputs Outputs

SINR WideBand CW1SINR WideBand CW2SINR per RB CW1SINR per RB CW2

SINR = Signal Interference plus Noise Ratio






1 � 2 � 30

3.3 CQI processing

3.3.1 Sub-Band CQI

� The Wideband CQI is coded on 4 bits

� Subband CQI value for each codeword are encoded differentially with respect to their respective wideband CQI using 2-bits as defined by:

� Subband differential CQI offset level = subband CQI index – wideband CQI index.

� The mapping from the 2-bit subband differential CQI value to the offset level is shown here:

� Each Sub-Band CQI represents the CQI for several RB (depends on the bandwidth)






1 � 2 � 31


3.4 Measurement Reporting

� A UE shall perform aperiodic CQI, PMI and RI reporting using the PUSCH

� Upon receiving DCI format 0 with the CQI request field set to 1

� The CQI report mode is configured at RRC setup.

� The CQI, PMI & RI reports are following a fixed pattern of 20ms

eNodeBPUSCH

CQI, RI and PMI

PDCCHDCI for UE1 with CQI request

UE1

The DCI format 0 is the UL grant. It is transmitted on the PDCCH to grant resources in UL.






1 � 2 � 32


3.4.1 Reporting Mode

� There are 2 report formats:

� Mode 3-0� The UE reports one wideband CQI value

� The UE also reports one sub-band CQI value for each set S sub-band

� Mode 3-1� A single precoding matrix is selected from the codebook subset assuming transmission on set S sub-bands.

� The UE reports one sub-band CQI value per codeword for each set S sub-band

� The UE reports a wideband CQI value per codeword

� The UE reports the single selected precoding matrix indicator

The cqiReportingModeAperiodic parameter must be set in accordance with the TransmissionMode

parameter.






1 � 2 � 33


3.4.2 Averaging Coefficient

� A forgetting factor is applied on the Rank provided by the UE in order to avoid too frequent changes from MIMO to TxDiv and vice-versa.

These averaging coefficients are used as follows:

Where:

� Xaverage (t) is the average value for the quantity X.

� X(t) is the value reported by the UE.

� Coeff is the cQIAveragingCoefficient or the rankAveragingCoefficient.

256

)()1()1()(

tXcoefftXaveragecoefftXaverage

×+−×−=






1 � 2 � 34

Blank Page







1 � 2 � 35

4 Schedulers






1 � 2 � 36

4 Schedulers

4.1 DL and UL Schedulers Location

� UL and DL schedulers are located in the eNodeB (in the CEM boards).

� They handle the allocation of the radio resources to all the DL and UL channels taking into account:

� The link adaptation (MCS selection)� The measurement reporting configuration� The Transmission mode selection� The H-ARQ retransmission � The resource allocation� Inter-Cell Interference Coordination

eNodeB

UL and DLSchedulers






1 � 2 � 37

4 Schedulers

4.2 Schedulers Principles

� The scheduler is split into 3 functional parts:

� The Static Scheduler: Which assigns a fixed amount of Transport Blocks for the PBCH and the synchronization signals. Those resources are permanently allocated.

� The Semi-static Scheduler: Which assigns PDSCH resources for PCCH and CCCH and the D-BCH. 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.

For the semi-static scheduler, the PCCH, CCCH and D-BCH refer to the paging messages, the signaling

used to establish the RRC connection and the system broadcast except for the MIB.






1 � 2 � 38


4.2.1 TimeFrequencyResBlockOccupancy Matrix

� This matrix is used by the static and semi-static scheduler to flag the RBswhich are pre-booked for their needs

� This matrix has a 20ms depth

� 20 sub-frames or 2 radio frames

� This bitmap is 25-RB long in 5MHz bandwidth, and 50-RB long in 10MHz bandwidth

TimeFrequencyResBlockOccupancy[t][rb] are flagged with for example:

� FREE

� USED_D_BCH

� USED_PCCH

� RESERVED_SRB_TA

� USED_VOIP






1 � 2 � 39


4.2.2 Pre-booking and Scheduling stages

Pre-booking stage

Scheduling stage

The downlink scheduler is composed of 2 main algorithms:

• A prebooking stage which reserves resources for the static and semi-static

schedulers.

• A scheduling stage which assigns the resources for effective traffic.






1 � 2 � 40


4.2.3 DL Static Scheduler

� The static scheduler is in charge of scheduling all the logical channels which have stringent timing constraints and regular usage of the resource

� It prebooks resources in the TimeFrequencyResBlockOccupancy matrix which are always used and thus can never be retrieved by the Dynamic Scheduler

� It manages:

� The BCCH information that goes over the BCH channel, i.e the MIB in the PBCH.

� The primary and secondary synchronization signals.

The static scheduler allocates the following resources for PBCH:

� RBs 9-15 (7 RBs) of sub-frame 0, in a 5MHz bandwidth system.

� RBs 22-27 (6 RBs) of sub-frame 0, in a 10MHz bandwidth system.

The static scheduler is configured at cell setup, and does only change with a cell restart.






1 � 2 � 41


4.2.4 Semi-Static Scheduler

� In DL, the semi-static scheduler is in charge of scheduling all the logical channels which have stringent timing constraints and non-regular usage of the resource.

� It handles the D-BCH, PCCH, CCCH, SRB, Timing Advance and DTCH for VoIP.

� It is made up of 2 stages:

� Pre-booking stage

� The semi-static scheduler prebooks resources for the channels listed above in the TimeFrequencyResBlockOccupancy matrix Scheduling stage

� Scheduling Stage

� Every 1 ms, the semi-static scheduler checks if data need to be sent in that particular sub-frame and decides whether to use the pre-booked resources or free them to the benefit of the dynamic scheduler.

There is no pre-booking of SRB/TA resources at 10 MHz. It is handled by the dynamic scheduler.






1 � 2 � 42

4 Schedulers

4.3 UL Semi-Static Scheduler

� The semi-static scheduler is in charge of scheduling the transmission of information with stringent timing constraints and non-regular usage of the resource.

� VoIP DTCH (GBR-1 bearers).

� Aperiodic CQI/RI/ACK-NACK.

� Buffer Status reporting

� Power Headroom reporting

The period of the semi-static pattern is configured by parameter periodicRate. Every periodicRate

seconds, a 1st HARQ transmission grant is issued for each active UE in preconfigured resources. The size

of the grant depends on whether the UE has an ongoing VoIP call or not.






1 � 2 � 43

4 Schedulers

4.4 Dynamic Scheduler

� The dynamic scheduler is in charge of scheduling all the logicalchannels which have non-stringent timing constraints AND non-regular usage of the resource.

� The dynamic scheduler never pre-books resources. Every TTI, the Dynamic Scheduler uses the resources which are left available by the static and semi-static schedulers.

� The Dynamic scheduler can be decomposed into 3 sequential functions:

Measurement processing & SU-MIMO Selection

which are updated every TTI

H-ARQ processing functions which are managing in priority

the users with H-ARQ re-transmissions

Initial transmissions processing functions which are allocating

the remainingresources to new

frames

� The DL Scheduler is made up of: power budget, TM configuration, Measurement management, H-ARQ, Link adaptation (detailed later).






1 � 2 � 44

4.4 Dynamic Scheduler

4.4.1 Fairness Factor

� This parameter provides flexibility as to the choice of scheduler behavior, allowing the operator to choose the scheduler behavior it wants for its network

� alphaFairnessFactor = 0 yields a maximum C/I scheduler.

� alphaFairnessFactor = 1 yields a fair scheduler

� alphaFairnessFactor = 2 yields an increased fairness scheduler

The dynamic scheduling algorithm is the so-called Alpha Fairness scheduler, which is a generalisation, by

means of parameter alphaFairnessFactor, of the widely used Proportional Fair scheduler.

alphaFairnessFactor = 0 yields a maximum C/I scheduler. The scheduler provides more resources to UEs in

better conditions. The better the radio conditions of the UE, the more resources (and hence the higher

the data rate) it gets.

alphaFairnessFactor = 1 yields a fair scheduler. The scheduler attempts to provide the same number of

RBs to all the UEs (despite their different conditions).

alphaFairnessFactor = 2 yields an increased fairness scheduler. The scheduler attempts to allocate the

resources in such a way that all the UEs eventually get the same data rate (which is not the case of the

fair scheduler since different radio conditions result in different data rates even when the number of

resources is the same, hence the increased fairness of the scheduler, as compared to the “regular” fair

scheduler).






1 � 2 � 45

4 Schedulers

4.5 PRB Allocation

� The number of allocated PRBs must be a multiple of the Resource Block Group (RBG) size:

� The scheduling of HARQ retransmissions is done prior to that of HARQ first transmissions.

� Dynamic HARQ first transmissions scheduling: Every RBG available (after static, semi-static and dynamic HARQ retransmissions) is “up for grabs”.

� A metric is computed for every bearer based on QoS constraints and NB-CQI

� The RBG is assigned to the bearer with the highest metric

� only 6 bearers can be scheduled in a given TTI.

HARQ retransmissions are scheduled according to the following priority:

1. Timing Advance.

2. SRB1 and SRB2.

3. Other radio bearers.






1 � 2 � 46

4 Schedulers

4.6 Scheduler Grants: DCI

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






1 � 2 � 47

4.5 Scheduler Grants

4.6.1 DCI format

Format Purpose Description # of bits

0 UL GrantRB assignment, MCS, hopping flag, NDI, cylic-shift of DM-RS, CQI request, 2-bit PUSCH TPC command; mask for antenna

selection44

1 DL Grant for SIMOResource alloc. header, RB allocation, MCS, HARQ PID, NDI,

RV, 2-bit PUCCH TPC command55

1A/1BCompact DL Grant

for SIMO

Same as format 1, but with reduced RB allocation flexibility and addition of distributed transmission flag. Format 1B for

precoding.44

1CPaging, RACH

response, D-BCH

Reduced payload for improved coverage: always uses QPSK on assoc. PDSCH, restricted RB allocation, restricted TBS, no

HARQ information26

2 MIMO DL GrantSimilar to format 1, but MCS/NDI/RV is per codeword, and information on selected # of layers and precoding matrix is

included71

31-bit UL Power

ControlTPC commands for 28 UEs plus 16 bit CRC 44

3A2-bit UL Power

ControlTPC commands for 14 UEs plus 16 bit CRC 44






1 � 2 � 48

Blank Page







1 � 2 � 49







1 � 2 � 50


5.1 Resources Unit Definition

� REG and CCE are defined to allocate resources to control channel

� REG = 4 consecutive useful RE

� CCE = set of 9 Resource Element Groups (REGs), i.e 36 useful RE

Reference symbols

1 slo

t

1 REG=4 RE

1 CCE= 9 REG=36 useful RE

5 MHz

1 CCE bandwidth = 0.62 MHz

REG = Resource Element Group

CCE = Control Channel Element






1 � 2 � 51


5.2 PCFICH

� PCFICH indicates the number of OFDM symbols which are used to transmit L1/L2 control (PHICH and PDCCH)� CFI = {1, 2, 3} coded to 32 bits

� QPSK modulation is used

� PCFICH uses 4 REGs (= 16 RE) and is mapped to the 1st OFDM symbol in fixed positions

PCFICH Reference Signal Nulled Resource Element

The cFI depends on the system bandwidth.

5 and 10 MHz -> cFI = 3

20 MHz -> cFI= 2

The REG assigned to PCFICH are uniformly distributed over the system bandwidth for diversity and shifted

according to cell ID






1 � 2 � 52

5.2 DL Channel Configuration

5.2.1 PHICH

� PHICH carries the ACK/NACK in the downlink to support uplink HARQ

� Multiple PHICHs are mapped to the same set of REs, and are called a PHICH group� PHICH group occupies 3 REGs (= 12 RE) and uses BPSK modulation

� The PHICH is transmitted on all the sub-frames over the 1st symbol

•REG for PCFICH REG for PHICH group 1= 3 RE

REG for PHICH group 2= 3 RE

•cell ID=0

PHICH group supports 8 PHICHs (i.e. 8 ACK/NACKs), separated by orthogonal sequences

Physical HARQ Indicator Channel = PHICH

Implicit mapping is used between location of 1st PRB in UL allocation and PHICH group/sequence

REGs within a PHICH group scattered for interference randomization and diversity






1 � 2 � 53


5.2.1 PHICH [cont.]

� The number of PHICH groups per sub-frame is given by the following formula:

� Where Ng is given by the following parameters:

In LA2.0, the only supported value for parameter phichResource is “one”. As

a result, the total number of PHICH groups is:

• 4 with a 5 MHz bandwidth.

• 7 with a 10 MHz bandwidth.13 with a 20 MHz bandwidth.






1 � 2 � 54


5.3 PDCCH

� It carries scheduling grants and uplink power control

� DCI with different format depending on the need (cf 4.5.1)

� cFI defines the number of symbol used to L1/L2 signaling.

� PCFICH

� PHICH

� PDDCH which can used the rest of resources

PDCCH = Physical Downlink Control channel

DCI uses QPSK with R=1/3 convolutional code

16-bit CRC is attached which is scrambled with the UE ID






1 � 2 � 55

5.4 PDCCH

5.3.1 Search Space

� The PDCCH is divided into 2 spaces:

� The common search space

� The common search space is used by the DL scheduler to send pages and D-BCH data. It is decoded by any UE in the Idle or in RRC Connected state.

� UE-specific search space

� The principle is that a given UE does not decode all the CCEs over PDCCH but only part of them, i.e. its specific search space CCEs

1 sub-frame PDCCH

Common search spaceCCCH, Paging and D-BCH

UE-specific search spaceDL & UL Grant

The common search space occupies CCEs 0-15.

The UE monitors the candidate PDCCHs of a UE-specific search space (the starting CCE index of which

is a function of the UE assigned C-RNTI).






1 � 2 � 56


5.3.2 PDCCH [cont.]

� In terms of radio resources, a DCI is carried over a PDCCH candidate.

� The number of CCEs per PDCCH candidate is given by the aggregation level.

� The aggregation level, in addition to the fixed number of bits per DCI format, implicitly selects a Coding Rate for each DCI format.

� A high aggregation level allows a more robust DCI but reduces the number of DCIs (or PDCCH candidates) per sub-frame.

Set of candidate PDCCHs are organized into “search spaces”

� A search space is a contiguous set of CCEs at a particular aggregation level

UE attempts to decode each of the PDCCHs in the set according to all monitored DCI formats

� UE monitors a common search space at aggregation level 4 and 8

� UE monitors 1 UE-specific search space at each aggregation level 1, 2, 4, and 8

� UE not required to attempt decode of a DCI format with code rate > 0.75

The effective code rate for the PDCCH transmission depends on the PDCCH format as well as the

number of aggregated CCEs

Aggregation level 2 corresponds to 2 CCEs = 2×(9×REG) = 2× (9× (4×REs)), i.e. to 2× (9× (4×2)) = 144

bits.

Aggregation level 4 corresponds to twice aggregation level 2, i.e. to 288 bits.






1 � 2 � 57


5.3.2 PDCCH [cont.]

� pdcchAggregationLevelForCommonSearchSpace sets the aggregation level for the Common Search Space.

� pdcchAggregationLevelForUESearchSpace sets the aggregation level for the UE Search Space.

Parameters pdcchAggregationLevelForUESearchSpace and

pdcchAggregationLevelForCommonSearchSpace configure the aggregation level L for UE search

spaces and the common search space, respectively. As a result, these parameters also configure the

robustness of UE search spaces and the common search space (higher values provide increased

robustness).

The common search space occupies the first 16 CCEs in the PDCCH region.

The UE-specific search space is identified by the UE’s C-RNTI; PDCCH candidate m of UE-specific

search space S(C-RNTI) in subframe k occupies the L (the aggregation level) consecutive CCEs.






1 � 2 � 58


5.4 DL Power Setting

� The transmission power for the DL-RS signal is an absolute power applied per Resource Element (RE) and per Transmit antenna.

� This parameter influences directly the cell size.

� It is expressed in dBm

� In watt:

Example of Radio module and transmission power:

� RRH 2x30W: Two 30-W transmit antennas per RRH, (1 RRH necessary per cell to perform 2×2 DL-

MIMO).

� TRDU: Two 40-W transmit antennas per TRDU (1 TRDU necessary per cell to perform 2×2 DL-MIMO).






1 � 2 � 59


5.4.1 DL Channel Configuration

� The absolute is set by the RS Signal.

� The transmission of the other signals and channels is set by a power offset.

RS (dBm)

PSS & SSS (dB)

PBCH (dB)

PCFICH (dB)

PDCCH (dB)

PDSCH (dB)

PHICH (dB)






1 � 2 � 60


5.4.2 Synchronization Signals

� The synchronization signals, PSS and SSS, are used to:

� Be synchronized to slots and frames

� Identify the cell ID.

� They are sent over 6 Resource Blocks, i.e. 72 Sub-Carriers.

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

Frame

TS0

SF1

TS1 TS2 TS3

SF0 SF5 SF9

TS10 TS11 TS18 TS19

Sb0 Sb1 Sb2Sb

NDL-2

Sb

NDL-1

…….. ……..

…….. ……..

Sb0 Sb1 Sb2Sb

NDL-2

Sb

NDL-1

SSSPSS

SSSPSS

SSSPSS

SSSPSS






1 � 2 � 61


5.4.2 Synchronization Signals [cont.]

� The tuning of these parameters is a trade-off:

� Larger values facilitate cell synchronization at the UE within the cell coverage area, but reduce the amount of power available for traffic channels.

� Smaller settings will impair cell synchronization at the UE.

These 2 parameters are expressed in dB, relative to the RS power, PREF. They are converted into

linear scale (milliwatt) according to:

� PP−SCH = PREF ×10 primarySyncSignalPowerOffset/10

� PS−SCH = PREF ×10 secondarySyncSignalPowerOffset/10






1 � 2 � 62


5.4.3 PBCH Power Setting

� The pBCHPowerOffset parameter configures the transmit power per RE (expressed in dB relative to Pref ) for the PBCH channel.

� Pref is the RS signal transmission power

� It is a key RF optimization parameter:

� The higher the setting, the more robust the PBCH reception within the cell coverage area.

� But this reduces the power available for other DL channels.

This parameter is expressed in dB, relative to the RS power, PREF. It is converted into linear scale

(milliwatt) according to:

PPBCH = PREF ×10 pBCHPowerOffset/10






1 � 2 � 63


5.4.4 PCFICH Power Setting

� The pCFICHPowerOffset parameter configures the transmit power per RE (expressed in dB relative to PREF) for the PCFICH channel.


� The higher the setting, the more robust the CFI reception within the cell coverage area, but this reduces power available for other DL channels.

� Smaller settings will impair CFI, hence PDCCH reception and ultimately the UE may miss grants/PC commands.



PPCFICH = PREF ×10 pCFICHPowerOffset/10






1 � 2 � 64


5.4.5 PDCCH Power Setting

� The PDCCH is transmitted over the first symbols of the sub-frame.

� The number of symbols is equal to 3 symbols with 5 and 10 MHz






1 � 2 � 65


5.4.5 PDCCH Power Setting [cont.]

� The parameters linked to the PDCCH are:

� pDCCHPowerOffsetSymbol1

� pDCCHPowerOffsetSymbol2and3

The RS signal is present in symbol 1 but not in symbols 2 and 3. That explains the need for making the

distinction in terms of power setting between these channels.






1 � 2 � 66


5.4.6 PDSCH Power Setting

� There are 2 parameters to set the PDSCH transmission power.

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

RF #1

10 sub-frames

Tu= 66.7µs

#6#5#4#3#2#1#0

#2#1

paOffsetPdsch

pbOffsetPdsch

The mapping between the possible values and the actual value of the ratio ρ B / ρ A is as follows:

pbOffsetPdsch ρ B / ρ A

pb0 (0) 5/4

pb1 (1) 1

pb2 (2) 3/4

pb3 (3) 1/2






1 � 2 � 67


5.4.7 PHICH Power Setting

� PHICH is always transmitted using TxDiv and BPSK modulation.

� The pHICHPowerOffset parameter configures the transmit power per RE (expressed in dB relative to PREF) for the PHICH channel.


� The higher the setting, the more robust the PHICH reception within the cell coverage area, but this reduces the power available for other DL channels.

� Smaller settings impair PHICH reception causing many retransmissions and consequently lower UL throughputs.



PPHICH = PREF ×10pHICHPowerOffset/10






1 � 2 � 68


5.4.8 Cell Power Budget

� The cell DL total power is configured by the cellDLTotalPowerparameter.

� The maximum total power is the minimum value between this parameter and the RF module power capacity. The RF modules are the TRDU2x and the RRH2x.

� Other RF modules will be available in future releases






1 � 2 � 69

Blank Page







1 � 2 � 70

6 Link Adaptation






1 � 2 � 71

6 Link Adaption

6.1 Link Adaptation Principles

� Link adaptation is applied on the following channels:

� In DL:

� PDSCH: Based on MCS selection, no power control

� In UL:

� PUSCH: Based on MCS selection, with power control

eNodeB

PDSCH

PUSCH

In LTE, the link adaptation is mainly based on the selection of the best combination of modulation and

coding rate, called MCS (Modulation Coding Scheme). That means for a UE in bad radio condition, the

eNodeB selects a robust modulation and a high coding rate (QPSK ¾) for example. On the other hand, a

UE with good radio condition receives data with an efficient modulation and less parity bits.

So to send the same data, the eNodeB uses more radio resources for the UE with bad radio condition,

i.e. more Resource Blocks.






1 � 2 � 72

6 Link Adaption

6.2 PDSCH Link Adaptation

� To transmit on the PDSCH, the DL scheduler selects the most adapted MCS.

� 1. The UE reports the CQI.

� 2. The eNodeB estimates the SINR with the cQIToSINRLookUpTableparameter.

� 3. The eNodeB selects the MCS from the dlMCSTransitionTable parameter.

eNodeB

CQI1

2

SINR

SINR Conversionfrom cQIToSINRLookUpTable

3

MCS and associated TBS

Link adaptation is a key feature of the dynamic scheduler. It is the process by which the Modulation

and Coding Scheme (MCS) used (to transmit data on the scheduled bearer) is adapted to changing radio

conditions (or radio link quality) of the UE. An improvement in the radio link quality causes the

transmitter to use a less robust MCS and hence a higher data transmission rate. Conversely, a

degradation in the radio link quality causes the transmitter to use a more robust MCS and hence a

lower data transmission rate. The selected MCS is the one that maximizes the transmission rate for a

given target BLER.

At each new TTI, the link adaptation provides each scheduled bearer with a coding scheme common to

all its PRBs. The algorithm takes a set of allocated PRBs and the associated reported values as inputs,

and outputs:

• The common MCS index to be applied for transmission over the allocated PRBs

• The associated TBS.

The link adaptation algorithm converts CQI values into SINR values using a lookup table configured by

parameter cQIToSINRLookUpTable. These SINR values are used to produce one SINR value that is used

to derive the MCS ( MCS SINR ). Twentynine MCS SINR intervals are defined. Each of them corresponds

to an MCS. The lowest interval corresponds to the most robust MCS (and hence to the lowest

transmission rate). The highest interval corresponds to the least robust MCS (and hence to the highest

transmission rate). The selected MCS is the one that is mapped to the interval MCS SINR falls into. The

intervals do not overlap and the transition from an interval to another is defined by a threshold value






1 � 2 � 73


6.2.1 dlMCSTransitionTable

� This table is made up of 28 transition thresholds.

� It represents the thresholds of SINRs values for which the DL modulation is being changed.

� Higher threshold values will result in lower data rates.

� Lower values will lead to more optimistic MCS assignments and hence, more HARQ retransmissions and higher BLERs.

The intervals do not overlap and the transition from an interval to another is defined by a threshold

value

Example of MCS Transition table:

23<=SNR2315

19<=SNR<231914

17<=SNR<191713

15,25<=SNR<1715,2512

13,25<=SNR<15,2513,2511

11,5<=SNR<13,2511,510

9,75<=SNR<11,59,759

7,75<=SNR<9,757,758

6,5<=SNR<7,756,57

4,5<=SNR<6,54,56

2,75<=SNR<4,52,755

1,25<=SNR<2,751,254

-0,5<=SNR<1,25-0,53

-1,25<=SNR<-0,5-1,252

SNR<-1,251

SNR Range ClarificationSNR ThresholdMCS Index






1 � 2 � 74


6.2.2 BLER Control Loop

� A BLER Control loop control the MSC selection in long term.

CQI and ACK/NACK1

SINR

Selected MCS for the TTI

2

from cQIToSINRLookUpTable

SINR Conversion

CQI

3

MCS Selection Algorithms

From dlMCSTransitionTable

BLER Control Loop

ACK/NACK

BLER estimation

Only when the BLER estimation is too high (or too low) compared to the BLER target (10%)

CorrectionIn dB

Performances of the adaptive modulation and coding functionality is upper limited by the CQI feedback

compared to the real radio channel quality. The purpose of the Bler control loop is to adaptively

control link adaptation by introducing an ACK/NACK dependent power offset.






1 � 2 � 75

6 Link Adaption

6.3 PUSCH Link Adaptation

� Like in DL, the MCS selection is based on a lookup table, but the UL radio conditions are estimated on the SRS reception and not CQI.

� The Sounding Reference Signal (SRS) is measured by the eNodeB to estimate the UL radio condition.

eNodeB

SRS

Sounding Reference Signal

1

2

SINR Estimation from the SRS

3

MCS Selection using the SINR-to-MCS lookup table

The MCS is derived using a hardcoded SINR-to-MCS lookup table. The inputs of the table are the

number of PRBs and the estimated SINR. The lookup table outputs the MCS scheme, i.e.:

� The selected modulation: {QPSK, 16QAM}

� The selected coding scheme: Choices available are:

� {1/3; ½; 2/3; ¾} for QPSK,

� {1/2; 2/3; 3/4;7/8} for 16QAM SIMO,

� {1/2; 2/3;3/4} for 16QAM MU-MIMO.






1 � 2 � 76


6.3.1 SRS Signal

� The SRS signal is transmitted on the last SC-FDMA symbol of the sub-frame.

� The SRS sequences are orthogonal to multiplex UEs in the same sub-frame.

� In addition, the UEs are time multiplexed.

UE 1

UE 2

UE 3

Slot = 0.5ms

Slot = 0.5ms

SRS (wideband)

1 sub-frame SRS

UE1 UE4 UE2 UE8 UE5UE3 UE6 UE9 UE0 UE7

SRS is used to provide information on uplink channel quality on a wider bandwidth than the current

PUSCH transmission or when a terminal has no transmission on PUSCH. The channel is estimated on the

eNodeB and the obtained channel information can be used for the optimization of the uplink

scheduling. SRS can then be considered as an uplink counterpart for the CQI reporting of the downlink

channel.

SRS parameters are UE specific and configured semi-statically

� SC-FDMA symbol position (one symbol in subframe used for SRS)

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

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

carrier transmission)

The UE receives during the RRC connection establishment the parameters to transmit regularly the SRS

channel to the eNodeB.






1 � 2 � 77


6.3.1 SRS Signal [cont.]

� Sounding RS signal power, channel estimates and noise power measurement reports from L1 to UL scheduler.

� From the SRS signal, the eNodeB measures the SRS SINR per PRB.

� The Following parameters can activate/desactivate the SRS signal.






1 � 2 � 78


6.3.1 SRS Signal [cont.]

�SRS bandwidth is not tunable in LA2.0 and uses almost all the system bandwidth.

20 MHz

100 PRB

96 PRB

10 MHz

50 PRB

36 PRB

5 MHz

25 PRB

20 PRB

System BandwidthSRS Bandwidth

(in PRB)






1 � 2 � 79

6 Link Adaption

6.4 PUSCH Power Control

� To compensate the path loss, the eNodeB controls the UE transmission power.

eNodeB

UL Transmission

PUSCH

2

UL Grant on PDCCH

Power down

1

UL Transmission

PUSCH

UL Grant on PDCCH

Power up

For PUSCH power control, the TPC command is embedded into the UL scheduling grant in PDCCH with

DCI format 0.

By this way, the eNodeB can increase the UE transmission power when it moves towards the cell edge.

And oppositely, if the user moves towards the eNodeB, it can decrease the transmission power.






1 � 2 � 80


6.4.1 Principle

� The UE transmission power is:

Tx(dBm) = α PL(dB) + Po_PUSCHl (dB) + Pouser (dB) + f(d)

� Where f(d) is the TPC command transmitted on the DCI format 0.

eNodeB

BCCH/DL-SCHSIB2: P0 nominal and P0 user

PL Estimationthanks to RS Signal

Transmission on the PUSCH

RS Signal

PDCCHF(d) -> TPC Command

PL: DL Pathloss estimated by the UE based on DL RS measurements

Ponominal (dB) : 8-bit cell-specific parameter broadcast in SIB2 and configured by parameter

p0NominalPUSCH

PoUE (dB) : 4-bit logical channel specific parameter broadcast in SIB2 and configured parameter

p0UePUSCH






1 � 2 � 81


6.4.1 Principle[cont.]

� P0 _ NOMINAL _ PUSCH

� an 8-bit cell specific nominal component configured by parameter p0NominalPUSCH

� P0 _UE _ PUSCH

� a 4-bit logical channel specific component configured by parameter p0UePUSCH

� If there are several logical channel (i.e 2 DTCH), the highest value is used.

PO_PUSCH ( j) is the sum of an 8-bit cell specific nominal component O_NOMINAL_ PUSCH P ( j)

configured by the p0NominalPUSCH parameter and a 4-bit component O_UE_PUSCH P ( j) configured

by the p0UePUSCH parameter.

The p0UePUSCH parameter is logical channel specific. In case more than one logical channel is

configured, the highest value over the different logical channels is used.

The p0NominalPUSCH and p0uePUSCH parameters are key RF optimization parameters. Higher

settings will improve PUSCH reception, but will also drive higher UE Tx power leading to interference

to neighboring cells, and vice-versa






1 � 2 � 82


6.4.2 TPC Command

� The TPC command is a UE specific correction value. It is computed by a specific algorithm based on the SIR target an the estimated SIR.

� After a given number of measurements:

� The SIR target is updated .

� The correction factor is computed by a specific internal algorithm.

� The TPC command (containing the correction factor) is sent.

eNodeB

SRS1

SIR Estimation

2

Correction Factor is computedBased on SIR estimation/target comparison

34UL Grant on PDDCHIncluding TPC command

5UL Transmission on PUSCHCorrected transmission power

The eNB estimates the PUSCH SINR from the SRS measurement reports and the noise power received from L1.

UL scheduling grant (DCI Format 0): 2 bit PUSCH TPC command






1 � 2 � 83


6.4.2 TPC Command [cont.]

� Each time the number of measurements reaches the value of the following parameter:

� The SIR is updated

� The correction factor computed by a specific algorithm.

� The TPC command (containing the correction factor) is sent.

In case of semi-static scheduling (VoIP), the following parameter set the number of measurement

required to update the SIR estimation.






1 � 2 � 84


6.4.2 TPC Command [cont.]

� When there is no active semi-static pattern for the UE, the SIR target is initialized to initialSIRtargetValueForPUSCHnonSemiStaticUsers

For semi-static pattern:






1 � 2 � 85


6.4.3 Fractional power control

� Fractional Power Control is used in order to limit the interference that cell edge-users create to the neighboring cells.

� PL compensates for only a fraction of the estimated path loss PL

� If α = 1 the Path loss is fully compensated. It deactivates fractional power control.

� If α <1 the Path loss is partially compensated

Tx(dBm) = α PL(dB) + Po_PUSCHl (dB) + Pouser (dB) + f(d)

In fractional power control, the transmit power adjustment pUSCHPowerControlAlphaFactor . PL

compensates for only a fraction of the estimated path loss PL . The result is that the SINR achieved by

the UE at the eNB varies linearly with the path loss. Higher levels of path loss are associated with lower

SINR and vice versa.






1 � 2 � 86


6.4.3 Fractional power control

� The result is that the SINR achieved by the UE at the eNB varies linearly with the path loss. Higher levels of path loss are associated with lower SINR and vice versa.

When the UE is close to the cell center, the pathloss decreases and hence the target SINR is increased.

When the UE is at the cell edge, the pathloss increases and hence the target SINR is decreased






1 � 2 � 87


6.4.3 Fractional power control [cont.]

� At the eNB level, The target SINR is first initialized to InitialSIRtargetValueForPUSCHnonSemiStaticUsers

� It is then updated as follows:

� Parameter pathLossNominal is a configurable nominal path loss and corresponds to the path loss at which we want the SIR target to be initialSIRtargetValueForPUSCHnonSemiStaticUsers

� PLav is an estimate of the average path loss based on the average SRS power






1 � 2 � 88

7 H-ARQ






1 � 2 � 89

7 H-ARQ

7.1 Principles

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

CombiningRx packets

Packet transmission

(PDSCH)

H-ARQ Re-Tx

(PDSCH)

H-ARQ NACK (PUCCH)

H-ARQ ACK (PUCCH)

eNode-B UE

CombiningRx

(PUCCH)

packets

Packet transmission

(PUSCH)

H-ARQ Re-Tx

(PUSCH)

H-ARQ NACK (PHICH)

H-ARQ ACK (PHICH)

eNode-B UE

In Downlink In Uplink

Fast Hybrid ARQ with soft combining is used in LTE to allow the terminal to rapidly request

retransmissions of erroneously received transport blocks and to provide a tool for implicit rate

adaptation. Retransmissions can be rapidly requested after each packet transmission, thereby

minimizing the impact on end-user performance from erroneously received packets.

The Hybrid ARQ protocol is part of the MAC layer, while the soft-combining operation is handled by the

physical layer. Upon reception of a transport block, the receiver makes an attempt to decode the

transport block and informs the transmitter about the outcome of the decoding operation through a

single ACK/NACK bit indicating whether the decoding was successful or if a retransmission of the

transport block is required.

This mechanism runs in UL and DL.






1 � 2 � 90

7 H-ARQ

7.2 H-ARQ Process

� The underlying H-ARQ protocol is that of multiple parallel stop-and-wait hybrid ARQ processes.

� The H-ARQ used is a hard H-ARQ technique (the same PRBs and the same MCS are used for retransmissions and initial transmissions).

� One user queue H-ARQ process is allocated for each fresh transmitted codeword.

1

2

H-ARQ UE1

TB#1

TB#2ACK

ACK

The entity handled is the H-ARQ process. It is directly linked to the codeword and consequently to the

transport block.

Each H-ARQ process is associated with a H-ARQ buffer. Each H-ARQ process maintains a state variable

which indicates the number of transmissions that have taken place for the MAC PDU currently in the

buffer. This variable is initialized to 0 when a new transmission is requested and incremented with

each retransmission.

For a new transmission, the H-ARQ process delivers the MAC PDU, the uplink grant and the H-ARQ

information to the identified H-ARQ process, and then instructs the identified H-ARQ process to trigger

a new transmission.






1 � 2 � 91

7 H-ARQ

7.3 H-ARQ Timing

1 ms

TB for UE1

ACK or Nack on the PUCCH

DL

UL

� The answer of the H-ARQ process is always synchronized (T + 4 TTI) and the value is considered as a negative acknowledgment by default (no answer detected by layer one, i.e. DTX) until a positive acknowledgment is received from the UE.

For the schedulers, retransmissions have always a higher priority than a first transmission.






1 � 2 � 92

7 H-ARQ

7.4 H-ARQ Parameters

� The following H-ARQ parameters are function of the radio bearer type:� Signaling or data radio bearer and QCI.

� The maximum number of H-ARQ attempts is configured by the hARQMaxNumberOfTransmission parameter.

� The hARQMaxTimer timer is used for each H-ARQ process. It is started at the time of the first transmission of the H-ARQ process in question. On timer expiry, the H-ARQ process is killed.

A process is also killed after the maximum number of transmissions for that process is reached. After a

process is killed, all the related allocated resources are freed.

Example of bearer configuration:






1 � 2 � 93

Exercise 1

� Do you remind of LTE Radio Principles?

� Fill in the boxes with ??? with the appropriate channel.

� How the UE can know on which PRB it can transmit in UL ?

� Which channel is used to transmit the H-ARQ ACK/NACK in UL? In DL?

� What is transmitted on the PRACH

PHY Layer

UL-SCH??? BCH RACH MCH

PDCCH

PDSCH ???

PUCCH

PBCH

Transport Channel

PMCHPRACH

PCH

Physical control channel in DL and UL

BCCHPCCH ??? MCCHDCCH DTCH MTCH

Logical Channel

MAC Layer

PCFICH

PHICH






1 � 2 � 94

Exercise 2

� From the table 1 (3 cell conf) and the table 2 (3 radio conditions), fill the table 3 with the following list:

� OL MIMO, TxDiv, CL MIMO 1L, CL MIMO 2L

16

14

15

True

TM4

Conf 3

1515dlSinrThresholdBetweenCLMimoTwoLayersAndOneLayer

1616lSinrThresholdBetweenCLMimoAndTxDiv

1415dlSinrThresholdBetweenOLMimoAndTxDiv

FalseFalsedlFullCLMimoMode

TM4TM3TransmissionMode

Conf 2Conf 1

16.514.512SINR

221RI

Radio 3Radio 2Radio 1

table1

table2

Warning: Values for the threshold are not optimized values

Conf 3

Conf 2

Conf 1

Radio 3Radio 2 Radio 1




Exercise 3

Objective: Determine the total transmission power symbol per symbol in the sub-frame only from the power parameter seen previously for 10 MHz bandwidth.

1. Answer to the following questions and fill the grey boxes in table 1

1. How many RE are used for the RS signal. Note only 1 of the 2 antennas is

considered.

2. How many RE are used for the PCFICH in the first symbol ?

3. How many RE are used for the PHICH in the first symbol ?

4. From these results, could you determine the number of RE available for the

PDCCH

1. In the first symbol ?

2. In symbol 2 and 3 ?

2. From the following parameters and the conversion table mW/dBm (last page) could

answer to fill the grey boxes in the table 2 ?

� ReferenceSignalPower = 18 dBm

� PrimarySyncSignalPwerOffset = 2.3 dB

� SecondarySyncSignalPwerOffset = 2.3 dB

� pBCHPowerOffset = 1.6 dB

� pCFICHPowerOffset = 3dB

� pDCCHPowerOffsetSymbol1 = 0.2 dB

� pDCCHPowerOffsetSymbol2and3 = 0.2 dB

� paOffsetPdsch = -3 dB

� pbOffsetPdsch = 1

� pHICHPowerOffs = 3.4 dB

3. Finally, from the 2 tables, could you fill the table 3 ? Including the total

transmission power per symbol ?




Exercise 3

Table 1

Table 2

Table 3




Exercise 3






1 � 2 � 98

End of Module

Module 3 � Page 1





Module 3Session Management



Module 3 � Page 2




LTE � 9400 LTE LA2.0 Radio Algorithms and Parameters DescriptionSession Management

3 � 2

Blank Page



Document History

Module 3 � Page 3





3 � 3

Module Objectives


� Describe the system information broadcast and the associated parameters

� Describe the Random Access procedure and the associated parameters

� Describe the RRC Connection procedure and the associated parameters

� Describe the Attach and the associated parameters

� Describe the Admission control and the associated parameters

� Describe the paging mechanism and the associated parameters

Module 3 � Page 4





3 � 4



Module 3 � Page 5





3 � 5

Table of Contents

Switch to notes view!Page

1 Introduction 71.1 Overview 8

2 System Broadcast 92.1 Introduction 102.2 List of the SIBs 112.3 Information Block Periodicity 12

3 Random Access Procedure 143.1 Principles 153.2 Timing 173.3 PRACH Configuration 193.4 Message 2 213.5 Message 3: RRC Connection Request 223.6 Message 4: Contention Resolution 233.7 Random Access Failure 243.8 RA Preamble Power Allocation 253.8.1 Parameters 26

4 RRC Connection 284.1 Introduction 294.2 Procedure 314.3 Timers 32

5 eUTRAN in the Attach 345.1 Introduction 355.2 Attach Call Flow 365.3 S1 Dedicated Connection 375.4 Initial Context Setup 395.4.1 SRB2 and DRB Establishment 40

6 RRC Connection Re-Establishment 416.1 Introduction 426.2 Procedure 43

7 Admission Control 447.1 Max Number of Bearers per UE 457.2 Max Number of Users 46

8 Paging 478.1 Introduction 488.2 Paging Occasion Determination 49

Module 3 � Page 6





3 � 6




Module 3 � Page 7





3 � 7

1 Introduction

Module 3 � Page 8





3 � 8

1 Introduction

1.1 Overview

� At the end of the attach, the default EPS bearer is established and the UE can reach the PDN

eNodeB

UE obtains system information: SIB

RRC Connection

Random Access Procedure

RRC Connection Establishment

Attach

S1 dedicated Connection

SRB2 and DRB establishment

ePCePC

UE Synchronization (including PCI)

Module 3 � Page 9





3 � 9

2 Physical Cell ID






3 � 10

2 Physical Cell ID

2.1 Reminder

� An important information used by the UE during the idle mode procedures, as well as in connected mode (/mobility procedures) is the information related to the eUTRAN Cell identity. Two elements are used for LTE cell identification:

� The Global Cell Identity (ECGI) is a cell identifier unique in the world.

� It has a global scope, and is used for cell identification purposes with MME, with another eNB, etc. It represents a combination of PLMN identity and E-UTRAN Cell Identifier (ECI)

� The Physical Cell Identity (PCI) is used in the generation of the cell-specific reference signal, as well as the primary and secondary synchronization signals.

� It has a local scope, and is only used for identification purposes between UE and eNB. Physical cell identity must be unique within a given region, as it is used to identify an LTE cell in UE – eNB interactions.






3 � 11

2 Physical Cell ID

2.1 Reminder [cont.]

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

� LTE supports 504 different cell identities.

� They are divided into 168 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






3 � 12

2 Physical Cell ID

2.1 Reminder [cont.]

� PCI planning is required to avoid:

� PCI Collision: A PCI collision occurs when in a given location; the signals from two different cells radiating the same PCI can be received by a UE.

� PCI confusion: It appears when a given cell, knowingly or unknowingly, has two neighbors sharing the same PCI.

In case of PCI collision, a UE may be unable to access either of the two cells due to the interference

generated. At best, a UE will be able to access one of the cells but will be highly interfered

In case of PCI confusion, since the UE uses the PCI to identify the cell on which it reports measurements this

will cause confusion in the eNB, as it will not know which of the two cells the report relates to. In the best

case, the eNB knows of the two cells and will ask the UE to report the CGI before triggering a handover. In

the worst case, the eNB knows of only one cell and will trigger a handover to that cell, whereas the UE may

have been reporting the other cell. This may lead to a high number of handover failures and/or call drops.






3 � 13

2 Physical Cell ID

2.2 PCI planning

� Each Physical cell Identity corresponding to a unique combination of one orthogonal sequence and one pseudo-random sequence, we can count on 504 unique cell identities (168 cell identity groups with 3 cell identities in each group).

eNodeB






3 � 14

2 Physical Cell ID

2.2 PCI planning [cont.]

� Rule of “PCI MOD 6”� The cell-specific frequency shift is given by PCI mod6.

� It is shift of 1 Resource Element.

� The PCI value Modulo 6 of all LteCell belonging to the same eNodeB must be different.

� This part of algorithm is integrated in the WPS cell creation wizard and the objective is to allocate each cell the first PCI found in the list of available PCIs that is not already used by another cell having the same frequency and located closer than a configurable secure distance (called Secured Radius)

Note that even PCI mod6 are equal and so uses the same Resource Elements, the RS sequence are different

like they are generated from the PCI.






3 � 15

3 System Broadcast






3 � 16

3 System Broadcast

3.1 Introduction

� System Information messages are carried over the BCCH logical channel and provide the mobiles with network-related configuration data. The BCCH is mapped onto both:

� the BCH transport channel (for the MasterInformationBlock) which is carried by the PBCH physical channel

� the DL-SCH transport channel (for all other system information blocks) which is carried on the PDSCH.






3 � 17

3 System Broadcast

3.2 List of the SIBs

� The 3GPP defines a maximum of 32 System Information Blocks, in addition to the MasterInformationBlock. Currently only eleven have been standardized.

� Hereafter is a brief description of the information blocks content:

� MIB: essential physical layer information.� SIB1: cell access information and scheduling of other system information messages.

� SIB2: common and shared channel information� SIB3: cell re-selection information� SIB4: intra-frequency neighboring cells

� SIB5: inter-frequency neighboring cells� SIB6: inter-RAT cell re-selection towards UTRAN� SIB7: inter-RAT cell re-selection towards GERAN� SIB8: inter-RAT cell re-selection towards CDMA2000� SIB9: home eNB identifier

� SIB10 and SIB11: Earthquake and Tsunami Warning System or ETWS

In bolt, the supported SIB






3 � 18

3 System Broadcast

3.3 Information Block Periodicity

� The MIB and SIB1 use fixed scheduling, whereas all other system information blocks are carried in System Information Messages whose scheduling is defined in SIB1.

� The MIB is scheduled in sub-frame 0 of frames with SFN mod 4 = 0, i.e. with a periodicity of 40 ms, but it is repeated every 10 ms.

� The SystemInformationBlockType1 is scheduled in sub-frame 5 of frames with SFN mod 8 = 0, and is repeated in sub-frame 5 of every even frame. It therefore has a periodicity of 80ms, with a repetition rate of 20ms.

The MasterInformationBlock (MIB) is scheduled in sub-frame 0 of frames with SFN mod 4 = 0, with

repetitions in sub-frame 0 of every radio frame. It therefore has a periodicity of 40ms (a

MasterInformationBlock with a new System Frame Number is sent every 40 ms) and a repetition rate of

10ms (the MasterInformationBlock is repeated 3 times at 10ms intervals without changing the SFN).






3 � 19

3 System Broadcast

3.3 Information Block Periodicity [cont.]

� For the other SIB (SIB2, SIB3, SIB5, SIB6, SIB7 and SIB8), the following parameters set their respective periodicity.

Other parameters configure the SIB5, 6 and 7 periodicity.






3 � 20







3 � 21


4.1 Principles

eNodeB

� The Random Access procedure is managed by the MAC layer.

� It occurs in different UE situations, mainly when it is not connected and need to establish an RRC Connection.

� It uses uplink common resources to contact the eNodeB

� PRACH channel

eNodeB

Initial Access

HandOver

The random access procedure is performed for the following five events:

� Initial access from RRC_IDLE

� RRC Connection Re-establishment procedure (after radio link failure).

� After handover, in the target cell.

� DL data arrival during RRC_CONNECTED requiring random access procedure, e.g. when UL synchronization

status is “non-synchronized”

� UL data arrival during RRC_CONNECTED requiring random access procedure, e.g. when UL synchronization

status is "non-synchronized" or when there are no PUCCH resources for Scheduling Request available.






3 � 22


4.1 Principles [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

The four steps of the contention based random access procedure are:

� Message 1 (Random Access Preamble): This message contains, among other Information Elements, a 5-bit

random ID.

� Message 2 (Random Access Response): generated by MAC on DL-SCH: This message contains, among other

Information Elements, the RA preamble identifier and the initial UL grant. This message does not use H-

ARQ.

� Message 3 (First scheduled UL transmission on UL-SCH): This message conveys the RRC connection

Request generated by the RRC layer and transmitted via CCCH.

� Message 4 (Contention Resolution on DL-SCH): This message is not synchronized with Message 3 and uses

H-ARQ. H-ARQ feedback is only transmitted by the UE which detects its own UE identity, as provided in

message 3, echoed in the RRC Contention Resolution message.






3 � 23


4.2 PRACH Configuration

� The RACH preamble occupies 6 PRBs and 1 sub-frame for the transmission of the RACH Preamble.

� The parameter prachConfigurationIndex sets the sub-frame number for the transmission of the preamble.

� The sub-frame may the number 1, 4 or 7

RACH

The sub-frame number for RACH message 1 is configured by the parameter prachConfigurationIndex. In LA2.0, this parameter can only take values between 3 and 5:

� prachConfigurationIndex = 3, RACHMsg1SubFrameNumber = 1








3 � 24


4.2 PRACH configuration [cont.]

� The physical layer random access preamble consists of a cyclic prefix of length Tcp and a sequence part of lengthTseq. Values of Tcp and Tseqdepend on the preamble format:

� The format is fixed = format 0

� The preamble length is 839 bits.

� There are 64 preambles available






3 � 25


4.3 Message 2

� The message 2 is:

� Is semi-synchronous (within a flexible window of which the size is one or more TTI) with message 1.

� Does not support H-ARQ.

� Is addressed to RA-RNTI on the L1/L2 control channel.

� It conveys:

� RA-preamble identifier

� Timing Alignment information

� Initial UL grant

� Assignment of Temporary C-RNTI (which may or may not be made permanent upon RRC Contention Resolution).

eNodeB

Preamble

msg2

Message 2 (Random Access Response): This message is generated by MAC on DL-SCH and intended for a

variable number of UEs.

It conveys a Random Access preamble identifier, assignment of Temporary C-RNTI, as well as timing

advance information and initial grant for the transmission of message 3.

It is addressed to RA-RNTI on PDCCH and does not use HARQ.

RACH message 2 is sent to the UE within a time window (named the RA Response window) after the

transmission of RACH message1. This time window starts at the 3rd subframe, starting from the frame that

contains the end of the preamble transmission.

If no Random Access Response is received within the RA Response window, or if none of all received

Random Access Responses contains a Random Access Preamble identifier corresponding to the transmitted

Random Access Preamble, the Random Access Response reception is considered not successful.






3 � 26


4.3 Message 2 [CONT.]

� The message 2 is sent to the UE within a time window after the transmission of RACH message 1.

� This time window is defined as follows:

� The window starts at the 3rd sub-frame, starting from the frame that contains the end of the preamble transmission.

� The window size is configured by parameter raResponseWindowSize.

Preamble (msg1)

UL

DL

raResponseWindowSize sub-frame

Msg2 on PDCCH (temp C-RNTI, UL Grant)






3 � 27


4.4 Message 3: RRC Connection Request

� Message 3 (first scheduled UL transmission on UL-SCH):

� This message conveys the RRC connection Request generated by the RRC layer and transmitted via CCCH.

� H-ARQ is used for this message and with the maximum number of transmissions configured by the maxHARQmsg3Tx parameter.

eNodeB

Preamble

msg2

Msg3: RRC Connection Request

Message 3 (First scheduled UL transmission on UL-SCH):

For users that already have a C-RNTI, this message conveys, among other information elements, the C-RNTI

of the UE and the RRC Handover Confirm (in case the RACH procedure is performed after handover)

which is transmitted via DCCH.

For users that do not already have a C-RNTI, this message conveys either the RRC Connection Request (for

initial access from RRC_IDLE) or the RRC Connection Re-establishment Request (after radio link failure).

Both these messages are transmitted via the CCCH logical channel.

This message uses HARQ. Parameter maxHARQmsg3Tx configures the maximum number of attempts for

this message.

After the first transmission of message 3, the UE starts the mac-contention resolution timer. This timer is

restarted after each HARQ retransmission of message 3.

After the (re)transmission of message 3, the UE monitors the PDCCH for a PDCCH transmission (message 4),

identified by either C-RNTI (for UEs that already have a C-RNTI) or Temporary C-RNTI (for UEs that

already have a C-RNTI)

After a radio link failure, this message conveys the RRC Connection Re-establishment Request.

After a handover, this message conveys the ciphered and integrity protected RRC Handover Confirm.






3 � 28


4.5 Message 4: Contention Resolution

� Message 4 is the Contention Resolution on DL-SCH:

� This message is not synchronized with Message 3 and uses H-ARQ.

� H-ARQ feedback is only transmitted by the UE which detects its own UE identity, as provided in message 3, echoed in the RRC Contention Resolution message.

� The maximum number of transmissions is configured by the maximumNumberOfDLTransmisionsRACHMessage4 parameter.

eNodeB

Preamble

msg2

Msg3: RRC Connection Request including UE id

Msg4: Contention ResolutionUE id <-> C-RNTI

Message 4 (Contention Resolution on DL-SCH): This message contains a UE Contention Resolution identity.

It is addressed on PDCCH either to the C-RNTI (for UEs that already have one) or to the Temporary C-RNTI

(for UEs that do not already have a CRNTI).

This message uses HARQ. Parameter maximumNumberOfDLTransmisionsRACHMessage4 configures the

maximum number of attempts for this message.

If message 4 is successfully received and the UE contention resolution identity contained in the message

matches the content of message 3 (RRC connection request or RRC Connection Re-establishment Request)

for UEs that do not already have a C-RNTI), the Contention Resolution is considered

successful and:

o The mac-contention resolution timer is stopped.

o The UEs that already have a C-RNTI resume using it.

o The UEs that do not already have a C-RNTI promote their Temporary C-RNTI to a C-RNTI.

If the mac-contention resolution timer expires, the contention resolution is considered not successful.

Parameter macContentionResolutionTimer configures the mac-contention resolution timer.






3 � 29


4.5 Message 4: Contention Resolution [CONT.]

� After the transmission of RACH message 3, the UE monitors the PDCCH for a given number of sub-frames the number of which is configured by the macContentionResolutionTimer parameter.

Msg3 (RRC Connection Request)

UL

DL

Msg4, Contention Resolution

macContentionResolutionTimer






3 � 30


4.6 Ramp Up process

� After a certain number of attempts (configured by the preambleTransMax parameter), the MAC layer declares the Random Access procedure as failed.

eNodeB

PRACH

No answer from the eNodeB on the PDCCH (msg2)

Random Access Failure if

preambleTransMax = 4






3 � 31


4.7 RA Preamble Power Allocation

� The Open-loop power control is applied for initial transmission of RACH.

� The transmit power is determined by the UE taking into account the total UL interference level and the required SINR operating point.

eNodeB

PreamblePower?

msg2

The term PL is the DL path loss estimated at the UE from DL RS.

The preambleInitialReceivedTargetPower parameter configures P_0_PREAMBLE (initial preamble receive

power).

∆Preamble is the power offset value dependent on the PRACH preamble format. It is hardcoded to 0 dB.

∆PRAMP _UP is the power ramping step size. It is configured by the preambleTransmitPowerStepSizeparameter.

PREAMBLE N is the preamble transmission number.






3 � 32


4.7.1 Parameters

� The preambleInitialReceivedTargetPower parameter configures the initial preamble received power.

� The preambleTransmitPowerStepSize parameter configures the offset between 2 consecutive preambles.

The preambleInitialReceivedTargetPower parameter is a key RF optimization parameter that impacts call

setup performance and UL interference to neighboring cells. Higher values will minimize the repetitions/

RACH attempts and hence expedite call setup, but will cause higher interference to other cells. Lower

values will tend to increase RACH repetition/ call setup delay and do not necessarily lower interference

due to higher number of probes. Ideally initial power should be set high enough to achieve good success at

1st attempt at reasonable IoT loading levels.






3 � 33


4.7.1 Parameters [cont.]

� Minimum and Maximum transmission powers are defined by the following parameters:






3 � 34

5 RRC Connection






3 � 35

5 RRC Connection

5.1 Introduction

� The RRC connection establishes the SRB1 between the UE and the eNB.

� It is triggered by the initial random access procedure.

� The "Signaling Radio Bearers" (SRBs) are defined as Radio Bearers (RBs) that are 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, used to establish the SRB1.

� SRB1 is for RRC messages (which may include a piggybacked NAS message) 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 during the Attach.

Note: the SRB0 is established at cell setup.






3 � 36

5 RRC Connection


� The SRB0 is a common channel used during the establishment of the RRC Connection.

RRCSystem Info

RRCPaging

RRCDL Conn SetupUL Conn Req

SRB 0RRC

System Info

RRCPaging

RRCDL Conn SetupUL Conn Req

SRB 0

RRCAnd NAS

SRB 1

After the RRC connection






3 � 37

5 RRC Connection

5.2 Procedure

� The RRC connection Call Flow is as follows:

eNodeBRRC Connection Request (msg3)CCCH/SRB0

RRC Connection SetupCCCH/SRB0

RRC Connection setup completeDCCH/SRB1

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

Radio resources configuration to establish the SRB1

Id of selected PLMNNAS dedicated information

Upon reception of this MAC PDU (containing the RRCConnectionRequest message), MAC will retrieve the

temp C-RNTI previously associated with these resources where the MAC PDU was received. This identity is sent to the RRC entity together with the MAC SDU.

In case of Initial Access, the UE identity in the RRCConnectionRequest message is either a NAS identity (i.e.

S-TMSI if valid), or a random number (S-TMSI not valid).

If the RRCConnectionRequest included the ue-Identity set to S-TMSI, the eNB will store it in order to

include it in the INITIAL UE MESSAGE message.

SRB matching is performed and associated radio configuration is retrieved. If ADMISSION CONTROL is

passed, a new UE context is created and SRB1 is set up in the eNB. The initial UE identity and the allocated

C-RNTI are stored in the UE context.

The RRCConnectionSetup is transmitted to the UE using CCCH. The message will contain SRB1

configuration. The MAC contention resolution is based on UL CCCH SDU used as a UE Contention Resolution

Identity in the MAC control element. The measurement configuration setup management at call

establishment later.

Defense mechanisms: An internal guard timer is started on transmission of the RRCConnectionSetup

message. The procedure ends on the eNB when it receives the RRCConnectionSetupComplete message and

the guard timer is stopped.

On reception of the RRCConnectionSetupComplete message, the eNB will use the IEs NAS-DedicatedInformation , SelectedPLMN-Identity, RegisteredMME (if present) to initiate the S1 dedicated

establishment procedure.

Final state

The UE is in RRC connected state. SRB1 is established.






3 � 38

5 RRC Connection

5.3 Timers

� This UE timer is started when sending RRCConnectionRequest and is stopped upon reception of RRCConnectionSetup or RRCConnectionReject. Defined in TS 36.331. Broadcast in SIB2

eNodeBRRC Connection RequestCCCH/SRB0

RRC Connection SetupCCCH/SRB0

RRC Connection setup completeDCCH/SRB1

T300






3 � 39

5 RRC Connection

5.3 Timers [cont.]

� In case of failure, the eNodeB sends to the UE in the RRCConnectionReject a wait time called T302.

� The reject reason may be:

� Admission control

� Cell is barred

� S1 is down

� Internal reasons

eNodeBRRC Connection RequestCCCH/SRB0

RRC Connection RejectCCCH/SRB0, T302

.

.

.

RRC Connection RequestCCCH/SRB0

T302






3 � 40







3 � 41


6.1 Introduction

� At the end of the attach, the default EPS Bearer is established.

� At the eUTRAN level, the following steps have been done:

� Authentication

� Keys derivation

� S1 dedicated connection

� Initial Context setup (SRB2 and DRB creation)

� Measurement configuration

eNodeB

Attach

S1 dedicated Connection

SRB2 and DRB establishment






3 � 42


6.2 Attach Call Flow

Ue IP

allocation

RRC Connection Request

RRC Connection SetupMME SGW PGW

RRC Connection Setup Complete

Attach request

Create Bearer Request Create Bearer

Request

Create Bearer

ResponseCreate Bearer ResponseS1AP Initial UE Context Setup Request

Attach Accept

Activate Default EPS bearer context

UL NAS transport

Attach Complete

Activate Default EPS bearer context accept

S1AP Initial UE Context Setup

Response

Update Bearer

Request

Update Bearer

Response

Initial Context Setup

S1AP Initial UE Message

Attach Request

NAS PDU Security Mode Command

NAS PDU Security Mode Complete

Security Mode complete

RRC Connection reconf Complete

UL NAS transfer

(Attach Complete)

Security Mode Command

RRC Connection Reconf

(RB setup) (Attach Accept)

HSS

Insert Subscriber Data (diameter protocol)

Update Location (diameter protocol)

Authentication (diameter protocol)

Default Bearer Ctxt

created in MME/SGW

security Mode Command

security Mode Complete

Measurement

configuration

Measurement

configuration

UE Capability Enquiry

UE Capability Information

The security Mode Command messages on the air interface and the S1 interface aims at:

� The authentication between the UE and the HSS. The EPS AKA authentication method allows a mutual

authentication. The UE can authenticate the network and then the network checks the UE identity.

� The transfer of the key. From a successful authentication, keys to secure the air interface and eventually

the S1-MME are derived. The data plane on the air interface is fully encrypted by the PDCP protocol.






3 � 43


6.3 S1 Dedicated Connection

One STCP Association

One RRCconnection

One RRCconnection

One Logical Connection(S1 dedicated connection)

One Logical Connection(S1 dedicated connection)

UE Context

UE Context

•SCTP Stream MME

� There is one SCTP association between one eNB and one MME.

� There is one signaling connection between a UE and an MME made from the following:

� One RRC connection (per UE) between one UE and one eNB.

� One logical connection (per UE) between one eNB and one MME which is established by the S1 dedicated connection.

The logical connection is mapped on the unique SCTP association aforementioned. This per-UE logical

connection is uniquely identified by couple (eNB S1-AP UE Identity; MME S1-AP UE Identity). Many UE logical

connections are multiplexed on the unique eNB-MME SCTP association.






3 � 44


6.3 S1 Dedicated Connection [cont.]

� This logical connection at S1AP level is uniquely identified by:� the eNB S1-AP UE Identity in the eNB.

� the MME S1AP UE identity in the MME.

eNodeB MME

UE Context

ENB S1AP UEMME S1AP UE

UE Context

ENB S1AP UEMME S1AP UE

SCTP association

Trigger

For the eNB S1-AP UE Identity to be allocated, stored in the UE context and sent to the MME, the

RRCConnectionSetupComplete message triggers the S1 dedicated connection establishment.

For the MME S1-AP UE Identity to be stored in the UE context upon receipt from the MME, the S1AP

DOWNLINK NAS TRANSPORT message terminates the S1 dedicated connection establishment without SAE

bearer






3 � 45


6.4 Initial Context Setup

S1AP Initial UE Context Setup Request

Attach Accept



Response

Initial Context Setup

UL NAS transport

Attach Complete


UL NAS transfer

(Attach Complete)








When the MME transmits the S1AP Initial UE Context Setup Request, it includes the QoS parameters for the

default radio bearer.

After storing the UE capabilities in the UE Context, the eNB initiates the Security activation over the radio

interface prior to the establishment of SRB2 and or DRBs.

The eNB will:

� Perform key derivation function and integrity/ciphering algorithm selection.

� Configure PDCP to start integrity protection and ciphering.

� Transmit the SecurityModeCommand to initiate the AS security using the integrity protection and

ciphering algorithms determined previously.

Then the eNodeB initiates the SRB2 and DRB establishment.






3 � 46

6.4 Initial Context Setup

6.4.1 SRB2 and DRB Establishment

� For each E-RAB to be setup in the S1-AP INITIAL CONTEXT SETUP REQUEST, the eNB will:

� Perform E-RAB matching based on requested S1 QoS (e.g. QCI, MBR, GBR) and UE capabilities

� Select the associated L1/L2 dedicated resources configuration.

� Perform Admission Control:

� Radio ADMISSION CONTROL

� Transport Layer ADMISSION CONTROL






3 � 47







3 � 48


7.1 Introduction

� Purpose: Re-establish the SRB1, SRB2 and DRB(s) and resume normal operation

� The UE initiates the RRC connection re-establishment procedure when one of the following conditions is met:

� upon detecting radio link failure,

� upon handover failure,

� upon mobility from E-UTRA failure,

� upon integrity check failure indication from lower layers;

� upon an RRC connection reconfiguration failure:

� Failure during RRC connection reconfiguration for Bearer Management; or

� Failure during RRC connection reconfiguration for Security Management; or

� Failure during RRC connection reconfiguration for Measurement Management;






3 � 49


7.2 Feature Benefits

� The RRC Re-establishment benefits are:

� to avoid call drops in area of poor coverage

� to re-activate the security in case of integrity check fails.

� When a user temporarily moves into an area of poor coverage, andmoves back into good coverage, the call will not be dropped.

�

� The user will experience a few seconds of silence while the call is re-established onto the new cell.

� The call drop rate will decrease for the end-user.

This is especially beneficial to users on calls whilst travelling through tunnels etc, the call will not drop, the

user will not have to re-dial.

Call re-establishment is also reattempted on failure occurring during mobility or call reconfiguration.






3 � 50


7.1 Introduction

� The following parameter authorizes the RRC Re-establishment:






3 � 51


7.2 Procedure

RrcConnectionReestablishment Request

SRB0/CCCH

UE Context

Reactivation

RrcConnectionReestablishment

SRB0/CCCH

SRB1

Re-established

RrcConnectionReestablishment Complete

SRB1/DCCH

RrcConnectionReConfiguration

SRB1/DCCH Resume

SRB2, DRBRrcConnectionReConfiguration Complete

SRB1/DCCH

T311

The UE initiates the RRC Re-establishment procedure by sending RrcReestablishmentRequest including its

identity allowing the eNB to determine if the UE context exists. If the UE context already exists then the re-establishment procedure is initiated. Otherwise, the request is rejected and the UE moves to idle

mode.

Admission control is not performed. RAB matching is not performed at reception of

RrcConnectionReestablishmentRequest. New RLC/MAC contexts are created for SRB1, SRB2, DRBs. PDCP is

re-established and PDCP is switched to new RLC contexts.

The eNB allocates a new C-RNTI and reconfigures the SRB1 by transmitting RrcConnectionReestablishment

including SRB1 configuration.

After reception of RrcConnectionReestablishmentComplete, the eNB initiates an RRC reconfiguration procedure to reconfigure the SRB2 and DRBs.

If the eNB detects by itself a radio link failure, it will just start a guard timer and wait for re-establishment

request from the UE. If such request is not received and the timer elapses, then the eNB triggers UE

context release to the MME.

Failure cases:

No RRCConnectionReestablishmentComplete received

No RRCConnectionReconfigurationComplete received

Reception of a RRCConnectionReestablishmentRequest while an ongoing re-establishment procedure is not

completed with the same UE

In all these cases, the eNB triggers UE context release to the MME.






3 � 52

8 Admission Control






3 � 53

8 Admission Control

8.1 Max Number of Bearers per UE

� The Admission Control rejects a new request if there are already 2 established data Radio Bearers.

� maxNbOfDataBearersPerUe: This parameter defines the maximum number of Data Bearers (DRB) that can be configured for any UE.






3 � 54

8 Admission Control

8.2 Max Number of Users

� Upon request for the creation of a UE context, the CAC function shall reject the request if the number of already registered users is equal or larger than the value of maxNbrOfUsers.

� Upon request for the creation of a VoIP bearer, the CAC function shall reject the request if the number of active VoIP calls is already equal or larger than the value of ulMaxNbrOfVoIPBearers.

Default Bearer

VoIP

Default Bearer

VoIPConnection request

VoIP Request

Default Bearer

Default Bearer

VoIP

maxNbrOfUsers = 7

ulMaxNbrOfVoIPBearers = 3

VoIP Bearer = 3 + 1= 4 -> Request Rejected

With the configuration (just for example) a new user will be able to be connected maxNbrOfUsers = 7 and

the new user is the 5th.

But since ulMaxNbrOfVoIPBearers = 3 and it is the 4th VoIP request, the VoIP is rejected






3 � 55

8 Admission Control

8.3 Resource Consumption Checking

� The CAC check the resource consumption for:

� Signaling Radio Bearer Creation� Best Effort Radio Bearer Creation� VoIP Radio Bearer Creation� Guaranteed Bit Rate Radio Bearer Creation

� The principle is the same for the 4 events:

� ((Rdl + dlConsumption) / dlTotalResourceCount x 100) < dlAdmissionThreshold� ((Rul + ulConsumption) / ulTotalResourceCount x 100) < ulAdmissionThreshold

� Where � Rdl and Rul the metrics related to the total resource currently used by calls and common channels on the downlink and uplink respectively

� dlConsumption and ulConsumption are OAM defined parameters estimating the resource consumption for each type of bearer

� dlAdmissionThreshold and ulAdmissionThreshold are the threshold (OAM parameters) used to take the decision






3 � 56

9 Paging






3 � 57

Paging messages are sent over

PCCH/PCH/PDSCH

9 Paging

9.1 Introduction

� Upon receipt of a Paging message on the S1 interface, the eNodeBdetermines the list of cells on which to page the UE from the TAIList IE in the S1 Paging message.

� For each cell on which the UE must be paged, it shall:

� Compute the frame number and sub-frame number of the UE paging occasion.

� Encode the paging record for the given UE.

� Send this data to the Scheduler along with the paging cycle to be used.

Paging message

Paging message

PCCH uses the RLC TM mode and MAC transparent mode. As a consequence, the RRC has the function to

perform padding up to the Transport Block Size. The size of the Transport Block is selected such as the best

robustness is achieved given the RRC Paging message size.

Paging messages are sent over the PCCH logical channel. PCCH is mapped onto the PCH transport channel,

which itself is carried on the PDSCH physical channel. Transport format and resource allocation for the PCH

channel is signaled on the PDCCH channel, using the dedicated P-RNTI.






3 � 58

9 Paging

9.2 Paging Occasion Determination

� The moment at which a given UE can be paged is called a Paging Occasion. It is determined by 3 parameters:

� The UE_ID, equal to the UE IMSI modulo 1024.

� The DRX Paging Cycle

� The parameter nB, transmitted in the System Information (in SIB2), which defines a sort of "paging occasion density" within a radio frame

� These three parameters participate in creating time diversity for the sending of paging messages. In other words, they spread out in time the opportunities for paging and in this way, limit the scheduling conflicts while allowing the UEs to go into DRX mode and reduce their power consumption.

The UE ID is provided to the eNodeB in the S1 Paging message by mandatory information element "UE

Identity Index Value“.

The DRX Paging cycle is either the default value transmitted in the System Information

(defaultPagingCycle in SIB2), or the UE-specific value received in the S1 Paging message if it is shorter.






3 � 59

9 Paging

9.2 Paging Occasion Determination [cont.]

� The paging cycle is defined by the following parameter:

� For a UE, there is one paging occasion per cycle

� Parameter nB is expressed as a multiple or divisor of the paging cycle: it defines the ratio of paging occasions to the number of radio frames.

� oneT means one paging occasion

per radio frame

Paging cycle

Radio frame (10 ms)






3 � 60

Exercise 1

� From the following parameters, could you compute the transmission power of each preamble ?

� preambleInitialReceivedTargetPower = -104 dBm

� Pathloss = 110 dBm

� preambleTransMax = 3

� preambleTransmitPowerStepSize = 6

� MaxRACHTransmitPower = 17 dBM

eNodeBPRACH

10 min

t






3 � 61

End of ModuleSession Management


TMO 18315 D0 SG DEN Issue 3Module 4 � Page 1





Module 4 Mobility Management




LTE � 9400 LTE LA2.0 Radio Algorithms and Parameters Description

Mobility Management � 2

Blank Page



Document History






Module Objectives


� Describe the Cell Reselection mechanism and list the associated parameters

� Describe the Handover mechanism and list the associated parameters

� Describe the measurement configuration and list the associated parameters

� Describe the ANR SON feature






Table of Contents

Switch to notes view!Page

1 Cell Reselection in Idle Mode 71.1 Cell Selection 81.2 Cell Reselection 91.3 Cell Ranking 11

2 Handover 152.1 Introduction 162.2 Intra-eNodeB HO 172.3 Inter-eNodeB HO 182.3.1 Parameters 20

2.4 Random Access Procedure 222.5 PS Handover to UTRAN 232.5.1 Blind PS Handover 242.5.2 Blind PS Handover Triggering 252.5.2.1 “priorityOfBandUtraFdd” Parameter 26

2.5.3 PS Handover (eUTRAN To UTRAN) Pre-R8 272.5.3 PS Handover (eUTRAN To UTRAN) R8 282.5.3.1 Handover Preparation Phase 292.5.3.2 PS HO Execution 332.5.3.3 PS HO Completion 34

3 Measurement Configuration 353.1 Introduction 363.2 Measurement Configuration 373.2.1 Measured Object 393.2.2 Event Reporting Configuration: Event A3 413.2.3 Event Reporting Configuration: Event A2 483.2.3 Call Flow Mobility Intra-Frequency (A2_Blind) 493.2.3.1 Inter RAT threshold for Event A2_blind 51

3.3 UE Measurements 523.4 Example 53

4 Automatic Neighbour Relation ANR 544.1 ANR Overview 554.1 ANR Overview : anrEnable 574.1.1 ANR Phases 584.1.1 ANR Phases 59

4.2 Parameters Included in Neighbor Relation 604.2.1 discoveredByAnr & noRemove Parameters 62

4.3 ANR Measurement Configuration 634.4 Set Up X2 Links 64






1 Cell Reselection in Idle Mode






1 Cell Reselection in idle Mode

1.1 Cell Selection

� The cell selection criterion S is fulfilled when:

� qRxLevMin defines the minimum reception level to be able to select the cell.

� qRxLevMeas is the RSRP measured on the Reference Signal.

� qRxLevMinOffset is an offset which can be applied.

where

SRxlev is the quantity used for the cell selection criteria.

If the criteria are fulfilled, the UE moves to the camped normally state in which the following tasks will

be performed:

� Select and monitor the indicated PCH.

� Monitor relevant System Information.

� Perform measurements for the cell reselection evaluation procedure.

If the criteria are not fulfilled, the UE will attempt to camp on the strongest cell of any PLMN and enter

in the camped on any cell state where it can only obtain limited service (emergency calls). The following

tasks will be performed in the camped on any cell state:

� Monitor relevant System Information.

� Perform measurements for the cell reselection evaluation procedure.

� Regularly attempt to find a suitable cell trying all radio access technologies that are supported by the

UE. If a suitable cell is found, the cell selection process restarts.







1.2 Cell Reselection

Refere

nce Sig

nal

eNodeB

� The UE does not measure adjacent cells permanently. It measures them only if it is necessary.

� The cell selection and reselection are controlled by the System Information parameters provided in SIB1 and SIB3

No need to measure

Refere

nce Sig

nal

eNodeB

Need to measure

SIB3 SIB

3







1.2 Cell Reselection [cont.]

� sIntraSearch defines the threshold for serving cell reception level under which the UE shall trigger intra-frequency measurements for cell reselection.

� Broadcast in SystemInformationBlockType3

Refere

nce Sig

nal

eNodeB

Example:If qRxLevMin = -50 dBm and sIntraSearch = 5 dB, The UE starts the measurements when the reception level is under -45 dBm

The sIntraSearch parameter defines when the UE in idle state shall measure adjacent cells to prepare

the cell reselection. It is an offset (in dB) from the qRxLevMin.







1.3 Cell Ranking

� To reselect a cell, the UE ranks the serving and the adjacent cell.

� All ranked cells fulfill the S criterion.

� The cells are ranked with the R criterion defined as follows:

� For the Serving cell:

� For the candidates:

� Where Qmeas are averaged RSRP results







1.3 Cell Ranking [cont.]

t

Serving Cell

Cell 1

tReselectionEUTRAN

Cell 2

Cell2 is reselected

sIntraSearch

UE triggers intra-frequency measurements

RSRP

Timer is aborted

Qoffset

QHyst

Cell2 becomes better than the serving cell

Timer is started

Serving cell

Cell 2

The main diagram shows the reselection of the cell2 without taking in account the QHyst and Qoffset

parameters. The diagram in the upper right corner illustrates that the decision is taken with the

corrected value (QOffset and QHyst).






1 Cell Reselection in idle Mode

1.3 Cell Ranking [cont.]

� The Qoffset and QHyst parameters allow to make easier, more difficult or impossible the reselection between 2 cells depending on the topology.

Indoor cell

Outdoor1

2Outdoor

Qoffsetcell is defined per adjacencies

QHyst is defined per cell

When the UE is moving outside from cell 1 towards cell 2, the aim is to reselect cell 2. But if the

adjacencies are defined in the same way, the UE will select during a while the indoor cell. To avoid this

situation, it is possible to tune differently the adjacencies thanks to the Qoffset parameter.

For example:

Qoffset cell1->cell2 = 1 dB

Qoffset cell1->cell_indoor = 10 dB to make it not possible to reselect the indoor when the UE is outside.







Blank Page







2 Handover






2 Handover

2.1 Introduction

� The following procedure is supported to manage the mobility in connected mode:� Intra-eNB mobility

� Inter-eNB mobility with and without data forwarding� The inter-eNodeB mobility over S1 is not supported

� Intra-LTE HOs are triggered by the event A3.

eNodeBeNodeB

X2






2 Handover

2.2 Intra-eNodeB HO

� For the MME and the SGW, there is no impact

eNB

HO Decision

Setup of UE associated resources in the target cells

Detach from old cellSynchro with new cell

RRC ReconfigMeasurement conf

RRC Reconfig Complete

Measurement conf

Measurement Report

RRC ReconfigHO Command

Random Access

RRC Reconfig Complete

Release UE in source cell

eNodeB

MME

SGW

Source cell Target cell

Initial state:

UE in RRC CONNECTED in the source cell: SRB1/SIB2 + default bearer (+dedicated bearer) are

established.

Applicable eNB procedures:

RRC Connection Reconfiguration (mobility)

Final state:

UE in RRC CONNECTED in the target cell: SRB1/SIB2 + default bearer (+dedicated bearer). If the

handover occurs, all the bearers from the source are handed over to the target cell.

UE context and associated resources in the source cell are deleted.






2 Handover

2.3 Inter-eNodeB HO

Source eNB Target eNB MME/SGW

� The difference between an intra-eNodeB and an inter-eNodeB HO is the need of data forwarding for the inter-eNodeB HO

Note: In the above call flow, the Downlink user plane actions are mentioned for information. The yellow

boxes and blue text apply in case of DL data forwarding. For the sake of simplicity, the UL user plane

actions were omitted from the call flow. UL data forwarding is not supported.

Phase 1: handover preparation

� In case of inter-eNB handover trigger, the Source eNB will initiate the X2-AP handover preparation

providing in X2-AP HANDOVER REQUEST the necessary information to prepare the handover in the Target

eNB. If the data forwarding is enabled in the Source eNB via MIM configuration then the Source eNBwill propose to the target eNB to perform DL data forwarding via X2.

� The target eNB prepares the handover based on the received request from the Source eNB and includes

in HANDOVER REQUEST ACKNOWLEDGE the RRC CONNECTION RECONFIGURATION message to be

transmitted transparently by the Source eNB to the UE. If the data forwarding is enabled in the Target eNB via MIM configuration then the Target eNB will accept the proposal from the Source eNB to perform

DL data forwarding via X2 by establishing the one DL X2 tunnel for each SAE bearer subject to forwarding. After this step the target eNB is ready to receive UL transmission from the UE and DL data forwarded over X2 from the Source eNB if configured previously.

� The Source eNB transmits the RRC CONNECTION RECONFIGURATION message to the UE

� The Source eNB transmits the X2-AP SN STATUS TRANSFER to the Target eNB to convey the DL PDCP SN

of bearers. When this message is transmitted the Source eNB stops transmitting/receiving PDCP PDUs in

the source cell.

Phase 2: handover execution

� If data forwarding was configured in the handover preparation phase, the Source eNB forwards over X2

the DL PDCP SDUs received from S1 after HANDOVER REQUEST ACKNOWLEDGE reception and stops

transmitting in the source cell the fresh unnumbered DL PDCP SDUs.

� When the UE receives RRC CONNECTION RECONFIGURATION in the source cell, it will stop

receiving/transmitting data in the source cell and will initiate synchronization to the target cell followed

by a random access procedure as indicated in the received message. Both contention-based and non-

contention based random access is supported. If resources are available, the eNB allocates a dedicated

preamble to the UE.






2 Handover

2.3 Inter-eNodeB HO [cont.]

Source eNB Target eNB MME/SGW

Phase 2: handover execution

When the UE random access is successful, it will transmit the RRC CONNECTION RECONFIGURATION COMPLETE. Starting from this point, the UL and DL data transmission is resumed. The handover procedure ends in the UE.

Phase 3: handover completion

� When the Target eNB receives the RRC CONNECTION RECONFIGURATION COMPLETE it will send the S1-AP PATH SWITCH REQUEST to the MME to inform that the UE changed the cell.

� After the transmission of S1-AP PATH SWITCH REQUEST, the Target eNB is ready to receive DL data over S1.

� Upon request from the MME (at reception of S1-AP PATH SWITCH REQUEST), the SGW switches the DL data path to the Target eNB. The SGW sends one or more GTP-U End Markers per GTP-U tunnel through the old path (i.e. old S1 U-plane interface) to the Source eNB and then releases the U-plane resources and confirms the path switch to the MME which in turn sends S1 PATH SWITH REQUEST ACKNOWLEDEGE to the Target eNB.

� During the handover completion, the UL data transmission occurs normally in the Source or the Target eNB:

o if DL data forwarding was configured, the Source eNB continues to forward via X2 interface the received DL S1 packets until reception of the GTP-U End Marker or until resources are released

o if DL data forwarding was configured, the Target eNB shall transmit over the radio the DL X2 received packets until reception of the X2 GTP-U End Marker or until resources are released. Only after that DL S1 packets are transmitted.

o if DL data forwarding was not configured, the Target eNB will transmit the S1 DL packets normally.

� At the reception of S1 PATH SWITH REQUEST ACKNOWLEDEGE, the Target eNB transmits X2-AP RELEASE RESOURCE to the Source eNB.

� After the target eNB transmitted the X2-AP RELEASE RESOURCE, the handover procedure ends. The specific trigger to end the procedure depends on whether the X2 data forwarding occurred and specific GTP-U End Marker handling as specified later in this document.

� After the Source eNB received the X2-AP RELEASE RESOURCE, the handover procedure ends and the UE associated resources are deleted. The specific trigger to end the procedure depends on whether the X2 data forwarding occurred and specific GTP-U End Marker handling.






2.3 Inter-eNodeB HO

2.3.1 Parameters

� The data forwarding is allowed with the following parameter:

� It is managed per bearer type:






2.3 Inter-eNodeB HO

2.3.1 Parameters [cont.]

� The parameters below are in the scope of mobility information options.

They are “Fixed” category and they are class A parameters.






2 Handover

2.4 Random Access Procedure

� The non-contention-based random access procedure is intended to be used in the context of LTE handover.

msg0

msg1

msg2

The non-contention-based random access procedure can be seen as a variant of the contention based

procedure, used in handover scenarios.

1) Message 0 (Random Access Preamble assignment): The source cell sends a Handover command RRC

message to trigger the random access procedure on the target cell.

2) Message 1: The UE sends a RACH preamble to the target cell. The UE has to transmit the Random

Access Preamble assigned in Message 0.

3) Message 2: The eNB sends a Random Access Response on the DL-SCH.






2 Handover

2.5 PS Handover to UTRAN

� eUTRAN-to-UTRAN Packet Switched (PS) handover mobility mechanism in RRC connected mode, allows continuous service to a target UMTS cell.

� Compared with a redirection, the PS handover aims at ensuring a minimum interruption time for the RRC connection (thanks to the resource allocation in the target RNC duringthe preparation phase).

� The Blind PS Handover is supported without any inter RAT measurement, it is triggeredbased on LTE radio condition degradation in the source cell below a predefined thresholdand relies on the support of event A2.

In LA2.0.2, only blind eUTRAN-to-UTRAN PS handover without any inter-RAT measurements is supported and

the triggering for PS handover is based ondegradation of LTE radio conditions in the source cell below a

pre-

defined thresholdand relies on the support of RRC measurement Event A2.

PS handover with inter-RAT measurements is expected to be supported in a future release (LA3.0) and will

replace blind PS handover.

Also in LA2.0.2, PS handover is supported only for non-VoIP data bearers. The capability to perform PS

handover of a VoIP bearer may be a candidate for a future release. This will rely on the capability of the

target UTRAN cell supporting VoIP bearers.







2.5.1 Blind PS Handover

In order for blind PS handover to be activated, the following conditions are required:

1) Feature activated: parameter ‘isBlindPsHoToUtraFddAllowed’ is set to TRUE.

2) The UE must support (PS HO to UTRAN; UTRA-FDD and one or more UTRA-FDD bands

corresponding to provisioned neighbor UTRA-FDD cell(s) with the Same UTRA-FDD

band(s)

3) UTRA-FDD provisioned neighbor cells correspond to an RNC with an administrative

state which is unlocked and supports PS Handover:

• RncAccess::administrativeState = UNLOCKED

• RncAccess::psHandoverUtraFddEnabled = TRUE.

4) Since only blind inter-RAT PS handover is supported, the eNB will use

intra-frequency measurement reports with event trigger A2 for handover triggering.

Only PS Handover to UTRAN for non-VoIP data bearers is in the scope of LA2.0.2. Parameter

voiceOverIpEnabled is expected to be supported in a future release when UTRAN cell capability supports VoIP

bearers.

Only blind inter-RAT PS Handover from eUTRAN towards UTRAN is in the scope of LA2.0.2. This restriction is

expected to be removed in a future release (LA3.0).

Also in LA2.0.2, PS handover is supported only for non-VoIP data bearers. The capability to perform PS

handover of a VoIP bearer may be a candidate for a future release. This will rely on the capability of the

target UTRAN cell supporting VoIP bearers.

psHandoverUtraFddEnabled: flag is used to indicate whether or not the neighbor RNC is able to support PS

handover from eUTRAN to UTRA-FDD. True indicates that the neighbor RNC is capable of supporting the PS

handover from eUTRAN to UTRA-FDD.







2.5.2 Blind PS Handover Triggering

When the conditions are met such that blind PS Handover is possible, then the Target-UTRAN-Cell is selected based on the following criteria:

� The target cell is a provisioned UTRA-FDD neighbor of the serving LTE cell. (An LTE cell can have up to 3 provisioned UTRA-FDD neighboring cells)

� The RNC associated with the target cell supports PS Handover to UTRAN, that is, RncAccess:psHandoverUtraFddEnabled = TRUE.

� The UE supports the UTRA-FDD band of the target cell.

� The cell has the highest priority UTRA-FDD band According to the parameter setting of UtraFddNeighboringFreqConf:priorityOfBandUtraFdd

When an RRC measurement report for Event A2 is received with a measurement purpose set to Blind-PS-

Handover-To-UTRA-FDD or Blind-Redirection-Or-PSHandover- To-UTRA-FDD, and the conditions are met such

that blind PSHandover is possible, then the Target-UTRAN-Cell is selected based on the following

criteria:

- the target cell is a provisioned UTRA-FDD neighbor of the serving LTE cell. An LTE cell can have up to 3

provisioned UTRA-FDD neighboring cells, with each UTRA-FDD neighboring assigned to a different UTRA-FDD

band.

- the RNC associated with the target cell supports PS Handover to UTRAN, that is,

RncAccess::psHandoverUtraFddEnabled = TRUE. The rncAccessId is an association parameter (also called

indirection or pointer). which refers to the instance of RncAccess MO that must be considered to retrieve all

the information related to the target RNC controlling the UTRA FDD cell modeled by this instance

of the MO UtraFddNeighboringCellRelation.

the UE supports the UTRA-FDD band of the target cell.

- the cell has the highest priority UTRA-FDD band according to the parameter setting of

- UtraFddNeighboringFreqConf::priorityOfBandUtraFdd






2.5.2 Blind PS Handover Triggering

2.5.2.1 “priorityOfBandUtraFdd” Parameter

� Inter-RAT UtraFdd frequencies are indicated in in

systemInformationBlockType6

� Cell priority setting to favour EUTRAN coverage:

Priority (EUTRAN cells) > Priority (UMTS cells) > Priority (GSM cells)

In a LA 2.0.2 configuration, parameter priorityOfBandUtraFdd should be set whenever multiple bands will be

supported in the UE and provisioned UTRA-FDD neighbor cells to optimize target cell selection.

Parameter priorityOfBandUtraFdd is used only for blind PS Handover in LA2.0.2.

This parameter is not expected to be used in future releases when the blind mechanism is replaced by

inter-

RAT measurements






2.5 Overview Inter-RAT 3GPP Handover

2.5.3 PS Handover (eUTRAN To UTRAN) Pre-R8

Supported in LM2.0(LA2.0)

The eNodeB provides the following functions for EUTRA-to-UTRAN PS handover:

(1) EUTRA-to-UTRAN handover preparation phase

(2) EUTRA-to-UTRAN handover execution phase

(3) EUTRA-to-UTRAN handover completion phase






2.5 Overview Inter-RAT 3GPP Handover

2.5.3 PS Handover (eUTRAN To UTRAN) R8

Supported in LM3.0(LA3.0)






2.5.3 Control Of PS Handover

2.5.3.1 Handover Preparation Phase

� The handover decision to trigger PS handover is the result of the measurement report

analysis.

� Upon PS Handover triggering, the eNB will enter the preparation phase by sending the S1

HANDOVER REQUIRED message to the Source MME.

Upon PS Handover triggering, the eNB will enter the preparation phase by sending the S1 HANDOVER

REQUIRED message to the Source MME. This message includes the following parameters:

> Target RNC-ID: selected by handover decision algorithm, consisting of:

• RncAccess::plmnMCC + plmnMNC







PS HO Preparation Phase Related Parameters

� S1 HANDOVER REQUIRED message sent by eNB to the Source MME includes the following

parameters:

• Target RNC-ID

• Direct Forwarding Path Availability.

• Source RNC To Target RNC Transparent Container.

� Target RNC-ID: selected by handover decision algorithm, consisting of:

• RncAccess::plmnMCC + plmnMNC

• RncAccess::rncId

plmnMobileCountryCode identifies the country covered and is used to help identify the Target-RNC selected

for PS handover.

plmnMobileNetworkCode identifies the operator covered and is used to help identify the Target-RNC

selected for PS handover.

RncAccess::extendedRncId (used if RNC identity has value > 4095) extendedRncId uniquely identifies the

Target RNC in the UTRAN for LTE-UMTS handover as selected by the eNB. Set for an rncId value greater than

4095.








� UtraFddNeighboringCellRelation: cId (Tcell Id): cId uniquely identifies one cell in one

Target RNC in the UTRAN for LTE UMTS handover as selected by the eNB.

directFwdPathAvailability is a flag to indicate whether or not a direct data forwarding path for downlink

data is available with the target RNC. True indicates that a direct path to the RNC is available. False indicates

indirect data forwarding in which case downlink data is forwarded through the core network (SGW and

possibly SGSN).

Source RNC To Target RNC Transparent Container. This is the same Transparent Container which is used by

the

UMTS network via the RANAP protocol for the RNC interface with the SGSN/core network. It is also used for

LTE to UMTS handover to allow inter-operability with the target RNC in the UMTS network. This Transparent

Container includes:

• Target Cell-ID

� The UE capabilities are also passed to the target RNC in theTransparent Container.








� Once the S1 HANDOVER COMMAND is sent to the Source MME, timer

S1RelocPrepForPsHandoverToUtraFdd is started.

S1RelocPrepForPsHandoverToUtraFdd is

started.

The duration of this timer is set by a MIM parameter .

When the call admission allocation on the UTRAN target is done, the Source MME ends the PS handover

preparation to the Source eNB by sending the S1 HANDOVER COMMAND message which ends the preparation

phase. This message contains a Target to Source Transparent Container. At this point, the timer

S1RelocPrepForPsHandoverToUtraFdd is stopped.







2.5.3.2 PS HO Execution

� The Target to Source transparent container has the RRC MOBILITY FROM EUTRA Command message, built by the Target RNC, which contains all radio related information that the UE needs for handover.

S1RelocPrepForPsHandoverToUtraFdd

If the S1 HANDOVER COMMAND also contains at least one E-RAB subject to forwarding with a DL Transport

Layer Address, then data is forwarded either over the S1-U (indirect forwarding) or directly towards the

RNC

(direct forwarding) depending on the parameter setting of RncAccess:: directFwdPathAvailability.

Upon reception of the RRC MOBILITY FROM EUTRA COMMAND message, the UE switches from the old LTE

cell

and sends the RRC HANDOVER to UTRAN COMPLETE message. The target RNC requests the target SGSN to

perform the path switch by sending the RANAP RELOCATION COMPLETE message which ends the

execution phase.







2.5.3.3 PS HO Completion

The target SGSN propagates the end of PS handover to the Source MME by sending the S1 UE CONTEXT

RELEASE COMMAND message. At this point, timer S1RelocOverallForPsHandoverToUtraFdd is stopped.

Once the user plane conditions are met, the Source eNB confirms the PS handover completion by sending

the S1 UE CONTEXT RELEASE COMPLETE message.







3.1 Introduction

� The handover strategy relies entirely on measurement reports from the UE.

� The UE reports to the eNB when the handover trigger conditions are met. Upon receipt of the measurement report, the eNB is expected to trigger a handover procedure.

� The measurements are set up, modified or deleted in the UE using RRC signaling, more precisely the RRCConnectionReconfiguration message including the IE “MeasurementConfiguration”.

eNodeB

Measurement report







3.2 Measurement Configuration

� The measurements defined as intra-frequency LTE mobility triggers are configured as early as possible in the UE:

� At the transition to RRC connected mode

� Upon completion of a Handover

RRC Connection Request

RRC Connection Setup

RRC Connection Setup Complete

(Attach request IMSI/GUTI +

PDN Connectivity Request)

S1AP Initial UE Context Setup Request

Attach Accept


UL NAS transport

Attach Complete



Response

RRC Connection

Establishment

S1AP Initial UE Message

(Attach Request +

PDN Connectivity Request)

S1AP DL NAS TRANSPORT

NAS PDU Security Mode Command

S1AP UL NAS TRANSPORT

NAS PDU Security Mode Complete



UL NAS transfer

(Attach Complete)




MME Selects SGW and

Allocates Default Bearer id

Default Bearer Ctxt

created in MME/SGW

DL information Transfer

security Mode Command

UL Information Transfer

security Mode Complete

Measurement

configuration



Measurement

configuration

To configure the measurement

To provide the cell list

If the intra-frequency mobility is enabled via MIM configuration (i.e. isIntraFreqMobilityAllowed set to TRUE in MO ActivationService), the eNB will initiate an RRC Connection reconfiguration procedure afterthe RRC Connection establishment completion to set up the intra-frequency measurements corresponding

to the instances of the MOs MeasurementIdentityConf having the parameter measurementPurpose set to “intra-frequency handover trigger”.

If the procedure fails the UE will transit to idle mode. Indeed, according to 3GPP, if an RRC reconfiguration procedure fails in the UE, the UE will initiate an RRC Connection Re-establishment procedure. If this happens before the security activation, the UE will transit directly to idle mode.

The eNB will initiate after the default bearer establishment (and security activation) another RRC

connection reconfiguration procedure to set up intra-frequency measurements corresponding to the

instances of the MOs MeasurementIdentityConf having the parameter measurementPurpose different from “intra-frequency handover trigger” (if any). If this reconfiguration fails, the UE will initiate RRC

Connection Reestablishment.

The RRC message RRCConnectionReconfiguration includes the IE “measurementConfiguration” used to

configure the intra-frequency measurement profile. This profile is applicable for the cell on which the call is established.

If the measurement configuration fails in the UE, it will initiate RRC Connection Reestablishment.







3.2 Measurement Configuration [cont.]

� The first measurement configuration provides:

� Definition of the Measured Object

� Only on eUTRAN cells

� Configure the event reporting

� It is possible to define several reporting configurations per event

� Activation of the measurement

� The second measurement configuration provides the list of the adjacent cells.







3.2.1 Measured Object

� Definition of the Measured Object

� The Measured Object EUTRAN is defined by the following parameters:

� The unit of measurementBandwidth is the block







3.2.1 Measured Object [cont.]

� The carrier frequency f0 in downlink (f0,DL) is designated by the DL E-UTRA Absolute Radio Frequency Channel Number (dlEARFCN).

The relation between EARFCN and the downlink carrier frequency f0,DL (in MHz) is given by the equation

below, where FDL_low and NOffs-DL are given in the above table and dlEARFCN is the parameter that configures the downlink EARFCN.

f0,DL = FDL_low + 0.1(dlEARFCN – NOffs-DL)







3.2.2 Event Reporting Configuration: Event A3

� When the UE is leaving a cell and is entering in a new one, the criteria to trigger the event A3 are fullfilled.

� The UE reports the event A3 to the eNodeB which can take the decision to launch an HO toward the target eNodeB.

� There are 2 inequalities the UE shall fulfill:

� Source cell leaving condition

� Target cell entering condition

Measurement reportEvent A3

eNodeB

HO Decision







3.2.2 Event Reporting Configuration: Event A3 [cont.]

Mn is the adjacent cell measurement

Ms is the source cell measurement

Mn is the measurement result of the neighboring cell.

Ofn is the frequency specific offset of the frequency of the neighbour cell (equals Ofs for intra-frequency measurements and is included in MeasObjectEUTRA corresponding to the inter frequency as offsetFreq for inter-frequency measurements).

Ocn is the cell-specific offset of the neighbor cell. If not configured, zero offset shall be applied (included in MeasObjectEUTRA of the serving frequency as parameter cellIndividualOffset for intra-f measurements and included in MeasObjectEUTRA corresponding to the inter frequency as parameter cellIndividualOffset for interfrequency measurements).

Ms is the measurement result of the serving cell, not taking into account any cell individual offset.

Ofs is the frequency-specific offset of the serving frequency (i.e. offsetFreq within the MeasObjectEUTRA corresponding to the serving frequency).

Ocs is the cell-specific offset of the serving cell (included in MeasObjectEUTRA of the serving frequency as parameter cellIndividualOffset).

Hys is the hysteresis parameter for this event (i.e. hysteresis as defined within the VarMeasurementConfiguration for this event).

Off is the offset parameter for this event (i.e. a3-Offset as defined within the VarMeasurementConfiguration for this event).

Mn, Ms are expressed in dBm in case of RSRP, or in dB in case of RSRQ.

Ofn, Ocn, Ofs, Ocs, Hys, Off are expressed in dB.








� The cell offset and the cell hysteresis are defined by the following parameters:

Measurement

t

Ms

off

Ms + Off

Mn

hyst

Mn - Hyst








� This parameter defines the period of time during which the conditions to trigger an event report have to be satisfied before sending an RRC measurement report in event triggered mode.

Measurement

t

Ms

off

Ms + Off

Mn

hyst

Mn - Hyst

TimeToTrigger

eventA3, it triggers the HO








� The triggerQuantity parameter configures the type of measurement done to trigger the event:

� RSRP: Reference Signal Received Power

� RSRQ: Reference signal Received Quality

� You can set RSRP within the instance ReportConfigEUTRA/0 and/or RSRQ within ReportConfigEUTRA/1

� If both measurements are activated, the measurement which trigger the HO is this one which is the first to reach the HO criteria.








� The reportQuantity parameter configures the reported quantity to the eNodeB:

� Same as TriggerQuantity.

� Both RSRP and RSRQ are reported.








� The number of cells reported in an event is tunable by the parameter maxReportCells.� Excluding the serving cell measurement present in all reports








� The blind Handover is triggered when the UE is entering bad radio

conditions in the source cell without sending to the eNB any measurement

report on any target cell







3.2.3 Call Flow Mobility Intra-Frequency (A2_Blind)

MME

RRC Connection Establishment S1-AP Initial UE Message

Measurement Configuration

Phase N°01

Algorithm for RRC Measurement Configuration

RRC Connection Reconfiguration

RRC Connection Reconfiguration complete

S1-AP Initial context setup request

Only for Intra-Frequency Mobility

RRC Ue Capability Enquiry

RRC Ue Capability Information

Algorithm for Callp UeCapability Information

Security mode Command


Security mode Command complete

RRC Reconfiguration CompleteS1-AP Initial context setup response

1







3.2.3 Call Flow Mobility Intra-Frequency (A2_Blind) [cont.]

MME

Measurement Configuration

Phase N°02


RRC Connection Reconfiguration complete RRC MeasurementConfiguration 2

S1-AP Initial context setup response

RRC Measurement Report

Report Event A2_Bind (serving cell degradation for blid redirection)

Algorithm for RRC Measurement Configuration

Triggers the Algorithm for Control Procedures

Blind Redirection to UTRAN-FDD Blind Redirection to GERAN-FDD

Not supportedin LA2.0







3.2.3.1 Inter RAT threshold for Event A2_blind







3.3 UE Measurements

� The measurements are configured as soon as possible but the UE doesn’t measure neighbor cells all the time.

� The sMeasure parameters configure a threshold below which the reception is not so good and requires measurements of the neighbors.



message c1 : rrcConnectionReconfiguration :

{

rrc-TransactionIdentifier 1,

criticalExtensions c1 : rrcConnectionReconfiguration-r8 :

{

measurementConfiguration

{

measObjectToAddModifyList

{

{

measObjectId 1,

measObject measObjectEUTRA :

{

eutra-CarrierInfo 3350,

measurementBandwidth mbw50

}

}

},

reportConfigToAddModifyList

{

{

reportConfigId 1,

reportConfig reportConfigEUTRA :

{

triggerType event :

{

eventId eventA3 :

{

a3-Offset 4,

reportOnLeave FALSE

},

hysteresis 6,

timeToTrigger ms20

},

triggerQuantity rsrp,

reportQuantity sameAsTriggerQuantity,

maxReportCells 1,

reportInterval ms1024,

reportAmount r1

}

},

measIdToAddModifyList

{

{

measId 1,

measObjectId 1,

reportConfigId 1

},

quantityConfig

{

quantityConfigEUTRA

{

filterCoefficientRSRP fc11

}

},

s-Measure 97

}






4 Automatic Neighbour Relation ANR






4 Automatic Neighbour Relation ANR

4.1 ANR Overview

� According to 3GPP specifications, the purpose of the Automatic Neighbour Relation

(ANR) functionality is to relieve the operator from the burden of manually

managing Neighbor Relations (NRs).

� Automatic Neighbour Relation (ANR) feature participates to:

� Minimize the need for the manual provisioning of the neighbor relations by

operators.

� Provide more accurate neighbor relations than the manual method.

� Reduce to the minimum manual configuration of the neighbouring relationships.

� It relies on various types of data received and processed by the eNB.

� It ensures full automatic neighbouring configuration.

� It is able to add or remove neighbour relations to adapt the eNB configuration to

network evolutions.

>>> ANR feature participates in:

�Minimize the need for the manual provisioning of the neighbor relations by operators.

� Provide more accurate neighbor relations than the manual method which are created and constantly updated based on the actual measurement and report from UE.

� Reduce to the minimum manual configuration of the neighbouring relationships during network planning and subsequent phases of the network configuration.

� It relies on various types of data received and processed by the eNB(dynamic X2 configuration, configuration parameters, radio measurements performed by UEs…).

� It ensures full automatic neighbouring configuration: autonomousacquisition of all neighbour cell identifiers (PCI, ECGI, TAC) and associated transport information (IP address) to establish X2 link to the serving eNB.

� It is able to add or remove neighbour relations to adapt the eNBconfiguration to network evolutions (addition of eNB in its vicinity, radio parameters tuning that affect neighbour cells coverage…).






PCI#2

PCI#1

PCI#3

PCI#5

PCI#4

PCI#6

PCI#7

PCI#8

4 Automatic Neigbhbour Relation (ANR)

4.1 ANR Overview [cont.]

� The Automatic Neighbor Relation (ANR) Configuration and Optimization feature

is for the eNB cells to automatically create and update their neighbor relations.

The ANR feature includes the ANR neighbor relation creation function, the ANR neighbor relation

maintenance function, the ANR synchronization function and the ANR reset function.

The ANR neighbor relation creation function builds up the neighbor relations by requesting the UEs to

search for neighbor cells or by receiving the neighbor relations from the neighbor eNB The ANR neighbor

relation maintenance function (aka garbage collection) deletes the obsolete neighbor relations and

obsolete X2 links .

Since the operator can enter the new neighbor relations through XMS or modify the neighbor relations

created by ANR even when ANR is activated, the ANR synchronization function is needed to provide the

automatic synchronization between eNB and XMS.

The ANR reset function allows the tester to reset the internal counters and to delete neighbor relations

created by ANR or provisioned by operator so that testing can restart from the initial status.

The ANR feature activation (ActivationService::anrEnable) is controlled on per eNB basis. When ANR is

activated, each of its cells can be in one of the three phases independently, ANR active phase , ANR

dormant phase and ANR wake-up phase







4.1 ANR Overview : anrEnable

� This parameter is used to activate/deactivate the ANR feature.

When setting anrEnable to ‘True’:

1. Each LteCell instance served by the eNB must add a reference (through rrcMeasurementconfId attribute)

to an instance of

RrcMeasurementConf that references (through measurementIdentityConfIdList attribute) one and only one

instance of MeasurementIdentityConf with measurementPurpose set to ‘Automatic-Neighbour-Relation’.

2. Each LteCell instance served by the eNB must add a reference (through rrcMeasurementConfId attribute)

to an instance of

RrcMeasurementConf that references (through measurementIdentityConfIdList attribute) an instance of

MeasurementIdentityConf with measurement Purpose set to

‘Report-CGI’.






4.1 ANR Overview

4.1.1 ANR Phases

ANR Idle

ANR Active Phase

ANR DormantPhase

ANR Wake up phase

ANR activation& (LTE Cell>anrstate=Not complete)

ANR deactivation

ANR deactivation

(Nb PCI meas > Threshold 1) & (Nb PCI meas w/o unknown PCI> threshold2)

ANR activation& (LTE Cell>anrstate

=complete)

HO eas report wtbest PCI being

unknown

Dormat Phase Timer for ecgDiscovery Timeout

ANR deactivation

HO meas report wtBest PCI being unknown

ANR function in Alcatel-Lucent implementation works in different phases:

• An “active” phase, which is triggered at first ANR activation and aims at pro-actively search new

neighbours by soliciting all establishing UEs that will then all participate to the ANR task.

� A “dormant” phase, following the active phase, in which ANR function is no longer configuring any

specific measurements.

Transition from active to dormant phase is triggered when thresholds, defined in terms of UE measurement

reports received, are crossed.

� A “wake-up” phase, which is triggered by a UE reporting (through mobility measurement) an unknown

neighbour. ANR behaviour in this phase is quite similar to the one in the active phase,

with differences being that the aim is only to look at one particular neighbour and the duration of the

wake-up phase is limited.






� Typical ANR function behaviour is the following:

4.1 ANR Overview

4.1.2 ANR Procedure

eNB A

MME

Configure ANR meas

Report ANR meas (PCI = 5)

Configure reportCGI (PCI 5)

Report ECGI (ECGI = 19)Read SIB1 to get ECGI

Request eNBB IP @

Provide eNBB IP @Pr

ovide eNB B IP @

Request eNBB IP @

Cell BPCI = 5ECGI = 19

eNB B

Cell APCI = 3ECGI = 17

Establish SCTP and X2 link

When Cell A is in ANR active phase:

1. eNB A will send ANR measurement configuration to all UEs that are in RRC connected state in Cell A to

search for neighbor cells.

2. UE will send a measurement report with Cell B’s PCI when triggered by ANR measurement configuration.

3. If eNB A does not know the ECGI associated with the reported PCI, it will direct UE to read from PBCH of

Cell B to obtain the ECGI.

4&5. After UE finds out the ECGI of Cell B, it will report back to eNB A.

6. After ECGI of Cell B is received, if the X2 link does not already exist between eNB A and eNB B, ANR will

attempt to set up the X2 link of. X2 link may already exist if any cell in eNB A already has a neighbor

relation with one or more cells in eNB.







4.2 Parameters Included in Neighbor Relation

� A summary is provided below on how ANR will set the parameters in the

LteNeighboringCellRelation MO for an automatically created instance of neighbor

relation:

Parameter Description Default Value

cellIndividualOffset Indicates the cell individual offset of the

neighbor cell provided to UE in connected mode to

perform measurement

It is set to the

default value of 0 dB.

discoveredByAnr Indicates whether the neighbor relation is

discovered by ANR

It is set to ‘true’.

macroEnbId This parameter indicates

whether handover to the neighbor cell is permitted

It is set to the default

value of ‘false

noRemove Indicates whether the neighbor relation can be

removed by the ANR garbage collection function

It is set to the default

value

of ‘false’

physicalLayerCellInd

entityGroupIndex

Indicates the physical layer cell identity group.

It is calculated from PCI of the neighbor cell

physicalLayerCellIndentityIndex

Neighbor relations are used in a cell to route the handover request. When a UE reports the PCI of a

handover target candidate cell, source cell will check the storedneighbor relations to find out whether the

X2 link exists between the source eNB and the target eNB. If the X2 link exists, and X2 handover is

permitted, source eNB will initiate the X2 handover procedure. If X2 link does not exist, or X2 handover is

not permitted, but S1 handover is possible, S1 handover will be attempted. Otherwise, the handover

request will be discarded.

Some parameters in the neighbor relations are used to build different types of neighbor lists to be included

in SIB or in the RRCConnectionReconfiguration message to help UE with their neighbor cell search. One

example is to use the no handover neighbors to build the black cell list included in

RRCConnectionReconfiguration message. It is to help UE to avoid the useless measuring and reporting of the

Black cells that are forbidden to be used as handover target cells.







4.2 Parameters Included in Neighbor Relation [cont.]

Parameter Description Default Value

plmnMobileCountryCode indicates the Mobile Country

Code (MCC) of the EUTRA system the neighbor

cell belong to. It is obtained

from PLMNID of the neighbor cell

plmnMobileNetworkCode indicates the Mobile Network

Code (MNC) of the EUTRA system the neighbor

cell belongs to.

It is obtained

from PLMNID of the

neighbor cell

qOffsetCell indicates the offset between the serving cell

and the neighbor cell

is set to default value

of 3 dB

relativeCellIdentity This parameter is the rightmost 8 bits of the E-

UTRAN Cell Identifier contained in ECGI of the

neighbor cell.

trackingAreaCode TAC is used to identify the tracking area within

the

scope of a PLMN. It is reported by UE or

received from neighbor eNB through X2

messages

x2AccessId This parameter refers to the instance of

X2Access MO that represents the X2 link to the

eNB of the neighbor cell

It is set to X2Access

rdnId of the X2 link.






4.2 Parameters Included in Neighbor Relation

4.2.1 discoveredByAnr & noRemove Parameters

� discoveredByAnr:This parameter indicates whether the teNeighboringCellRelation is

created by ANR or is provisioned by operator.

� noRemove: This parameter indicates whether the LteNeighboringCellRelation is allowed

to be removed by the ANR garbage collection function.

Rule: Set noRemove to ‘True’ when noHO is set to ‘True’

If ‘noHO’ is set to ‘True’, the ‘noRemove’ must also be set to ‘True’ for the

same LteNeighboringCellRelation instance to make the neighbor relation

belong to the HO black list.






Serving Cell

4 Automatic Neigbhbor Relation (ANR)

4.3 ANR Measurement Configuration

� Three events can be used to trigger the UE to send an ANR measurement report.

� At any given time, only one of the three following triggers can be used for ANR measurement configuration:� Event A3: the neighbor cell becomes a given offset better than the serving cell.

� Event A4: the neighbor cell becomes better than a given absolute threshold.

� Event A5: the serving cell becomes worse than a given threshold and the neighbor cell

becomes better than a given absolute threshold2.

� The selection is made through ReportConfigEUTRA:triggerTypeEUTRA

Neighbor Cell

Event A3 is recommended for ANR measurement configuration.






4 Automatic Neigbhbor Relation (ANR)

4.4 Set Up X2 Links

� Setting up X2 link is essential to create a neighbor relation.

� There are three steps for this procedure:

1. Automatically retrieve the X2 IP address of the eNB B from MME through S1

procedure

2. Set up SCTP association between eNB A and eNB B

3. Establish X2 link between eNB A and eNB B

Local eNB MME Distant eNB

eNB CONFIGURATION TRANSFER(Source Global eNB ID & TAI, Target Global eNB ID & TAI,

SON information request)

MME CONFIGURATION TRANSFER

MME CONFIGURATION TRANSFER (Source eNB ID & TAI, Target eNB ID & TAI, SON information reply

= 1 or 2 transport address(es) )

eNB CONFIGURATION TRANSFER

The direct X2 handover provides better performance than S1 handover in general as S1 handover has to go

through SGW which normally takes much longer time.

Once a new PCI is detected and its ECGI is found, ANR on eNB A will automatically attempt to establish the

X2 link to neighbor eNB B if the X2 link does not already exist.






Exercise






Exercise 1: Cell Reselection

� Could you fill the diagram in the comment part with the following parameters:

� qRxLevMin = -110 dBm

� sIntraSearch = 3 dB

� tReselectionEUTRAN = 2 second

t

Serving Cell

Cell 1

Cell 2

RSRP

-110 dBm

-107dBm

-108dBm

-109 dBm

2s1s 4s3s 6s5s






Exercise 2: Cell Reselection

� Could you determine at each time what is the UE decision ? (No reselection, Cell 1, Cell 2)

� qOffsetCell, cell1 = - 1 dB

� qOffsetCell, cell2 = 3 dB

� qHyst = 1 dBCell 2

Serving Cell

Cell 1

t1 t2 t3 t4

Serving Cell - 90 dBm -91 dBm -90 dBm -93 dBm

Cell 1 - 90 dBm - 92 dBm - 90 dBm - 90 dBm

Cell 2 - 90 dBm - 88 dBm - 87 dBm - 88 dBm

UE decision






End of ModuleMobility Management




Acronyms



Abbreviations and Acronyms

Switch to notes view!# 16QAM 16-state Quadrature Amplitude Modulation B BLER Block Error Ratio BPSK Binary Phase Shift Keying C CCCH Common Control CHannel CCE Common Control Element CEM Channel Element Module CFI Canonical Format Identifer CL-MIMO Closed-Loop MIMO CM Configuration Model CQI Channel Quality Indicator C-RNTI Cell - Radio Network Temporary Identifier D D-BCH DL Downlink DL-RS DownLink Reference Signal DL-SCH Downlink Shared Channel DRA Dynamic Resource Allocation DRA&PS Dynamic Resource Allocation & Packet Scheduling DRB Data Bearer DTCH Dedicated Traffic Channel DTX Discontinuous Transmission E EARFCN E-UTRA Absolute Radio Frequency Channel Number eNB evolved Node B EPS evolved Packet Switch E-RAB evolved Radio Access Bearer ETWS Earth and Tsunami Warining System e-UTRAN evolved UTRAN G GBR Guaranteed Bit Rate GERAN GSM EDGE Radio Access Network GTP-U GTP for transfer of user data in separated tunnels for each PDP context H H-ARQ Hybrid Automatic Request HO Handover HSS Home Subscriber Server I IE Information Element IMSI International Mobile Subscriber Identity IP Internet Protocol L LTE Long-Term Evolution

M MBR Maximum Bit Rate MIMO Multiple-Input Multiple-Output MME Mobility Management Entity MTCH MBMS point-to-multipoint Traffic Channel N NAS Non Access Stratum NEM Network Element Manager O OAM Operation, Administration and Maintenance OL-MIMO Open-Loop MIMO P PBCH Physical Broadcast Channel PCCH Paging Control Channel PCFICH Physical Control Format Indication Channel PCH Paging Channel 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 Pilot Gateway PHICH Physical Hybrid ARQ Indicator Channel PLMN Public Land Mobile Network PMCH Physical Multicast Channel PRACH Packet Random Access Channel PSS Primary Synchronization Signal PUCCH Physical Uplink Control Channel PUSCH Physical Uplink Shared Channel Q QoS Quality of Service QPSK Quadrature Phase Shift Keying R RACH Random Access CHannel RB Resource Block RE Resource Element REG Resource Element Group RF Radio Frequency RI Rank Indicator RLC Radio Link Control RPB RRC Remote Radio Connection RRH Remote Radio Head RRM Radio Resources Management RS Reference Signal RSRP Reference Signal Received Power RSRQ Reference Signal Received Quality RX Reception



Abbreviations and Acronyms [cont.]

Switch to notes view!S SAE System Architecture Evolution SB-CQI Sub-Band CQI SC-FDMA Single Carrier - Frequency Division Multiple Access SCTP Stream Control Transmission Protocol SDU Service Data unit SFN System Frame Number S-GW Serving Gateway SI System Information SIB System Information Block SIMO Single-Input Multiple-Output SINR Signal Interference plus Noise Ratio SIR Signal-to-Interference Ratio SNR Signal-to-Noise Ratio SRB Signaling Radio Bearer SRS Sounding Reference Signal SSS Secondary Synchronization Signal S-TMSI TA Timing Advance TB Transport Block TBS Transport Block Size TM Transmission Mode TMSI Temporary Mobile Subscriber Identity TPC Transmit Power Control TRDU Transmi Receive Duplexer TTI Transmission Time Interval Tx Transmission TxDiv Transmit Diversity U UE User Equipment UL UpLink UL-SCH Uplink Shared Channel UTRAN Universal Terrestrial Radio Access Network V VoIP Voice over IP W WB CQI Wideband CQI WPS Wireless Provisioning System X XMS eXtended Management System



End of Module@@MODULETITLE

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