ANR Management (eRAN3.0_07).PDF

ANR Management eRAN3.0

Feature Parameter Description

Issue 07

Date 2013-03-15

HUAWEI TECHNOLOGIES CO., LTD.

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eRAN

ANR Management Contents

Issue 07 (2013-03-15) Huawei Proprietary and Confidential

Copyright Huawei Technologies Co., Ltd.

i

Contents

1 Introduction ................................................................................................................................ 1-1

1.1 Scope ............................................................................................................................................ 1-1

1.2 Intended Audience......................................................................................................................... 1-1

1.3 Change History .............................................................................................................................. 1-1

2 Overview of ANR ....................................................................................................................... 2-1

3 Concepts Related to ANR ....................................................................................................... 3-1

3.1 Overview ....................................................................................................................................... 3-1

3.2 NCL ............................................................................................................................................... 3-1

3.3 NRT ............................................................................................................................................... 3-1

3.4 Blacklists ....................................................................................................................................... 3-2

3.4.1 HO Blacklist .......................................................................................................................... 3-2

3.4.2 X2 Blacklist ........................................................................................................................... 3-2

3.4.3 RRC Blacklist ........................................................................................................................ 3-2

3.5 Whitelist ......................................................................................................................................... 3-2

3.5.1 HO Whitelist .......................................................................................................................... 3-2

3.5.2 X2 Whitelist ........................................................................................................................... 3-3

3.6 Abnormal Neighboring Cell Coverage ........................................................................................... 3-3

3.7 ANR Capabilities of UEs ............................................................................................................... 3-3

4 Intra-RAT ANR ............................................................................................................................ 4-1

4.1 Overview ....................................................................................................................................... 4-1

4.2 Intra-RAT Event-triggered ANR ..................................................................................................... 4-1

4.2.1 Automatic Detection of Missing Neighboring Cells ............................................................... 4-1

4.2.2 Automatic Maintenance of NCLs and NRTs ......................................................................... 4-4

4.2.3 Automatic Detection of Abnormal Neighboring Cell Coverage ............................................. 4-5

4.3 Intra-RAT Fast ANR ....................................................................................................................... 4-5

5 Inter-RAT ANR ............................................................................................................................ 5-1

5.1 Overview ....................................................................................................................................... 5-1

5.2 Inter-RAT Event-triggered ANR ..................................................................................................... 5-1

5.2.1 Automatic Detection of Missing Neighboring Cells ............................................................... 5-1

5.2.2 Automatic Maintenance of NCLs and NRTs ......................................................................... 5-2

5.3 Inter-RAT Fast ANR ....................................................................................................................... 5-4

6 ANR with Shared Cells ............................................................................................................ 6-1

6.1 Shared Neighboring Cell Broadcasting PLMN List in an RR Manner ........................................... 6-1

6.2 Shared Neighboring Cell Not Broadcasting PLMN List in an RR Manner .................................... 6-2

7 Manual Management of Neighbor Relations ..................................................................... 7-1

7.1 Overview ....................................................................................................................................... 7-1

7.2 Adding or Removing a Neighbor Relation ..................................................................................... 7-1

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7.3 Blacklisting a Neighbor Relation ................................................................................................... 7-1

7.3.1 Configuring an HO Blacklist ................................................................................................. 7-1

7.3.2 Configuring an X2 Blacklist................................................................................................... 7-2

7.3.3 Configuring an RRC Blacklist ............................................................................................... 7-2

7.4 Whitelisting a Neighbor Relation ................................................................................................... 7-3

7.4.1 Configuring an HO Whitelist ................................................................................................. 7-3

7.4.2 Configuring an X2 Whitelist .................................................................................................. 7-3

8 X2 Self-Setup.............................................................................................................................. 8-1

8.1 Overview ....................................................................................................................................... 8-1

8.2 X2 Self-Setup in X2 over S1 Mode ............................................................................................... 8-2

8.3 X2 Self-Setup in X2 over M2000 Mode ......................................................................................... 8-4

9 Related Features ....................................................................................................................... 9-1

9.1 Intra-RAT ANR ............................................................................................................................... 9-1

9.1.1 Required Features ................................................................................................................ 9-1

9.1.2 Mutually Exclusive Features ................................................................................................. 9-1

9.1.3 Affected Features ................................................................................................................. 9-1

9.2 Inter-RAT ANR ............................................................................................................................... 9-1




9.3 X2 Self-Setup ................................................................................................................................ 9-1




10 Impact on the Network ........................................................................................................ 10-1

10.1 Intra-RAT ANR ........................................................................................................................... 10-1

10.1.1 Impact on System Capacity .............................................................................................. 10-1

10.1.2 Impact on Network Performance ...................................................................................... 10-1

10.2 Inter-RAT ANR ........................................................................................................................... 10-1



10.3 ANR with Shared Cells .............................................................................................................. 10-2



10.4 X2 Self-Setup ............................................................................................................................ 10-2



11 Engineering Guidelines ....................................................................................................... 11-1

11.1 When to Use ANR ..................................................................................................................... 11-1

11.1.1 Intra-RAT ANR .................................................................................................................. 11-1

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11.1.2 Inter-RAT ANR .................................................................................................................. 11-2

11.1.3 ANR with Shared Cells ..................................................................................................... 11-2

11.1.4 X2 Self-Setup .................................................................................................................... 11-2

11.2 Information to Be Collected ....................................................................................................... 11-3

11.2.1 Intra-RAT ANR .................................................................................................................. 11-3

11.2.2 Inter-RAT ANR .................................................................................................................. 11-3

11.2.3 ANR with Shared Cells ..................................................................................................... 11-3

11.2.4 X2 Self-Setup .................................................................................................................... 11-3

11.3 Network Planning ...................................................................................................................... 11-3

11.4 Overall Deployment Procedure ................................................................................................. 11-3

11.5 Deploying Intra-RAT ANR .......................................................................................................... 11-3

11.5.1 Deployment Procedure ..................................................................................................... 11-3

11.5.2 Deployment Requirements ............................................................................................... 11-4

11.5.3 Data Preparation ............................................................................................................... 11-4

11.5.4 Precautions ....................................................................................................................... 11-5

11.5.5 Hardware Adjustment ....................................................................................................... 11-5

11.5.6 Feature Activation ............................................................................................................. 11-5

11.5.7 Activation Observation ...................................................................................................... 11-6

11.5.8 Reconfiguration ................................................................................................................. 11-7

11.5.9 Deactivation ...................................................................................................................... 11-7

11.6 Deploying Inter-RAT ANR .......................................................................................................... 11-7

11.6.1 Deployment Procedure ..................................................................................................... 11-7

11.6.2 Deployment Requirements ............................................................................................... 11-8

11.6.3 Data Preparation ............................................................................................................... 11-8

11.6.4 Precautions ....................................................................................................................... 11-9

11.6.5 Hardware Adjustment ....................................................................................................... 11-9

11.6.6 Feature Activation ............................................................................................................. 11-9

11.6.7 Activation Observation .................................................................................................... 11-10

11.6.8 Reconfiguration ............................................................................................................... 11-10

11.6.9 Deactivation .................................................................................................................... 11-10

11.7 Deploying ANR with Shared Cells ........................................................................................... 11-10

11.7.1 Deployment Procedure ................................................................................................... 11-10

11.7.2 Deployment Requirements ............................................................................................. 11-10

11.7.3 Data Preparation ............................................................................................................. 11-10

11.7.4 Precautions ...................................................................................................................... 11-11

11.7.5 Hardware Adjustment ...................................................................................................... 11-11

11.7.6 Feature Activation ............................................................................................................ 11-11



11.7.9 Deactivation .................................................................................................................... 11-12

11.8 Deploying X2 Self-Setup ......................................................................................................... 11-12

11.8.1 Deployment Procedure ................................................................................................... 11-12

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11.8.2 Deployment Requirements ............................................................................................. 11-12

11.8.3 Data Preparation ............................................................................................................. 11-13

11.8.4 Precautions ..................................................................................................................... 11-13

11.8.5 Hardware Adjustment ..................................................................................................... 11-13

11.8.6 Feature Activation ........................................................................................................... 11-13



11.8.9 Deactivation .................................................................................................................... 11-15

11.9 Performance Optimization ....................................................................................................... 11-15

11.9.1 Intra-RAT ANR ................................................................................................................ 11-15

11.9.2 Inter-RAT ANR ................................................................................................................ 11-18

11.9.3 ANR with Shared Cells ................................................................................................... 11-20

11.9.4 X2 Self-Setup .................................................................................................................. 11-20

11.10 Troubleshooting ..................................................................................................................... 11-25

11.10.1 Intra-RAT ANR .............................................................................................................. 11-25

11.10.2 Inter-RAT ANR .............................................................................................................. 11-26

11.10.3 ANR with Shared Cells ................................................................................................. 11-27

11.10.4 X2 Self-Setup ................................................................................................................ 11-27

12 Parameters ............................................................................................................................. 12-1

13 Counters.................................................................................................................................. 13-1

14 Glossary .................................................................................................................................. 14-1

15 Reference Documents ......................................................................................................... 15-1

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1 Introduction

1.1 Scope

This document describes the Automatic Neighbor Relation (ANR) management feature in terms of implementation principles, parameter adjustments, feature dependencies, network impact, and engineering guidelines.

The ANR management feature involves the following optional features:

LOFD-002001 Automatic Neighbour Relation (ANR)

LOFD-002002 Inter-RAT ANR

Any managed objects (MOs), parameters, alarms, or counters described in this document correspond to the software release delivered with this document. In the event of updates, the updates will be described in the product documentation delivered with the latest software release.

1.2 Intended Audience

This document is intended for:

Personnel who need to understand ANR management

Personnel who work with Huawei Long Term Evolution (LTE) products

1.3 Change History

This section provides information about the changes in different document versions.

There are two types of changes, which are defined as follows:

Feature change: refers to a change in the ANR management feature of a specific product version.

Editorial change: refers to a change in wording or the addition of information that was not described in the earlier version.

Document Issues

The document issues are as follows:

07 (2013-03-15)

06 (2013-02-27)

05 (2012-12-29)

04 (2012-09-20)

03 (2012-06-30)

02 (2012-05-11)

01 (2012-03-30)

Draft A (2012-01-10)

07 (2013-03-15)

Compared with issue 06 (2013-02-27) of eRAN3.0, issue 07 (2013-03-15) of eRAN3.0 includes the following changes.

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Change Type Change Description Parameter Change

Feature change None None

Editorial change Modified the flow chat for X2 self-setup. For details, see Figure 8-2 and Figure 8-3.

Added the description that both the source and target eNodeBs can send the X2 Setup Request message during X2 self-setup. For details, see section 8.2 "X2 Self-Setup in X2 over S1 Mode" and section 8.3 "X2 Self-Setup in X2 over M2000 Mode."

None

06 (2013-02-27)




Editorial change Revised some descriptions. For details, see sections 6 "ANR with Shared Cells."

None

05 (2012-12-29)



Feature change Added X2 self-setup. For details, see the following chapters or sections:

8 "X2 Self-Setup"

9.3 "X2 Self-Setup"

10.4 "X2 Self-Setup"

11.1.4 "X2 Self-Setup"


11.8 "Deploying X2 Self-Setup"



Added the following parameters:

GlobalProcSwitch.X2SonLinkSetupType

GlobalProcSwitch.X2SonSetupSwitch

X2SigIP.LOCIP

X2eNodeB.FIRSTSIGIP

Editorial change Moved the license control ID. None

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04 (2012-09-20)




Editorial change Revised some descriptions. For details, see sections 11.5.6 "Feature Activation", 11.6.6 "Feature Activation" and 11.7.6 "Feature Activation."

None

03 (2012-06-30)



Feature change Added the function of ANR with shared cells.

For details about the principles, see chapter 6 "ANR with Shared Cells."

For details about the impact on the network, see section 10.3 "ANR with Shared Cells."

For details about engineering guidelines, see chapter 11 "Engineering Guidelines."

Added the ENodeBAlgoSwitch.RanSharingAnrSwitch parameter.

Editorial change Revised some descriptions. For details, see section 7.3.1 "Configuring an HO Blacklist."

None

02 (2012-05-11)




Editorial change Revised some descriptions in the document. None

01 (2012-03-30)

This is the first official release.

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Compared with draft A (2012-01-10) of eRAN3.0, issue01 (2012-03-30) of eRAN3.0 includes the following changes.



Editorial change Revised the engineering guidelines. For details, see chapter 11 "Engineering Guidelines."

None

Draft A (2012-01-10)

Compared with draft A (2011-07-15) of eRAN2.2, draft A (2012-01-10) of eRAN3.0 includes the following changes.


Feature change Removed TempNRTs. None

Modified the mechanism for adding a newly detected external neighboring cell to an NCL.

Modified the mechanism for adding a neighbor relation to an NRT.

For details, see "Automatic Maintenance of NCLsDuring intra-RAT neighbor relation addition through ANR, attributes that cannot be obtained through measurement reports or UE history information use default values.

" and "Automatic Maintenance of NRTs" in section 4.2.2 "Automatic Maintenance of NCLs and NRTs."

Deleted the AddCellThd parameter.

Modified the mechanism for removing an external cell from an NCL.

Modified the mechanism for removing a neighbor relation from an NRT.

For details, see "Automatic Maintenance of NCLsDuring intra-RAT neighbor relation addition through ANR, attributes that cannot be obtained through measurement reports or UE history information use default values.

" and "Automatic Maintenance of NRTs" in section 4.2.2 "Automatic Maintenance of NCLs and NRTs."

Changed the default value of the ANR.DelCellThd parameter.

Added the following parameters:

ANR.StatisticPeriodForNRTDel

ANR.StatisticNumForNRTDel

Modified the conditions for starting fast ANR.

Changed the default value of the ANR.FastAnrRprtInterval parameter.

Editorial change Optimized the engineering guidelines. None

Moved the information about PCI conflict detection to a new document named PCI Conflict Detection and Self-Optimization.

None

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2 Overview of ANR

Operation and maintenance (OM) of the radio access network has become increasingly complex, difficult, and costly because of the large number of network elements, the implementation of different system standards, and the coexistence of different equipment vendors and telecom operators. To address this situation, the self-organizing network (SON) concept is proposed. The main functions of SON are self-configuration, self-optimization, and self-healing.

ANR is a self-optimization function. It automatically maintains the integrity and effectiveness of neighbor cell lists (NCLs) and neighbor relation tables (NRTs) to increase handover success rates and improve network performance. In addition, ANR does not require manual intervention, which reduces the costs of network planning and optimization.

Neighbor relations are classified as normal and abnormal. Abnormal neighbor relations exist in the cases of missing neighboring cells, physical cell identifier (PCI) conflicts, abnormal neighboring cell coverage, and unstable neighbor relations. ANR automatically detects missing neighboring cells, PCI conflicts, and abnormal neighboring cell coverage, and maintains neighbor relations.

Based on neighbor relations, ANR is classified into intra-RAT ANR and inter-RAT ANR. Based on the methods of measuring neighboring cells, ANR is classified into event-triggered ANR and fast ANR (also known as periodic ANR). RAT is short for radio access technology. Figure 2-1 shows ANR classifications.

Figure 2-1 ANR classifications

Intra-RAT ANR handles neighbor relations with E-UTRAN cells, while inter-RAT ANR handles neighbor relations with GERAN, UTRAN, and CDMA2000 cells. Here, UTRAN, E-UTRAN, GERAN, and CDMA2000 are short for universal terrestrial radio access network, evolved UTRAN, GSM/EDGE radio access network, and code division multiple access 2000, respectively.

To implement ANR, the eNodeB collaborates with UEs and the M2000.

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3 Concepts Related to ANR

3.1 Overview

This chapter describes basic ANR-related concepts, which include NCL, NRT, HO blacklist, X2 blacklist, HO whitelist, X2 whitelist, radio resource control (RRC) blacklist, and abnormal neighboring cell coverage.

3.2 NCL

The NCLs of an eNodeB contain information about the external cells of the eNodeB. The external cells of an eNodeB are provided by base stations other than the eNodeB.

NCLs are classified into intra-RAT NCLs and inter-RAT NCLs. Each eNodeB has one intra-RAT NCL and multiple inter-RAT NCLs.

The intra-RAT NCL records the ECGIs, PCIs, and E-UTRA absolute radio frequency channel numbers (EARFCNs) of the external E-UTRAN cells.

The GERAN NCL records the cell IDs, base transceiver station identity codes (BSICs), and ARFCNs of the external GERAN cells.

The UTRAN NCL records the cell IDs, scrambling codes, and UTRA ARFCNs (UARFCNs) of the external UTRAN cells.

The CDMA2000 NCL records the cell IDs, frequencies, and PCIs of the external CDMA2000 cells.

NCLs are used as a basis for creating neighbor relations. The eNodeB adds newly detected external cells to NCLs. External cells can be automatically managed (for example, added, deleted, or modified) by ANR.

3.3 NRT

The NRTs of a cell contain information about the neighbor relations between a cell and its neighboring cells. NRTs are classified into intra-RAT NRTs and inter-RAT NRTs. Each cell has one intra-RAT intra-frequency NRT, one intra-RAT inter-frequency NRT, and multiple inter-RAT NRTs. The intra-RAT intra-frequency NRT and intra-RAT inter-frequency NRT are referred to as the intra-RAT NRT in this document.

Table 3-1 shows an example of the NRT. The information in this table is for reference only.

Table 3-1 An example of the NRT

SN LCI Target Cell PLMN eNodeB ID Cell ID Removal Control Handover Control

1 LCI#1 46001 eNodeB ID#1 Cell ID#1 Prohibited Prohibited

2 LCI#1 46001 eNodeB ID#2 Cell ID#2 Allowed Allowed

3 LCI#1 46001 eNodeB ID#3 Cell ID#3 Prohibited Prohibited

NOTE

For details about the NRT, see 3GPP TS 36.300. Huawei NRT does not include the attribute that controls whether to allow X2 setup.

NRT structures are the same for intra- and inter-eNodeB neighbor relations. Intra-eNodeB neighbor relations only exist in NRTs, not in NCLs.

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The NRT in Table 3-1 is an intra-RAT NRT. An inter-RAT NRT differs greatly from an intra-RAT NRT.

The NRT contains the following information, which can be updated automatically or manually:

Local cell identifier (LCI): uniquely identifies the source cell in a neighbor relation. This attribute is defined by Cell.LocalCellId.

Target cell PLMN: identifies the PLMN of the operator that owns the target cell.

eNodeB ID: identifies the eNodeB that provides the target cell.

Cell ID: identifies the target cell.

Removal control: indicates whether a neighbor relation can be removed from the NRT by ANR. By default, this attribute is set to allow removal. It can also be set to prohibit removal.

Handover control: indicates whether this neighbor relation can be used for a handover. By default, this attribute is set to allow handover. It can also be set to prohibit removal.

NRTs can be managed (for example, added, deleted, or modified) automatically by ANR.

NOTE

eRAN3.0 eNodeBs maintain only NRTs, whereas eNodeBs of earlier versions maintain both NRTs and TempNRTs.

3.4 Blacklists

3.4.1 HO Blacklist

An HO blacklist contains the information about neighbor relations that cannot be used for a handover or removed automatically from the NRT by ANR. The neighbor relations in the HO blacklist must meet the following conditions:

Removal control = prohibited

Handover control = prohibited

A neighbor relation can be added to the HO blacklist manually. For details, see 3GPP TS 32.511.

3.4.2 X2 Blacklist

An X2 blacklist contains information about the neighboring eNodeBs with which the local eNodeB is not allowed to set up X2 interfaces. If an X2 interface has been set up between the local eNodeB and a neighboring eNodeB on the X2 blacklist, the interface will be removed automatically.

NOTE

To remove an X2 interface, the eNodeB removes the X2 logical connection but retains the configuration data for the X2 interface. This ensures that the configuration data is not lost due to exceptions such as misoperations.

3.4.3 RRC Blacklist

An RRC blacklist contains the neighboring E-UTRAN cells whose information will not be measured and reported to the eNodeB by UEs. You can manually add an intra- or inter-frequency neighboring cell to an RRC blacklist.

3.5 Whitelist

3.5.1 HO Whitelist

An HO whitelist contains the information about neighbor relations that can be used for a handover but cannot be removed automatically from the NRT by ANR. The neighbor relations in the HO whitelist must meet the following conditions:

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Removal control = prohibited

Handover control = allowed

A neighbor relation can be added to the HO whitelist manually. For details, see 3GPP TS 32.511.

3.5.2 X2 Whitelist

An X2 whitelist contains information about the neighboring eNodeBs with which the local eNodeB has set up X2 interfaces. These X2 interfaces cannot be removed automatically.

3.6 Abnormal Neighboring Cell Coverage

Abnormal neighboring cell coverage may exist between intra-frequency E-UTRAN cells. As shown in Figure 3-1, assume UEs in cell A detect signals from cell B. Then, ANR considers cell B to be a neighboring cell of cell A and adds related information to an NCL or NRT. However, from a topology perspective, the two cells do not meet the requirements for neighbor relations. In this situation, the coverage of cell B is regarded as abnormal. This type of coverage is also called coverage overlap.

Figure 3-1 Abnormal neighboring cell coverage

The coverage of neighboring cells may be abnormal in any of the following scenarios:

The antenna tilt or orientation changes because of improper installation or a natural phenomenon such as strong wind.

In mountainous terrain, the signals of the umbrella cell cover lower cells.

3.7 ANR Capabilities of UEs

The ANR capabilities of a UE refer to the ability of the UE to read the ECGIs of neighboring cells. According to 3GPP TS 36.331, the Feature Group Indicators bit string contained in the UE Capability Information message indicates the ANR capability of the UE. Table 3-2 provides the definitions and setting descriptions of the ANR-related indicators.

Table 3-2 Definitions and setting descriptions of the ANR-related indicators

Indicator Index

Supported Functions (When the Indicator Is Set to 1)

Remarks Applicability

5 Long discontinuous reception (DRX) cycle

DRX command Media Access Control (MAC) element

N/A Yes

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Indicator Index

Supported Functions (When the Indicator Is Set to 1)

Remarks Applicability

16 Reporting of non-ANR-related periodical intra-frequency measurements

Reporting of non-ANR-related periodical inter-frequency measurements is supported if indicator 25 is also set to 1

Reporting of non-ANR-related periodical measurements of the UTRAN, GERAN, CDMA2000 1xRTT, or CDMA2000 HRPD is supported if indicator 22, 23, 24, or 26 is also set to 1

NOTE

Non-ANR-related periodical measurements are the measurements with trigger type and purpose set to periodical and reportStrongestCells,

respectively. Event-triggered periodical measurements are the measurements with trigger type and reportAmount set to event and a value

greater than 1, respectively. Reporting of event-triggered periodical measurements is a mandatory function of event-triggered reporting and therefore is not denoted by this indicator.

N/A Yes

17 Reporting of SON-related or ANR-related periodical measurements

Reporting of ANR-related intra-frequency events

This indicator can only be set to 1 when indicator 5 is set to 1.

Yes

18 Reporting of ANR-related inter-frequency events

This indicator can only be set to 1 when indicator 5 is set to 1.

Yes (unless the UE only supports band 13)

19 Reporting of ANR-related inter-RAT events This indicator can only be set to 1 when indicator 5 is set to 1.

N/A

NOTE

In the preceding table, if an Applicability cell is marked with Yes, the functions mentioned in the Supported Functions (When the Indicator Is Set to 1) cell have been implemented and successfully tested on the eNodeB.

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4 Intra-RAT ANR

4.1 Overview

This chapter describes the optional feature LOFD-002001 Automatic Neighbour Relation (ANR).

Intra-RAT ANR is classified into intra-RAT event-triggered ANR and intra-RAT fast ANR. Intra-RAT event-triggered ANR detects missing neighboring cells by using event-triggered UE measurements or UE history information. In addition, it detects abnormal neighboring cell coverage and maintains neighbor relations. For details, see section 4.2 "Intra-RAT Event-triggered ANR".

Based on the reporting of periodic UE measurements, intra-RAT fast ANR obtains information about all possible intra-RAT neighboring cells before a handover is performed. This reduces the negative effects of event-triggered UE measurements on handover performance. For details, see section 4.3 "Intra-RAT Fast ANR."

4.2 Intra-RAT Event-triggered ANR

Intra-RAT event-triggered ANR is controlled by the IntraRatEventAnrSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter. The intra-RAT event-triggered ANR function is activated when the IntraRatEventAnrSwitch check box is selected.

Intra-RAT event-triggered ANR detects missing intra-RAT neighboring cells and abnormal neighboring cell coverage, and maintains neighbor relations. For details, see the following sections in this chapter.

4.2.1 Automatic Detection of Missing Neighboring Cells

3GPP TS 36.300 defines the procedure for detecting missing neighboring cells by using event-triggered UE measurements.

ANR can detect missing neighboring cells by using UE history information in addition to even-triggered UE measurements.

Detecting Missing Neighboring Cells by Using Event-triggered UE Measurements

Intra-RAT event-triggered ANR detects cells with unknown PCIs based on the intra- and inter-frequency measurement reports that contain information about cells meeting the handover requirements.

Assume that cell A and cell B are involved in a handover. The UE is under the coverage of cell A of the source eNodeB, and cell B is a neighboring cell of cell A.

Table 4-1 lists the identification information about cell A and cell B.

Table 4-1 Identification information about cell A and cell B

Cell PCI ECGI

Cell A 3 17

Cell B 5 19

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Figure 4-1 shows how the eNodeB detects cell B by using event-triggered UE measurements.

Figure 4-1 Procedure for detecting a missing intra-RAT neighboring cell by using event-triggered UE measurements

The procedure is described as follows:

2. The source eNodeB delivers the inter-frequency measurement configuration to the UE, instructing the UE to measure inter-frequency neighboring cells that work on the frequencies specified in the measurement configuration.

NOTE

The UE performs intra-frequency neighboring cell measurements by default. When a UE establishes radio bearers, the eNodeB delivers by default the intra-frequency neighboring cell measurement configuration to the UE by using the RRC Connection Reconfiguration message. Therefore, if the UE needs to perform inter-frequency neighboring cell measurements, the eNodeB must deliver the inter-frequency neighboring cell measurement configuration to the UE and activate the measurement gap mode. For details about intra- and inter-frequency handover measurements, see Mobility Management in Connected Mode Feature Parameter Feature.

3. The UE detects that the PCI of cell B meets the measurement requirements, and reports the PCI to the source eNodeB. Note that the UE does not report the PCIs of the neighboring cells in the RRC blacklist to the eNodeB.

4. The source eNodeB checks whether its intra-RAT NCL includes the PCI of cell B. If so, the procedure ends. If not, the source eNodeB sends the measurement configuration to the UE, instructing the UE to read the ECGI, tracking area code (TAC), and PLMN ID list of cell B.

5. The source eNodeB allows the UE to read these parameters over the broadcast channel (BCH).

NOTE

The maximum time that a UE can spend on ECGI reading is controlled by timer T321. The following table defines T321 as quoted directly from 3GPP TS 36.331.

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Timer Start Stop At Expiry

T321 Upon receiving measConfig including a reportConfig with the purpose set to reportCGI

Upon acquiring the information needed to set all fields of cellGlobalId for the requested cell, upon receiving measConfig that includes removal of the reportConfig with the purpose set to reportCGI

Initiate the measurement reporting procedure, stop performing the related measurements and remove the corresponding measId

6. The UE reports the parameter values to the source eNodeB.

The source eNodeB adds the newly detected neighboring cell (cell B) to the intra-RAT NCL and adds the neighbor relation to the intra-RAT NRT of cell A.

Detecting Missing Neighboring Cells by Using UE History Information

During a handover, the source eNodeB sends UE history information to the target eNodeB. Figure 4-2 shows the procedure for detecting a missing intra-RAT neighboring cell by using UE history information.

NOTE

UE history information defined in 3GPP TS 36.413 is the information about the cells that provided services for the UE. The information contains:

ECGI of the last visited cell

Type of the last visited cell

Duration of the UE for camping on the cell

Figure 4-2 Procedure for detecting a missing neighboring cell based on UE history information


2. The source eNodeB sends a Handover Request message to the target eNodeB.

3. The target eNodeB obtains the UE history information from the message. If the target eNodeB detects that the ECGI of the last visited cell (that is, cell A, the source cell) does not exist in the NCL of the target eNodeB, cell A is considered a new neighboring cell of the target cell (cell B).

4. The target eNodeB reports the ECGI of cell A to the M2000.

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5. The M2000 queries the PCI, TAC, and PLMN ID list of cell A based on the reported ECGI and sends the parameters to the target eNodeB.

The target eNodeB adds cell A to the intra-RAT NCL of the target eNodeB.

NOTE

eRAN3.0 eNodeBs do not manage TempNRTs. Therefore, upon detecting a missing neighboring cell by using event-triggered UE measurements or using UE history information, an eRAN3.0 eNodeB adds this neighbor relation directly to the NRT. For details about how NRTs are maintained, see section 4.2.2 "Automatic Maintenance of NCLs and NRTs."

4.2.2 Automatic Maintenance of NCLs and NRTs

Automatic maintenance of NCLs and NRTs ensures the effectiveness of neighbor relations and therefore significantly improves network performance.

To enable automatic removal of intra-RAT neighbor relations, select the IntraRatAnrAutoDelSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter.

When a network is unstable or in the early stage of deployment, you are advised to disable this automatic removal by clearing the IntraRatAnrAutoDelSwitch check box. The purpose is to prevent frequent NCL/NRT updating and to complete the collection of neighbor relations as soon as possible.

NOTE

During intra-RAT neighbor relation addition through ANR, attributes that cannot be obtained through measurement reports or UE history information use default values.

Automatic Maintenance of NCLs

During automatic maintenance of NCLs, the eNodeB can automatically add a newly detected external neighboring cell to or remove an external cell from an NCL:

The eNodeB automatically adds a cell to an NCL in either of the following cases:

The eNodeB detects a missing neighboring cell based on UE measurements and receives information about this cell, including the ECGI, TAC, and PLMN ID list.

The eNodeB detects a missing intra-RAT neighboring cell based on UE history information

The eNodeB automatically removes an external cell from an NCL if the following conditions are all met:

The IntraRatAnrAutoDelSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter is selected. External cells can be automatically removed from NCLs only when this check box is selected.

The measurement period, which equals four times the value of ANR.StatisticPeriodForNRTDel, has elapsed.

The NRTs of all cells under the local eNodeB do not contain any neighbor relations with this external cell.

No X2 interface has been set up between the local eNodeB and the eNodeB of this external cell.

Automatic Maintenance of NRTs

During automatic maintenance of NRTs, the eNodeB can automatically add a neighbor relation to or remove a neighbor relation from an NRT:

The eNodeB automatically adds a neighbor relation to an NRT if the eNodeB detects a missing neighboring cell based on UE measurements, receives information about this cell, and adds this information to the NCL.

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The eNodeB automatically removes a neighbor relation (for example, with cell A) from an NRT if the IntraRatAnrAutoDelSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter is selected, the removal control flag is set to allow removal, and either of the following criteria is met:

Criterion 1, which includes the following two conditions:

Within a measurement period specified by the ANR.StatisticPeriodForNRTDel parameter, the total number of all types of handover from the local cell to its neighboring cells is greater than or equal to the value of ANR.StatisticNumForNRTDel.

In the same measurement period, cell A's PCI has never been included in any handover measurement reports in the same measurement period.

Criterion 2, which includes the following two conditions:

Within a measurement period specified by the ANR.StatisticPeriod parameter, the number of handovers from each of the cells under the eNodeB to cell A is greater than or equal to the value of ANR.NcellHoStatNum.

In the same measurement period, the handover success rate is less than or equal to the value of ANR.DelCellThd.

Note that when conditions in criterion 2 are met, not only is the neighbor relation with cell A removed from the NRT, but also information about cell A is removed from the NCL.

4.2.3 Automatic Detection of Abnormal Neighboring Cell Coverage

Abnormal neighboring cell coverage may exist between intra-frequency E-UTRAN cells. Abnormal neighboring cell coverage decreases the handover success rate because of the abnormal neighbor relations it causes. Therefore, detecting and eliminating abnormal neighboring cell coverage plays an important role in network optimization.

If the IntraRatEventAnrSwitch check box is selected, automatic detection of abnormal neighboring cell coverage is activated. When the M2000 receives an operator's request to query the information about abnormal neighboring cell coverage, it triggers the algorithm for detecting abnormal neighboring cell coverage and listing abnormal neighboring cells.

The M2000 checks for abnormal neighboring cell coverage based on the latitudes and longitudes of the serving cell and its neighboring cells. Then, the M2000 collects statistics about abnormal neighboring cell coverage and generates a list of abnormal neighboring cells for the serving cell.

NOTE

The algorithm for automatically detecting abnormal neighboring cell coverage requires that the longitudes and latitudes of the associated eNodeBs and sectors be accurately set and that the settings have taken effect. If the longitudes and latitudes are not set or the settings do not meet the requirement, the detection results may not be accurate.

To view abnormal neighboring cells, perform the following steps:

Step 1 Log in to the M2000.

Step 2 Choose Configuration > LTE Self Optimization > ANR Management.

Step 3 On the Neighbor Cell Management tab page, view abnormal neighboring cells in the Query Cross-Coverage Cell pane.

----End

4.3 Intra-RAT Fast ANR

Intra-RAT fast ANR enables the eNodeB to quickly obtain information about all qualified neighboring cells based on periodic UE measurements. This reduces the adverse impact of event-triggered UE measurements on handover performance.

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Intra-RAT fast ANR is enabled if the IntraRatFastAnrSwitch check box is selected.

Before UEs perform handovers, they periodically send measurement reports so that the eNodeB learns about all neighboring cells whose reference signal received power (RSRP) values are greater than or equal to the value of ANR.FastAnrRsrpThd.

After intra-RAT fast ANR is enabled, the eNodeB randomly selects fast-ANR-capable UEs to perform intra- and inter-frequency measurements. After receiving periodic measurement reports from these UEs, the eNodeB adds missing neighboring cells to NCLs. The procedure for detecting a missing neighboring cell using fast ANR is the same as that using event-triggered ANR based on UE measurements, which is detailed in "Detecting Missing Neighboring Cells by Using Event-triggered UE Measurements" in section 4.2.1 "Automatic Detection of Missing Neighboring Cells." However, after detecting a missing neighboring cell, the eNodeB operation differs. In fast ANR, this newly detected neighboring cell is added immediately only to the NCL. The neighbor relation will be added to the NRT only after a successful handover from the serving cell to this neighboring cell.

Periodic UE measurements negatively affect the uplink throughput of the network. Therefore, intra-RAT fast ANR restricts the number of concurrent UEs involved in intra-RAT periodic measurements. When the number of involved UEs reaches the upper limit, the eNodeB does not select a new UE for periodic measurements until a UE stops periodic measurements. The upper limit is specified by the ANR.FastAnrIntraRatMeasUeNum parameter.

Periodic UE measurements also increase the power consumption of a UE. Therefore, intra-RAT fast ANR restricts the number of periodic measurement reports by each UE. When the number of periodic measurement reports by a UE reaches the upper limit, the UE stops periodic measurements so that the eNodeB can select another UE for periodic measurements. This is repeated until the eNodeB deactivates intra-RAT fast ANR. The upper limit is specified by the ANR.FastAnrRprtAmount parameter. The interval for UEs to report periodic measurements is specified by the ANR.FastAnrRprtInterval parameter.

The total number of neighboring cells that meet the RSRP requirement is limited, and periodic UE measurements negatively affect the uplink throughput of the network. Therefore, intra-RAT fast ANR restricts the total number of UEs involved in intra-RAT periodic measurements. At a regular interval, specified by the ANR.FastAnrCheckPeriod parameter, the eNodeB checks whether the total number of involved UEs is greater than the upper limit. The upper limit is specified by the ANR.FastAnrIntraRatUeNumThd parameter. If yes, the eNodeB automatically deactivates intra-RAT fast ANR. If no, periodic UE measurements continue.

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Process

Figure 4-3 shows an intra-RAT fast ANR process.

Figure 4-3 Intra-RAT fast ANR process

In summary, an intra-RAT fast ANR process is as follows:

2. After intra-RAT fast ANR is activated, the eNodeB starts a check period (ANR.FastAnrCheckPeriod) and selects UEs to perform intra- and inter-frequency measurements to detect the PCIs of unknown

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cells. The number of UEs that can be selected is specified by the ANR.FastAnrIntraRatMeasUeNum parameter.

3. During the check period, the eNodeB operates as follows:

If the PCI of an unknown cell is reported, the eNodeB adds the information of this cell to the NCL, sets the number of UEs that have performed measurements in the check period to 0, and then selects UEs to perform measurements. The number of UEs that can be selected is also specified by the ANR.FastAnrIntraRatMeasUeNum parameter. Fast ANR does not select VoIP users to perform fast ANR measurements.

If no PCI is reported, the eNodeB proceeds to the end of the check period.

4. At the end of each check period, the eNodeB performs the following operations:

If the total number of UEs involved in intra- and inter-frequency measurements exceeds the value of ANR.FastAnrIntraRatUeNumThd, the eNodeB enters the monitoring state. In this state, the eNodeB monitors whether the PCI of an unknown cell is reported in an event-triggered ANR measurement report. If an unknown PCI is reported during the monitoring state, the eNodeB starts fast ANR measurements again.

If the total number of UEs involved in intra- and inter-frequency measurements is less than or equal to the value of ANR.FastAnrIntraRatUeNumThd, the eNodeB directly starts the next round of fast ANR measurements.

During a fast ANR procedure, after a UE reports the PCI of an unknown cell, the eNodeB will instruct the UE to read the ECGI of the cell. After the UE reports the ECGI of the cell, the eNodeB adds the information about this cell to the NCL. Then, after a successful handover from the serving cell to this cell, the eNodeB adds the neighbor relation to the NRT. For details about automatic maintenance of NCLs and NRTs, see section 4.2.2 "Automatic Maintenance of NCLs and NRTs."

Impact on System Performance

Generalized from intra-RAT fast ANR, fast ANR includes two UE-performed processes: periodical PCI reporting and CGI reading. In the periodical PCI reporting process, the UE periodically reports the PCI of the neighboring cell with the best signal quality. In the CGI reading process, the UE reads the CGIs of unknown cells.

Periodical PCI reporting

With respect to intra-frequency fast ANR, this process does not impact UE throughput, because the UE does not need to listen to extra frequencies to perform intra-frequency measurements.

With respect to inter-frequency or inter-RAT fast ANR, this process impacts UE throughput because gap-assisted measurements are used. Two measurement gap patterns are defined in 3GPP TS 36.133: pattern 0 and pattern 1. They are described in Table 4-2. To accelerate measurements, patter 0 is used by default.

Table 4-2 Gap patterns

Measurement Gap Pattern

Gap Width (Unit: ms) Gap Repetition Period (Unit: ms)

Target RAT

0 6 40 Inter-Frequency FDD E-UTRAN

Inter-Frequency TDD E-UTRAN

FDD UTRAN

GERAN

TDD low chip rate (LCR)

CDMA2000 HRPD

CDMA2000 1X

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Measurement Gap Pattern

Gap Width (Unit: ms) Gap Repetition Period (Unit: ms)

Target RAT

1 6 80 Inter-Frequency FDD E-UTRAN

Inter-Frequency TDD E-UTRAN

FDD UTRAN

GERAN

TDD LCR

CDMA2000 HRPD

CDMA2000 1X

CGI reading

This process impacts all fast ANR processes. To read the CGI of an unknown cell, the UE needs to listen to system information block type 1 (SIB1) of the unknown cell to obtain the PLMN ID, CGI, and TAC of the cell. After obtaining this information, the UE must report it to the local eNodeB. The reading and reporting processes decrease UE throughput.

In conclusion, fast ANR impacts system performance as follows:

With respect to intra-frequency fast ANR, periodical PCI reporting does not impact system performance, whereas CGI reading interrupts UE services.

With respect to inter-frequency and inter-RAT fast ANR, periodical PCI reporting impacts UE throughput, and CGI reading interrupts UE services.

NOTE

For details about the process in which a UE reads the ECGI of a neighboring cell, see "Detecting Missing Neighboring Cells by Using Event-triggered UE Measurements" in section 4.2.1 "Automatic Detection of Missing Neighboring Cells."

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5 Inter-RAT ANR

5.1 Overview

This chapter describes the optional feature LOFD-002002 Inter-RAT ANR.

Inter-RAT ANR is classified into inter-RAT event-triggered ANR and inter-RAT fast ANR.

Inter-RAT event-triggered ANR automatically detects missing neighboring inter-RAT cells by means of event-triggered UE measurements. Inter-RAT fast ANR automatically detects missing neighboring cells by instructing UEs to perform periodic measurements. Inter-RAT fast ANR enables eNodeBs to collect neighboring cell information before handovers. This, to some degree, protects handover performance from the adverse effects of inter-RAT event-triggered ANR measurements by UEs during handovers.

5.2 Inter-RAT Event-triggered ANR

Inter-RAT event-triggered ANR is enabled if the GeranEventAnrSwitch or UtranEventAnrSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter is selected.

After inter-RAT event-triggered ANR is activated, the eNodeB delivers inter-RAT measurement configurations to the UE and instructs the UE to perform periodic measurements on neighboring GERAN or UTRAN cells.

NOTE

Information about neighboring CDMA cells can be collected only by inter-RAT fast ANR. CDMA cells include CDMA2000 High Rate Packet Data (HRPD) cells and CDMA2000 1x Radio Transmission Technology (CDMA2000 1xRTT) cells.

Inter-RAT ANR does not check for PCI conflicts and abnormal neighboring cell coverage because of the following reasons:

The E-UTRAN has only a small number of standardized interfaces with other RATs.

It is complex for the E-UTRAN to detect anomalies in other RATs.

5.2.1 Automatic Detection of Missing Neighboring Cells

This section describes how inter-RAT event-triggered ANR detects a missing neighboring UTRAN cell. Assume that cell A is an E-UTRAN cell and cell B is a UTRAN cell. The UE is under the coverage of cell A, and cell B is an inter-RAT neighboring cell of cell A.

Figure 5-1 shows how the eNodeB detects cell B by using event-triggered UE measurements.

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Figure 5-1 Procedure for detecting a missing inter-RAT neighboring cell by using event-triggered UE measurements


2. The source eNodeB delivers the inter-RAT measurement configuration (including target RATs and ARFCNs) to the UE, activates the measurement gap mode, and instructs the UE to measure the neighboring cells that meet the measurement requirements.

NOTE

For details about inter-RAT handover measurements, see Mobility Management in Connected Mode Feature Parameter Feature.

3. The UE detects that cell B meets the measurement requirements and reports its scrambling code to cell A. If the NCL of the source eNodeB includes the scrambling code of cell B, the procedure ends. If the NCL of cell A does not include the scrambling code of cell B, the source eNodeB proceeds to the next step.

4. The source eNodeB requests the UE to read the parameters of cell B. If cell B is a GERAN or UTRAN cell, the parameters to be read are the CGI, location area code (LAC), and routing area code (RAC).

5. The source eNodeB schedules appropriate call gapping to allow the UE to read the CGI and other parameters of cell B over the BCH.

6. The UE reports the CGI and other parameters of cell B to the source eNodeB.

The source eNodeB adds the newly detected neighboring cell to its inter-RAT NCL and adds the neighbor relation to the inter-RAT NRT.

5.2.2 Automatic Maintenance of NCLs and NRTs

Automatic maintenance of NCLs and NRTs ensures the effectiveness of neighbor relations, which improves network performance.

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To enable automatic removal of neighbor relations with UTRAN, GERAN, or CDMA2000, select the UtranAutoNrtDeleteSwitch, GeranAutoNrtDeleteSwitch, or CdmaAutoNrtDeleteSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter. When a network is unstable or in the early stage of deployment, you are advised to disable automatic removal by clearing these check boxes. The purpose of disabling automatic removal is to prevent frequent NCL/NRT updates so the collection of neighbor relations can be completed as quickly as possible. Information about the external cells of a RAT can be removed from the NCL and neighbor relations with the RAT can be automatically removed from the NRT only when the corresponding check box is selected.

NOTE

The UtranAutoNrtDeleteSwitch, GeranAutoNrtDeleteSwitch, and CdmaAutoNrtDeleteSwitch check boxes under the ENodeBAlgoSwitch.AnrSwitch parameter control the automatic removal of neighbor relations with

UTRAN, GERAN, and CDMA2000, respectively.

During inter-RAT neighbor relation addition through ANR, attributes that cannot be obtained through measurement reports or UE history information use default values.

Automatic Maintenance of NCLs

During automatic maintenance of NCLs, the eNodeB can automatically add a newly detected external neighboring cell to or remove an external cell from an NCL:

The eNodeB adds a detected external neighboring cell to an NCL if the eNodeB detects a missing neighboring cell based on UE measurements and receives information about this cell (including the CGI).

The eNodeB automatically removes an external cell from an NCL if all of the following conditions are met:

The UtranAutoNrtDeleteSwitch, GeranAutoNrtDeleteSwitch, or CdmaAutoNrtDeleteSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter is selected.

The measurement period, which equals four times the value of ANR.StatisticPeriodForNRTDel, has elapsed.

The NRTs of all cells under the local eNodeB do not contain any neighbor relations with this external cell.

Automatic Maintenance of NRTs

During automatic maintenance of NRTs, the eNodeB can automatically add a neighbor relation to or remove a neighbor relation from an NRT:

The eNodeB automatically adds a neighbor relation to an NRT if the eNodeB detects a missing neighboring cell based on UE measurements, receives information about this cell, and adds this information to the NCL.

The eNodeB automatically removes a neighbor relation from an NRT when the corresponding check box under the ENodeBAlgoSwitch.AnrSwitch parameter is selected and all of the following conditions are met:

The number of neighbor relations in the NRT has reached the maximum specification and a new neighbor relation is to be added to the NRT.

Within a measurement period specified by the ANR.StatisticPeriodForNRTDel parameter, the number of handovers from the local cell to its inter-RAT neighboring cells is greater than or equal to the value of ANR.StatisticNumForNRTDel. A group of neighboring cells that have the removal control flag set to allow removal have never been measured as the target cell of these handovers. In this case, the eNodeB randomly removes a neighboring cell in this group from the NRT.

NOTE

Automatic removal of neighbor relations with CDMA2000 is not yet a requirement; therefore, it is not implemented in eRAN3.0.

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5.3 Inter-RAT Fast ANR

Inter-RAT fast ANR is enabled if the GeranFastAnrSwitch, UtranFastAnrSwitch, or CdmaFastAnrSwitch check box under the ENodeBAlgoSwitch.AnrSwitch parameter is selected.

After inter-RAT fast ANR is activated, the eNodeB delivers inter-RAT measurement configurations to the UE and instructs the UE to perform periodic measurements on neighboring GERAN, UTRAN, and CDMA cells.

The principles of inter-RAT fast ANR are almost the same as those of intra-RAT fast ANR. For details about the principles and relevant parameter settings, see section 4.3 "Intra-RAT Fast ANR."

For fast ANR with UTRAN and CDMA2000, the information element (IE) reportStrongestCellsForSON is configured on the eNodeB for fast ANR measurements. According to 3GPP TS 36.331, when the measurement type is set to reportStrongestCellsForSON, reportAmount can only be set to 1, which means that the UE sends only one measurement report to the eNodeB at one time. In this case, the user-defined measurement period does not take effect. For the UE to periodically transmit measurement reports, the fast ANR algorithm sets and sends reportStrongestCellsForSON to the UE at an unconfigurable period.

In terms of parameters, inter-RAT fast ANR differs from intra-RAT fast ANR in the following ways:

The signal quality threshold used to determine whether to periodically report a neighboring cell's PCI is determined by the ANR.FastAnrRsrpThd parameter in intra-RAT fast ANR and by the following parameters in inter-RAT fast ANR.

Target RAT Parameter Determining the Signal Quality Threshold

UTRAN ANR.FastAnrRscpThd

GERAN ANR.FastAnrRssiThd

CDMA2000 1xRTT ANR.FastAnrCdma1xrttPilotThd

CDMA2000 HRPD ANR.FastAnrCdmahrpdPilotThd

The upper limit on the number of concurrent UEs involved in fast ANR measurements is specified by the ANR.FastAnrInterRatMeasUeNum parameter in inter-RAT fast ANR and by the ANR.FastAnrIntraRatMeasUeNum parameter in intra-RAT fast ANR.

The upper limit on the total number of concurrent UEs involved in fast ANR measurements is specified by the ANR.FastAnrInterRatUeNumThd parameter in inter-RAT fast ANR and by the ANR.FastAnrIntraRatUeNumThd parameter in intra-RAT fast ANR.

Inter-RAT fast ANR has the same impact on network performance as intra-RAT fast ANR. For details, see section 4.3 "Intra-RAT Fast ANR."

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6 ANR with Shared Cells

Currently, the ANR with shared cells function automatically sets up neighbor relations with E-UTRAN cells that are shared by PLMNs. In this chapter, neighboring cells refer to neighboring E-UTRAN cells unless otherwise stated.

If a neighboring cell is shared by PLMNs and broadcasts its PLMN list in a round robin (RR) manner, a UE in its serving cell might not be able to obtain the correct serving PLMN list of the neighboring cell. If the shared neighboring cell does not broadcast its PLMN list in an RR manner, a UE in its serving cell might not report a complete PLMN list of the neighboring cell to the serving cell. As a result of either case, neighbor relations cannot be correctly added. To solve this problem, the serving cell can request that the M2000 send the serving PLMN list of the neighboring cell. This solution works if the serving and neighboring cells are managed by the same M2000, which stores the configuration data and status information about the neighboring cell.

NOTE

eRAN3.0 does not support ANR with shared UTRAN or GERAN cells.

6.1 Shared Neighboring Cell Broadcasting PLMN List in an RR Manner

ANR with shared cells that broadcast PLMN lists in an RR manner requires that NBSLTEPLMNRoundSwitch under the ENodeBAlgoSwitch.RanSharingAnrSwitch parameter be turned on.

If NBSLTEPLMNRoundSwitch is turned on and the serving eNodeB of a UE receives a measurement report containing the CGI (PLMN ID+eNodeB ID+cell ID) of a neighboring cell, the serving eNodeB reports the PCI and CGI obtained by the UE to the M2000. The M2000 queries the primary PLMN and serving PLMN list of the neighboring cell based on the PCI, eNodeB ID, and cell ID. The M2000 then sends the query result to the serving eNodeB. The serving eNodeB adds the PLMN information to the external cell configuration and PLMN list configuration corresponding to the neighboring cell.

In a handover procedure, as shown in Figure 6-1, if cell A (the source cell) is shared by PLMNs and the target eNodeB providing cell B detects from UE history information that cell A has not been configured as a neighboring cell of cell B, the target eNodeB adds the information about cell A to the intra-RAT NCL. The target eNodeB also adds the information about the secondary operators of cell A to the PLMN list configurations of the external cell for cell B.

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Figure 6-1 Procedure for detecting a missing neighboring cell based on UE history information

NOTE

If serving cells and neighboring cells are not managed by the same the NMS, the PLMN round function and ANR functions are mutually exclusive when ENodeBSharingMode.EnodeBSharingMode is set to SHARED_FREQ.

6.2 Shared Neighboring Cell Not Broadcasting PLMN List in an RR Manner

ANR with shared cells that do not broadcast PLMN lists in an RR manner requires that NBSLTERANSharingSwitch under the ENodeBAlgoSwitch.RanSharingAnrSwitch parameter be turned on.

If NBSLTERANSharingSwitch is turned on and NBSLTEPLMNRoundSwitch is turned off, and if the serving eNodeB of a UE receives a measurement report containing the CGI of a neighboring cell, the serving eNodeB takes one of the following actions:

If the UE reports the PLMN list of the neighboring cell, the serving eNodeB starts a normal ANR procedure.

After the UE reports the CGI and PLMN list to the serving eNodeB, the serving eNodeB adds the information about the missing neighboring cell to the intra-RAT NCL and NRT and adds the PLMN information to the PLMN list configurations.

If the UE does not report the PLMN list of the neighboring cell, the serving eNodeB adds the information about the missing neighboring cell to the intra-RAT NCL and NRT and reports the CGI obtained by the UE to the M2000. The M2000 queries the PLMN list of the neighboring cell and sends the query result to the serving eNodeB. The serving eNodeB adds the PLMN information to the PLMN list configurations.

If the eNodeB detects a missing neighboring cell based on the UE history information, the eNodeB adds the neighboring cell according to the same procedure described in section 6.1 "Shared Neighboring Cell Broadcasting PLMN List in an RR Manner."

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7 Manual Management of Neighbor Relations

7.1 Overview

Generally, neighbor relations are managed by ANR automatically. In some cases, they need to be managed manually.

The manual management tasks are as follows:

Adding or removing a neighbor relation

Blacklisting a neighbor relation

Whitelisting a neighbor relation

The latest manually maintained neighbor relations are kept in NRTs.

7.2 Adding or Removing a Neighbor Relation

To manually add or remove a neighbor relation, configure the corresponding managed objects (MOs), as listed in the following table.

To Add or Remove a Neighbor Relation with... Configure the MO...

Intra-frequency E-UTRAN cell EutranIntraFreqNCell

Inter-frequency E-UTRAN cell EutranInterFreqNCell

UTRAN cell UtranNCell

GERAN cell GeranNcell

CDMA2000 1xRTT cell Cdma20001XRTTNcell

CDMA2000 HRPD cell Cdma2000HrpdNcell

For details, see Mobility Management in Connected Mode Feature Parameter Description.

If ANR is activated, neighbor relations are added or removed automatically.

7.3 Blacklisting a Neighbor Relation

7.3.1 Configuring an HO Blacklist

HO blacklists can only be configured manually. If an NRT contains a neighbor relation that has been included in an HO blacklist, this neighbor relation cannot be automatically removed from the NRT.

A neighbor relation needs to be added to an HO blacklist in some special cases, for example, if the neighbor relation causes coverage overlap and leads to unstable handovers.

To blacklist a neighbor relation, perform the following steps:



Step 3 On the Neighbor Cell Management tab page, select a neighbor relation to be blacklisted in the Neighboring Cell pane.

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Step 4 Set both Deletion Prohibited and Handover Prohibited to TRUE in the displayed Set dialog box.

----End

Alternatively, to blacklist a neighbor relation, you can set the EutranInterFreqNCell.NoHoFlag parameter to FORBID_HO_ENUM and the EutranInterFreqNCell.NoRmvFlag parameter to FORBID_RMV_ENUM. Depending on the neighbor relation type, these two parameters belong to different MOs:

For a neighbor relation with an intra-frequency E-UTRAN cell, they belong to the EutranIntraFreqNCell MO.

For a neighbor relation with an inter-frequency E-UTRAN cell, they belong to the EutranInterFreqNCell MO.

For a neighbor relation with a UTRAN cell, they belong to the UtranNCell MO.

For a neighbor relation with a GERAN cell, they belong to the GeranNcell MO.

For a neighbor relation with a CDMA2000 HRPD cell, they belong to the Cdma2000HrpdNCell MO.

For a neighbor relation with a CDMA2000 1xRTT cell, they belong to the Cdma20001XRTTNCell MO.

7.3.2 Configuring an X2 Blacklist

X2 blacklists can only be configured manually.

An X2 blacklist contains information about the neighboring eNodeBs with which the local eNodeB is not allowed to set up X2 interfaces. If an X2 interface has been set up between the local eNodeB and a neighboring eNodeB on the X2 blacklist, the interface will be removed automatically.

NOTE

To remove an X2 interface, the eNodeB removes the X2 logical connection but retains the configuration data for the X2 interface. This ensures that the configuration data is not lost due to exceptions such as misoperations.

X2 blacklists can be configured as required by operators. For example, X2 setup between different base station models is prohibited.

To configure an X2 blacklist, perform the following steps:



Step 3 Click the X2 Management tab on the ANR Management tab page.

----End

Alternatively, you can use the X2BlackWhiteList MO to configure an X2 blacklist.

7.3.3 Configuring an RRC Blacklist

UEs are not allowed to measure or be handed over to the cells contained in RRC blacklists. To configure intra- or inter-frequency RRC blacklists, configure the IntraFreqBlkCell and InterFreqBlkCell MOs.

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7.4 Whitelisting a Neighbor Relation

7.4.1 Configuring an HO Whitelist

HO whitelists can only be configured manually. If an NRT contains a neighbor relation that has been included in an HO whitelist, this neighbor relation cannot be automatically removed from the NRT for a handover.

HO whitelists are especially useful in the early phase of network construction. In this phase, there are usually a small number of UEs. Therefore, the best practice to collect neighbor relation information as soon as possible is to prohibit ANR from automatically removing neighbor relations.

To whitelist a neighbor relation, perform the following steps:



Step 3 On the Neighbor Cell Management tab page, select a neighbor relation to be whitelisted in the Neighboring Cell pane.

Step 4 Set Deletion Prohibited to TRUE and Handover Prohibited to FALSE in the displayed Set dialog box.

----End

Alternatively, to whitelist a neighbor relation, you can set the EutranInterFreqNCell.NoHoFlag parameter to PERMIT_HO_ENUM and the EutranInterFreqNCell.NoRmvFlag parameter to FORBID_RMV_ENUM. Depending on the neighbor relation type, these two parameters belong to different MOs:

For a neighbor relation with an intra-frequency E-UTRAN cell, they belong to the EutranIntraFreqNCell MO.

For a neighbor relation with an inter-frequency E-UTRAN cell, they belong to the EutranInterFreqNCell MO.

For a neighbor relation with a UTRAN cell, they belong to the UtranNCell MO.

For a neighbor relation with a GERAN cell, they belong to the GeranNcell MO.

For a neighbor relation with a CDMA2000 HRPD cell, they belong to the Cdma2000HrpdNCell MO.

For a neighbor relation with a CDMA2000 1xRTT cell, they belong to the Cdma20001XRTTNCell MO.

7.4.2 Configuring an X2 Whitelist

X2 whitelists can only be configured manually.

An X2 whitelist is especially useful when it takes a long time to maintain an eNodeB. During the maintenance, the eNodeB cannot provide any services, and the NRTs of this eNodeB and its surrounding eNodeBs may change. To avoid this situation, you can add the associated eNodeBs to the X2 whitelist.

To configure an X2 whitelist, perform the following steps:



Step 3 Click the X2 Management tab on the ANR Management tab page.

eRAN




7-4

----End

Alternatively, you can use the X2BlackWhiteList MO to configure an X2 whitelist.

eRAN




8-1

8 X2 Self-Setup

8.1 Overview

This chapter describes the principles of X2 self-setup, which is implemented by the optional feature LOFD-002004 Self-configuration.

In E-UTRAN, X2 interfaces exist between neighboring eNodeBs. The X2 interfaces allow some messages to be directly exchanged between neighboring eNodeBs, which meets the requirements of a flat LTE network architecture.

An X2 interface can be set up in either link configuration mode or end point configuration mode. Figure 8-1 shows the classifications of X2 setup modes.

Figure 8-1 X2 setup modes

The X2 setup modes are described as follows:

Link configuration mode

Users configure control-plane bearers (SCTP links) and user-plane bearers (IP paths) and negotiate port information about the local eNodeB and peer eNodeB.

End point configuration mode (also called self-setup mode)

After users configure ports, the eNodeBs automatically set up control-plane bearers (SCTP links) and user-plane bearers (IP paths) for the X2 interface between the eNodeBs.

In end point configuration mode, the X2 self-setup procedure varies depending on whether the neighboring eNodeB has been manually configured using an X2eNodeB MO.

X2 self-setup with X2eNodeB manually configured

The eNodeB can set up an X2 interface based on the X2eNodeB MO. One X2eNodeB MO is used to set up one X2 interface; therefore, multiple X2eNodeB MOs are required to set up multiple X2 interfaces.

X2 self-setup with X2eNodeB automatically configured

If X2eNodeB is not manually configured, the eNodeB can set up an X2 interface in X2 over S1 or X2 over M2000 mode. The mode is specified by the GlobalProcSwitch.X2SonLinkSetupType parameter.

eRAN




8-2

Both self-setup modes require that neighboring cell information be configured and that the X2 self-setup switch (specified by the GlobalProcSwitch.X2SonSetupSwit

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