PCI Conflict Detection and Self-Optimization(ERAN3.0_03)

7/25/2019 PCI Conflict Detection and Self-Optimization(ERAN3.0_03)

http://slidepdf.com/reader/full/pci-conflict-detection-and-self-optimizationeran3003 1/40

PCI Conflict Detection and Self-OptimizationeRAN3.0

Feature Parameter Description

Issue 03

Date 2012-09-20

HUAWEI TECHNOLOGIES CO., LTD.



Copyright © Huawei Technologies Co., Ltd. 2012. All rights reserved.

No part of this document may be reproduced or transmitted in any form or by any means without prior

written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions

and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.

All other trademarks and trade names mentioned in this document are the property of their respective

holders.

Notice

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 orrepresentations 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 the warranty of any kind, express or implied.

Huawei Technologies Co., Ltd.

Address: Huawei Industrial Base

Bantian, Longgang

Shenzhen 518129

People's Republic of China

Website: http://www.huawei.com

Email: [email protected]

http://www.huawei.com/


mailto:[email protected]






eRAN

PCI Conflict Detection and Self-Optimization Contents

Issue 03 (2012-09-20) 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 PCI Conflict Detection and Self-Optimization ........................................... 2-1

3 PCI Conflict Detection ............................................................................................................. 3-1

3.1 PCI Conflict Types ......................................................................................................................... 3-1

3.1.1 PCI Collision ......................................................................................................................... 3-1

3.1.2 PCI Confusion ...................................................................................................................... 3-1

3.2 PCI Conflict Detection Methods .................................................................................................... 3-2

3.2.1 PCI Conflict Detection Triggered by eNodeB Parameter Adjustment .................................. 3-3

3.2.2 PCI Conflict Detection Based on ANR .................................................................................. 3-3

3.2.3 PCI Conflict Detection Based on X2 Messages ................................................................... 3-5

4 PCI Self-Optimization ............................................................................................................... 4-1

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

4.2 Related Concepts .......................................................................................................................... 4-1

4.2.1 First-Order Neighboring Cell................................................................................................. 4-1

4.2.2 Second-Order Neighboring Cell ........................................................................................... 4-1

4.2.3 Bidirectional Neighboring Cell .............................................................................................. 4-1

4.2.4 PCI Self-Optimization Principles .......................................................................................... 4-1

5 Related Features ....................................................................................................................... 5-1

5.1 Required Features......................................................................................................................... 5-1

5.2 Mutually Exclusive Features ......................................................................................................... 5-1

5.3 Affected Features .......................................................................................................................... 5-1

6 Impact on the Network............................................................................................................. 6-1

6.1 PCI Conflict Detection ................................................................................................................... 6-1

6.2 PCI Self-Optimization .................................................................................................................... 6-1

7 Engineering Guidelines ........................................................................................................... 7-1

7.1 When to Use PCI Conflict Detection and Self-Optimization ......................................................... 7-1

7.1.1 PCI Conflict Detection .......................................................................................................... 7-1

7.1.2 PCI Self-Optimization ........................................................................................................... 7-1

7.2 Information to Be Collected ........................................................................................................... 7-1

7.3 Network Planning .......................................................................................................................... 7-1

7.3.1 RF Planning .......................................................................................................................... 7-1

7.3.2 Network Topology ................................................................................................................. 7-1

7.3.3 Hardware Planning ............................................................................................................... 7-2

7.4 Deploying PCI Conflict Detection and Self-Optimization .............................................................. 7-2



eRAN

PCI Conflict Detection and Self-Optimization Contents



ii

7.4.1 Deployment Requirements ................................................................................................... 7-2

7.4.2 Data Preparation................................................................................................................... 7-2

7.4.3 Precautions ........................................................................................................................... 7-4

7.4.4 Hardware Adjustment ........................................................................................................... 7-4

7.4.5 Initial Configuration ............................................................................................................... 7-4

7.4.6 Commissioning ..................................................................................................................... 7-7

7.4.7 Activation Observation .......................................................................................................... 7-7

7.4.8 Reconfiguration .................................................................................................................... 7-9

7.4.9 Deactivation .......................................................................................................................... 7-9

7.5 Performance Optimization ............................................................................................................. 7-9

7.5.1 Monitoring ............................................................................................................................. 7-9

7.5.2 Parameter Optimization ...................................................................................................... 7-10

7.6 Troubleshooting ........................................................................................................................... 7-10

7.6.1 Fault Description ................................................................................................................. 7-10

7.6.2 Fault Handling .................................................................................................................... 7-10

8 Parameters.................................................................................................................................. 8-1

9 Counters ...................................................................................................................................... 9-1

10 Glossary .................................................................................................................................. 10-1

11 Reference Documents ......................................................................................................... 11-1



eRAN

PCI Conflict Detection and Self-Optimization 1 Introduction



1-1

1 Introduction

1.1 Scope

This document describes the LOFD-002007 PCI Collision Detection & Self-Optimization feature in termsof how it works, how it relates to other features, and how it affects the network. This document alsoprovides engineering guidelines for this feature.

The MOs, parameters, alarms, and counters mentioned in this document match with the latest softwarerelease. For detailed information, refer to the product documentation delivered with the latest software.

1.2 Intended Audience

This document is intended for:

Personnel who need to understand physical cell identifier (PCI) conflict detection and self-optimization

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

1.3 Change History

Document Issues

The document issues are as follows:

03 (2012-09-20)

02 (2012-05-11)

01 (2012-03-30)

Draft A (2012-01-10)

03 (2012-09-20)

Compared with issue 02 (2012-05-11) of eRAN3.0, issue 03 (2012-09-20) of eRAN3.0 includes thefollowing changes.

ChangeType

Change Description Parameter Change

Featurechange

Added contents related toX2BasedUptENodeBCfgSwitch .For details, see section 3.2 "PCIConflict Detection Methods."

Added the parameterX2BasedUptENodeBCfgSwitch .

Editorialchange

None None

02 (2012-05-11)

Compared with issue 01 (2012-03-30) of eRAN3.0, issue 02 (2012-05-11) of eRAN3.0 includes thefollowing changes.

Change Type Change Description Parameter Change

Feature change None None



eRAN

PCI Conflict Detection and Self-Optimization 1 Introduction



1-2


Editorial change Revised the following sections:

Impact on System Capacity in

sections 6.1 "PCI Conflict Detection" and 6.2 "PCI Self-Optimization"

7.1.1 "PCI Conflict Detection"

7.5.1 "Monitoring"

None

01 (2012-03-30)

This is the first official release.

Compared with draft A (2012-01-10) of eRAN3.0, issue 01 (2012-03-30) of eRAN3.0 includes thefollowing changes.


Feature change None None

Editorial change Revised chapter 7 "EngineeringGuidelines."

None

Draft A (2012-01-10)

This is a draft.

Compared with issue 01 (2011-09-15) of eRAN2.2, draft A (2012-01-10) of eRAN3.0 includes thefollowing changes.


Featurechange

Added application scenarios, where someengineering parameters are not configured orthe cells use compressed bandwidth.

None

Added the ANR-based proactive PCI conflictdetection function. ANR stands for automaticneighbor relation.

Added the following parameters:

ActivePCIConfl ictSwitch

ANR.StartTime ANR.StopTime

Editorialchange

This document is derived from ANRManagement Feature Parameter Description ofeRAN2.2 and provides more details onimplementation principles and engineeringguidelines.

None



eRAN

PCI Conflict Detection and Self-Optimization

2 Overview of PCI Conflict Detection and

Self-Optimization



2-1

2 Overview of PCI Conflict Detection andSelf-Optimization

Physical cell identifiers (PCIs) are used for signal synchronization and random access. There are 504PCIs in the LTE system. These PCIs are divided into 168 groups, each containing 3 PCIs.

Each evolved universal terrestrial radio access network (E-UTRAN) cell is allocated a PCI. When manycells exist in an LTE system, some cells must share one PCI. A PCI conflict between neighboring cellsmay occur if PCIs are planned inappropriately or changed manually, or if neighboring cell parameters aremodified.

To solve this problem, Huawei developed the PCI conflict detection and self-optimization feature. It helpsdetect and resolve the PCI conflict between neighboring cells, allocate optimized PCIs to conflicting cells,and therefore reduce service drop rates.

Figure 2-1 shows a networking example for PCI conflict detection and self-optimization based on theM2000.

Figure 2-1 Networking example for PCI conflict detection and self-optimization based on the M2000

Table 2-1 lists the functions of network components.

Table 2-1 Functions of network componentsNetwork Component Function

UE UEs report measurement results to eNodeBs during PCI conflict detectionbased on ANR.

eNodeB eNodeBs check for PCI conflicts separately and report the PCI conflictinformation about the detected and resolved PCI conflicts to the M2000.

M2000 The M2000 allocates new PCIs to cells that experience PCI conflicts andsends the PCIs to eNodeBs.



eRAN

PCI Conflict Detection and Self-Optimization

2 Overview of PCI Conflict Detection and

Self-Optimization



2-2

NOTE

If the eCoordinator has started a PCI self-optimization task, it can detect and display the PCI self-optimization task runningon the M2000.



eRAN

PCI Conflict Detection and Self-Optimization 3 PCI Conflict Detection



3-1

3 PCI Conflict Detection

3.1 PCI Conflict Types

The PCI conflict is classified into PCI collision and PCI confusion.

3.1.1 PCI Collision

A PCI collision occurs between two intra-frequency cells that use an identical PCI but are insufficientlyisolated. In this case, UEs in the overlapping area of the two cells cannot implement signalsynchronization or decoding. Figure 3-1 shows a PCI collision between cell A and cell B.

Figure 3-1 PCI collision

If a cell has the same frequency and PCI as one of its configured neighboring cells, there is a PCI

collision between the cell and the neighboring cell.

3.1.2 PCI Confusion

A PCI confusion occurs between a detected cell and a neighboring cell if the two cells have the samefrequency and PCI and if the reference signal received power (RSRP) of the two cells reaches thehandover threshold. The PCI confusion may lead to UE handover failures or service drops.

A PCI confusion occurs in the following scenarios:

The detected cell is a configured neighboring cell of the serving cell, as shown in Figure 3-2.

Figure 3-2 PCI confusion when the detected cell is a configured neighboring cell





eRAN




3-3

NOTE

For details about NCLs and NRTs, see ANR Management Feature Parameter Description.

Before changing the configuration of an eNodeB through the CME, turn off X2BasedUptENodeBCfgSwitch to avoidconfiguration data loss. This is because when the configuration (such as the PCI or frequency) of an eNodeB is changed

on the CME, the CME updates the parameters of the eNodeB in the neighboring cell list (NCL), which triggers PCI conflictdetection and may change neighboring cell data. This conflicts with the neighboring cell data change triggered whenX2BasedUptENodeBCfgSwitch is turned on.

3.2.1 PCI Conflict Detection Triggered by eNodeB ParameterAdjustment

The eNodeB detects PCI conflicts when the following adjustments are made to its parameters:

If the PCI or frequency of an eNodeB's local cell is changed, the eNodeB checks for PCI collisionsbetween the local cells or between the local cell and the neighboring cell configured in the NCL.

If a neighboring cell of an eNodeB's local cell is added or removed, or if the PCI or frequency of aneighboring cell is changed, the eNodeB checks for PCI collisions between the local cell and theneighboring cell or for PCI confusions between the neighboring cells of the local cell.

NOTE

The eNodeB checks only the neighboring cells contained in the NCL and NRTs, not other cells.

3.2.2 PCI Conflict Detection Based on ANR

ANR is a self-optimization function. It automatically ensures complete and correct neighbor relationshipsand therefore helps reduce abnormal handovers and improve network performance. This sectiondescribes two methods for PCI conflict detection based on ANR.

PCI Conflict Detection Triggered by Intra-RAT ANR

The eNodeB uses the intra-RAT ANR function (event-triggered ANR or fast ANR) to detect missingneighboring cells and PCI conflicts between the local cells and their neighboring cells. This function iscontrolled by the switches IntraRatEventAnrSwitch and IntraRatFastAnrSwitch under the AnrSwi tch parameter. If the switches are turned on, the intra-RAT ANR functions are enabled. For details, see ANRManagement Feature Parameter Description.

The eNodeB checks for PCI conflicts by using the ANR functions in the following situations:

The eNodeB detects missing neighboring cells based on UE measurements.

− If a detected cell has a different PCI or ECGI from the configured neighboring cell of the serving cell,the eNodeB adds the detected cell to the NCL and NRT and triggers PCI conflict detection. However,if fast ANR is used, the eNodeB does not add the detected cell to the NRT.

− If a detected cell has the same ECGI as but a different PCI or frequency from the configuredneighboring cell of the serving cell (that is, there is inconsistency between the configured and actualvalues), the eNodeB updates the PCI or frequency of the detected cell and triggers PCI conflictdetection.

NOTE

An ECGI uniquely identifies an E-UTRAN cell. If a detected cell has the same ECGI as a configured neighboring cell, thetwo cells are the same cell.

The ANR function detects missing neighboring cells based on the measurement results and only considers cells that havedifferent PCIs from the configured neighboring cells. Therefore, a cell added to the NCL does not have a PCI conflict witha serving cell or a configured neighboring cell of the serving cell, but it possibly has a PCI conflict with other local cells ofthe eNodeB that serves the serving cell.



eRAN




3-4

The eNodeB detects missing neighboring cells based on UE history information. If the source cell foran incoming handover has a different ECGI from any configured neighboring cell of the target cell, theeNodeB configures the source cell as a neighboring cell of the target cell and triggers PCI conflictdetection.

Proactive PCI Conflict Detection Based on ANR

Proactive PCI conflict detection is used to detect PCI confusion between configured and unconfiguredneighboring cells.

Proactive PCI conflict detection based on ANR is controlled by the ActivePCIConfl ictSwitch parameter. After this switch is turned on, the eNodeB proactively checks for PCI conflict over the period specified byANR.StartTime and ANR.StopTime .

Figure 3-4 shows the procedure for proactive PCI conflict detection based on ANR.

Figure 3-4 Proactive PCI conflict detection based on ANR

In a detection period, the procedure for proactive PCI conflict detection based on ANR is as follows:

1. The eNodeB chooses UEs that support ANR and initially access the network. Then, the eNodeBsends measurement configurations related to events A3 and A4, requesting the UEs to measure allE-UTRAN frequencies configured on the eNodeB.

NOTE

Events A3 and A4 used in proactive PCI conflict detection are more easily triggered than those used in handovers.

2. Each of the chosen UEs reports information about the neighboring cell with the highest handoverpriority to the eNodeB of the serving cell. This priority is determined by the RSRP and cell individualoffset (CIO).

NOTE

The following steps use one UE as an example.

3. The eNodeB sends a measurement configuration to the UE based on the received measurementreport, requesting the UE to report the parameters of this best neighboring cell. These parametersinclude the ECGI, tracking area code (TAC), and public land mobile network (PLMN) ID list.

4. The UE reports these parameters to the eNodeB.

5. The eNodeB performs the following operations:

If the ECGI of this best neighboring cell differs from the ECGI of the configured best neighboring cell ofthe serving cell, the eNodeB adds this best neighboring cell (with the measured PCI, ECGI, and



eRAN




3-5

frequency) to the NCL and adds the neighbor relation to the NRT. Then, the eNodeB starts PCI conflictdetection.

If the ECGI of this best neighboring cell equals the ECGI of the configured best neighboring cell of theserving cell but the corresponding PCI is different from the configured one, the eNodeB updates the

PCIs in the NCL and then starts PCI conflict detection.If the serving cell has multiple neighboring cells with the same frequency and PCI but different ECGIs,the eNodeB can detect PCI conflicts.

3.2.3 PCI Conflict Detection Based on X2 Messages

If an X2 interface is set up or an eNodeB parameter changes after the X2 interface is set up, theeNodeBs involved are notified through the X2 interfaces.

PCI Conflict Detection Based on X2 Setup Messages

During the setup of an X2 interface, the source eNodeB sends an X2 Setup Request message to thetarget eNodeB. If the request is acceptable, the target eNodeB sends an X2 Setup Response messageto the source eNodeB. The request message contains information about the local cells of the sourceeNodeB. This information includes the ECGI, PCI, and frequency.

Figure 3-5 shows the X2 setup signaling procedure.

Figure 3-5 X2 setup signaling procedure

As shown in Figure 3-5, after eNodeB 2 receives the X2 Setup Request message, it checks whether theNCL contains information about the local cells of eNodeB 1. If the NCL does not contain such informationand X2BasedUptENodeBCfgSwitch is turned on for eNodeB 2, eNodeB 2 adds these cells to the NCLand checks whether their PCIs collide with the PCIs of the local cells of eNodeB 2.

After eNodeB 1 receives the X2 Setup Response message, it checks whether the NCL containsinformation about the local cells of eNodeB 2. If the NCL does not contain such information andX2BasedUptENodeBCfgSwitch is turned on for eNodeB 1, eNodeB 1 adds these cells to the NCL andchecks whether their PCIs collide with the PCIs of the local cells of eNodeB 1.

PCI Conflict Detection Based on X2 eNodeB Configuration Update Messages

If the parameters of a source eNodeB, such as the PCI, TAC, and neighboring cell information of theserving cell, are changed, this eNodeB sends an X2 eNodeB Configuration Update message to itsneighboring eNodeBs (target eNodeBs) through X2 interfaces. Based on this message, the targeteNodeB updates its neighboring cell information. The message contains information about the local cellof the source eNodeB, including CGI, PCI, and frequency, based on which the target eNodeB updates itsneighboring cell information.

Figure 3-6 shows the signaling procedure for an X2 eNodeB configuration update.



eRAN




3-6

Figure 3-6 Signaling procedure for an X2 eNodeB configuration update

As shown in Figure 3-6, after eNodeB 2 receives an X2 eNodeB Configuration Update message fromeNodeB 1, eNodeB 2 updates the corresponding parameters and checks for PCI conflict as follows ifX2BasedUptENodeBCfgSwitch is turned on for eNodeB 2:

Checks whether there is PCI collision between the local cells of eNodeB 2 and their neighboring cells.

Checks whether there is PCI confusion between the neighboring cells of the local cells of eNodeB 2.

If the NCL on eNodeB 2 does not contain information about the local cells of eNodeB 1 andX2BasedUptENodeBCfgSwitch is turned on for eNodeB 2, eNodeB 2 adds these cells to the NCL andchecks for PCI collisions between the local cells of eNodeB 1 and the local cells of eNodeB 2.



eRAN

PCI Conflict Detection and Self-Optimization 4 PCI Self-Optimization



4-1

4 PCI Self-Optimization

4.1 Overview

If the eNodeB detects that the PCI of a cell conflicts with a configured PCI, the eNodeB notifies theM2000 of the conflict. The M2000 then allocates an appropriate PCI to this conflicting cell. The new PCItakes effect after the M2000 sends it to the eNodeB.

PCI self-optimization applies to 3900 series base stations and the BTS3202E. It also applies when somenetwork element (NE) engineering parameters are not configured or the cells use compressedbandwidth. These parameters include longitude, latitude, azimuth, and beamwidth.

4.2 Related Concepts

4.2.1 First-Order Neighboring Cell

Each eNodeB stores an NCL and NRTs. The NCL and NRTs contain information about the neighboringcells of the local cells of this eNodeB. These neighboring cells are the first-order neighboring cells.These cells may be intra-frequency, inter-frequency, or inter-RAT neighboring cells. RAT is short for radioaccess technology.

NOTE

For details about NCLs and NRTs, see ANR Management Feature Parameter Description.

4.2.2 Second-Order Neighboring Cell

The first-order neighboring cells of the first-order neighboring cells of a cell are the second-orderneighboring cells of this cell. Assume that cell B is a first-order neighboring cell of cell A and cell C is afirst-order neighboring cell of cell B. Then, cell C is a second-order neighboring cell of cell A.

4.2.3 Bidirectional Neighboring Cell

If two cells are first- or second-order neighboring cells of each other, they are bidirectional neighboringcells.

4.2.4 PCI Self-Optimization Principles

PCI self-optimization preferentially allocates an appropriate PCI to a cell with the highest conflict leveland then (if necessary) performs a similar operation on another cell until all PCI conflicts are eliminatedor no further self-optimization can be performed. The conflict level of a cell is calculated by PCIself-optimization based on the number of cells whose PCIs conflict with the PCI of this cell. PCI

self-optimization adheres to the following principles:

NOTE

For simplicity, the following uses "new PCI" to represent a PCI to be allocated to a conflicting cell.

A new PCI must be different from the PCI of any first-order or bidirectional second-orderintra-frequency neighboring cell of the conflicting cell. If the new PCI is the same as the PCI of anothercell, the two cells must be as far apart as possible, with as many eNodeBs as possible between thetwo cells.

A new PCI must be different from the PCI of any blacklisted intra-frequency cell of the conflicting cell. Ifthe conflicting cell is not in the intra- or inter-frequency cell blacklist of any of its first-order neighboringcells, the new PCI must be different from the PCI of any of these blacklisted cells. The UE does notmeasure the blacklisted cells so that the previously detected conflicting cells are still detectable afterPCI self-optimization.



eRAN

PCI Conflict Detection and Self-Optimization 4 PCI Self-Optimization



4-2

The PCIs of three cells with adjacent azimuths under an eNodeB must have different primarysynchronization codes. That is, these cells must have different primary synchronization signals.

In addition, PCI self-optimization considers the following factors:

Positions of physical resource blocks (PRBs) occupied by the physical HARQ indicator channel(PHICH) and physical control format indicator channel (PCFICH)

If the conflicting cell uses compressed bandwidth, the M2000 avoids allocating some restricted PCIs tothe conflicting cell. This prevents the PHICH and PCFICH from being allocated nonexistent PRBs.

Frequency-domain positions of downlink reference signals

If downlink reference signals are transmitted on the same frequency-domain position in neighboringcells, the quality of these signals is poor when the network load is low. To separate these signals, theM2000 allocates the most appropriate PCI to the conflicting cell if required engineering parameters areconfigured.

If the conflicting cell is not allocated a new PCI in a self-optimization period, this cell still uses the old PCI,and the M2000 does not display this PCI as a suggested PCI.



eRAN

PCI Conflict Detection and Self-Optimization 5 Related Features



5-1

5 Related Features

5.1 Required Features

PCI conflict detection based on intra-RAT ANR requires the support of the feature LOFD-002001 Automatic Neighbor Relation (ANR).

The eNodeB updates the configuration based on X2 messages and triggers PCI conflict detection onlywhen X2BasedUptENodeBCfgSwitch is turned on.

Other methods for PCI conflict detection and self-optimization do not depend on other features.

5.2 Mutually Exclusive Features

None

5.3 Affected Features

None



eRAN

PCI Conflict Detection and Self-Optimization 6 Impact on the Network



6-1

6 Impact on the Network

6.1 PCI Conflict Detection

Impact on System Capacity

PCI conflict detection based on ANR affects system capacity. To detect PCI conflicts, UEs need toperform measurements to obtain ECGIs in discontinuous reception (DRX) mode. The UEs inmeasurements cannot be scheduled, and this affects uplink and downlink throughput. Other methods forPCI conflict detection have no impact on system capacity.

Impact on Network Performance

eNodeBs' delivery and handling of measurement information occupies system resources such as centralprocessing unit (CPU) and memory, affecting network performance.

6.2 PCI Self-Optimization

Impact on System Capacity

PCI self-optimization has no adverse impact on system capacity. However, after the eNodeB receives anew PCI allocated to a cell, the eNodeB needs to block and then unblock this cell to make the PCI takeeffect. This process affects UEs' access to the cell, normal services, and handovers, and thereforereduces access and handover success rates.

PCI self-optimization can reduce or eliminate PCI conflicts between a cell and its neighboring cells andbetween the neighboring cells of a cell. This reduces service drops.

Impact on Network Performance

To make a new PCI take effect, the eNodeB needs to block and then unblock the cell. This processdisables the cell.

NOTE

After the PCI of a cell is manually changed, the cell is automatically blocked and then unblocked.



eRAN

PCI Conflict Detection and Self-Optimization 7 Engineering Guidelines



7-1

7 Engineering Guidelines

7.1 When to Use PCI Conflict Detection and Self-Optimization

7.1.1 PCI Conflict Detection

PCI conflict detection can be enabled by using the following methods:

PCI conflict detection triggered by eNodeB parameter adjustment

This is a basic method of PCI conflict detection. This function is enabled by default.

PCI conflict detection based on X2 messages

Changes in neighboring cell information and PCIs of neighboring cells will trigger PCI conflict detection,and the change messages are carried over the X2 interfaces if X2BasedUptENodeBCfgSwitch isturned on or the NE configuration is changed through the CME.

PCI conflict detection based on ANR

− PCI conflict detection based on intra-RAT event-triggered ANR

This function is enabled based on the intra-RAT event-triggered ANR function.

− Proactive PCI conflict detection based on ANR

When there are a large number of UEs in the network, especially at the cell boundaries, PCI conflictsare more likely to occur. Therefore, this function is enabled for cells that experience high service droprates when serving a large number of UEs.

7.1.2 PCI Self-Optimization

PCI self-optimization is implemented on the M2000 client. PCI self-optimization starts only after a PCIself-optimization task is created on the M2000 client. A PCI conflict can be reduced or resolved only after

an optimized PCI is delivered to the eNodeB. Therefore, it is recommended that PCI self-optimization beenabled.

It is also recommended that the M2000 deliver the optimized PCI in low-traffic hours because cells willbe automatically blocked during the delivery. The interval between the time that a PCI self-optimizationtask is started and the time that an optimized PCI is delivered should not be too long. This ensures thatthe PCI is optimized based on the latest PCI conflict information.

NOTE

Before manually starting a PCI self-optimization task, you can view the PCI conflict information on the M2000 client. If theinformation is not frequently updated, you can start the PCI self-optimization task. Note that the M2000 should not deliverPCIs during a PCI self-optimization process.

7.2 Information to Be CollectedN/A

7.3 Network Planning

7.3.1 RF Planning

N/A

7.3.2 Network Topology

N/A



eRAN




7-2

7.3.3 Hardware Planning

N/A

7.4 Deploying PCI Conflict Detection and Self-Optimization

7.4.1 Deployment Requirements

PCI Conflict Detection

Operators must purchase and activate the following license.

Table 7-1 PCI conflict detection license control item

Feature License Control Item Name License Control Item ID

LOFD-002007 PCI CollisionDetection & Self-Optimization

PCI Collision Detection andSelf-Optimization

LLT1PCISO01

Proactive PCI conflict detection based on ANR requires that UEs on the network must supportdiscontinuous reception (DRX) and ANR-related measurements on intra-frequency or inter-frequencyneighboring cells.

PCI Self-Optimization

The M2000 must be V200R012C00B007 or a later version.

7.4.2 Data Preparation


Data to be collected for PCI conflict detection is as follows:

(Optional) PCI conflict alarm switch

Table 7-2 describes the PCI conflict alarm switch.

Table 7-2 PCI conflict alarm switch

Parameter Name Parameter ID Setting Description Source

PCI conflict alarmswitch

PCICONFLICTALMSWITCH When the PCI conflictalarm switch is turned on,

the eNodeB reports the PCIconflict alarm to the M2000alarm console when a PCIconflict is detected.

User-defined


N/A

PCI conflict detection based on X2 messages



eRAN




7-3

If X2BasedUptENodeBCfgSwitch is turned on or if NE configuration (such as the PCI and frequency) ischanged through the CME, the neighboring cell PCI conflict detection will be triggered. Table 7-3 lists theinformation of X2BasedUptENodeBCfgSwitch .

Table 7-3 Switch for controlling NE configuration update based on X2 messages

Parameter Name Parameter ID Setting Description Source

Update eNBConfiguration Via X2Switch

X2BasedUptENodeBCfgSwit

ch

This switch determineswhether the eNodeBautomatically updates theconfiguration ofneighboring cells based onthe messages receivedover the X2 interface. Themessages include X2SETUP REQUEST, X2SETUP RESPONSE, and

ENB CONFIGURATIONUPDATE. Before changingthe eNodeB configurationby using the CME, turn offthis switch to disableautomatic update. If thisswitch is turned on, theconfiguration data may belost or become abnormalduring the automaticupdate.

User-defined

Proactive PCI conflict detection based on ANR

Table 7-4 describes the parameters associated with proactive PCI conflict detection based on ANR.

Table 7-4 Parameters associated with proactive PCI conflict detection based on ANR

ParameterName

Parameter ID Setting Description Source

ANR Active PCIConflictDetection Switch

ActivePCIConfl ictSwitch If this switch is turned on at the timespecified for proactive PCI conflictdetection, proactive PCI conflictdetection based on ANR is enabled.

If this switch is turned off, proactivePCI conflict detection based on ANR isdisabled.

It is recommended that this switch beturned on for cells that experiencehigh service drop rates or low outgoinghandover success rates.

User-defined



eRAN




7-4

ParameterName

Parameter ID Setting Description Source

Start time ANR.StartTime This parameter specifies the start timeof proactive PCI conflict detection.

If ActivePCIConfl ictSwitch is set toON(On), the proactive PCI conflictdetection is started at the timespecified by this parameter.

It is recommended that proactive PCIconflict detection based on ANR bestarted when there are many UEs onthe network. This is because PCIconflict is easier to detect at that time.

User-defined

Stop time ANR.StopTime This parameter specifies the stop timeof proactive PCI conflict detection.

If ActivePCIConfl ictSwitch is set toON(On), the proactive PCI conflictdetection is stopped at the timespecified by this parameter.

Similar to ANR.StartTime , it isrecommended that proactive PCIconflict detection based on ANR bestopped when there are many UEs onthe network.

User-defined


None

7.4.3 Precautions

None

7.4.4 Hardware Adjustment

N/A

7.4.5 Initial ConfigurationThe initial configuration of PCI conflict detection and self-optimization involves the following processes:

Activating proactive PCI conflict detection on the eNodeB

Creating PCI self-optimization tasks on the M2000 client


The initial configuration of PCI conflict detection is as follows:


N/A

PCI conflict detection triggered based on X2 messages



eRAN




7-5

Run the MML command MOD GLOBALPROCSWITCH with X2BasedUptENodeBCfgSwitch set toON(On).


Run the MML command MOD ANR to set the ActivePCIConfl ictSwitch , ANR.StartTime , and

ANR.StopTime parameters. (Optional) PCI conflict alarm reporting

Run the MML command MOD ENODEBALGOSWITCH with PciConf l ictAlmSwitch set to ON(On).Then, the eNodeB reports an alarm to the M2000 alarm console when it detects a PCI conflict.


The initial configuration procedure for PCI self-optimization is as follows:

Step 1 On the M2000 client, choose Configuration > LTE Self Optimization > PCI ConflictOptimization.

The PCI Conflict Optimization window is displayed, as shown in Figure 7-1.

Figure 7-1 PCI Conflict Optimization window

Step 2 Click the refresh button in the PCI Collision Information area.

The PCI conflict information reported by all eNodeBs is displayed. There are four buttons in theOptimization Task area: refresh, launch, stop, and modify task, as shown in Figure 7-2.



eRAN




7-6

Figure 7-2 Optimization Task area

Step 3 Click the launch button.

The dialog box for setting the Optimization Analysis Mode and Optimization Implementation

Mode parameters is displayed, as shown in Figure 7-3.

Figure 7-3 Optimization modes

Table 7-5 describes the Optimization Analysis Mode and Optimization Implementation Modeparameters.

Table 7-5 Optimization Analysis Mode and Optimization Implementation Mode parameters

ParameterName

Setting Description

Optimization Analysis Mode

If this parameter is set to Immediate, a PCI self-optimization task is immediatelystarted.

If this parameter is set to Periodic, a PCI self-optimization task is started at a fixed

time every day. This setting is also used to automatically start a PCIself-optimization task. The interval between the time that a PCI self-optimizationtask is started and the time that an optimized PCI is delivered should not be toolong. This ensures that the PCI is optimized based on the latest PCI conflictinformation.



eRAN




7-7

ParameterName

Setting Description

OptimizationImplementationMode

If this parameter is set to Manual, the optimized PCIs need to be manuallydelivered after the PCI self-optimization process is complete. This setting is usedfor querying PCI self-optimization results. The interval between the time that a PCIself-optimization task is started and the time that an optimized PCI is deliveredshould not be too long. This ensures that the PCI is optimized based on the latestPCI conflict information.

If this parameter is set to Immediate, the optimized PCIs will be immediatelydelivered after the PCI self-optimization process is complete. This setting is usedfor immediate delivery of PCIs.

If this parameter is set to Periodic, the latest optimized PCI is delivered at a fixedtime every day. The time for Deliver PCI must be set within the period specified forPCI Optimization to prevent optimized PCIs from being delivered during theoptimization. It is recommended that the optimized PCIs be delivered in low-traffic

hours. The interval between the time that a PCI self-optimization task is started andthe time that an optimized PCI is delivered should not be too long. This ensures thatthe PCI is optimized based on the latest PCI conflict information.

----End

7.4.6 Commissioning

N/A

7.4.7 Activation ObservationPCI Conflict Detection

To verify the activation of PCI conflict detection, use either of the following methods:

If PciConf l ictAlmSwitch set to ON(On), check whether a PCI conflict alarm is reported to the M2000alarm console. If the alarm is reported, the PCI conflict detection function is successfully activated.

On the M2000 client, open the PCI Conflict Optimization window and click the refresh button in thePCI Collision Information area, as shown in Figure 7-4. You can also choose Configuration > LTESelf Optimization > Query SON Log. Select PCI Conflict Optimization Log under Log Category and Not Limited under Event Name, Event Source, and Time. Then click Query. If all theinformation is displayed, the PCI conflict detection function is successfully activated.

NOTE

The SON log information on the M2000 client is automatically synchronized once a day. You can also click Synchronize at the lower right corner of the Query SON Log window to manually synchronize SON logs, as shown in Figure 7-5.



eRAN




7-8

Figure 7-4 PCI conflict information

Figure 7-5 PCI conflict optimization log


The M2000 generates optimization suggestions after the PCI self-optimization process is complete. Ifthese optimization suggestions can be queried, the PCI conflict detection function is successfullyactivated. There are two types of optimization suggestions:

If the M2000 delivers a new PCI for the cell that experiences PCI conflicts, the recommended PCI isdisplayed under Recommended PCI in the PCI Collision Neighboring Cell area and the followinginformation is displayed under Optimization Advice: the cell assigned a new PCI, the cell's originalPCI and the new PCI.

If the M2000 does not deliver a new PCI for the cell, Not Set is displayed under Recommended PCI in the PCI Collision Neighboring Cell area, and no information is displayed under OptimizationAdvice, as shown in Figure 7-7.



eRAN




7-9

Figure 7-6 PCI conflict information

Figure 7-7 Optimization advice

7.4.8 Reconfiguration

N/A

7.4.9 Deactivation

The deactivation of PCI conflict detection is as follows:

PCI conflict detection triggered by eNodeB parameter adjustment or based on X2 messages

N/A


Run the MML command MOD ANR with ActivePciConf l ictSwitch set to OFF(Off).

(Optional) PCI conflict alarm reporting

Run the MML command MOD ENODEBALGOSWITCH with PciConf l ictAlmSwitch set to OFF(Off).The eNodeB does not report an alarm to the M2000 alarm console when it detects a PCI conflict.

7.5 Performance Optimization

7.5.1 Monitoring

You can monitor the performance of the PCI conflict detection and self-optimization feature by checkingthe service drop rates: Call Drop Rate(all) and Call Drop Rate(VoIP).

If the service drop rate decreases, the performance of the feature that has been activated is satisfactory;otherwise, the performance is unsatisfactory.



eRAN




7-10

7.5.2 Parameter Optimization

PCI conflict detection triggered by eNodeB parameter adjustment or based on X2 messages

N/A

Proactive PCI conflict detection based on ANRThe ANR.StartTime and ANR.StopTime parameters need to be optimized. For recommendedsettings of these parameters, see section 7.4.2 "Data Preparation."

7.6 Troubleshooting

7.6.1 Fault Description

A PCI conflict is manually detected between neighboring cells or between a neighboring cell and asource cell, but the PCI conflict detection and self-optimization feature cannot solve this problem.

7.6.2 Fault Handling

To clear the fault, perform the following steps:

Step 1 On the M2000 client, check whether the PCI conflict information is displayed.

Open the PCI Conflict Optimization window and click the refresh button in the PCI CollisionInformation area.

− If the PCI conflict information is not displayed, go to Step 2.

− If the PCI conflict information is displayed, go to Step 3.

Step 2 Check the NCL of the eNodeB of the source cell and the NRT of the source cell. Determinewhether the neighboring cell parameters are updated or PCI conflict detection at the eNodeB isineffective.

If the following conditions are met:

− There is a PCI conflict between neighboring cells of the source cell, and at least one conflicting cell isthe external cell of the source cell.

− There is a PCI conflict between the source cell and its neighboring cell, and the neighboring cell is theexternal cell of the source cell.

Then check whether the PCI of the conflicting cell in the NCL is consistent with the configuredneighboring cell parameter and is identical to the conflicted PCI.

If the PCI of the conflicting cell in the NCL is inconsistent with the configured neighboring cellparameter, update the PCI in the NCL.

Otherwise, contact Huawei technical support.

NOTE

Run the MML command LST CELL to query the configured parameters of the cell.

Run the MML command LST EUTRANEXTERNALCELL to query the NCL.

Run the MML command LST EUTRANINTRAFREQNCELL to query the intra-frequency neighboring cell relationship.

Run the MML command LST EUTRANINTERFREQNCELL to query the inter-frequency neighboring cell relationship.

Step 3 Check the PCI self-optimization task status to determine whether the task is running properly.

If... Then...

A PCI self-optimization task is not created Create a PCI self-optimization task. For details, see

7.4.5 "Initial Configuration."



eRAN




7-11

If... Then...

A PCI self-optimization task has been createdand is running properly, and the optimizationsuggestion is generated

Go to Step 4.

A PCI self-optimization task has been createdand its Optimization Implementation Mode is set to Daily Scheduled, but the task failedto start as scheduled

Contact Huawei technical support.

A PCI self-optimization task has been createdand its Optimization Implementation Mode is set to Immediate, but the task failed to startimmediately

Contact Huawei technical support.

Other faults occur Contact Huawei technical support.

Step 4 Check whether the PCI optimization suggestions are displayed.

− If the PCI optimization suggestions are displayed but PCI conflicts persist on the network, newPCI conflicts may occur during the optimization or the M2000 may fail to deliver an appropriatePCI for the conflicting cells in the last optimization. To solve this problem, you can removesome neighboring cells that are not used as handover cells or add some available PCIs for anew PCI self-optimization task.

− If the PCI optimization suggestions are not displayed, contact Huawei technical support.

NOTE

The M2000 can display the PCI delivery status.

----End



eRAN

PCI Conflict Detection and Self-Optimization 8 Parameters



8-1

8 Parameters

Table 8-1 Parameter description

MO Parameter ID MML Command Feature ID FeatureName Description

ANR ActivePciConflictSwitch

MOD ANR

LST ANR

LOFD-002001 /TDLOFD-002001

AutomaticNeighbourRelation(ANR)

Meaning:Indicates theswitch used to enable ordisable proactive PCIconflict detection. Withina specified duration afterthis switch is turned on,the eNodeB deliversmeasurementconfigurations forproactive PCI conflict

detection to UEs thatmeet specificrequirements. Then, theeNodeB starts thedetection based on themeasurement reportsfrom the UEs.

GUI ValueRange:OFF(Off),ON(On)

Unit:None

Actual ValueRange:OFF, ON

Default Value:OFF(Off)

ENodeBAlgoSwitch

AnrSwitch MODENODEBALGOSWITCH

LSTENODEBALGOSWITCH

LOFD-002001 /TDLOFD-002001

LOFD-002002 /TDLOFD-002002


Inter-RAT ANR

Meaning:Indicates the ANR algorithm switch.Switches related to ANRare described asfollows:IntraRatEventAnrSwitch

: If this switch is turnedon, intra-RATevent-triggered ANR isenabled to constructand optimize intra-RATneighboring relations bytriggering intra-RAThandover events.IntraRatFastAnrSwitch:If this switch is turnedon, intra-RAT fast ANRis enabled to constructand optimize intra-RATneighboring relations by



eRAN




8-2

MO Parameter ID MML Command Feature ID FeatureName

Description

performing periodicintra-RAT

measurements.IntraRatAnrAutoDelSwitch: If bothIntraRatEventAnrSwitchand this switch areturned on and NoRemove of an intra-RATneighboring relation (aflag in the neighboringrelation table) is set toFalse, automaticremoval of the intra-RAT

neighboring relation isallowed. If this switch isturned off, automaticremoval of the intra-RATneighboring relation isprohibited.UtranEventAnrSwitch: Ifthis switch is turned on,event-triggered ANRwith UTRAN is enabledto construct andoptimize inter-RATneighboring relationswith UTRAN cells bytriggering events forinter-RAT handovers toUTRAN.GeranEventAnrSwitch:If this switch is turnedon, event-triggered ANRwith GERAN is enabledto construct andoptimize inter-RATneighboring relationswith GERAN cells by

triggering events forinter-RAT handovers toGERAN.UtranFastAnrSwitch: Ifthis switch is turned on,fast ANR with UTRAN isenabled to constructand optimize inter-RATneighboring relationswith UTRAN cells byperforming periodicinter-RAT

measurements on



eRAN




8-3


Description

UTRAN. The eNodeBdoes not deliver

information aboutexternal UTRAN cells inthe measurementconfiguration to UEsand the UEs measureonly neighboringUTRAN cells containedin the measurementconfiguration.Therefore, if you wantexternal UTRAN cellsadded by fast ANR with

UTRAN to be measuredin handovers, you areadvised to turn onUtranEventAnrSwitch aswell.

GeranFastAnrSwitch: Ifthis switch is turned on,fast ANR with GERAN isenabled to constructand optimize inter-RATneighboring relationswith GERAN cells by

performing periodicinter-RATmeasurements onGERAN.CdmaFastAnrSwitch: Ifthis switch is turned on,fast ANR withCDMA2000 is enabledto construct andoptimize inter-RATneighboring relationswith CDMA2000 cells by

performing periodicintra-RATmeasurements onCDMA2000 networks.UtranAutoNrtDeleteSwitch: If bothUtranEventAnrSwitchand this switch areturned on and NoRemove of theinter-RAT neighboringrelation with a UTRANcell (a flag in theneighbor relations table)



eRAN




8-4


Description

is set to False,automatic removal of

the inter-RATneighboring relation isallowed. If this switch isturned off, automaticremoval of the inter-RATneighboring relation isprohibited.GeranAutoNrtDeleteSwitch: If bothGeranEventAnrSwitchand this switch areturned on and No

Remove of theinter-RAT neighboringrelation with a GERANcell (a flag in theneighboring relationtable) is set to False,automatic removal ofthe inter-RATneighboring relation isallowed. If this switch isturned off, automaticremoval of the inter-RATneighboring relation isprohibited.CdmaAutoNrtDeleteSwitch: If this switch isturned on and NoRemove of theinter-RAT neighboringrelation with aCDMA2000 cell (a flagin the neighboringrelation table) is set toFalse, automaticremoval of the inter-RAT

neighboring relation isallowed. If this switch isturned off, automaticremoval of the inter-RATneighboring relation isprohibited.

ExtendIntraRatAnrSwitch: This switch is used tospecify whetherunknown cellscorresponding to thedetected PCIs can beconfigured as external



eRAN




8-5


Description

cells of the eNodeB byusing the eCoordinator.

If this switch is turnedon, unknown cellscorresponding to thedetected PCIs can beconfigured as externalcells of the eNodeB byusing the eCoordinatorin any of the followingscenarios: When PCIsof unknown cells aredetected by triggeringintra-RAT handover

events,IntraRatEventAnrSwitchis turned off or the UE isincapable of measuringCGIs. When PCIs ofunknown cells aredetected by performingperiodic intra-RATmeasurements, the UEis incapable ofmeasuring CGIs. If thisswitch is turned off,unknown cellscorresponding to thedetected PCIs cannotbe configured asexternal cells of theeNodeB by using theeCoordinator.

GUI ValueRange:IntraRatEventAnrSwitch,IntraRatFastAnrSwitch,IntraRatAnrAutoDelSwit

ch,UtranEventAnrSwitch,GeranEventAnrSwitch,UtranFastAnrSwitch,GeranFastAnrSwitch,CdmaFastAnrSwitch,UtranAutoNrtDeleteSwitch,GeranAutoNrtDeleteSwitch,CdmaAutoNrtDeleteSwitch,ExtendIntraRatAnrSwitc



eRAN




8-6


Description

h

Unit:None Actual ValueRange:IntraRatEventAnrSwitch,IntraRatFastAnrSwitch,IntraRatAnrAutoDelSwitch,UtranEventAnrSwitch,GeranEventAnrSwitch,UtranFastAnrSwitch,GeranFastAnrSwitch,CdmaFastAnrSwitch,

UtranAutoNrtDeleteSwitch,GeranAutoNrtDeleteSwitch,CdmaAutoNrtDeleteSwitch,ExtendIntraRatAnrSwitch

DefaultValue:IntraRatEventAnr Switch:Off,IntraRatFastAnrSwitch:Off,IntraRatAnrAutoDelSwitch:On,UtranEventAnrSwitch:Of f,GeranEventAnrSwitch:Off,UtranFastAnrSwitch:Off,GeranFastAnrSwitch:Off ,CdmaFastAnrSwitch:Off ,

UtranAutoNrtDeleteSwitch:On,GeranAutoNrtDeleteSwitch:On,CdmaAutoNrtDeleteSwitch:On,ExtendIntraRatAnrSwitch:Off

ENodeBAlgoSwitch

PciConflictAlmSwitch MODENODEBALGOSWITCH

LOFD-002007 /TDLOFD-00

PCICollisionDetection &

Self-Optimi

Meaning:Indicates theswitch for reporting PCIconflict alarms. If the

switch is turned on, the



eRAN




8-7


Description

LSTENODEBALGOS

WITCH

2007 zation PCI conflict alarm isdisplayed on the local

maintenance terminal(LMT) when a PCIcollision among externalcells or a confusionamong neighboring celloccurs. If the switch isturned off, the PCIconflict alarm is notdisplayed when such aPCI conflict actuallyoccurs.

GUI ValueRange:OFF(Off),ON(On)

Unit:None



ANR StartTime MOD ANR

LST ANR

LOFD-002001 /TDLOFD-002001


Meaning:Indicates thestart time of the activePCI conflict detection. Ifthe stop time is earlierthan or the same as thestart time, the stop timeis assumed to be thetime of the next day.

GUI ValueRange:00:00:00~23:59:59

Unit:None

Actual Value

Range:00:00:00~23:59:59

Default Value:14:00:00

ANR StopTime MOD ANR

LST ANR

LOFD-002001 /TDLOFD-002001


Meaning:Indicates thestop time of the activePCI conflict detection. Ifthe stop time is earlierthan or the same as thestart time, the stop timeis assumed to be the

time of the next day.



eRAN




8-8


Description

GUI ValueRange:00:00:00~23:59:

59

Unit:None

Actual ValueRange:00:00:00~23:59:59

Default Value:15:00:00

GlobalProcSwitch

X2BasedUptENodeBCfgSwitch

MODGLOBALPROCSWITCH

LSTGLOBALPROCSWITCH

None None Meaning:Indicateswhether the eNodeBautomatically updates

the configuration ofneighboring cells basedon the messagesreceived over the X2interface. Themessages include X2SETUP REQUEST, X2SETUP RESPONSE,and ENBCONFIGURATIONUPDATE.Before theeNodeB configuration

data is modified byusing the CME, it isrecommended that thisswitch be turned off todisable the automaticupdate. If this switch isturned on, theconfiguration data maybe lost or becomeabnormal during theautomatic update.

GUI Value

Range:OFF(Off),ON(On)

Unit:None





eRAN

PCI Conflict Detection and Self-Optimization 9 Counters



9-1

9 Counters

There are no specific counters associated with this feature.



eRAN

PCI Conflict Detection and Self-Optimization 10 Glossary



10-1

10 Glossary

For the acronyms, abbreviations, terms, and definitions, see Glossary .



eRAN

PCI Conflict Detection and Self-Optimization 11 Reference Documents

11 Reference Documents

This chapter lists the reference documents related to PCI conflict detection and self-optimization.

[1] eNodeB MO Reference

[2] ANR Management Feature Parameter Description