ANR Feature Huawei

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eRAN

ANR Management

Feature Parameter Description

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The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS" without warranties, guarantees or representations of any kind, either express or implied.

The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute a warranty of any kind, express or implied.

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10.7 Deploying ANR with Shared Cells 10.7.1 Deployment Procedure 10.7.2 Deployment Requirements 10.7.3 Data Preparation 10.7.4 Precautions 10.7.5 Hardware Adjustment 10.7.6 Feature Activation 10.7.7 Activation Observation 10.7.8 Reconfiguration 10.7.9 Deactivation 10.8 Performance Optimization 10.8.1 Intra-RAT ANR 10.8.2 Inter-RAT ANR 10.8.3 ANR with Shared Cells 10.9 Troubleshooting

10.9.1 Intra-RAT ANR 10.9.2 Inter-RAT ANR 10.9.3 ANR with Shared Cells

11 Parameters 12 Counters 13 Glossary

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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: 04 (2012-09-20) 03 (2012-06-30) 02 (2012-05-11) 01 (2012-03-30) Draft A (2012-01-10)

04 (2012-09-20)

Compared with issue 03 (2012-06-30), issue 04 (2012-09-20) includes the following changes.

Change Type Change Description Parameter Change

Feature change None None

Editorial change Revised some descriptions. For details, see sections 10.5.6 "Feature Activation", 10.6.6

"Feature Activation" and 10.7.6 "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 9.3 "ANR with Shared Cells."

For details about engineering guidelines, see chapter 10 "Engineering Guidelines."

Added the

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.

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 10 "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.

Change Change Description Parameter Change

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

Changed the default value of the

DelCellThd parameter. Added the following parameters:

StatisticPeriodForNRTDel StatisticNumForNRTDel

Modified the conditions for starting fast ANR. Changed the default value of the

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 l l

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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 a huge amount of network elements, implementation of different system standards, and coexistence of different equipment vendors and telecom operators. To overcome 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, and 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.

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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 under 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

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. 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 of a neighbor relation is set to allow removal. −If this attribute of a neighbor relation is set to prohibit removal, this neighbor relation cannot be removed from the NRT by ANR.

−If this attribute of a neighbor relation is set to allow removal, this neighbor relation can be removed from the NRT by ANR.

Handover control: indicates whether this neighbor relation can be used for a handover. By default, this attribute of a neighbor relation is set to allow handover. −If this attribute of a neighbor relation is set to prohibit handover, this neighbor relation cannot be used for a handover.

−If this attribute of a neighbor relation is set to allow handover, this neighbor relation can be used for a handover. NRTs can be managed (for example, added, deleted, or modified) automatically by ANR.

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

3.4 Blacklist

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 in the X2 blacklist, this X2 interface will be removed automatically.

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-frequency 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:

Removal control = prohibited Handover control = allowed

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

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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 cross-cell coverage.

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 mountains, 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 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 25 is also set to 1

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

Yes (unless the UE only supports band 13)

19 Reporting of ANR-related inter-RAT events

N/A

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. l l l l l l l l l

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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 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 information about cell A and cell B. Table 4-1 Information about cell A and cell B

Cell PCI ECGI

Cell A 3 17

Cell B 5 19

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:

1. 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.

The UE performs intra-frequency neighboring cell measurements by default. When a UE establishes radio bearers, the eNodeB delivers the intra-frequency neighboring cell measurement configuration to the UE by using the RRC Connection Reconfiguration message by default. 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-frequency handover measurements and inter-frequency handover measurements, see Mobility

Management in Connected Mode Feature Parameter Feature.

2. 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.

3. 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.

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

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

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

5. The UE reports the obtained parameter values to the source eNodeB.

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

Detecting Missing Neighboring Cells by Using UE History Information

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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.

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

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

2. 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 as a new neighboring cell of the target cell (cell B).

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

4. 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.

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 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.

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 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 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.

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

−Criterion 1: Within a measurement period specified by the 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 StatisticNumForNRTDel and cell A's PCI has never been included in any handover measurement reports.

−Criterion 2: Within a measurement period specified by the 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 NcellHoStatNum and the handover success rate is less than or equal to the value of DelCellThd. Note that in this case, 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 play an important role in network optimization.

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

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.

The algorithm of 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 take 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

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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.

Intra-RAT fast ANR is controlled by the IntraRatFastAnrSwitch check box and is enabled if the 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 FastAnrRsrpThd.

After intra-RAT fast ANR is enabled, the eNodeB randomly selects fast-ANR-capable UEs to perform intra-frequency 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 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 until the eNodeB deactivates intra-RAT fast ANR. The upper limit is specified by the FastAnrRprtAmount parameter. The interval for UEs to report periodic measurements is specified by the 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. The eNodeB checks whether the total number of involved UEs is greater than the upper limit at a regular interval, which is specified by the FastAnrCheckPeriod parameter. The upper limit is specified by the FastAnrIntraRatUeNumThd parameter. If yes, the eNodeB automatically deactivates intra-RAT fast ANR. If no, periodic UE measurements continue.

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:

1. After intra-RAT fast ANR is activated, the eNodeB starts a check period (FastAnrCheckPeriod) and selects UEs to perform intra-frequency and inter-frequency measurements to detect the PCIs of unknown cells. The number of UEs that can be selected is specified by the FastAnrIntraRatMeasUeNum parameter.

2. 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 FastAnrIntraRatMeasUeNum parameter.

−If no PCI is reported, the eNodeB proceeds to the end of the check period. 3. At the end of each check period, the eNodeB performs the following operations:

−If the total number of UEs involved in intra-frequency and inter-frequency measurements exceeds the value of FastAnrIntraRatUeNumThd, the eNodeB enters the monitoring state to monitor 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-frequency and inter-frequency measurements is less than or equal to the value of 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.

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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 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, 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.

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 controlled by the GeranEventAnrSwitch and UtranEventAnrSwitch check boxes under the AnrSwitch parameter. The inter-RAT event-triggered ANR function is activated if the corresponding check box 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.

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.

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

1. 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.

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

2. 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.

3. 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). −If cell B is a CDMA2000 cell, only the CGI is to be read.

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

To enable automatic removal of neighbor relations with UTRAN, GERAN, or CDMA2000, select the UtranAutoNrtDeleteSwitch, GeranAutoNrtDeleteSwitch, or

CdmaAutoNrtDeleteSwitch check box under the 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 update so that 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.

The UtranAutoNrtDeleteSwitch, GeranAutoNrtDeleteSwitch, and CdmaAutoNrtDeleteSwitch check boxes under the AnrSwitch parameter control the automatic removal of neighbor relations with UTRAN, GERAN, and CDMA2000, respectively.

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 AnrSwitch parameter is selected. −The measurement period, which equals four times the value of 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

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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 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 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 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.

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

5.3 Inter-RAT Fast ANR

Inter-RAT fast ANR is controlled by the GeranFastAnrSwitch, UtranFastAnrSwitch, and CdmaFastAnrSwitch check boxes under the AnrSwitch parameter. The inter-RAT fast ANR function is activated if the corresponding check box 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 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 in the evaluation of whether to periodically report a neighboring cell's PCI is specified by the FastAnrRsrpThd parameter in intra-RAT fast ANR and specified by the following parameters in inter-RAT fast ANR.

Target RAT Parameter Specifying Signal Quality Threshold

UTRAN FastAnrRscpThd

GERAN FastAnrRssiThd

CDMA2000 1xRTT FastAnrCdma1xrttPilotThd

CDMA2000 HRPD FastAnrCdmahrpdPilotThd

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

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6 ANR with Shared Cells

Currently, this 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 sends 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.

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 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 and PLMN list configurations 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.

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

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 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 in 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 cross-cell coverage and leads to unstable handovers. To blacklist a neighbor relation, perform the following steps:

Step 1 Log in to the M2000.

Step 3 On the Neighbor Cell Management tab page, select a neighbor relation to be blacklisted in the Neighboring Cell pane. Step 4 Set both Deletion Prohibited and Handover Prohibited to TRUE in the displayed Set dialog box.

----End

Alternatively, you can set the EUTRANINTERFREQNCELL.NoHoFlag parameter to FORBID_HO_ENUM and the EutranInterFreqNCell.NoRmvFlag parameter to FORBID_RMV_ENUM to blacklist a neighbor relation. 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 in the X2 blacklist, this X2 interface will be removed automatically.

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 interfaces cannot be set up between different base station models. To configure an X2 blacklist, perform the following steps:

Step 1 Log in to the M2000.

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-frequency or inter-frequency RRC blacklists, configure the IntraFreqBlkCell and InterFreqBlkCell MO.

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.

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To whitelist a neighbor relation, perform the following steps: Step 1 Log in to the M2000.

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, you can set the EUTRANINTERFREQNCELL.NoHoFlag parameter to PERMIT_HO_ENUM and the EutranInterFreqNCell.NoRmvFlag parameter to FORBID_RMV_ENUM to whitelist a neighbor relation. 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 needs to take 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 the changes, you can add the associated eNodeBs to the X2 whitelist.

To configure an X2 whitelist, perform the following steps: Step 1 Log in to the M2000.

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

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8 Related Features

8.1 Intra-RAT ANR

8.1.1 Required Features

Intra-RAT ANR depends on the feature LBFD-002017 DRX. If ANR measurements need to be performed, a temporary dedicated DRX cycle needs to be configured for the UE. During this cycle, the UE obtains the CGIs of neighboring cells in dormancy periods. For details about DRX, see DRX Feature Parameter Description.

8.1.2 Mutually Exclusive Features

None

8.1.3 Affected Features

Intra-RAT ANR has an impact on LOFD-002007 PCI Collision Detection & Self-Optimization.

When neighboring cell information changes because of intra-RAT ANR, PCI conflict detection is triggered.

8.2 Inter-RAT ANR

8.2.1 Required Features

Inter-RAT ANR depends on the feature LBFD-002017 DRX. If ANR measurements need to be performed, a temporary dedicated DRX cycle needs to be configured for the UE. For details about DRX, see DRX Feature Parameter Description.

8.2.2 Mutually Exclusive Features

None

8.2.3 Affected Features

None

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9 Impact on the Network

9.1 Intra-RAT ANR

9.1.1 Impact on System Capacity

N/A

9.1.2 Impact on Network Performance

Intra-RAT event-triggered ANR introduces extra delays in handovers of the UEs that meet the handover conditions but are still performing ANR periodic measurements. In addition, it affects the UE throughput because UEs cannot be scheduled when reading the CGI and other information about an unknown cell during DRX periods.

Intra-RAT fast ANR has the following influences on network performance:

The UE throughput is unaffected during the process that the UE periodically measures intra-frequency neighboring cells and reports the PCI of the neighboring cell with the highest signal quality.

The UE throughput drops when:

−The UE reads the CGI and other information about an unknown cell during DRX periods. This drop occurs because the UE cannot be scheduled during DRX periods. −The UE performs gap-assisted measurements on inter-frequency or inter-RAT neighboring cells.

Overall, the influences that fast ANR exerts over network performance are controllable and acceptable, because of the upper limits on the number of UEs involved in fast ANR per cell and on the number of periodic measurement reports by a UE within each period.

Intra-RAT ANR optimizes and manages intra-RAT neighbor relations, thereby reducing call drops and handovers caused by inappropriate neighbor relations. As a result, the value of the Service Drop Rate decreases and the values of the following key performance indicators (KPIs) increase:

Intra-frequency Handover Out Success Rate Inter-frequency Handover Out Success Rate Handover In Success Rate

9.2 Inter-RAT ANR

9.2.1 Impact on System Capacity

N/A

9.2.2 Impact on Network Performance

Inter-RAT ANR has basically the same influences on network performance with intra-RAT ANR. The difference is that inter-RAT ANR has an impact on the following KPIs: Inter-RAT Handover Out Success Rate (LTE to CDMA)

Inter-RAT Handover Out Success Rate (LTE to WCDMA) Inter-RAT Handover Out Success Rate (LTE to GSM)

9.3 ANR with Shared Cells

9.3.1 Impact on System Capacity

N/A

9.3.2 Impact on Network Performance

If the switch for ANR with shared cells (specified by the RanSharingAnrSwitch parameter) is turned on, the serving eNodeB of a UE may query the M2000 for the neighboring cell information. The query time is long and therefore might affect the handover. If no other neighboring cells are available for the handover, a service drop may occur. After the serving eNodeB obtains the neighboring cell information from the M2000, the information can be used in subsequent handovers to the neighboring cell.

ANR with shared cells decreases the service drop rate and increases the handover success rate. The related KPIs are as follows: Intra-frequency Handover Out Success Rate

Inter-frequency Handover Out Success Rate Handover In Success Rate

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10 Engineering Guidelines

10.1 When to Use ANR

10.1.1 Intra-RAT ANR

Intra-RAT ANR consists of intra-RAT event-triggered ANR and intra-RAT fast ANR.

Use intra-RAT fast ANR when quick detection of neighbor relations is required, for example, in the early stage of deployment or during network capacity expansion. Use intra-RAT event-triggered ANR to supplement and optimize neighbor relations.

Intra-RAT Event-triggered ANR

Consider the following when determining whether to use intra-RAT event-triggered ANR: The prerequisites for using intra-RAT event-triggered ANR are as follows:

Operators have deployed ANR-capable UEs on the network. Intra-RAT event-triggered ANR is enabled in any of the following cases:

−Network construction is in progress. The purpose is to complete and optimize existing neighbor relations.

−Network capacity expansion or eNodeB relocation has occurred. In this situation, cells or eNodeBs are removed from one place and added to another, which causes changes to neighbor relations. Intra-RAT event-triggered ANR can effectively deal with these types of changes and achieve optimization.

−Intra-RAT fast ANR is enabled. The neighboring cells detected using fast ANR are added to NCLs. To use these neighboring cells for handovers, intra-RAT event-triggered ANR is required.

In the early stage of deployment, disable automatic removal of neighbor relations. This can prevent stable neighbor relations from being removed simply because only a few handovers have been performed.

Intra-RAT event-triggered ANR is not recommended if users want to manually manage neighbor relations. In this situation, disable both intra-RAT event-triggered ANR and intra-RAT fast ANR.

Intra-RAT Fast ANR

Consider the following when determining whether to use intra-RAT fast ANR. The prerequisites for using intra-RAT fast ANR are as follows:

Operators have deployed ANR-capable UEs on the network. Intra-RAT fast ANR is enabled in any of the following cases:

−Network construction is at an early stage. The purpose is to quickly collect neighbor relations.

−Network capacity expansion or eNodeB relocation has occurred. In this situation, cells or eNodeBs are removed from one place and added to another, which causes changes to neighbor relations. Intra-RAT fast ANR can effectively deal with these types of changes and achieve optimization.

Intra-RAT event-triggered ANR is not recommended in either of the following cases:

−The network is well constructed and serves a moderate number of UEs, and basic neighbor relations are configured. −Users want to manually manage neighbor relations.

If both event-triggered ANR and fast ANR are enabled, they separately detect missing neighboring cells by using their own mechanisms.

10.1.2 Inter-RAT ANR

Inter-RAT ANR consists of inter-RAT event-triggered ANR and inter-RAT fast ANR. The same considerations should be made when determining whether to use inter-RAT ANR as when determining whether to use intra-RAT ANR. For details, see section 10.1.1 "Intra-RAT ANR."

10.1.3 ANR with Shared Cells

Enable the function of ANR with shared cells when all the following conditions are met: The neighboring cells are shared by multiple PLMNs.

If the shared neighboring cells broadcast the PLMN lists in an RR manner, turn on NBSLTEPLMNRoundSwitch under the RanSharingAnrSwitch parameter.

If the shared neighboring cells do not broadcast the PLMN lists in an RR manner, turn off NBSLTEPLMNRoundSwitch and turn on NBSLTERANSharingSwitch under the

RanSharingAnrSwitch parameter.

Some ANR-supporting UEs are used in the network.

IntraRatEventAnrSwitch under the AnrSwitch parameter is turned on for UEs to read CGI over the radio interface. Disable the function of ANR with shared cells under either of the following conditions:

The neighboring cells are not shared by PLMNs.

The neighboring cells are shared by PLMNs, but the operators prefer manual maintenance of neighbor relations to ANR. In this situation, disable intra-RAT event-triggered ANR, intra-RAT fast ANR, and ANR with shared cells.

10.2 Information to Be Collected

10.2.1 Intra-RAT ANR

Collect the following information:

Proportion and distribution of UEs that support intra-RAT ANR in the network A UE supports intra-RAT ANR if it supports intra- or inter-frequency ANR. Networking mode (intra- or inter-frequency networking)

10.2.2 Inter-RAT ANR

Proportion and distribution of UEs that support inter-RAT ANR in the network

RAT (UTRAN, GERAN, or CDMA2000) that constructs inter-RAT networking with the E-UTRAN

10.2.3 ANR with Shared Cells

Network configuration: whether RAN sharing and PLMN list broadcast in an RR manner are to be enabled For details about the network configuration, see RAN Sharing Feature Parameter Description. Proportion and distribution of UEs that support intra-RAT ANR in the network

A UE supports intra-RAT ANR if it supports intra- or inter-frequency ANR. Networking mode (intra- or inter-frequency networking)

10.3 Network Planning

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ANR Feature Huawei

eRAN

ANR Management

Contents

1 Introduction

1.1 Scope

1.2 Intended Audience

1.3 Change History

Document Issues

04 (2012-09-20)

03 (2012-06-30)

02 (2012-05-11)

01 (2012-03-30)

Draft A (2012-01-10)

2 Overview of ANR

3 Concepts Related to ANR

3.1 Overview

3.2 NCL

3.3 NRT

3.4 Blacklist

3.4.1 HO Blacklist

3.4.2 X2 Blacklist

3.4.3 RRC Blacklist

3.5 Whitelist

3.5.1 HO Whitelist

3.5.2 X2 Whitelist

3.6 Abnormal Neighboring Cell Coverage

3.7 ANR Capabilities of UEs

4 Intra-RAT ANR

4.1 Overview

4.2 Intra-RAT Event-triggered ANR

4.2.1 Automatic Detection of Missing Neighboring Cells

Detecting Missing Neighboring Cells by Using Event-triggered UE Measurements

Detecting Missing Neighboring Cells by Using UE History Information

4.2.2 Automatic Maintenance of NCLs and NRTs

Automatic Maintenance of NCLs

Automatic Maintenance of NRTs

4.2.3 Automatic Detection of Abnormal Neighboring Cell Coverage

4.3 Intra-RAT Fast ANR

Process

Impact on System Performance

5 Inter-RAT ANR

5.1 Overview

5.2 Inter-RAT Event-triggered ANR

5.2.1 Automatic Detection of Missing Neighboring Cells

5.2.2 Automatic Maintenance of NCLs and NRTs

Automatic Maintenance of NCLs

Automatic Maintenance of NRTs

5.3 Inter-RAT Fast ANR

6 ANR with Shared Cells

6.1 Shared Neighboring Cell Broadcasting PLMN List in an RR Manner

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

7 Manual Management of Neighbor Relations

7.1 Overview

7.2 Adding or Removing a Neighbor Relation

7.3 Blacklisting a Neighbor Relation

7.3.1 Configuring an HO Blacklist

7.3.2 Configuring an X2 Blacklist

7.3.3 Configuring an RRC Blacklist

7.4 Whitelisting a Neighbor Relation

7.4.1 Configuring an HO Whitelist

7.4.2 Configuring an X2 Whitelist

8 Related Features

8.1 Intra-RAT ANR

8.1.1 Required Features

8.1.2 Mutually Exclusive Features

8.1.3 Affected Features

8.2 Inter-RAT ANR

8.2.1 Required Features

8.2.2 Mutually Exclusive Features

8.2.3 Affected Features

9 Impact on the Network

9.1 Intra-RAT ANR

9.1.1 Impact on System Capacity

9.1.2 Impact on Network Performance

9.2 Inter-RAT ANR

9.2.1 Impact on System Capacity

9.2.2 Impact on Network Performance

9.3 ANR with Shared Cells

9.3.1 Impact on System Capacity