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LTE Radio Access, Rel. RL60,

Operating Documentation,Issue 03

Automatic Neighbor Relation(ANR)

DN0989276

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Automatic Neighbor Relation (ANR)

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Table of Contents

This document has 65 pages

Summary of changes..................................................................... 8

1 Introduction to Automatic Neighbor Relation (ANR).......................9

2 Automatic Neighbor Relation (ANR) Features............................. 10

2.1 LTE724: LTE Automatic Neighbor Cell Configuration...................11

2.2 LTE539: Central ANR...................................................................12

2.3 LTE492: Automatic Neighbor Relation (ANR).............................. 12

2.4 LTE510: Synchronization of InterRAT Neighbors.........................13

2.5 LTE783: ANR InterRAT UTRAN...................................................13

2.6 LTE784: ANR InterRAT GERAN.................................................. 132.7 LTE782: ANR Fully UE based...................................................... 14

2.8 LTE771: Optimization of Intra-LTE Neighbor Relations................14

2.9 LTE1019: SON Reports................................................................15

2.10 LTE1045: Full SON Support for Distributed Sites........................ 15

2.11 LTE1222: SON Automation Modes..............................................15

2.12 LTE507: Inter-RAT Neighbor Relation Optimization.....................15

2.13 LTE1383: Cell-specific Neighbor Relation/PCI Handling............. 16

2.14 LTE556: ANR Intra-LTE, Inter-frequency - UE Based.................. 16

2.15 LTE1708: Extend Maximum Numberof X2 Links.........................16

3 Architecture of Automatic Neighbor Relation (ANR).................... 17

4 Functional Description for ANR....................................................18

4.1 LTE724: Automatic Neighbor Cell Configuration..........................18

4.1.1 Benefits........................................................................................ 18

4.1.2 Pre-planning................................................................................. 18

4.1.3 Commissioning and integration phase of a new eNB.................. 18

4.1.4 Neighbor cell update.................................................................... 18

4.1.5 Configuration data exchange via X2............................................ 19

4.1.6 LTE724 Interaction with Common Object Model.......................... 20

4.2 LTE539: Central ANR...................................................................20

4.2.1 Functional overview..................................................................... 20

4.2.1.1 NetAct Optimizer.......................................................................... 21

4.2.1.2 NetAct Configurator......................................................................23

4.2.1.3 Integration in the auto-configuration workflow..............................23

4.3 External LTE Cell Support in NetAct............................................ 24

4.3.1 NetAct SON features support for the external LTE cells.............. 24

4.3.2 Intra-system adjacency border area management.......................25

4.3.3 External LTE cell support for the LTE492: ANR in NetAct............25

4.3.4 External LTE object support for LTE468: PCI Management inNetAct.......................................................................................... 25


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4.3.5 External LTE cell support for the LTE539: Central ANR in NetAct...26

4.3.6 External LTE cell support for the LTE581: PRACH Management inNetAct..........................................................................................26

4.4 X2 link management.................................................................... 26

4.4.1 oamControlled X2 links................................................................ 26

4.4.2 enbControlled X2 links................................................................. 26

4.4.2.1 Outgoing enbControlled X2 link (establishment triggered by theeNB)............................................................................................. 27

4.4.2.2 Incoming enbControlled X2 link (establishment triggered byneighbor eNB).............................................................................. 27

4.5 LTE1708: Extend Maximum Number of X2 Links.........................28

4.6 LTE492: Automatic Neighbor Relation(ANR) ............................. 29

4.6.1 Prerequisites................................................................................ 29

4.6.2 Functional overview/details..........................................................304.6.2.1 NetAct Optimizer: neighbor evaluation procedure....................... 32

4.6.2.2 NetAct Configurator: automated neighbor site IP connectivityconfiguration completion.............................................................. 32

4.6.2.3 Use cases....................................................................................33

4.7 Neighbor relation clean up in the NetAct......................................33

4.7.1 Optimizer: select and delete.........................................................33

4.7.2 Configurator: delete consistently..................................................34

4.8 LTE510: Synchronization of InterRAT Neighbors.........................34


4.10 LTE784: ANR InterRAT GERAN..................................................38

4.11 LTE782: ANR Fully UE based......................................................404.12 LTE771: Optimization of Intra-LTE Neighbor Relations................45

4.12.1 Functional description.................................................................. 45

4.12.1.1 RAN system level scope.............................................................. 47

4.13 LTE1019: SON Reports................................................................48

4.14 LTE1045: Full SON Support for Distributed Sites........................ 49

4.15 LTE1222: SON Automation Modes .............................................52

4.16 LTE507: Inter-RAT Neighbor Relation Optimization.....................53

4.17 LTE1383: Cell-specific Neighbor Relation/PCI Handling............. 53

4.18 LTE556: ANR Intra-LTE, Inter-frequency - UE Based..................57

5 Management data for ANR.......................................................... 58

6 Operating Tasks Related to ANR................................................. 59

6.1 LTE771: Optimization of Intra-LTE Neighbor Relations................59

6.1.1 Scheduled workflow for LTE771: Optimization of Intra-LTENeighbor Relations.......................................................................59

6.1.2 ANR Optimization.........................................................................60

6.2 LTE782: ANR - UE based............................................................ 60

6.2.1 UE-based ANR Retrieval by eNB.................................................60


6.3.1 The establishment of NR for Inter-RAT UTRAN...........................61


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6.3.2 New UTRAN neighborship generation during LTE auto-configuration.................................................................................62

6.4 LTE784: ANR InterRAT GERAN.................................................. 62

6.4.1 Establishment of NR for Inter-RAT GERAN................................. 626.4.2 New GERAN neighbor ship generation during LTE auto-

configuration.................................................................................63

6.5 LTE539: Central ANR...................................................................64

6.5.1 Central ANR for New eNBs..........................................................64


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List of FiguresFigure 1 Architecture of ANR............................................................................17

Figure 2 Configuration of neighbor cells........................................................... 19Figure 3 Border area management - info model...............................................25

Figure 4 LTE492: ANR......................................................................................29

Figure 5 LNREL deletion.................................................................................. 34

Figure 6 LTE510 Synchronization of InterRAT Neighbors................................ 35

Figure 7 LTE784: ANR InterRAT GERAN.........................................................39

Figure 8 ANR principle......................................................................................41

Figure 9 LTE771: Optimization of Intra-LTE Neighbor Relations......................47

Figure 10 Centralized and decentralized parameter change..............................49

Figure 11 LTE NRs of eNB-A for a given LTE carrier......................................... 55Figure 12 UE-based ANR Retrieval by eNB....................................................... 61


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List of TablesTable 1 ANR features...................................................................................... 11

Table 2 Minimum number of supported neighbor objects............................... 28


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Summary of changes

Changes between issues 04 (2014-03-24, RL60) and 04A (2014-06-16, RL60)

All chapters: editorial changes

The following chapters have been updated:

LTE1222: SON Automation Modes

LTE782: ANR Fully UE based

LTE771: Optimization of Intra-LTE Neighbor Relations

Changes between issues 03B (2013-12-05, RL50) and 04 (2014-03-24, RL60)

All chapters: editorial changes

The following features have been added:

LTE556: ANR Intra-LTE, Inter-frequency - UE Based

LTE1708: Extend Maximum Number of X2 Links

Changes between issues 03A (2013-09-20, RL50) and 03B (2013-12-05, RL50)

TheANR principle figure has been changed.

Summary of changes Automatic Neighbor Relation (ANR)

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1 Introduction to Automatic Neighbor Relation(ANR)

3GPP defines LTE network support for the ANR feature in 3GPP TS 32.511 Automatic

Neighbor Relation (ANR) management.

NSN supports ANR on a different level of interworking of eNB and NetAct, to give the

operator full control of the the neighbor relation management.

For all ANR functions it is the goal to provide the neighbor cell configuration data at the

source eNB to support a handover to the target eNB.

Basic X2 Link Establishment

The establishment of neighbors is based on information, which is prepared in a pre

planning phase. Only a subset of standard configuration information is required. For allneighbor cells only the Node-ID and the IP address of the neighbor LTE eNB hosting the

expected neighbor cells need to be configured by offline pre-planning. All other

configuration information for cells of neighbor LTE eNBs are automatically derived and

updated via the X2 interface. For the LTE782: ANR-UE-basedfeature, this info is

autonomously retrieved by the eNB.

ANR-Intra-LTE

If an unknown physical cell ID is reported by UE, the eNB derives the cell configuration

information of the LTE neighbor cell (that is ECGI, TAC, and supported PLMNs) with the

help of the UE. This information is stored for further use by mobility management in the

eNB.

ANR-Optimization of Intra-LTE neighbor relations

Optimization of Intra-LTE neighbor relations is a part of the overall ANR functionality. LTE

neighbor cells will be discovered and added by ANR features or manual input by the

operator.

The NetAct Optimizer evaluates all current relations between neighboring LTE cells if

they are still valid and reliable candidates to be a handover destination. When the

outcome results in an inefficient neighbor relation the according cell relation may be

blacklisted for handover.

ANR to other Radio Access Technology (UTRAN)

The features are requested as centralized SON features. The O&M based inter-RAT

feature supports operator initiated and/or automatic set-up and maintenance of

neighborship to other RAT (radio access technology). The target of these features is to

keep the operator's effort low for inter-RAT neighborship configuration based on site

planning data.

For more information on SON management, see:

Functional area description: SON management

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2 Automatic Neighbor Relation (ANR) Features

NSN features offer the following ANR features:

LTE724: LTE Automatic Neighbor Cell Configuration

Manual setup of the X2 link target to a neighbor eNB to learn neighbor information.

LTE539: Central ANR

Automatic preparation of X2 link targets from the NetAct-known neighbor eNBs.

LTE492: Automatic Neighbor Relation (ANR)

Provision of a look-up table for X2 link targets from the NetAct-known neighbor

eNBs.

LTE782: ANR Fully UE based

Learning the neighbor information as 3GPP TS 32.511 ANR, without the NetAct

support.

LTE783: ANR InterRAT UTRANAutomatic configuration of UTRAN target cells and control data from the NetAct-

known neighbor RNCs.

LTE784: ANR InterRAT GERAN

Automatic configuration of GERAN target cells and control data from the NetAct-

known neighbor BSCs.

LTE510: Synchronization of InterRAT NeighborsEstablishing a new inter-RAT NRs when new UTRAN/GERAN cells are created

within the optimization scope of an existing LTE cell.

LTE1019: SONreports

Provision of a report mechanism for the parameter changes done in the network.

LTE1045: Full SON support for distributed sites

Introduction of antenna site location information differentiation for distributed sitedeployments.

LTE1222: SON Automation Modes

Automatization of the inter-RAT neighbor-related features and optimization of intra-

LTE.

LTE507: Inter-RAT Neighbor Relation Optimization

Managing and optimizing the existing inter-RAT neighbor relations (NRs) between:

LTE and WCDMA and/or LTE and GERAN for a defined set of mobility procedures.

LTE1383: Cell-specific Neighbor Relation/PCI Handling

Supporting of 64 X2-links, cell-specific NR and PCI handling.

LTE556: ANR Intra-LTE, Inter-frequency - UE BasedEstablishment of new NRs between intra-LTE cells with different frequencies.

LTE1708: Extend Maximum Number of X2 LinksExtending the number of supported X2 links within the eNB to 256 for FSMr3 and to

128 for FSMr2.

For all features, the NetAct supports suitable means for activation, control, and

monitoring of the ANR features. For more information on the management, see NetAct

Customer Documentation or the online help support. This functional area description

aims to provide the content of the ANR features with focus on the eNB.

Table 1: ANR featuresshows all features related to ANR per release.

Automatic Neighbor Relation (ANR) Features Automatic Neighbor Relation (ANR)

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Table 1 ANR features

Feature:

Related documents

Release

LTE724: LTE Automatic Neighbor Cell

Configuration

FAD: ANR RL09

LTE539: Central ANR FAD: ANR RL10

LTE492: Automatic Neighbor Relation (ANR) FAD: ANR RL20

LTE510: Synchronization of InterRAT

Neighbors

FAD: ANR RL30

LTE783: ANR InterRAT UTRAN FAD: ANR RL30

LTE784: ANR InterRAT GERAN FAD: ANR RL30

LTE782: ANR Fully UE based FAD: ANR RL30

LTE771: Optimization of Neighbor Relations FAD: ANR RL30

LTE1019: SON reports FAD: ANR RL40

LTE1045: Full SON Support for Distributed

Sites

FAD: ANR RL40

LTE1222: SON Automation Modes FAD: ANR RL40

LTE507: Inter-RAT Neighbor Relation

Optimization

FAD: ANR RL50

LTE1383: Cell-specific Neighbor Relation/PCI

Handling

FAD: ANR RL50

LTE556: ANR Intra-LTE, Inter-frequency - UE

Based

FAD: ANR RL60

LTE1708: Extend Maximum Number of X2

Links

FAD: ANR RL60

2.1 LTE724: LTE Automatic Neighbor CellConfiguration

This feature supports manual configuration of intra-LTE neighbors for all cells of the

target and source eNB by the operator. With the configuration of the neighbor

identification, the X2 link is established and both eNB exchange their cell configuration to

be prepared for HO. The neighbor identification can be prepared in a pre-planning phase

or configured during operation of the eNBs.

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Only a subset of the standard information configuration is required. Off-line planning

applies to the Node-ID and/or the IP address of the neighbor LTE eNB hosting the

expected neighbor cells. All other configuration information for cells of neighbor LTE

eNBs are automatically derived and updated via the X2 interface.

2.2 LTE539: Central ANR

The LTE539: Central ANR feature is a centralized SON process for automatic neighbor

relation (ANR) preparation. During auto-configuration (see the LTE720: SON LTE Auto

Configurationfeature) or manually triggered by the operator at the NetAct, the NetAct

prepares for these eNB the most suitable neighbor cells based on geo-locations. The

NetAct considers all LTE cells (inter- or intra-frequency) known within its scope. In

addition the operator can add external LTE cells in border situations. The NetAct

generates the configuration data that an operator would manually generate for the

LTE724: Automatic Neighbor Cell Configurationfeature. The NetAct supports anoperator policy to define the wanted minimum and maximum number of neighbor cells

per served cell. From that all closest intra-LTE neighbor cells within a distance limit are

collected and their hosting eNB configuration is prepared.

2.3 LTE492: Automatic Neighbor Relation (ANR)

The LTE492: Automatic Neighbor Relation (ANR)feature is a hybrid SON process for

ANR finding. During auto configuration (see the LTE720: SON LTE Auto Configuration

feature) or manually triggered configuration by the operator at the NetAct, the NetAct

prepares for these eNBs a look-up table for resolving the neighbor eNB X2-IP address

from a newly found PCI value. The look-up table keeps a wider number of most suitable

neighbor cells based on geo-locations for this eNB.

The NetAct considers all LTE cells (inter- or intra-frequency) known within its scope. In

addition, the operator can add external LTE cells in border situations.

During the operation of the eNB, the mobility measurements are activated for each UE. If

the UE measurement reports show PCI values without existing configuration, the eNB

will search the PCI value in the look-up table.

If the value is found, the eNB itself generates this configuration data, which an operator

would manually generate for the LTE724: Automatic Neighbor Cell Configurationfeature.

The target eNB supports the LTE492: Automatic Neighbor Relation (ANR)feature as

well, and will accept incoming X2 link setup from the other peer. The X2 link set-up

happens as for the LTE724: Automatic Neighbor Cell Configuration feature. The LTE492:

Automatic Neighbor Relation (ANR) feature allows still manual neighbor configuration, or

even running of the LTE539: Central ANR feature.


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2.4 LTE510: Synchronization of InterRAT Neighbors

The LTE510: Synchronization of InterRAT Neighborsfeature is a centralized SON

process for automatic inter-RAT neighbor relation (IRAT-ANR) preparation. During

normal operation by a scheduled, or manually triggered process by the operator at the

NetAct, the NetAct checks for new inter-RAT cells and selects those eNB, for which this

inter-RAT cell would be a suitable inter-RAT neighbor cells based on geo-locations.

The NetAct considers all inter-RAT (GERAN or UTRAN) cells for all LTE cells.

In addition, the operator can add external inter-RAT cells in border situations. The NetAct

activates for the selected eNBs either the LTE783: ANR InterRAT UTRANfeature or the

LTE784:ANR InterRAT GERAN feature to set-up the wanted inter-RAT neighbor

configuration.

2.5 LTE783: ANR InterRAT UTRAN

The automatic planning of neighbor relations to UTRAN cells is done on NMS (network

management system) level with the help of the NetAct Configurator and Optimizer. This

feature prepares neighbor relations for each LTE cell in the optimization scope and

UTRAN automatically based on current LTE and legacy UTRAN network configuration

data with an intelligent algorithm in Optimizer to identify possible UTRAN neighbor cells.

The established relations are updated and synchronized automatically in case of

changes occurring at the UTRAN side (deletion of cell or change of the parameters),

ensuring up-to-date inter-RAT neighbor relationships.

This functionality is a part of auto configuration process of the LTE site. In addition, it is

possible to trigger the functionality manually.

The NetAct configures at the eNB plan file the inter-RAT cell configuration table

according to the UTRAN cell configuration. In addition, the dependent inter-RAT SIB,

measurement and redirect configuration is aligned. The NetAct supports inter-RAT

UTRAN user-templates to control inter-RAT configuration data.

2.6 LTE784: ANR InterRAT GERAN

The automatic planning of neighbor relations to GERAN cells is done on NMS level withthe help of the NetAct Configurator and Optimizer. This feature prepares neighbor

relations for each LTE cell in the optimization scope and GERAN automatically based on

current LTE and legacy GERAN network configuration data with an intelligent algorithm

in Optimizer to identify possible GERAN neighbor cells. The established relations are

updated/synchronized automatically if any changes occur at the GERAN side (for

example, deletion of cell or change of the parameters), ensuring up-to-date inter-RAT

neighbor relationships.

This functionality is a part of the auto-configuration process of the LTE site. In addition, it

is possible to trigger the functionality manually.


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The NetAct configures at the eNB plan file the inter-RAT cell configuration table

according to the GERAN cell configuration. In addition, the dependent inter-RAT SIB,

measurement and redirect configuration is aligned. The NetAct supports inter-RAT

GERAN user-templates to control inter-RAT configuration data.

2.7 LTE782: ANR Fully UE based

This feature covers Intra-LTE, Intra-frequency automatic neighbor relation configuration

(ANR). The neighbor relations stored by the eNB provide information about the neighbor

cell environment visible to each eNB cell. This information is persistently stored for

further use by the mobility management in the eNB. In this situation, S1 HO is supported

towards this neighbor cell.

Furthermore, the eNB resolves the X2 C-plane IP address of the node serving the

discovered LTE neighbor cell via S1 interface using the SON information exchange

procedure and establishes the X2 connection to exchange neighbor cell information with

the newly discovered site.

In addition to the LTE724: Automatic Neighbor Cell Configuration feature in RL30 the

LTE neighbor cell configuration is persistently stored at the eNB. This is a common

approach for all ANR features. According to the activated ANR features, the X2 link can

be re-established after each link drop based on:

oamControlled LNADJ: the IP address

enbControlled LNADJ and the LTE492: ANRfeature activated: the PCI/IP

address table with any PCI of a child LNADJL object

enbControlled LNADJ and the LTE782: ANR Fully UE basedfeature activated:

the MME-S1 based IP address resolution from global eNB ID, in case LTE492: ANRis also activated, then eNB tries first to check the PCI/IP address table.

For all cells on the eNB the persistent neighbor cell information allows S1 handover,

while X2 handover is preferred if the X2-link is active.

Whenever one camping UE sees one of these known neighbor cells and this neighbor is

selected as HO target, then within this cell a neighbor cell relation is established.

This feature needs no support from the NetAct level, even the found LTE cells can

remain unknown to the NetAct.

2.8 LTE771: Optimization of Intra-LTE NeighborRelations

The NetAct Optimizer supervises all registered cell relations between the neighboring

LTE cells if they are still valid and reliable candidates to be a handover destination.

When the outcome results in an inefficient neighbor relation the relevant cell relation

might be blacklisted for handover.


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2.9 LTE1019: SON Reports

The LTE1019: SON Reports feature provides a report mechanism for the parameter

changes made in the network, especially with focus to automatic changes made for

configuration parameters.

2.10 LTE1045: Full SON Support for Distributed Sites

This feature includes the introduction of antenna site location information differentiation

for distributed site deployments.

The SON algorithms calculating possible neighbor sites are adapted to consider the site

location info from antenna.

g Repeater supportThe LTE1195: FHCC Flexi 850 Repeater Interface Unit (RIU) or similar

LTE1106: FHCB Flexi RRH 2TX 850 Low Power for Optical Repeater Interface

and LTE1337: FHEC Flexi RRH 2TX 1800 Low Power features represent

repeater units that are usually installed within the same coverage area as the

macro cell. Therefore, the LTE1045: Full SON Support for Distributed Sites

feature has to check only for the macro cell. As repeater supports a dedicated

mode, where a repeater is configured like a normal cell with up to 20 km

distance, then operator needs to configure the correct antenna geo-location

data at NetAct. The LTE1045: Full SON Support for Distributed Sites feature

does not check consistency of such special deployments, as those are often 3 rd

party products.

2.11 LTE1222: SON Automation Modes

With the LTE1222: SON Automation Modes feature the inter-RAT neighbor-related

features and optimization of intra-LTE are executed in an automatic manner.

2.12 LTE507: Inter-RAT Neighbor Relation OptimizationThe LTE507: Inter-RAT Neighbor Relation Optimization feature enables automatic

blacklisting the individual mobility procedure of the existing inter-RAT NR. To be

considered by this feature, the NR must have the following parameter settings: the

LNRELx.nrControl parameter set to AUTOMATIC and the LNRELx.xyzAllowed

parameter set to ALLOWED.


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2.13 LTE1383: Cell-specific Neighbor Relation/PCI

HandlingCell-specific NR and PCI handling is needed to cope with network deployments with

distributed sites, respectively for non-optimized network environments, for which

handling of NRs per eNB is not sufficient. This enables the eNB to handle situations,

where different neighbor cells with the same PCI and frequency are visible for different

eNB cells. TheLTE1383: Cell-specific Neighbor Relation/PCI Handlingfeature also

provides the extension of supported X2-links number to 64.

2.14 LTE556: ANR Intra-LTE, Inter-frequency - UE Based

This feature enables establishment of new neighbor relations (NRs) between intra-LTE

cells with different frequencies. Automatic Neighbor Relation (ANR) for intra-LTE, inter-

frequency neighbor cells is based on UE measurements search on demand for the

currently unknown intra-LTE, inter-frequency neighbor cells. It can be started to properly

update and configure the neighbor cell list for adjacent LTE cells.

2.15 LTE1708: Extend Maximum Number of X2 Links

The LTE1708: Extend Maximum Number of X2 Links feature extends the number of

supported X2 links within the eNB from 64 to 256 X2 links for FSMr3 and from 64 to 128

for FSMr2.


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3 Architecture of Automatic Neighbor Relation(ANR)

Figure 1: Architecture of ANR shows the architecture of FAD: ANR.

Figure 1 Architecture of ANR

Triggered by the UE measurements Physical ID - Global ID Mapping doneby the UE Measurements; required:

- UE supporting ANR

Triggered by the UE measurements

Physical ID - Global IDmapping done by the NetAct- no UE supporting ANR needed

No pre-configuration

Neighbor cell entries automaticcompleted by the NetAct

No UE support

Neighbors preconfigured by IP address Neighbor cell entries completedautomatically by the NetAct duringpre-planning

Rl09

LTE539: Central ANR

LTE492: ANR for LTE

LTE782: ANR for LTEfully UE based

LTE724: AutomaticAdjacent Cell Configuration

- MME support for IP address resolution

Report of the automaticparameter changes in the networkLTE1019: SON reports

Additional information about theapplied change to the user

Introduction of antenna location informationdifferentiation for distributed site deploymentsLTE1045: Full SON Support

for Distributed Sites The SON algorithms calculatingpossible neighbor sites adapted

Additional functionality for theexisting centralized SON featuresLTE1222: SON Automation

Modes Inter-RAT auto setup andscheduled optimization

Optimizing the existing inter-RATNRs between LTE and 2G/3Gfor mobility procedures

LTE507: Inter-RATNeighbor Relation Optimization

NR and PCI support per eNB celland per carrierLTE1383: Cell Specific

Neighbor Relation/PCI Handling64 supported X2-links

RL50

Rl30

Rl20

Rl10

RL50

RL40

RL40

RL40

Establishing inter-RAT NRs whennew UTRAN/GERAN cells are created

RL30 LTE510: Synchronization

of InterRAT Neighbors

Establishing new NRs between intra-LTEcells with different frequencies

RL60 LTE556: ANR Intra-LTE,

Inter-frequency - UE Based

256 X2 links supported for FSMr3RL60

LTE1708: ExtendMaximum Number of X2 Links 128 X2 links supported for FSMr2

Automatic Neighbor Relation (ANR) Architecture of Automatic Neighbor Relation (ANR)

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4 Functional Description for ANR

4.1 LTE724: Automatic Neighbor Cell Configuration

4.1.1 Benefits

The operator considers only for the configuration of the eNB's served cells and the IP

connectivity to all its neighbor LTE eNBs.

For all LTE neighbor cells, the configuration data necessary for establishing the required

IP connectivity towards the hosting BTS site is pre-planned offline or can be re-

configured during operation.

The eNB establishes X2 connections to all neighbor eNBs, up to the supported number

of X2 links. With an established X2 link, at both peers the eNBs keep an up-to-dateknowledge of the neighbor cell configuration data for S1 and X2 handover.

4.1.2 Pre-planning

During offline planning with the NetAct planning tools or the BTS Site Manager, the

operator has to plan the IP addresses of all neighbor sites. All further neighbor base

station information about the hosted neighbor cell is derived automatically during the

corresponding X2 set-up procedures.

g Only one single X2 connection is established between two base stationsregardless of the number of supported cells per eNB. This means all cells of an

eNB, each assigned with a unique global Cell-ID, have the same X2 IP addressbecause IP addresses are assigned to the BTS nodes.

4.1.3 Commissioning and integration phase of a new eNB

If a newly deployed Flexi BTS for LTE has all the commissioning data including the

configuration data, it runs the X2 Set up procedure to each configured neighbor eNB.

When the connection is established successfully, for example the listed neighbor is

already installed and commissioned too, then after establishment of the control plane, all

required neighbor information is exchanged between the requesting eNB and all

responding ones. The information is stored in the corresponding NCL entries of the

involved eNB on both sides. If a listed neighbor does not respond, it is marked as notreachable without any further notification.

4.1.4 Neighbor cell update

When one eNB in operational mode receives an X2 Set-up request from another eNB, it

responds to the request, sends its own cell configuration data to the requesting eNB, and

stores the received configuration information in its own NCL list.

Functional Description for ANR Automatic Neighbor Relation (ANR)

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g Without activation of the LTE492: Automatic Neighbor Relation (ANR) and/orLTE782: ANR-UE basedfeature, the eNB will discard incoming connection

requests from a neighbor site if there is no IP address configuration available for

this particular site. In RL30, if either the LTE492: ANRfeature or theLTE782: ANR-UE basedfeature is activated at the target eNB, then for the

LTE724: LTE Automatic Neighbor Cell Configurationfeature X2 configuration it

is sufficient to configure the IP address, as OAM-controlled, at one peer.

If the requesting eNB of the X2 Set-up procedure is already known and the neighbor

configuration information is available, the responding Flexi LTE still sends its own cell

configuration to the initiating eNB. The received information is compared with the existing

information and is updated if modifications are identified.

4.1.5 Configuration data exchange via X2

The common X2 procedures on the control plane are used to derive and update theOAM neighbor cell configuration data.

g In RL10/20, these cells reported from the connected neighbor eNB becomeneighbors of the own cells. From RL30 more details are given in the common

Object Model behavior description. It is up to the operator to consider the

topology and configure the correct neighbors. The LTE539: Central ANRfeature

runs in the NetAct to find out the most suitable neighbors based on geo-

location.

Figure 2 Configuration of neighbor cells

NetAct

BTS Site manager

Datacommunication

network

Configurationof own cells

Configuration

of neighbor cells

X2 interfaceX2 interface

eNB1Cell #2

eNB2Cell #2

eNB2Cell #3

eNB2Cell #1

eNB1Cell #1

eNB1Cell #3

Automatic Neighbor Relation (ANR) Functional Description for ANR

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4.1.6 LTE724 Interaction with Common Object Model

With the introduction of the common object model approach, there is a common storage

of neighbor cell and relationship information for S1, X2 handover for manualconfiguration and/or automatic learning of neighbor cells, either in the auto configuration

or later during operation of the eNB. This has impact on the LTE724: LTE Automatic

Neighbor Cell Configuration, LTE539: Central ANR, LTE492: ANR and LTE782: ANR

Fully UE basedfeatures, and allows concurrent operation of all these features. The

operator can even configure neighbor eNB in a similar way as the LTE492: ANR/LTE782:

ANR - UE based feature would find those during operation of the eNB.

The eNB will not only store the neighbor IP address all the time, but also all the neighbor

cell information. This supports X2 as well as S1 handover to these neighbors. In case the

X2 link is dropped and X2 hand over is not possible, then automatically S1 handover is

applied. The cell's neighbor information will be resolved as soon as the UE reports the

neighbor PCI during mobility measurements. After an HO attempt is initiated to this cell,

a persistent neighbor relation is established. The management of the neighborships with

blacklists on the cell and the eNB levels are supported. More neighbor eNBs and cells

are supported to allow even more learning of neighbors. Still the manual configuration of

neighbor eNB and cells is possible in parallel to ANR functions.

The LTE724: Automatic Neighbor Cell Configurationfeature is a basic feature, together

with the activation of the optional features LTE492: ANR or LTE782: ANR - UE based,

the incoming X2 links are supported as well. The original LTE724: LTE Automatic

Neighbor Cell Configurationfeature behavior is obtained, if the IP address is configured

as oamControlled IP address. Applying the feature requires only configuring at both

peers the other neighbor eNB's IP address (neighbor identification).

4.2 LTE539: Central ANR

4.2.1 Functional overview

Feature scope

The LTE539: Central ANRfeature requests the NetAct Configurator and Optimizer to

generate automatically LTE intra- and inter-frequency neighbor relations for a new eNB

of an LTE network during auto-configuration, while the corresponding operational

neighbor eNBs are not configured. It is assumed, that those will accept the X2 setup

based on the LTE492: ANRor LTE782: ANR Fully UE based feature. The LTE539:

Central ANRis a feature purely of the NetAct Optimizer and Configurator; the BTS willnot be impacted by this feature.

The NetAct Optimizer generates adjacency information as required for UE mobility

management.

The operator can control with a profile the number of minimum and maximum

neighbor cell relation to be prepared for each served cell. The NetAct adapts this

information to the eNB level neighbor relations and configures the required eNB

identifications at the selected scope of eNBs. New installed eNBs will try to set-up

the X2 link to the other peer.

The NetAct Configurator will include neighbor cell relation information in the CM

database for eNB auto-configuration.


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For the eNB, the neighbor cell relation information is stored in the parameter

database. One Neighbor Relation is always affecting 2 eNB DB.

4.2.1.1 NetAct OptimizerTo support Central ANR, Optimizer creates for each (newly) planned eNB a list of

neighboring eNBs based on a priority function composed of distance and antenna

directions of the hosted LTE cells. The Optimizer identifies the neighbor relations based

on cell-eCGI and identifies the required eNB-global eNB ID to inform the Configurator

about the modifications.

The lists of neighboring eNBs:

The Optimizer passes lists of neighboring eNBs to the Configurator.

The Optimizer passes one neighbor list for each given eNB of the plan to the

Configurator.

The Optimizer and Configurator use the global eNB ID to identify eNBs.

The Optimizer ranks the list of cell neighbors according to a priority criterion and

enforces the number of neighbor cells to be in an operator-definable range between the

lower and the upper limit. The lower limit will only be enforced in case there are enough

neighbor cells fulfilling the priority criterion.

g The aim of the LTE539: Central ANRfeature is to provide a ranked list ofneighbor eNBs to a given eNB. To reserve free entries in the neighbor table for

not yet planned neighboring eNBs, it is possible to restrict the number of entries

by limiting the number of neighbor cells.

The policies, the lower and the upper number of neighbor cells and the prioritycriterion are existing mechanism for GSM and WCDMA neighbor cell

configurations.

Manual execution of Central ANR in Optimizer

Manual execution of the LTE539: Central ANR feature allows to determine neighbor

eNBs according to an operator selected scope of the eNBs based on geo-locations.

Usually the eNB is in operational state and has existing neighbor eNBs. The manual

execution of centralized ANR enforces the current policy. This means, that the

neighborships for the selected eNBs are adapted to the latest findings of this workflow.

As those eNBs run in a new NRT (Neighbor Relation Table) setup, the currently applied

neighbor relation settings (for example, black listings and CIO settings) for deletedneighbor eNBs are useless. To avoid race conditions with the current configuration of the

eNBs, the operator needs to disable existing decentralized ANR functions (the LTE782:

ANR - UE based and LTE492: Automatic Neighbor Relation (ANR)features) in the scope

of the selected eNBs. According to the described use cases, it is required, that the

LTE782: ANR - UE based and the LTE492: Automatic Neighbor Relation (ANR)features

are disabled during plan provisioning. Of course the operator can enable the two

features after the execution of the manually triggered the LTE539: Central ANRfeature.

The use cases for manual execution of the centralized ANR are:

Some eNBs have been installed without auto-configuration, no neighbors exist.

The operator creates eNBs and manually creates plan files to be activated by

installation personnel.


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Some eNBs failed during auto-configuration and need to be configured in a post-

process.

The operator runs the network without the LTE492: ANR feature or LTE782: ANR

UE based feature. Some eNBs have changed HW and cell deployment, and require re-configuration.

Some eNBs have too much useless neighbors and need to obtain a new NRT.

The operator can select a scope of planned and/or operational eNBs and execute in

NetAct Optimizer the tool for centralized ANR. This tool determines for each of the

selected eNB a list of neighboring eNBs based on a priority function described below.

The selected neighbor eNB might be:

a part of the selected set

other eNBs that are controlled by the same NetAct cluster

external cells, which are controlled by another element manager, even from other

vendorDuring auto-configuration Centralized ANR ignores already planned neighbor relations,

since it operates on a newly installed eNB.

In contrast, if the user manually starts Centralized ANR, the algorithm needs to apply a

certain replacement strategy to consider existing neighbors, that have been created

manually or by ANR. Existing neighbor cells might be whitelisted or blacklisted, neighbor

eNB might be blacklisted for handover via X2. Existing neighbors might have been

optimized with respect to - for example - time to trigger or cell individual offset.

Manual execution of centralized ANR supports distributed sites.

The operator can configure the execution of the neighbor finding algorithm with

preference settings:

minimum required number of neighbor eNBs (irrespective of distance)

maximum allowed number of neighbor eNBs (64 oamControlled LNADJ)

maximum allowed distance between any cell-pair of source and neighboring eNBs

The neighbor finding algorithm ranks for each served cell of the selected eNBs the

potential neighbor cells. The algorithm considers all managed cells of the NetAct cluster

as well as all external LTE cells. For each found neighbor eNB, the Optimizer creates the

respective LNADJ instances to the source eNB as required for each eNB.

The NetAct Optimizer creates the configuration plan file for further processing in

Configurator.

The Optimizer deletes all not required actual LNADJs and Configurator deletes their

LNADJLs.

The Optimizer creates all required LNADJs that are not yet existing and free

instances are available.

The Optimizer reconfigures all existing and required LNADJs to oamControlled.

Configurator also deletes all LNRELs related to deleted LNADJLs - no matter if those

are blacklisted, have CIO settings different from default (0) or their nrControl

property is set equal to manual.

The NetAct Optimizer creates new neighbor eNBs. The configurator provides all further

required information for the eNB to execute the LTE724: LTE Automatic Neighbor Cell

Configurationfeature functions to connect the X2 link.


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g During the execution of manually triggered centralized ANR the UE basedANR features need to be disabled to avoid a commissioning alarm and

abort of the plan activation.

The eNBs outside the scope of the selected eNBs will never be configured. The feature prepares the new LNADJs for the eNB feature

LTE724: LTE Automatic Neighbor Cell Configuration as oamControlled

LNADJs with the IP address. The IP address is not necessarily configured

at both peers. Therefore, the operator should temporary enable the

LTE782: ANR UE basedor the LTE492: ANR feature afterwards to enable

the acceptance of incoming X2 links at the other peer.

The workflow does not consider the capability of the eNBs to support ANR,

intra- or inter-frequency LTE HO. If the LTE782: ANR UE basedor

LTE492: ANR feature is configured at the other peer afterwards, then the

peer will accept incoming X2 links.

If the target global eNB ID is X2-black-listed, this is ignored for the

LTE539: Centralized ANRfeature, as still S1 HO is supported. TheLTE539: Centralized ANRfeature does not modify any X2-black-listing

setting.

The LTE539: Centralized ANR feature does not consider the PCI

configuration. It is left to the operator whether or not he runs the

LTE468: PCI Managementfeature to clean-up the PCI configuration

The manual execution of central ANR does not support former ADIPNO LTE

neighbor modeling as supported up to RL20.

The operator has to run and provision the manually executed the

LTE539: Central ANRfeature twice, if there are no sufficient free LNADJ

instances available. The NetAct Optimizer gives a hint to the operator on the

need for the second execution.

4.2.1.2 NetAct Configurator

The Configurator in turn finds for each global eNB ID the corresponding IP address,

completes the entry in the attribute adjEnbIPAddressMap of the object ADIPNO

(RL30: object LNADJ parameter cPlaneIpAddrCtrl) and writes this into a plan. In

addition the NetAct Configurator updates the other peer's plan files to have a

symmetrical X2 configuration. At each neighbor eNB, identified by the global eNB ID, the

attribute adjEnbIPAddressMap of the object ADIPNO is updated with the IP address

and global eNB ID of the new eNB. With introduction of the common object model in

RL30, the Configurator creates an LNADJ instance and sets the parameter

cPlaneIpAddr, cPlaneIpAddressCtrl=oamControlled.After downloading and activating the plan, the affected eNB proceeds as defined by the

LTE724: LTE Automatic Neighbor Cell Configuration feature:

The eNB starts X2 setup to another eNB (or other eNBs) and exchanges data about the

cell it hosts.

4.2.1.3 Integration in the auto-configuration workflow

The operator in front of the Configurator manually creates/imports a plan with newly

planned eNBs. The plan contains the global eNB Id, the geo-location and direction of

cells and possibly also the location of the sites. The IP addresses of the eNBs are

either pre-planned or manually configured by the operator. In addition, theConfigurator knows the actual configuration of the already running network.


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The auto-configuration workflow triggers the Optimizer.

The Optimizer retrieves a list of new eNBs in the master plan to be handled. The

Optimizer has already access to the actual configuration.

The Optimizer plans intra-LTE neighbors for the eNBs in the list. The Optimizer allocates collision and confusion free compliant PCI values (the

LTE468: PCI Managementfeature).

The Optimizer transfers information about PCIs and intra-LTE neighbors to the

Configurator.

The Configurator then uses this neighbor information to complete pre-planning for

the new eNBs and their impacted neighbor eNBs.

The Configurator adds the new eNB toADIPNO.adjEnbIPAddressMap or in

RL30 to LNADJ.cPlaneIpAddr&cPlaneIpAddrCtrl of the running

neighboring eNB. This update of the running eNB is necessary because the IP

address of the new eNB has not been available before auto configuration of the

new eNB. The Configurator creates entries in ADIPNO.adjEnbIPAddressMap or in RL30

to LNADJ.cPlaneIpAddr&cPlaneIpAddrCtrl for all the neighboring eNBs

that are already running

The Configurator downloads and activates the plan to the network. This results in:

Auto configuration of the new eNB

Update of the neighbor relation table in the already running eNB

4.3 External LTE Cell Support in NetAct

4.3.1 NetAct SON features support for the external LTE cells

The external LTE cells in the NetAct are cells of another NetAct region or another vendor

cells. The NetAct Configurator is able to support external LTE cells already with RL30.

With RL30 the external cell and adjacency (X2 or S1) to it can be created manually by

CM Editor or via northbound interface, XML, or CSV file input to Configurator.

The external cell information is available in the NetAct in a way that SON features, as the

LTE492: ANR, LTE469: PCI Management can use it also for the border management of

the external cells.

For that the location information and antenna information is provided as well for theexternal cells and used in Configurator and Optimizer.

The used OSS version is OSS5.4 CD2.


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4.3.2 Intra-system adjacency border area management

Figure 3 Border area management - info model

EXENBF

EXEUCE

EXENBF

EXEUCE

LNBTS-234

LNCEL

LNBTS-345

LNCEL

LNADJ

LNADJL

LNCEL

LNREL

MRBTS

LNBTS

PLMN

(Source eNB)

(External LTE eNB)

(External LTE cell)

(Target eNB)

(NetAct region border)

MCC:111MNC:10

Further PLMN ID, m5MCC:111MNC:20MCC:111MNC:30

Further PLMN ID, m5MCC:111MNC:20MCC:111MNC:30

0..64

1..3, max 192

0..194

1..3

1..1

MCC:111MNC:10

LNBTS ID: 123

(Target eNB)

MCC:111MNC:10

LNBTS:234

4.3.3 External LTE cell support for the LTE492: ANR in NetAct.

The NetAct Optimizers ANR algorithm for the LTE492: Automatic Neighbor Relation

(ANR) feature considers the external LTE objects as candidates for neighbor objects. If

an external eNB or external cell satisfies the conditions of the ANR algorithm, the

Optimizer adds this external cell to the mapping table (PCI, frequency, IP address) of a

corresponding eNB.

The ANR function in eNB detects new neighbor cells and the eNB creates corresponding

LNADJ and LNADJL objects. The NetAct creates suitable external LTE objects for those.

The NetAct synchronizes the parameter updates from the LNADJ and LNADJL objects

towards the external cell objects.

The geo-location data need to be maintained by the operator. The feature LTE492: ANR

ignores external objects if those do not have geo-location information assigned. This

behavior is different to the own-managed cells, for more information on distributed sites

see the LTE1045: Full SON Support for Distributed Sitesfeature.

4.3.4 External LTE object support for LTE468: PCI Managementin NetAct.

The LTE468: PCI Management feature considers all relevant LTE cells irrespective of the

management system they are connected to. Since the cells managed by another

management system also influence the selection of suitable PCI values, the NetAct's

algorithms consider external cells when assigning PCI values to own cells.

Nevertheless, the NetAct is not able to assign PCI values to external cells.


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4.3.5 External LTE cell support for the LTE539: Central ANR inNetAct.

The NetAct Optimizer considers external eNBs and its sub-ordinate cells as neighbor cell

candidates during the centralized ANR configuration (the LTE539: Central ANRfeature).

Similar as for the own-managed LTE cells the preference settings or the operator

selections are applied for external eNBs and its sub-ordinate cells during neighbor cell

candidate selection.

4.3.6 External LTE cell support for the LTE581: PRACHManagement in NetAct.

The NetAct Optimizer considers external eNBs and its subordinate cells during the

PRACH configuration (see the LTE581: PRACH Managementfeature description).

Similar as for the own-managed LTE cells the preference settings or operator selectionsare applied for external eNBs and its subordinate cells during neighbor cell candidate

selection.

4.4 X2 link management

The eNB supports two types of X2 links: oamControlled X2 links (that is X2 links which

are provided and controlled by the operator) and enbControlled X2 links (that is X2 links

that the eNB learned via ANR procedures, respectively the ones that are under control of

ANR). The type of the X2 link is provided in the associated LNADJ object instance.

4.4.1 oamControlled X2 links

The oamControlled X2 links have the following basic properties:

The IP-address to be used for the establishment of the oamControlled X2 link is

provided by the operator in the LNADJ object instance. It is the responsibility of the

operator to cater for correct configuration of the IP-address of the oamControlled X2

link.

The eNB automatically triggers the establishment of the oamControlled X2 link

configured by the operator (for example, if a startup of the eNB occurs). No further

conditions are checked by the eNB.

Establishment of the oamControlled X2 link has priority over establishment of the

enbControlled X2 link.

If the establishment of the oamControlled X2 link fails, an alarm is raised by the eNB.

To avoid inconsistencies regarding establishment/re-establishment behavior, it is

recommended to configure the same X2 link type at both sides of the X2 link (that is if

the X2 link is configured as oamControlled in eNB, then it should be also configured as

oamControlled in the peer eNB).

4.4.2 enbControlled X2 links

The enbControlled X2 links have the following basic properties:


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All X2 links which are automatically established by the ANR functions are labeled as

the enbControlled X2 links. Activation of at least one of the ANR features (either the

LTE492: Automatic Neighbor Relation (ANR)or LTE782: ANR Fully UE based) is a

pre-condition for the establishment of the enbControlled X2 link.

The ANR functions of the eNB trigger the automatic establishment of the

enbControlled X2 link, if the eNB detects that handover procedures to cells of the

neighbor eNB have to be performed.

The IP-address needed for X2 link establishment is automatically determined by the

eNB (for IP-address retrieval mechanisms, see LTE492: Automatic Neighbor

Relation (ANR)or LTE782: ANR Fully UE based).

Establishment of the enbControlled X2 link to some neighbor eNB might be forbidden

by the operator via X2 link blacklisting.

Regarding re-establishment of enbControlled X2 links, the eNB behaves as described in

Outgoing enbControlled X2 link (establishment triggered by the eNB) and Incoming

enbControlled X2 link (establishment triggered by neighbor eNB).

4.4.2.1 Outgoing enbControlled X2 link (establishment triggered by the eNB)

The eNB will trigger (re-)establishment of the enbControlled X2 link if all of the following

conditions are met:

The eNB has seen that cells of the neighbor eNB are necessary as targets for

handover (in this case LNREL/LNADJL object pairs are available associated with the

neighbor eNB).

The operator has not forbidden establishment of the enbControlled X2 link via X2 link

blacklisting (see the New parameterstable in the LTE782: ANR Fully UE based

feature).

Either LTE492: Automatic Neighbor Relation (ANR) or LTE782: ANR Fully UE based

isactivated.

The maximum number of X2 links, which can be established by the eNB, is not

reached yet.

4.4.2.2 Incoming enbControlled X2 link (establishment triggered byneighbor eNB)

The eNB will accept establishment request of the enbControlled X2 from the neighbor

eNB if all of the following conditions are met:

The operator has not forbidden establishment of the enbControlled X2 link via X2 link

blacklisting.

Either the LTE492: Automatic Neighbor Relation (ANR) or the LTE782: ANR Fully UE

basedis activated.

The maximum number of X2 links which can be established by the eNB is not

reached yet.


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g Automatic re-establishment of the enbControlled X2 links might occur only ifone of the ANR-features (either the

LTE492: Automatic Neighbor Relation (ANR)or LTE782: ANR Fully UE based)

or both of them are activated. If the operator wants to deactivate both ANRfeatures (the LTE492: Automatic Neighbor Relation (ANR) and the

LTE782: ANR Fully UE based) but still wants to be sure that an X2 link is always

re-established (for example after eNB re-start), then the X2 link has to be

defined by the operator as oamControlled.

Otherwise, after the eNB reset, the X2 link will be lost. If there is LNADJ

oamControlled and LNADJ enbControlled neighboring pair, the

Transport layer connection failure in X2 interfacealarm is

activated.

g In case when the LTE492: Automatic Neighbor Relation (ANR)feature isactivated, it is in addition required to have for the LNADJ to be re-established a

valid PCI/IP@ entry for one of the LNADJLs.

g It is recommended to run whole network or subclusters in common ANR mode(ANR ON or OFF).

4.5 LTE1708: Extend Maximum Number of X2 Links

TheLTE1708 Extend Maximum Number of X2 Links feature introduces the extension of

the number of supported X2 links within the eNB from 64 to 256 X2 links for FSMr3 and

from 64 to 128 for FSMr2.

The Table 2: Minimum number of supported neighbor objects shows the minimum

number of neighbor objects which are supported:

Table 2 Minimum number of supported neighbor objects

Object MO per FSMr2 FSMr3

neighbor eNB LNADJ source eNB 128 256

neighbor cell LNADJL neighbor eNB 24 24

neighbor cell (total) LNADJL source eNB 768 1536

source cell LNCEL source eNB 12 18

neighbor relationship LNREL source cell 389 389

neighbor relationship (total) LNREL source eNB 480 1728*

* assumption: 48 LNREL per carrier, 2 carriers per cell

In case that higher values, as presented in the Table 2: Minimum number of supported

neighbor objects are used, the system performance could be decreased.

The increase of the number of X2 links are realized in the following way:

The size of the X2 black-list table is increased.


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With the setup of 256 (128) X2 links, also the learned neighbor cells are considered.Taking 6 cells per eNB in average into account an overall amount of 256x6 = 1536(FSMr3) and 128x6 = 768 (FSMr2) neighbor cells can be considered.

4.6 LTE492: Automatic Neighbor Relation (ANR)

Figure 4 LTE492: ANR

4.6.1 Prerequisites

The prerequisites are as follows:

Geo-locations

Antenna direction has to be configured for all LTE cells at the NetAct Configurator

non-network parameters.

The external LTE cell can be configured in case of several NetAct clusters support

one LTE network.

The operator has to ensure, that the LTE cell black-lists (blacklistHoL) does not

contain the PCIs in the PCI/IP address table, that is learned by the LTE492: ANR

feature.

The neighboring eNBs have IP connectivity to establish an X2 link.

All the neighbor eNBs have the LTE492: ANR feature or the LTE782: ANR - UE

basedfeature activated to accept the incoming calls.


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4.6.2 Functional overview/details

In LTE networks, the UE mobility relies on information given by neighbor cell relations

and neighbor cell configurations. An automatic mechanism is implemented to discoverand integrate unknown cells. It supports and allows the automated configuration and

update of neighbor cell information without the need of an off-line planning update of the

neighbor cell configurations.

The neighbor cell configuration via X2 is initiated by the UE-measurements of a

connected UE. Only the connected UE reports this measurements during mobility

procedure.

The UE reports all detected/strongest cells above a given threshold. Therefore, it might

report strong cells whose PCI is currently not yet known to the Flexi Multiradio BTS. The

eNB checks in the A3/A5 measurement when there are more PCI reported, if the

unknown PCI is the only target to be selected. In this case, the Flexi Multiradio BTS

looks up the C-plane IP-connectivity information (IP address) of the relevant neighboreNB, hosting the unknown cell. The eNB uses only the strongest unknown PCI for this

and only if there is no other known PCI that could be selected for HO preparation.

If the Flexi Multiradio BTS successfully looks up the IP-connectivity information, the X2

signaling connectivity is set up, and an IPsec tunnel that is used for S1 traffic is also

used for the X2 traffic as configured, if the network domain security is applied. The X2

UP interface (X2_U) is set up during the first handover event between a pair of eNBs,

including IPsec tunnel over S1 interface, if network domain security is applied.

g The parameters limiting learning of new neighbors defined in ANRPRL areapplied also to the LTE492: ANRfeature.

g The ANR supports IPsec star topology configurations where an IPsec tunnelthat is used for S1 traffic is also used for X2 traffic as configured.

IPsec meshed topology configurations are not supported.

The resolution of PCI to IP-connectivity information is done by means of a PCI/RF/IP

address look up table stored at the eNB, provided by O&M-configuration (NetAct

Optimizer, NetAct Configurator).

The PCI/RF/IP address look-up table provides a mapping of PCI assigned to a neighbor

cell. The table includes information about the relation of the cell's PCI identification at a

certain RF-carrier to the C-plane IPaddress of the Flexi Multiradio BTS serving that cell.


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g The PCI values of neighbor cells are configured unique for the given centerfrequency (RF-carrier) and the geo-location area of the cells.

The LTE492: ANR feature supports finding of the neighbor on the same

(common) center frequency as the actual cell. It is a general assumption, that allcells are assigned to the same center frequency. Therefore, in the PCI/IP

address table all PCI values have usually the same RF-carrier.

In special cases, for example PLMN border areas or urban/rural multi vendor

borders, the operator might assign cells of one eNB to different center

frequencies, then the PCI/IP address table allows configuration of potential

neighbors for each center frequency (RF-carrier).

The selection inside the NetAct is based on the geo-data and collects in a

typical two center frequency network the potential neighbor cells from either

center frequency. This allows the operator to assign the cells later on to different

center frequencies without update of the eNB PCI/IP address table.

g It is not recommended to use the LTE492: ANR feature in a networkdeployment with three center frequencies and/or with huge difference in the cell

sizes on each center frequency, for example for 800 and 2600 MHz bands, as in

those cases some RF carriers might have less potential candidates prepared

than required.

The generation of the PCI/RF/IP address look-up table is part of the Auto-

connection/Auto-configuration procedure.

With introduction of the common object model in RL30, the feature is adapted to the new

modeling. The neighbor relation and the neighbor cell information is persistently stored.

This allows S1 handover, if X2 link is for any reason not running. The neighbor cellrelation is only generated if the PCI is reported by a UE connected to this cell. The cell-

specific relationship allows to see the relevant neighbor cells, while still all known cells at

the eNB level are available for handover.

The new neighbors found by the LTE492: ANRfeature will be created as LNADJ

instance and set the parameter cPlaneIpAddrCtrl=enbControled and all neighbor

data from the X2 link among them LNADJL.phyCellId. After each X2 link drop one of

the persistent configured LNADJL.phyCellId will be used to look-up the IP address again.

This behavior requires to have an up-to-date IP address/PCI look-up table in RL30. The

PCI update at the neighbor cell is informed to the neighbors connected via X2, but the

PCI/IP address table is not updated. The operator can do this manually triggered. Refer

to the LTE468: PCI Managementfeature and self-healing of PCI violation.

The LTE492: ANR and the LTE782: ANR - UE based features can be activated

concurrently in the eNB. In this case for resolving the IP address, the look-up table has

precedence before the MME look-up. In case of X2 link drop the re-connection of the X2

link for enbControled IP address will be resolved via the look-up table first, if no suitable

PCI value is found, then the MME procedure is applied. Dependent on PCI or IP address

changes, it is possible, that a different eNB is finally selected as neighbor, or before

established X2 link cannot be resolved. A work around is to set the IP address to

oamControled, if the IP address is still the same, see if the eNB sets up the X2 link

correctly, and then change to enbControled again. This can help updating the PCI values

in LNADJL so that there is a valid resolution next time.


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4.6.2.1 NetAct Optimizer: neighbor evaluation procedure

Triggered during the auto-configuration procedure for a new deployed eNB, the NetAct

Optimizer calculates the distance to other cells and creates a list of found neighbor cellrelations. Then the eNB selects the closest cells the eNB and adds all its cells into the

list. The result is given to the NetAct Configurator to complete the configuration plan file

for the new eNB. These are not "found neighbor cell relations" but simply a larger list of

geo-graphic closest neighbor sites as a look-up table for the eNB. With the intention, that

the eNB can establish an X2 link, only to those, that are actually visible and reported by

the connected UEs. Therefore, the look-up table has much more entries than X2 links

can establish in a single center frequency deployment. In a two center frequency

deployment and/or even one with unequal cell sizes, this is still sufficient with the current

limit of 200 entries.

The NetAct supports the operator preferences to control the content of the look-up table

in the following way:

search the distance to be limited so that far away cells are not considered, otherwise

up-to 100 km are used

limit of PCI per frequency carrier split for configured LNCEL-EARFCN of the eNB and

unknown ones

The NetAct drops all PCI values that would lead to duplication PCIs, so that only the

closest PCI is maintained in the list.

4.6.2.2 NetAct Configurator: automated neighbor site IP connectivityconfiguration completion

As soon as the NetAct Optimizer completes the neighbor evaluation, it hands over theresult to the NetAct Configurator that starts looking into the configuration files of the

neighbor eNB.

For each new eNB, the Configurator opens the configuration plan file and copies from

the neighbor eNB the PCIs, RFs, and IPaddress connectivity information relevant for X2

establishment to generate the look-up table.

The operator can manually trigger for a set of operational eNB the Configurator

generation the look-up table based on the current cell deployment for each eNB.

The updated configuration plan file (including the PCI/RF/IP address look-up table) is

now ready to be downloaded automatically as a part of the auto-configuration process.

After the new neighbor sites are successfully included into the local configuration data,the Flexi Multiradio BTS sends a configuration change notification to the Network

Management System (NetAct) to synchronize the local configuration changes.

As soon as a self-learned X2 connection has been successfully established, its IP

address becomes a part of the normal configuration data and thereby this X2 connection

becomes persistent (that is not needed to be detected by the UE measurements

anymore; BTS restart is safe).

If an operator has not licensed or does not want to use the ANR-feature, it is possible to

pre-configure X2-connectivity information (IP-addresses) by O&M-configuration (plan

file). The other possibility is the centralized SON function- the LTE539: Central ANR

feature.


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g Operator hintThe LTE492: ANR feature works in coverage-limited network deployments very

similar as the LTE782: ANR - UE based feature in passive ANR mode. In

addition it is required to have up-to-date PCI/IP address tables in all eNBs, forany change of a PCI value, this is automatically done by the NetAct. It is

proposed to switch off the LTE492: ANR feature when the

LTE782: ANR - UE basedfeature is activated, or use PCI/IP address tables

rather for inter-frequency HO support.

In capacity-limited network deployments the LTE492: ANRand the

LTE782: ANR - UE basedfeatures in passive ANR mode work quite similar as

well. Similarly the operator watches the neighbor relation (NR) from a

performance point of view. During the upgrade the operator should have

changed all the existing IP addresses to run in the eNB-controlled mode by

setting the LNADJ - parameter

cPlaneIpAddrCtrl = enbControlled (1).

4.6.2.3 Use cases

The use cases are as follows:

Integration and deployment of a new eNB within an installed base of other eNBs

The establishment of an X2 connection and the creation of the neighbor relations is

always triggered by the newly deployed eNB, that has the latest PCI/RF/IP address

look-up table available that is relevant for its environment. The installed base of the

eNBs has to accept an X2-setup request, with preceding SCTP connection

establishment and a preceding IPsec tunnel establishment if network domain

security is applied. Manually triggered neighbor site evaluation and IP/RF/PCI update

The operator can start the neighbor site evaluation and the configuration plan file

completion manually or within a script for selected eNBs. This helps to solve possible

inconsistencies if, for example, something went wrong during auto configuration or to

facilitate the manual plan file configuration. The manual planning completion results

in an updated configuration plan file but not in an automated download. This needs

to be initiated separately.

4.7 Neighbor relation clean up in the NetAct

The NetAct is offering a tool support to clean up neighbor relation entrances in the eNBdatabase. The operator has to select the entrances for deletion.

4.7.1 Optimizer: select and delete

In the NetAct Optimizer, a tool support for LNREL deletion is available and can be

started manually by the operator. The operator can use sorting or filtering of LNREL

instances based on available PM counter values as, for example, the number of HO

attempts. The operator can request the deletion of these instances. The deletion request

is provided to the NetAct Configurator via standard exchange of the plan file. See the

steps in figure Figure 5: LNREL deletion:


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Figure 5 LNREL deletion

4.7.2 Configurator: delete consistently

In the NetAct Configurator, a deletion plan file request is executed in a consistent way

with regard to related objects.

The routine executes the following steps in automatic manner within Plan/Prepare:

1. All specified LNRELs are going to be deleted.2. In the next step all LNADJ & LNADJL objects without LNRELs are detected and

deleted.

3. Deletions are done symmetrically for both ends of X2 (deletion of LNREL) (in one

NetAct region).

g The deletion routine is not preventing from the deletion of blacklisted neighbors.It is up to the operator to decide about the entrances for deletion.

4.8 LTE510: Synchronization of InterRAT Neighbors

Functional overview

The LTE510: Synchronization of InterRAT Neighbors feature adds a mechanism to

establish new inter-RAT neighbor relations in case new UTRAN/GERAN cells are

created.

All relevant parameters for inter-RAT NR establishment are provided by NSN

management system (NetAct) in case of a co-existing NSN 2G/3G network or by NSN

management via northbound interface (Itf-N), in case of another NSN NetAct regional

cluster or other vendor's co-existing 2G/3G network.

The creation of inter-RAT NRs is evaluated basing on:

the location (co-location) of the BTS


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the distance between the cell being configured and potential target cells

the radio antenna main lobe direction

The LTE510: Synchronization of InterRAT Neighbors feature identifies the impacted LTE

cells/eNBs, and runs for those, the LTE783: ANR InterRAT UTRAN/LTE784: ANR

InterRAT GERAN feature because of new inter-RAT cells.

Figure 6: LTE510 Synchronization of InterRAT Neighbors gives an overview about the

feature.

Figure 6 LTE510 Synchronization of InterRAT Neighbors

2G/3G BTS LTE BTS

CM

NetAct

Schedule defined by the user

CM

CM

Configuration file downloaded

Update

Changes atthe 2G/3Gside

2G/3G

LTE

CM

SON

Configuration file downloaded

Update

Update

Update Inter-RATneighbor relations,if necessary,depending on- location (co-location)- distance between BTS- antenna radio lobe

4.9 LTE783: ANR InterRAT UTRAN

Functional overview

The configuration of inter-RAT neighbor relations is handled by the NetAct, wherebyconfiguration data relevant for inter-RAT neighbor relations are uploaded and retrieved

from any existing UTRAN network configuration management database and

corresponding inter-RAT neighbor relations created for the relevant Flexi Multiradio BTS,

taking into account:

the geo-location of the source (LTE) and target UTRAN site/cell antenna

sectorization/antenna horizontal main lobe direction of source LTE and target

UTRAN cells. The algorithm does not consider whether the source and target are co-

located.


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The relevant parameters for inter-RAT neighbor relation establishment are provisioned

by the NetAct if there is a co-existing NSN UTRAN network, or by the NetAct northbound

interface (Itf-N) as external or foreign cells in case of another NSN NetAct regional

cluster or other vendor's co-existing 3G network.

The NetAct operates on the current configured external UTRAN cells for this feature.

Between those external UTRAN cells and the LTE cells the neighbor relations are

established automatically.

Changes that might trigger an update or synchronization of the LTE inter-RAT neighbor

relation configuration are:

UTRAN BTS deletion

UTRAN cell deletion

UTRAN cell-specific parameter change (for example, scrambling code, RAC, LAC)

The Inter-RAT neighbor relation, established before the LTE783: ANR InterRAT UTRAN

feature, might be overwritten. The operator can create neighbor relations (LNRELW) upfront with a certain black- and white-listing for one or more cell(s).

Within a newly generated plan, the operator is informed about each entry:

selected base on policy values (geo-locations)

added because of allowed setting

removed because of forbidden setting

In addition, the final selected maximum number of cells is highlighted.

The LTE783: ANR InterRAT UTRAN feature usually lists more inter-RAT cells which can

be eventually configured. As a result, the operator can adapt the setting of allowed and

forbidden inter-RAT cells (at the break point in confirmed mode); this also offers thepossibility to give the chance to adapt persistently the assignment of inter-RAT cells

within one eNB in, for example, unbalanced network deployments. As the LTE cells of

one eNB share the inter-RAT NR cells only based on geo-location, an urban/rural border

situation might assign to the rural cell only few inter-RAT NR cells.

It is recommended that the operator triggers manually from time to time the LTE783:

ANR InterRAT UTRAN feature for the whole network to ensure the update of each LTE

cell and eNB according to the latest NR configuration.


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g As neighbor relations significantly change the call processing and performancebehavior and the performance counters, the operator might want to keep the

impact low. It is therefore recommended not to start in the first establishment

inter-RAT neighbors with the maximum number of neighbors relations, but witha rather low number, and then it is possible to increase this number. The

operator can monitor the KPIs, for example, the call drop rate, throughput and

handover success rate. If those do not improve significant, then the actual

number of inter-RAT relations, controlled by the network wide policy, is

established properly.

The external UTRAN cells to be configured in the NetAct area for the managed

LTE cells have a different geo-graphical scope. The operator provides t

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