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LTE Radio Access, Rel. RL60, Operating Documentation, Issue 03 Automatic Neighbor Relation (ANR) DN0989276 Issue 04A Approval Date 2014-06-16
Automatic Neighbor Relation (ANR)
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Table of Contents This document has 65 pages
Summary of changes..................................................................... 8
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1
Introduction to Automatic Neighbor Relation (ANR).......................9
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 2.12 2.13 2.14 2.15
Automatic Neighbor Relation (ANR) Features............................. 10 LTE724: LTE Automatic Neighbor Cell Configuration...................11 LTE539: Central ANR...................................................................12 LTE492: Automatic Neighbor Relation (ANR).............................. 12 LTE510: Synchronization of InterRAT Neighbors.........................13 LTE783: ANR InterRAT UTRAN...................................................13 LTE784: ANR InterRAT GERAN.................................................. 13 LTE782: ANR Fully UE based...................................................... 14 LTE771: Optimization of Intra-LTE Neighbor Relations................14 LTE1019: SON Reports................................................................15 LTE1045: Full SON Support for Distributed Sites........................ 15 LTE1222: SON Automation Modes.............................................. 15 LTE507: Inter-RAT Neighbor Relation Optimization.....................15 LTE1383: Cell-specific Neighbor Relation/PCI Handling............. 16 LTE556: ANR Intra-LTE, Inter-frequency - UE Based.................. 16 LTE1708: Extend Maximum Number of X2 Links.........................16
3
Architecture of Automatic Neighbor Relation (ANR).................... 17
4 4.1 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.1.6 4.2 4.2.1 4.2.1.1 4.2.1.2 4.2.1.3 4.3 4.3.1 4.3.2 4.3.3 4.3.4
Functional Description for ANR....................................................18 LTE724: Automatic Neighbor Cell Configuration..........................18 Benefits........................................................................................ 18 Pre-planning.................................................................................18 Commissioning and integration phase of a new eNB.................. 18 Neighbor cell update.................................................................... 18 Configuration data exchange via X2............................................ 19 LTE724 Interaction with Common Object Model.......................... 20 LTE539: Central ANR...................................................................20 Functional overview..................................................................... 20 NetAct Optimizer.......................................................................... 21 NetAct Configurator......................................................................23 Integration in the auto-configuration workflow..............................23 External LTE Cell Support in NetAct............................................ 24 NetAct SON features support for the external LTE cells.............. 24 Intra-system adjacency border area management.......................25 External LTE cell support for the LTE492: ANR in NetAct............25 External LTE object support for LTE468: PCI Management in NetAct.......................................................................................... 25
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4.3.5
4.6.2.3 4.7 4.7.1 4.7.2 4.8 4.9 4.10 4.11 4.12 4.12.1 4.12.1.1 4.13 4.14 4.15 4.16 4.17 4.18
External LTE cell support for the LTE539: Central ANR in NetAct... 26 External LTE cell support for the LTE581: PRACH Management in NetAct.......................................................................................... 26 X2 link management.................................................................... 26 oamControlled X2 links................................................................ 26 enbControlled X2 links................................................................. 26 Outgoing enbControlled X2 link (establishment triggered by the eNB)............................................................................................. 27 Incoming enbControlled X2 link (establishment triggered by neighbor eNB).............................................................................. 27 LTE1708: Extend Maximum Number of X2 Links.........................28 LTE492: Automatic Neighbor Relation (ANR) ............................. 29 Prerequisites................................................................................ 29 Functional overview/details.......................................................... 30 NetAct Optimizer: neighbor evaluation procedure....................... 32 NetAct Configurator: automated neighbor site IP connectivity configuration completion.............................................................. 32 Use cases.................................................................................... 33 Neighbor relation clean up in the NetAct......................................33 Optimizer: select and delete.........................................................33 Configurator: delete consistently..................................................34 LTE510: Synchronization of InterRAT Neighbors.........................34 LTE783: ANR InterRAT UTRAN...................................................35 LTE784: ANR InterRAT GERAN.................................................. 38 LTE782: ANR Fully UE based...................................................... 40 LTE771: Optimization of Intra-LTE Neighbor Relations................45 Functional description.................................................................. 45 RAN system level scope.............................................................. 47 LTE1019: SON Reports................................................................48 LTE1045: Full SON Support for Distributed Sites........................ 49 LTE1222: SON Automation Modes ............................................. 52 LTE507: Inter-RAT Neighbor Relation Optimization.....................53 LTE1383: Cell-specific Neighbor Relation/PCI Handling............. 53 LTE556: ANR Intra-LTE, Inter-frequency - UE Based.................. 57
5
Management data for ANR.......................................................... 58
6 6.1 6.1.1
Operating Tasks Related to ANR................................................. 59 LTE771: Optimization of Intra-LTE Neighbor Relations................59 Scheduled workflow for LTE771: Optimization of Intra-LTE Neighbor Relations.......................................................................59 ANR Optimization.........................................................................60 LTE782: ANR - UE based............................................................ 60 UE-based ANR Retrieval by eNB.................................................60 LTE783: ANR InterRAT UTRAN...................................................61 The establishment of NR for Inter-RAT UTRAN...........................61
4.3.6 4.4 4.4.1 4.4.2 4.4.2.1 4.4.2.2 4.5 4.6 4.6.1 4.6.2 4.6.2.1 4.6.2.2
6.1.2 6.2 6.2.1 6.3 6.3.1
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6.3.2 6.4 6.4.1 6.4.2 6.5 6.5.1
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New UTRAN neighborship generation during LTE autoconfiguration.................................................................................62 LTE784: ANR InterRAT GERAN.................................................. 62 Establishment of NR for Inter-RAT GERAN................................. 62 New GERAN neighbor ship generation during LTE autoconfiguration.................................................................................63 LTE539: Central ANR...................................................................64 Central ANR for New eNBs..........................................................64
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List of Figures
6
Figure 1
Architecture of ANR............................................................................17
Figure 2
Configuration of neighbor cells........................................................... 19
Figure 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......................................... 55
Figure 12
UE-based ANR Retrieval by eNB....................................................... 61
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List of Tables
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Table 1
ANR features...................................................................................... 11
Table 2
Minimum number of supported neighbor objects............................... 28
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Summary of changes
Automatic Neighbor Relation (ANR)
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) The ANR principle figure has been changed.
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Introduction to Automatic Neighbor Relation (ANR)
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 all neighbor 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-based feature, 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: •
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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 UTRAN Automatic configuration of UTRAN target cells and control data from the NetActknown neighbor RNCs. LTE784: ANR InterRAT GERAN Automatic configuration of GERAN target cells and control data from the NetActknown neighbor BSCs. LTE510: Synchronization of InterRAT Neighbors Establishing a new inter-RAT NRs when new UTRAN/GERAN cells are created within the optimization scope of an existing LTE cell. LTE1019: SON reports 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 site deployments. LTE1222: SON Automation Modes Automatization of the inter-RAT neighbor-related features and optimization of intraLTE. 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 Based Establishment of new NRs between intra-LTE cells with different frequencies. LTE1708: Extend Maximum Number of X2 Links Extending 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 features shows all features related to ANR per release.
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Table 1
Automatic Neighbor Relation (ANR) Features
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 FAD: ANR Handling
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 Cell Configuration 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 Configuration feature) 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 Configuration feature. The NetAct supports an operator 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 Configuration feature. 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 Neighbors feature 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 UTRAN feature 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 with the 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: ANR feature activated: the PCI/IP address table with any PCI of a child LNADJL object enbControlled LNADJ and the LTE782: ANR Fully UE based feature activated: the MME-S1 based IP address resolution from global eNB ID, in case LTE492: ANR is 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 Neighbor Relations 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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Automatic Neighbor Relation (ANR) Features
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 support The 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 3rd 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 Optimization The 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 Handling Cell-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. The LTE1383: Cell-specific Neighbor Relation/PCI Handling feature 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, interfrequency 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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Architecture of Automatic Neighbor Relation (ANR)
3 Architecture of Automatic Neighbor Relation (ANR) Figure 1: Architecture of ANR shows the architecture of FAD: ANR. Figure 1
Rl09
Rl10
Architecture of ANR LTE724: Automatic Adjacent!Cell!Configuration
LTE539: Central ANR
• Neighbors!preconfigured!by IP address • Neighbor!cell!entries completed automatically!by!the!NetAct!during pre-planning
• No!pre-configuration • Neighbor!cell!entries!automatic completed!by!the!NetAct
• No!UE support Rl20
LTE492: ANR!for!LTE
Rl30
LTE782: ANR!for!LTE fully!UE!based
RL30
LTE510:!Synchronization of!InterRAT Neighbors
• Triggered!by!the!UE!measurements • Physical!ID!- Global!ID mapping!done!by!the!NetAct -!no!UE!supporting ANR!needed
• Triggered!by!the!UE!!measurements • Physical!ID!- Global!ID!Mapping!done by!the!UE!Measurements;!required: - UE!supporting ANR - MME!support!for!IP address!resolution
• Establishing!inter-RAT NRs!when new!UTRAN/GERAN!cells!are!created
• Report!of!the!automatic RL40
LTE1019:!SON!reports
parameter!changes!in!the!network
• Additional!information!about!the applied!change!to!the!user
RL40
LTE1045:!Full!SON!Support for!Distributed!Sites
• Introduction!of!antenna!location!information differentiation!for!distributed!site!deployments
• The!SON!algorithms!calculating
possible!neighbor!sites!adapted
• Additional!functionality!for!the RL40
LTE1222:!SON Automation Modes
existing!centralized!SON!features
• Inter-RAT auto!setup!and scheduled!optimization
RL50
LTE507:!Inter-RAT Neighbor!Relation!Optimization
RL50
LTE1383:!Cell!Specific Neighbor!Relation/PCI!Handling
RL60
LTE556: ANR!Intra-LTE, Inter-frequency!-!UE!Based
RL60
LTE1708:!Extend Maximum!Number!of!X2!Links
• Optimizing!the!existing!inter-RAT NRs!between!LTE!and!2G/3G for!mobility!procedures
• NR!and!PCI!support!per!eNB!cell
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and!per!carrier
• 64!supported X2-links • Establishing!new!NRs!between!intra-LTE cells!with!different!frequencies
• 256!X2!links!supported!for!FSMr3 • 128!X2!links!supported!for!FSMr2
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Functional Description for ANR
Automatic Neighbor Relation (ANR)
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 reconfigured 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-date knowledge 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 stations regardless 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 address because 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 not reachable 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.
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Functional Description for ANR
Without activation of the LTE492: Automatic Neighbor Relation (ANR) and/or LTE782: ANR-UE based feature, 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: ANR feature or the LTE782: ANR-UE based feature is activated at the target eNB, then for the LTE724: LTE Automatic Neighbor Cell Configuration feature 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 the OAM neighbor cell configuration data.
g
In RL10/20, these cells reported from the connected neighbor eNB become neighbors 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 ANR feature runs in the NetAct to find out the most suitable neighbors based on geolocation. Figure 2
Configuration of neighbor cells NetAct
Configuration ofowncells
BTSSitemanager eNB1 Cell#2 eNB1 Cell#3
eNB2 Cell#2 eNB2 Cell#1
eNB1 Cell#1
X2interface
eNB2 Cell#3
X2interface
Data communication network Configuration ofneighborcells
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Functional Description for ANR
Automatic Neighbor Relation (ANR)
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 manual configuration 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 based features, 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 Configuration feature 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 Configuration feature 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 ANR feature 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: ANR or LTE782: ANR Fully UE based feature. The LTE539: Central ANR is a feature purely of the NetAct Optimizer and Configurator; the BTS will not be impacted by this feature. • •
•
20
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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4.2.1.1
Functional Description for ANR
For the eNB, the neighbor cell relation information is stored in the parameter database. One “Neighbor Relation” is always affecting 2 eNB DB.
NetAct Optimizer To 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.
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The aim of the LTE539: Central ANR feature is to provide a ranked list of neighbor 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 priority criterion 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 deleted neighbor 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 ANR feature. The use cases for manual execution of the centralized ANR are: • •
Issue: 04A
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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Functional Description for ANR
• • • •
Automatic Neighbor Relation (ANR)
Some eNBs failed during auto-configuration and need to be configured in a postprocess. 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 vendor
During 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 Configuration feature functions to connect the X2 link.
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•
• •
•
•
•
• •
4.2.1.2
Functional Description for ANR
During the execution of manually triggered centralized ANR the UE based ANR 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 based or 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 based or 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 ANR feature, as still S1 HO is supported. The LTE539: Centralized ANR feature 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 Management feature 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 ANR feature 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.
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 •
Issue: 04A
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, the Configurator knows the actual configuration of the already running network.
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Functional Description for ANR
• • • • • •
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 Management feature). 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. –
–
•
Automatic Neighbor Relation (ANR)
The Configurator adds the new eNB to ADIPNO.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 the external 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 (TargeteNB)
MCC:111 MNC:10
LNBTS-234
LNCEL (ExternalLTEeNB) FurtherPLMNID,m5 MCC:111 MNC:20 MCC:111 MNC:30
EXENBF
PLMN
EXEUCE
MRBTS
(ExternalLTEcell)
1..1
(TargeteNB) LNBTS:234 MCC:111 MNC:10
LNBTS-345
LNCEL
LNBTS (SourceeNB)
EXENBF
EXEUCE
LNBTSID:123 MCC:111 MNC:10
0..64 1..3
FurtherPLMNID,m5 MCC:111 MNC:20 MCC:111 MNC:30
LNADJ 1..3,max192
LNADJL
(NetActregionborder)
LNCEL 0..194
LNREL
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 Sites feature.
4.3.4 External LTE object support for LTE468: PCI Management in 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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Functional Description for ANR
Automatic Neighbor Relation (ANR)
4.3.5 External LTE cell support for the LTE539: Central ANR in NetAct. The NetAct Optimizer considers external eNBs and its sub-ordinate cells as neighbor cell candidates during the centralized ANR configuration (the LTE539: Central ANR feature). 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: PRACH Management in NetAct. The NetAct Optimizer considers external eNBs and its subordinate cells during the PRACH configuration (see the LTE581: PRACH Management feature description). Similar as for the own-managed LTE cells the preference settings or operator selections are 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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•
•
•
Functional Description for ANR
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: •
•
• •
4.4.2.2
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 parameters table in the LTE782: ANR Fully UE based feature). Either LTE492: Automatic Neighbor Relation (ANR) or LTE782: ANR Fully UE based is activated. The maximum number of X2 links, which can be established by the eNB, is not reached yet.
Incoming enbControlled X2 link (establishment triggered by neighbor eNB) The eNB will accept establishment request of the enbControlled X2 from the neighbor eNB if all of the following conditions are met: • • •
Issue: 04A
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 based is activated. The maximum number of X2 links which can be established by the eNB is not reached yet.
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Functional Description for ANR
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Automatic Neighbor Relation (ANR)
Automatic re-establishment of the enbControlled X2 links might occur only if one 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 ANR features (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 interface alarm is activated.
g g
In case when the LTE492: Automatic Neighbor Relation (ANR) feature is activated, it is in addition required to have for the LNADJ to be re-established a valid PCI/IP@ entry for one of the LNADJLs. 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 The LTE1708 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: •
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The size of the X2 black-list table is increased.
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Functional Description for ANR
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: • • • •
• •
Issue: 04A
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 based feature activated to accept the incoming calls.
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Functional Description for ANR
Automatic Neighbor Relation (ANR)
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 discover and 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 neighbor eNB, 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.
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The parameters limiting learning of new neighbors defined in ANRPRL are applied also to the LTE492: ANR feature.
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The ANR supports IPsec star topology configurations where an IPsec tunnel that 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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Functional Description for ANR
The PCI values of neighbor cells are configured unique for the given center frequency (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 all cells 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.
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It is not recommended to use the LTE492: ANR feature in a network deployment 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 Autoconnection/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 cell relation is only generated if the PCI is reported by a UE connected to this cell. The cellspecific 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: ANR feature 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 Management feature 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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Functional Description for ANR
4.6.2.1
Automatic Neighbor Relation (ANR)
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 cell relations. 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 connectivity configuration completion As soon as the NetAct Optimizer completes the neighbor evaluation, it hands over the result 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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Functional Description for ANR
Operator hint The 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, for any 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 based feature is activated, or use PCI/IP address tables rather for inter-frequency HO support. In capacity-limited network deployments the LTE492: ANR and the LTE782: ANR - UE based features 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 eNB database. 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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Functional Description for ANR
Figure 5
Automatic Neighbor Relation (ANR)
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).
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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: •
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the location (co-location) of the BTS
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• •
Functional Description for ANR
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
Changesat the2G/3G side
2G/3GBTS
LTEBTS
NetAct
Scheduledefinedbytheuser 2G/3G
CM SON
LTE
CM
Update
UpdateInter-RAT neighborrelations, ifnecessary, dependingon -location(co-location) -distancebetweenBTS -antennaradiolobe
Configurationfiledownloaded Update Configurationfiledownloaded Update
CM
CM
4.9 LTE783: ANR InterRAT UTRAN Functional overview The configuration of inter-RAT neighbor relations is handled by the NetAct, whereby configuration 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: • •
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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 colocated.
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Functional Description for ANR
Automatic Neighbor Relation (ANR)
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) up front 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 the possibility 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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Functional Description for ANR
As neighbor relations significantly change the call processing and performance behavior 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 with a 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 the UTRAN cells over-lapping with the LTE cells and in addition a border range around the LTE cell area. In a typical case, the UEs connected to the LTE network should be supported to execute a coverage-based handover to the UTRAN network at the LTE network border. In addition inside the LTE network there can be service-based redirect support. Idle mode mobility support aims more at coverage-based information. There are two use cases to be considered: the establishment of NR for interRAT UTRAN and the maintenance of existing neighbor relations.
Neighbors finding algorithm The neighbor finding algorithm is based on geo-location information of the eNB/BTS or its cells and the antenna main lobe direction of their cells. The maximum distance value excludes far away cells if there are only few nearby cells and the minimum number of neighbors is not reached. The basic assumption behind the algorithm is that in cellular systems networks are planned in such a way that effort is made to minimize interference between cells on the same frequency layer. In addition, the reuse of existing sites with the nearby frequency bands results in quite similar cell deployments or LTE and UTRAN networks. In this case, the number of neighbor relation inside each RAT and also their inter-RAT neighbor relations are quite similar. The number of neighbor candidate cells is selected on the basis of site and antenna distance. Overlap of the antenna main lobe is estimated for the selected cells. This considers cells sending from the same site in the same direction as well as cells sending from different sites towards the same area. The distance and the main lobe overlap factor are considered to rank the given cells from the best candidate to worse neighbor candidate. At this point the selection of a suitable minimum number of inter-RAT cell neighborships is very important. If the number is too low, some suitable inter-RAT neighbors might be not considered. If the number is too high, too many useless interRAT neighbors are considered. Below you can find three cases showing a range of inter-RAT neighbor cells depending on frequency and cell density in networks. Case 1: Rather similar frequency and cell density in both networks. The minimum number of inter-RAT neighbor cells is expected to be in the range from 6 to 12. Case 2: Considerably low frequency and lower cell density in the inter-RAT network, than in the LTE network. The minimum number of inter-RAT neighbor cells is expected to be in the range from 3 to 9.
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Functional Description for ANR
Automatic Neighbor Relation (ANR)
Case 3: Quite a high frequency and higher cell density in the inter-RAT network, than in the LTE network. The minimum number of inter-RAT neighbor cells is expected to be in the range from 9 to 24. If the operator activates a UE-based ANR algorithm (in later releases) to find additional neighbor cells in the operational network, then the O&M based ANR policy, minimum number of inter-RAT neighbor cells, might be at the lower range to ensure an initial setup; this, however, lets the UEs find the next best cells. If the operator needs to assign two inter-RAT bands, for example of UTRAN, as neighbor to the LTE network cells, then the number of minimum inter-RAT neighbors needs to be doubled.
Main use cases to be considered: • • •
manual trigger for automatic generation of neighbors relations maintenance of existing neighbors relations auto-configuration triggers for automatic generation of neighbors relations
The operator can still reconfigure manually the UTRAN neighbors parameters at the eNB configuration plan. The operator can set at the NetAct Optimizer UTRAN neighbors (LNRELW) that are not modified.
4.10 LTE784: ANR InterRAT GERAN Functional overview The configuration of inter-RAT neighbor relations is handled by the NetAct whereby configuration data, relevant for inter-RAT neighbor relations, are uploaded/retrieved from any existing 2G network configuration management database and corresponding interRAT neighbor relations are created for the concerned Flexi Multiradio BTS, taking into account: • •
the geo-location of the source (LTE) and target GERAN site/cell antenna sectorization/antenna horizontal main lobe direction of source LTE and target GERAN cells (algorithm does not take into account whether the source and target are co-located)
The relevant parameters for inter-RAT neighbor relation establishment are provisioned by the NetAct in case of a co-existing NSN 2G network or by the NetAct northbound interface (Itf-N), in case of another NSN NetAct regional cluster or other vendor's coexisting 2G network. The NetAct operates on the current configured external GERAN cells for this feature. Between those external GERAN cells and the LTE cells the neighbor relations are established by manually triggered the LTE784: ANR InterRAT GERAN function. In addition, the NetAct Configurator updates/synchronizes LTE inter-RAT neighbor relation information automatically. Changes occurring at the GERAN cells, which are relevant for LTE inter-RAT neighbor relations point of view, cause the update of the interRAT neighbor relationships. This is a part of the the NetAct Configurator's plan functionality. Changes that might trigger an update of the LTE inter-RAT neighbor relation configuration are:
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• • •
Functional Description for ANR
GERAN BTS deletion GERAN cell deletion GERAN cell-specific parameter change (for example, ARFCN, BSIC, LAC)
Figure 7: LTE784: ANR InterRAT GERAN gives an overview of the feature. Figure 7
LTE784: ANR InterRAT GERAN
NetAct Optimizer CM Configurator CM Filter
LTEDomain Manager
CM
UTRAN/GERANHRPD DomainManagers
CM
NSNLTE
HRPD GERAN UTRAN
Network Policy The LTE442: Network Assisted Cell Change to GSM feature supports network-assisted cell change to EDGE networks. The required signaling of GERAN neighbors cells via SIB towards the UE is supported by the LTE762: Idle Mode Mobility from LTE to WCDMA, GSM or Other LTE Bands feature. This helps the UEs to camp on LTE cells to find quickly the most suitable GERAN cells. The UEs connected to a voice or data call to the LTE network can hand over to GERAN/EDGE cells offering the same service. The related objects and parameters can be manually configured by the operator. This is of course the situation, when the LTE784: ANR InterRAT GERAN feature is not activated. The LTE784: ANR InterRAT GERAN feature automates the configuration of GERAN neighbor information. An algorithm finds the suitable GERAN neighbor cells for all the given LTE cells, based on their geo-location and their antenna lobe main direction. The LTE cells can have existing GERAN neighbors relations or none. After the execution of the algorithm, the neighborship is updated to the current situation. It is the goal to run this algorithm for a huge number of LTE cells at once. For that reason, the operator can set some policy to influence the configuration, for example to limit the number of GERAN neighbor cells per LTE cell. This will be considered for all LTE cells. In addition, the operator can define allowed and forbidden GERAN cells for
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Functional Description for ANR
Automatic Neighbor Relation (ANR)
each LTE cell. This can consider service capabilities of the GERAN cells. For each automated generation of GERAN neighborship relations these profile settings can be entered. The NetAct allows a final check on the results of the algorithm, before the new delta configuration is downloaded and activated. The basic case is that one NetAct network area covers the same geographical area with LTE and GERAN cells. Otherwise, the NetAct network area covers only the LTE network and GERAN cells are modeled as external inter-RAT cells. In certain NetAct deployments only parts of the LTE network are covered and even LTE cells are modeled as external LTE cells, but this last case is not relevant for this feature. The external interRAT cells cover an additional border area around the LTE cells according to the range limits given by the radio signal propagation. In general case the NetAct areas are distinct and the NetAct assigned to manage the LTE network area allows configuration, via Itf-N, of the inter-RAT configuration from for example a configuration file. Optionally, the NetAct can identify the changes in the interRAT network with respect to the current inter-RAT configuration, whether the file is yet a delta configuration file. Main use cases to be considered: • • •
manual trigger for automatic generation of neighborship relations maintenance of existing neighborship relations new neighborship generation during LTE auto-configuration
The operator can still reconfigure manually the GERAN neighborship parameters at the eNB configuration plan. Of course the next automated generation rewrites this configuration. The operator can set at the NetAct Optimizer GERAN the neighborships that are not modified.
4.11 LTE782: ANR Fully UE based Functional overview In the LTE networks the UE mobility relies on the information given by neighbor cell relations and neighbor cell configurations. An automatic mechanism is implemented to discover and integrate the unknown cells. It supports and allows the automated configuration and update of neighbor cell information without the need for an off-line planning update of the neighbor cell configurations.
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Figure 8 Neighbor Site eNB-B
Functional Description for ANR
ANR principle Site eNB- A
MME
UE connected
Newcell discovered Newcell identified by ECGI
Neighborcellinformationcreation S1:RequestX2 TransportConfiguration(ECGI) S1:RequestX2 TransportConfiguration
relays request
CM S1:RespondX2 TransportConfiguration(IP@) S1:RespondX2 TransportConfiguration(IP@)
CM
AddSite&Cell parameterof eNB-A
X2Setup:Ipsec,SCTP,X2-AP[site&cellinfo]
CM
relays request
AddSite&Cell parameterof eNB-B
CM NeighborCell TablesinbotheNBupdated
Neighbor cell configuration via X2 initiated by camping UE The UE reports all detected/strongest cells above a given threshold. Therefore, it might report strong cells whose physical IDs are currently not yet known to the Flexi Multiradio BTS. In this case the Flexi Multiradio BTS might send a measurement request to the UE to discover and report the EUTRAN Cell Global ID (ECGI) for the previously reported unknown physical cell ID. After ECGI resolution the configuration of neighbor cell and neighbor relation is stored. The cell is available for S1HO. If there is no X2-link available and the X2-link establishment is not forbidden by the operator (via X2 neighbor blacklisting), the eNB retrieves the IP address serving the resolved neighbor cell and sets up the X2 connectivity. The X2 connectivity is set-up including establishment of the IPsec layer if network domain security is applied followed by the SCTP connection setup.
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Functional Description for ANR
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Automatic Neighbor Relation (ANR)
There might be cases when the Flexi Multiradio BTS cannot establish a X2 link: • •
if the Flexi Multiradio BTS has already set up the maximum number of X2 connections if the target Flexi Multiradio BTS is in the operator's blacklist for X2 link connection (but not for S1)
On X2 application layer the Flexi Multiradio BTS exchanges a list of served cells and subsequent configuration parameters with the new neighbor. The exchanged cell information covers all served cells of a site and is stored in the configuration databases of both sites. When the new neighbors are successfully included into the local configuration data, the Flexi Multiradio BTS sends a configuration change notification to the NetAct to inform the operator about the new cell configurations.
Active/Passive ANR To reduce the probability of call drops, the Flexi Multiradio BTS supports ANR mechanisms to detect and configure any unknown neighbor cell as early as possible and not at the time when the first HO to a newly detected cell is triggered. This kind of operational mode of ANR is further referred to as active ANR. Active ANR If active ANR handling is started, the Flexi Multiradio BTS will pro-actively scan for unknown intra-frequency LTE cells. The operator can limit the found LNREL instances in Active ANR mode with the nrLimitIntraFreq/nrLimitInterFreq parameters at cell level. Additionally the eNB suspends the Active ANR mode if for longer time no new neighbors have been reported by UEs. Passive ANR If no unknown cells need to be detected anymore, ANR operates as a background task, for example, Flexi Multiradio BTS does not configure ANR-specific measurements but uses normal measurement reports (as received for HO) for the detection of unknown cells. The operator can configure the ANR behavior of ANR, for more information see ANR configuration via ANRPRL. Monitoring of ANR is supported by means of performance measurements. The following events can be monitored: • • •
number of successful/failed/attempted ECGI-resolutions number of successful/failed/attempted MME-queries (IP address resolution) number of successful/failed/attempted X2-setups
After new neighbor cell relations have been successfully included into the local configuration data, the Flexi Multiradio BTS sends a configuration change notification to the NetAct to inform the operator about the new neighbor cell configurations.
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Functional Description for ANR
Interworking of the LTE782: ANR Fully UE based with the LTE492: ANR Both features LTE782: ANR Fully UE based and LTE492: ANR can be activated at the same time in the network. If a new PCI on a certain radio frequency (RF) is found and the PCI/EARFCN/IP address lookup table contains the mapping information for this PCI and RF, then the information in the PCI/EARFCN/IP address lookup table is applied. If the new PCI and RF is not included in the PCI/RF/IP address lookup table, then the LTE782: ANR Fully UE based feature mechanism is applied to detect the required information.
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The LTE492: ANR feature is needed, if inter-frequency LTE neighbor cells need to be resolved. The operator configures the required inter-frequency measurement configuration for the known center frequency. This measurement configuration supports neighbor finding as well as the preparation for HO to these neighbors.
Interworking with the LTE539: Central ANR or manual neighbor configuration The operator can manually add neighbors parallel to the ANR function. The LTE539: Central ANR feature can pre configure a certain number of neighbor eNBs based on geo-locations. ANR learns from the current neighbor configuration. If the LTE539: Central ANR and the LTE782: ANR Fully UE based features are activated, then the LTE539: Central ANR feature profile settings for minimum and maximum number of neighbor cells should be rather at 3...6 neighbor cells, so that there is more room for finding suitable neighbors by the LTE782: ANR Fully UE based feature on UE measurements.
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Operator hint The LTE782: ANR Fully UE Based feature works in coverage-limited network deployments (typical for rural and suburban) very well, as the radio path loss is high. The UE reports not too much neighbor cells and all cells have a meaningful number of neighbors. No X2 black-listing is required. Requirement of higher power level for measured neighbors in active mode at anrThresRSRPNbCell = 40 (= -100dBm) default value is proposed for coverage-limited networks deployments. The LTE771: Optimization of Neighbor Relations feature can find some few NR that leads to a higher number of failures, but the threshold for the required success rate should not be set above 80%. Blacklisting of neighbor relation (LNREL) in coveragelimited networks should be based on long term supervision, as mandatory neighbor relations is not black-listed. In such cases coverage holes might be the reason for call drops or HO failures, and those cannot be improved by black-listing. If there are, for any reason, far away neighbor eNBs connected via X2, with PCI values as for newly installed nearby eNBs, those will be detected by the LTE771: Optimization of Neighbor Relations feature and proposed to be black-listed in LNREL, while this does
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Automatic Neighbor Relation (ANR)
blacklist the nearby cell too. In addition the LTE468: PCI Management feature scheduled self-healing will check on neighbor's neighbors and propose to update the duplicate PCI values. Of course still the wrong neighbors are configured, but without negative impact. To remove wrong neighbor eNBs and their X2 link, first they are X2 black-listed, then the corresponding LNADJ&LNADJL is removed. This can be done for each eNB individually. Incoming HO via S1 are of course still supported. In capacity-limited network deployments (typical urban), the LTE782: ANR Fully UE based feature will receive a lot of UE measurements containing other cells visible to them. The LTE782: ANR - UE based feature will continue to add those cells. Therefore, the number of neighbors needs to be limited. Requirement of higher power level for measured neighbors in active mode at anrThresRSRPNbCell = 50 (= -90dBm)... 60 (= -80dBm) is proposed for capacitylimited network deployments. In addition, the operator is recommended to watch the found NR from a performance point of view. The LTE771: ANR Optimization feature finds NR with low HO success rate. The level of required HO success rate can be set to 90% from long term PM data supervision (for example, one week). Moreover, the operator can see the NR with insufficient HO attempts. If there is a high number of NR to all cells of one neighbor eNB, then this eNB can be X2 black-listed. This is done by adding the eNB's global eNB ID into the LNBTS - glbNbEnbldX2LinkBlacklist[64]{global eNB ID}. Still, the LNADJ and LNADJL are kept to execute S1 HO. The X2 HO reduces the core load for HO execution, so the NR with higher HO rate obtains one of the X2 links. Here we assume that all neighbor eNBs have set eNB-controlled IP addresses by the LNADJ parameter cPlanelpAddrCtrl = enbControlled(1). Having the X2 links on the main HO paths ensures in addition an in-time exchange of parameters between the eNBs, for example in case of PCI updates at one peer. For those LNADJL that do not have X2 link, the NetAct will trigger a plan preparation for updating their PCI value at LNADJL - phyCellId. This can take some time, but should be acceptable for low HO performance. If almost all of the 64 LNADJ instances are in use, the operator should remove some of those. Candidates are those neighbor relations having no HO attempts (via S1) to all cells of a neighbor eNB, and their X2 link was X2 black-listed before. Then their LNADJ & LNADJL can be deleted manually and the NetAct supports to remove all related LNREL automatically. The free LNADJ might be occupied by new neighbors after the LTE782: ANR Fully UE based feature finds new neighbors. Having a lot of neighbors per cell does influence LTE468: PCI management. As PCI management considers the existing NR, it is quickly impossible to find suitable PCI values.
Limitation of the “Addition of new neighbors” There is the possibility in ANR intra-frequency handling (either with the LTE782: ANR Fully UE based feature or the LTE492: Automatic Neighbor Relation) to limit the addition of new neighbors. For "passive ANR" the addition of new neighbors is limited to the following case: • •
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accept the strongest unknown PCI in A3/A5 as “Candidate for ANR” only if no other HO targets are available in addition to existing conditions, accept unknown PCI in reportStrongestCells (RSC) as “Candidate for ANR” only if it is the strongest PCI included in RSC
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Functional Description for ANR
The intention is as follows: If no or no other known HO target cells for HO preparation are available, then consider the strongest unknown PCI in A3/A5 as “Candidate for ANR”. Learning of new neighbors is allowed only up to a maximum amount that might be specified by the operator. The eNB supports a limit for creation of new NRs by the nrLimitIntraFreq/nrLimitInterFreq parameters. When the number of LTE intra/inter-frequency NRs of the eNB cell reaches the nrLimitIntraFreq/nrLimitInterFreq, the eNB stops autonomous learning of new neighbor cells via ANR.
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If the limits for the amount of neighbor relations have been crossed before already in the eNB database, no action is triggered in the eNB. If an unknown PCI is accepted as a Candidate for ANR, then the eNB resolves the neighbor information (via CGI measurement or via X2) and stores the related LNADJ/LNADJL objects.
4.12 LTE771: Optimization of Intra-LTE Neighbor Relations 4.12.1 Functional description Functional overview The LTE771: Optimization of Intra-LTE Neighbor Relations is part of the overall ANR (3GPP 36.300: Automatic Neighbor Relation) functionality. LTE neighbor cells will be discovered and added by ANR features or manual input by the operator. The neighbor eNB and cell configuration is configured or exchanged, via the X2 set-up procedure, in a bi-directional mode, so both peers can be the initiator. While the cell neighbors relation itself is first of all an uni-directional linkage from the source cell to the target cell. The eNB will establish cell neighbor relations based on UE events. The LTE771: Optimization of Intra-LTE Neighbor Relations feature focuses on cell neighbor relations in the following way: •
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The NetAct Optimizer supervises all current cell relations between neighboring LTE cells if they are still valid and reliable candidates to be a handover destination. When the PM counters show an inefficient neighbor relation, the according cell relation might be blacklisted for handover. The NetAct Optimizer uses Flexi Multiradio BTS configuration information and performance counters (intra-frequency and inter-frequency handovers) in order to perform the analysis task. The evaluation might result in no action or blacklisting of a neighbor cell relation.
The following use cases are supported:
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Functional Description for ANR
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Neighbor cell relations that have been created by the operator (network planning) or have been created by SON-mechanisms like ANR (automatic neighbor relation) and that have an insufficient handover performance (weak handover success ratio; threshold is operator configured) might be blacklisted by an optimization mechanism or, optionally, manually by an operator. Neighbor cell relations that have been created by the operator or have been created by SON-mechanisms like ANR (automated neighbor relation) that had been blacklisted, can be enabled again by the operator (for example, if an operator wants to re-evaluate the performance of a formerly blacklisted neighbor relation due to changed environment/topology). Neighbor cell relations that have been created by the operator or have been created by SON-mechanisms like ANR (automatic neighbor relation) can be marked by an operator in a way so that they are excluded from optimization.
Neighbor cell is blacklisted, no outgoing handover to the target cell is allowed, neither via X2, nor via S1-interface.
Possible results of optimization mechanism • •
No action: The analyzed relation showed suspicious not suspect Blacklisting: A given relation was identified as unreliable/weak performing. The NetAct suggests a new configuration plan file with updated entries for appropriate Telecom/RRM black lists.
While scheduled execution, the changes proposed by optimization algorithms can be taken over automatically (without any operator interaction) or after confirmation by the operator. One of both is configured in the LTE771: Optimization of Intra-LTE neighbor relations profile at the NetAct. When operated from the Optimizer GUI, the user makes the decision before saving the proposed changes to a plan. gives an overview of the feature.
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Figure 9
Functional Description for ANR
LTE771: Optimization of Intra-LTE Neighbor Relations
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RAN system level scope The centralized SON feature LTE771: Optimization of Intra-LTE neighbor relations operates on existing NR to intra-LTE neighbor cells. Those can be pre-configured, learnt from ANR functions, or generated from off-line tools. The PM data administration is expected to run for the whole NetAct cluster or even the whole network. The PM data are checked for being representative, so that enough HO attempts are considered. As there are a lot of NRs found by ANR functions, some of those are often used for HO others less. The prerequisite for the feature is that NR PM counters be available on weekly granularity period for the last two weeks at least. Each NR with at least the required HO number will be checked to ensure that their HO success rate is better then the defined threshold. The operator controls the feature with a network/cluster profile setting. This includes the configuration of the scheduled workflow, as well as the thresholds for the SON function itself. The LTE771: Optimization of Intra-LTE Neighbor Relations feature focuses on long term supervision of the HO performance. This task requires keeping and aggregation of PM data for a longer period of time at the NetAct. The feature blacklists bad performing NRs at eNB. The feature does not remove NR. The eNB interprets this to blacklist those neighbor cells in the measurement request and HO decision. The operator can trigger the feature manually. In this case the profile setting will be done interactively. The profile for automatic execution is not changed by this operation. The operator can request set of cells or eNBs optimization or eNBs.
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Functional Description for ANR
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If no or insufficient NR PM counters are available for a NR, then this is treated as the exit criterion for deciding on individual NR performance. The blacklisting does improve the KPI short-term, but for each blacklisted neighbor relation the operator should identify the root cause. Following situations can lead to bad HO performance in addition to missing MRO and general threshold mis-configuration: •
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•
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PCI-confusion on cell level: There are for one reported PCI for several UE different CGI visible, this is a classical PCI collision. The eNB takes one PCI/CGI association and will not recover from this situation. The SON function PCI management does resolve such situations. PCI-confusion on eNB level: There are for one reported PCI in different (mainly distributed) cells for several UE different CGI visible. This is a 3GPP-compliant PCI allocation, but the eNB will take one PCI/CGI association and will not recover from this situation. This requires to run the LTE468: PCI Management feature as this SON function recovers such a situation. pRACH-collision: The HO fails because of bad RACH performance. This requires manual execution of the LTE581: PRACH Management feature to recover this situation. pRACH-range configuration: The HO fails because of wrong RACH format for the actual distance from the UE towards the target cell. This requires manual execution of the LTE581: PRACH Management with a bigger ISD (Inter Cell Distance), to recover this situation.
4.13 LTE1019: SON Reports Functional overview In the LTE releases the set of SON features executing automatic parameter changes are increasing. The LTE1019: SON Reports feature provides a report mechanism for the parameter changes done in the network, especially with focus to automatic changes done for configuration parameters. All SON features (central once in this release), which generate automatic changes to parameters that are kept in the eNB CM database can make use of this feature and include additional information about the applied change to the user. This reporting mechanism is not limited to SON features only, but SON features are the ones using it first. In Figure 10: Centralized and decentralized parameter change the orange line describes the centralized (the NetAct-originated) SON parameter change where the Optimizer sends the SON feature information in addition with the plan to the Configurator (contains CM plan prepare, CM operations, CM mediator, CM event handler, RAC Access and CM history UI). The Configurator prepares and activates the plan into eNB(s). When the plan is activated the eNB(s) sends the configuration change notifications to the NetAct Configurator. The Configurator correlates the SON feature information into changed parameters. From the CM history the user is able to obtain the information which SON feature has changed parameter(s).The purple line in the figure below describes the decentralized parameter change where the eNB determines and makes SON parameter(s) change and reports this SON parameter change with configuration change notification(s) to the NetAct. When the configuration change notification contains SON
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feature information, the NetAct is able to attach the context information into the CM history database. With the CM history tool the user is able to view, search and generate reports for SON parameters. All entries in the history without information on the origin of the change implicitly are regarded as manually initiated modifications by the user. Figure 10
Centralized and decentralized parameter change
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changepayload changecontext
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4.14 LTE1045: Full SON Support for Distributed Sites Functional overview This feature includes the introduction of antenna location information differentiation for distributed site deployments: • •
support of RRH (remote radio head) configurations support of BTS hotel configurations
The SON algorithms calculating possible neighbor sites are adapted to consider the site location info from antenna. The following SON features are enhanced by the LTE1045: Full SON support for distributed sites feature: • • • •
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Functional Description for ANR
• • •
Automatic Neighbor Relation (ANR)
LTE783: ANR InterRAT UTRAN LTE784: ANR InterRAT GERAN LTE510: Synchronization of InterRAT Neighbors
to support: • • •
geo-location per cell the input of antenna geo-location data done manually by the operator check for distributed site deployment via the LNBTS - parameter actDistributedSite =
The approach is also applicable for RF sharing with separate cells.
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Distributed GERAN and UTRAN sites are out of scope of this feature. The correct provision of GERAN and UTRAN cell geo-location data is a basic requirement for the LTE783: ANR InterRAT UTRAN/LTE784: ANR InterRAT GERAN feature.
NetAct Optimizer For support of distributed RRH and BTS hotel configuration the service area of a cell can be up to 20 km (the LTE614: Distributed Site) away from the BTS location. The service area is defined rather by the location of the antenna than the BTS hardware. To take the difference in location into the account, the NetAct cell supports the usage of antenna coordinate information in the centralized SON solutions where applicable. If the antenna coordinate is missing, the NetAct uses the site coordinate information instead. If also the site coordination is missing, the related object is excluded from SON algorithms, the process aborts and the user is informed. For distributed sites the antenna/cell geo-location data are mandatory. If those are not available, the eNB plan file is not consistent and download is not allowed by the NetAct. The SON function running in auto-configuration or scheduled mode aborts. For PRACH and PCI management, the NetAct requires geo-location data for distributed site configurations. If those are missing, the SON function is stopped and the operator is informed. The NetAct identifies a distributed site configuration by the value of LNBTS parameter actDistributedSite to be set to true. The NetAct supports the usage of the antenna coordinate information for: •
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LTE468: PCI Management The NetAct Optimizer considers the antenna coordinates when optimizing the PCI reuse distance. Consistency check function. LTE539: Central ANR The NetAct Optimizer considers antenna coordinates when creating the list of preconfigured neighboring eNBs (LNAJDLs). LTE492: ANR The NetAct Optimizer considers antenna coordinates when building the PCI-RF-IP address mapping table entries from within the search distance based on the ranking (priority function). LTE720: SON LTE BTS Auto Configuration
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Functional Description for ANR
The NetAct Optimizer includes information into the feedback messages, where antenna coordinates were missing, the fallback to site coordinates has happened and where the coordinate information in total is missing. For distributed sites the antenna/cell geo-location data are mandatory. If those are not available the eNB plan file is not consistent and download is not allowed by the NetAct. LTE581: PRACH management The NetAct Optimizer considers antenna coordinates when determining the PRACH configuration reuse distance. Consistency check function. LTE783: ANR InterRAT UTRAN The NetAct Optimizer considers antenna coordinates in ranking the neighbor relation candidates (priority function) and defining the search distance. LTE784: ANR InterRAT GERAN This feature uses LTE site and/or LTE antenna geo-locations, instead of the site geolocation only. The GERAN geo-locations are provided as site locations. The LTE feature makes use of GERAN cell/antenna geo-locations as input. LTE510: Synchronization of InterRAT Neighbors The NetAct Optimizer considers antenna coordinates when automatically defining the LTE scope for which synchronization is executed. In all manual, interactive execution of relevant above feature components, the NetAct Optimizer informs the user up-front about missing coordinate information. The user can then decide to fix the missing information or to continue with fallback or skipping the objects with missing information (exclude from SON operation). For distributed sites the antenna/cell geo-location data are mandatory. If those are not available, the eNB plan file is not consistent and download is not allowed by the NetAct.
The LTE614: Distributed Sites feature requires a correct upgrade in RL40. Here the antenna/cell geo-location data is mandatory and need to be correctly referenced by the cell object. A SON function based on geo-locations (as the LTE539: Central ANR, LTE468: PCI Management, LTE492: ANR, LTE510: Synchronization of InterRAT Neighbors, LTE783: ANR InterRAT UTRAN, LTE784: ANR InterRAT GERAN)checks a lot of (potential) neighbors; therefore, not only the defined scope of cell need to have consistent data, but also the other cells. In numerous cases the NetAct scans through all cells. For example the PCI values of a new eNB's cells can only be correctly assigned, if all potential neighbors can be identified by their antenna geo-location to obtain the list of used PCI values in the neighborhood. The eNB-based ANR features LTE492: ANR and LTE782: ANR Fully UE based are based on the basic mobility handling of the eNB. The mobility management requires unique PCI values for all neighbor cells of one eNB. This is for distributed site deployments not considered in standard 3GPP compliant PCI management. The ANR function will find in one cell a PCI/CGI. This is then used in all cells at valid PCI/CGI assumption. Distributed cells might have other PCI/CGI assignments. It depends on the first UE reporting the PCI in one cell, and therefore this PCI/CGI assumptions might be wrong. The LTE468: PCI Management feature knows this eNB behavior and assigns PCI unique on eNB level as well.
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Functional Description for ANR
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For Repeater configurations (the LTE1195: FHCC Flexi 850 Repeater Interface Unit (RIU) feature) working in dedicated repeater mode, the operator has to care for the correct antenna geolocation data setting. The repeater configurations are not considered in the deployment compatibility check (as for the LTE614: Distributed Site).
4.15 LTE1222: SON Automation Modes Functional overview The LTE1222: SON Automation Modes itself is a basic feature adding functionality for the existing centralized SON features. The interaction with the LTE1019: SON Reports and the LTE1045: Support of Distributed Sites features is described in the specific feature descriptions. The execution of the features in scheduled mode during auto-configuration are controlled with preference settings, generically applicable for every execution of the work-flow. Details are explained at the specific features. The following SON features will be supported in Optimizer in an automated manner: 1. The auto-configuration can include the automatic execution of: • •
LTE783: ANR InterRAT UTRAN LTE784 ANR InterRAT GERAN
The execution depends on the operator settings for auto-configuration. Additionally the features can be started manually as before. 2. Time scheduled execution of: • • •
LTE510: Synchronization of InterRAT Neighbor Relations LTE533: Mobility Robustness LTE771: Optimization of Intra-LTE Neighbor Relations
The operator can define time schedules when the mentioned features are executed. Additionally the features can be started manually as before.
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The LTE1222: SON Automation Modes feature is handled as a basic feature adding additional functionality to the existing features for: LTE533: Mobility Robustness LTE771: Optimization of Intra-LTE Neighbor Relations LTE510: Synchronization of InterRAT Neighbors LTE783: ANR InterRAT UTRAN LTE784: ANR InterRAT GERAN Therefore, there are no specific SON Reports, CM parameter or PM counters or other preparation for the LTE1222: SON Automation Modes feature itself.
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4.16 LTE507: Inter-RAT Neighbor Relation Optimization Functional overview The LTE507: Inter-RAT Neighbor Relation Optimization feature is intended to manage and optimize the use of the inter-RAT NRs between LTE and WCDMA or between LTE and GSM for a defined set of mobility procedures, which transfer UE from one LTE cell to a cell of the other RAT. The goal of the LTE507: Inter-RAT Neighbor Relation Optimization feature is to keep only stable and reliable NRs active for given mobility procedures. The NetAct Optimizer supervises all registered inter-RAT neighbor cell relations between LTE cells and non-LTE cells whether their performance is good enough for handover (HO). When the outcome results in an inefficient NR, the neighbor cell relation might be blacklisted for HO.
Blacklisting The LTE507: Inter-RAT Neighbor Relation Optimization feature manages the blacklisting or inter- RAT NR via the dedicated LNRELW and LNRELG instances. For each mobility type the NR can be blacklisted individually. The LTE507: Inter-RAT Neighbor Relation Optimization feature does not consider the band or frequency allocation of the neighbor inter-RAT cells among themselves. Ongoing changes in the user behavior, topology, and deployment will change the need for blacklisting. To obtain a new judgment of the performance of an NR, this blacklisting needs to be switched back manually from time to time to allow HO. Only NRs for which LNRELx.nrControl is set to AUTOMATIC and LNRELx.xyzAllowed to ALLOWED are considered by the LTE507 Inter-RAT Neighbor Relation Optimization feature.
Configuration of the feature per mobility procedure For UTRAN: • •
inter-RAT HO to WCDMA (from LTE) and CS fallback to UTRAN (from LTE): can be executed only together (if taken individually, then only manual execution is allowed) single-radio voice call continuation (SRVCC) to WCDMA (from LTE)
For GERAN - there is only SRVCC to GERAN. The optimization works with independently defined thresholds and scheduler time setups per each mobility procedure per each RAT.
4.17 LTE1383: Cell-specific Neighbor Relation/PCI Handling Functional overview The LTE1383: Cell-specific Neighbor Relation/PCI Handling feature introduces additions to the existing ANR features to allow high stability of the feature, even in difficult network setups. The following improvements are included: • •
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Automatic Neighbor Relation (ANR)
The eNB supports cell-specific PCI and NR handling in the following ways: •
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• •
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The eNB establishes and handles the NRs associated to a certain PCI and frequency per eNB cell. The uniqueness of PCI/Freq is required for the NRs associated to the eNB cell. The NRs are validated by the eNB. To perform this validation the eNB retrieves cell global identification (CGI) measurements from suitable UEs if UE-based ANR is available. The eNB detects and stores NRs per eNB cell. HO procedures are triggered using the stored cell-specific NRs. The cell-specific NRs might be provided via O&M or learned automatically via ANR features (using mechanisms of the LTE492: ANR and the LTE782: ANR Fully UE Based features). For intra-frequency neighbor cells: – –
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The eNB automatically determines the correct NRs even if there are several neighbor cells in eNB service area with the same PCI/Freq. The eNB supports UE-based ANR, see the LTE782: ANR Fully UE Based feature.
For inter-frequency neighbor cells: – – – –
The eNB automatically determines the correct NRs, but only if PCI/Freq of all neighbor cells in the eNB service area are unique. The eNB supports only OAM-based ANR. To remove the restriction to have unique PCI/Freq in the eNB area, support of the LTE556: ANR Intra-LTE, Inter-frequency - UE Based feature is needed. If for a certain PCI/Freq several inter-frequency neighbor cells are visible for the eNB, the correct NRs have to be provided via O&M.
The cell-specific PCI handling is backward compatible in the sense that with respect to target cell selection the legacy behavior is supported even if UE-based ANR features are deactivated.
Assigning the same PCI/frequency values for neighbors of different eNB cells The eNB handles NRs for each LTE carrier per eNB cell. If the eNB receives a measurement report triggering a mobility procedure (that is, measurement report A3 triggering a handover), then the eNB uses for the mobility procedure the neighbor cell identified as NR of the respective eNB cell, see Figure 11: LTE NRs of eNB-A for a given LTE carrier. The HO is triggered to the neighbor cell that is identified as NR of the respective eNB cell. Identification of the NR occurs via ANR handling or via O&M configuration.
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The eNB validates the NRs used for the HO via CGI measurement if UE-based ANR is available.
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Functional Description for ANR
Figure 11
LTE NRs of eNB-A for a given LTE carrier Measurement Report
eNB-A Measurement Report
A1 (PCI=3)
C1 (PCI=8) A3 (PCI=4)
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C2 (PCI=9) C3 (PCI=10)
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Example of targeted network deployment, see Figure 11: LTE NRs of eNB-A for a given LTE carrier: • • •
NRs of cell A3 used for HO: A1, A2, C1, C3 NRs of cell A2 used for HO: A1, A3, B1, B2 NRs of cell A4 used for HO: D1, D2
ANR configuration via ANRPRL The Automatic Neighbor Relationship Profile LTE (ANRPRL), a new managed object class (MOC), defines carrier frequency-specific settings for automatic detection of LTE intra-frequency and inter-frequency neighbor cells. Up to 32 ANRPRL instances might exist per eNB, where they are persistently stored. The instance with id 0 (default profile) is mandatory independent from the activation of any ANR feature. The ANRPRL managed object class (MOC) includes the following parameters: •
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anrPrLId This parameter uniquely identifies an ANRPRL object. “anrPrLId=0” is the mandatory default profile and is applied to all target carriers, for which no other frequencyspecific ANR profile is available. targetCarrierFreq The parameter identifies the EUTRA target carrier frequency for which this ANR profile applies. The profile applies for intra/inter-frequency ANR dependent on the carrier frequency of the cell. If no target carrier is defined, the profile applies for any frequency which is measured by a UE. This profile is considered as default profile and must exist in any case. The parameter must be omitted in the ANRPRL instance with “anrPrLId=0” (default profile). The parameter is mandatory in ANRPRL instances with anrPrLId greater than 0.
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Functional Description for ANR
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Profile is effective only if measurements for targetCarrierFreq are performed by the eNB cell (for example, for inter-frequency case, measurements is activated only if LNHOIF for targetCarrierFreq is created). actAlsoForUeBasedANR The following states are possible: – –
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“true”: beside OAM-based ANR (if activated) also UE-based ANR (if activated) is allowed towards this targetCarrierFreq “false”: the profile is not applied for UE based ANR but still applied for not UEbased ANR features (for example, the LTE492: ANR feature)
nrLimitIntraFreq When the number of LTE intra-frequency NRs of the eNB cell reaches the nrLimitIntraFreq, the eNB stops autonomous learning of new intra-frequency PCIs and their related neighbor cell configuration via ANR. The number of intrafrequency NRs can exceed this limit since new neighbor cells/NRs still can be configured via O&M and autonomous creation of NRs for already available neighbor cells might occur. nrLimitInterFreq When the number of LTE inter-frequency NRs of the eNB cell reaches the nrLimitInterFreq, the eNB stops autonomous learning of new inter-frequency PCIs and their related neighbor cell configuration via ANR. The number of interfrequency NRs can exceed this limit since new neighbor cells/NRs still can be configured via O&M and autonomous creation of NRs for already available neighbor cells might occur. anrThresRSRPNbCell If RSRP of a neighbor cell included in ANR measurement “reportStrongestCells” is greater than anrThresRSRPNbCell, then a cell is accepted by eNB as a neighbor cell for which CGI is needed. The anrThresRSRPNbCell parameter is relevant only if the LTE782: ANR Fully UE Based feature is activated. The anrThresRSRPNbCell parameter is relevant for UE-based ANR only. anrThresRSRQNbCell The eNB requests to resolve the CGI of unknown cells detected via a “ReportStrongestCells” only if the respective RSRQ level measured by the UE is at least equal to the anrThresRSRQNbCell parameter. The anrThresRSRQNbCell parameter is relevant if the LTE782: ANR Fully UE Based feature is activated. The anrThresRSRQNbCell parameter is relevant for UE-based ANR only.
With the introduction of the LTE1383: Cell-specific Neighbor Relation/PCI Handling feature, the validityOfData parameter is deleted from LNADJL. The main difference coming with the LTE1383: Cell-specific Neighbor Relation/PCI Handling feature to the LTE782: ANR Fully UE Based and the LTE492: ANR features is the feature activation per carrier frequency (targetCarrierFreq), as defined by one or more ANRPRL instances. Each instance of ANRPRL defines for one carrier frequency (targetCarrierFreq) the behavior. It also depends on the feature flags for the LTE782: ANR Fully UE Based (actUeBasedAnrIntraFreqLte) and the LTE492: ANR (anrOmExtEnable), which ANR activity is working.
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The nLTEIntraNeighbours parameter is replaced by the nrLimitIntraFreq and the nrLimitInterFreq parameters, so the operator can set distinct values for intrafrequency and inter-frequency neighbors. Those values are applicable to the LTE492: ANR and the LTE782: ANR Fully UE Based features with the assignment of the ANRPRL instance to the carrier frequency (targetCarrierFreq). After upgrade to RL50 there is one default ANRPRL profile without a targetCarrierFreq parameter set, so this profile is valid for all carriers. For all carriers (actAlsoForUeBasedANR=“true”, default value) the LTE782: ANR Fully UE Based feature is activated if the actUeBasedAnrIntraFreqLte parameter is set to “true”. The LTE492: ANR feature is activated for all carriers if the anrOmExtEnable parameter is set to “true”. This is the same behavior as for RL40. The new LNREL parameter nrStatus has range = { unavailable, available }. When it is set to “unavailable”, it shows an LNREL that has no corresponding LNADJL.
4.18 LTE556: ANR Intra-LTE, Inter-frequency - UE Based With the LTE556: ANR Intra-LTE Inter-frequency UE Based feature, the eNB automatically establishes for its own cells the dedicated LTE inter-frequency neighbor relations (NRs). The LTE556: ANR Intra-LTE, Inter-frequency UE Based feature is built on the assumption that geographically separated eNB cells see LTE inter-frequency neighbors that have different CGI with the same physical identity (PCI and eARFCN). The operator configures the carrier frequencies (and other parameters if needed) that are used by the eNB for the automatic NR detection. The eNB informs the operator when new NRs are automatically created.
Detection of unknown cells The detection of unknown neighbor cells happens during event-triggered inter-frequency measurements or during periodic measurements activated by the Flexi Multiradio BTS for ANR-capable UEs. Upon the detection of an unknown cell, the Flexi Multiradio BTS tries to resolve the corresponding E-UTRAN cell global identifier (ECGI). This is done by ordering EGCI measurement at the UE, if supported by the UE, or via any other information locally available (for example, from X2 interface). Detection of unknown cells for discovering new NRs stops as soon as the pre-configured maximum number of automatically created NRs is achieved.
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5 Management data for ANR For management data of the functional area, see feature descriptions: • • • • • • • • • • •
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LTE492: ANR LTE510: Synchronization of InterRAT Neighbors LTE539: Central ANR LTE724: LTE Automatic Neighbor Cell Configuration LTE771: Optimization of Neighbor Relations LTE782: ANR Fully UE based LTE783: ANR InterRAT UTRAN LTE784: ANR InterRAT GERAN LTE1019: SON Reports LTE1045: Full SON Support for Distributed Sites LTE1222: SON Automation Modes
LTE507: Inter-RAT Neighbor Relation Optimization LTE1383: Cell -specific Neighbor Relation/PCI Handling LTE556: ANR Intra-LTE Inter-frequency UE Based LTE1708: Extend Maximum Number of X2 Links
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Operating Tasks Related to ANR
6 Operating Tasks Related to ANR 6.1 LTE771: Optimization of Intra-LTE Neighbor Relations 6.1.1 Scheduled workflow for LTE771: Optimization of Intra-LTE Neighbor Relations This workflow describes the HO performance optimization of intra-LTE NRs. The operator configures a scheduled job at the NetAct that analyzes all the eNBs or LTE cells with respect to their intra-LTE neighborship performance. The eNBs or the LTE cells will be the whole network or the actual the NetAct cluster. The operator cannot directly configure the scope of LTE cells. The operator can run the process autonomously or request break-points. In autonomous mode, all the resulting blacklisting of badly performing NRs are configured with one common plan file together for all the impacted eNB-cell-NRs.
Preconditions The LTE cells and eNBs exist and are under management of the NetAct. The operator has set the wanted NetAct policy values for optimization of intra-LTE NR optimization. The operator has enabled the scheduled job at the NetAct.
Description The following steps are supported by the NetAct: 1. The NetAct starts the workflow according to the configured week-day and day-time. 2. The NetAct collects all the eNBs and their cells in the current network, based on their actual configuration. It is ignored, if the eNB or its cells are locked in reset or other states. 3. The NetAct starts for the given list of cells, for each cell the performance evaluation of its NR. 4. This step is repeated for the whole list of cells. The NetAct updates the SON report of one eNB or cell. The NetAct informs the operator about the progress of the procedure to run in background. 5. The NetAct creates the new plan of the proposed blacklisted NR. 6. In case of automatic execution, this means without active break point, the NetAct downloads and activates the plan files to each eNB. A SON report is generated and notified to the operator. 7. Confirmed execution, the NetAct stops at this break-point. The operator can access the new plan of the proposed blacklisted NR(s). The operator can edit the plan and decide on the further steps, either to withdraw the plan file or to implement it. A SON report is generated and notified to the operator or stored at well-defined location.
Post-conditions In the network the NR that perform badly will be blacklisted.
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6.1.2 ANR Optimization This use case describes the optimization of intra-LTE NRs. The operator does configure a scheduled job at the NetAct that analyzes the LTE cells with respect to their intra-LTE neighborship performance. Preconditions The operator has set the wanted operator policy values for optimization of intra-LTE NR optimization. The operator has enabled the scheduled job at the NetAct. The KPI data for the NR are available. Description The following steps are supported by the NetAct: 1. Triggered by SON scheduler or from user manually via WFE UI, WFE does start the scheduled workflow. 2. The NetAct starts for all cells the performance evaluation of its NR. 3. The NetAct creates the new plan of the proposed blacklisted NR. 4. The NetAct provides the operator the feedback on the procedure, according to the level of details selected in the policy values. 5. In case of execution without break point, the NetAct downloads and activates the plan files to each eNB. 6. In case of execution with break point, the NetAct Configurator SON Scheduler exits at this break point. The operator can edit the plan and decide on the further steps. Post conditions In the network the NRs that are poorly performing will be blacklisted.
6.2 LTE782: ANR - UE based 6.2.1 UE-based ANR Retrieval by eNB Prerequisites • •
the NB-eNB cells operate on the same frequency as the cells of the eNB X2-link establishment is allowed/possible
Description • • • •
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The eNB detects so far unknown intra-frequency LTE neighbor cells The eNB retrieves the configuration information (for LTE: ECGI, TAC, PLMNs) of the detected neighbor cells with the help of the UE measurements The eNB stores the detected neighbor cells with known (and stored) configuration information as the Neighbor Relations to the eNB cells where they were detected The eNB determines the IP-addresses of the neighbor eNBs serving the detected neighbor cells (usually via S1-i/f) and establishes X2-links to the neighbor eNBs using the previously determined IP-addresses
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Operating Tasks Related to ANR
Result • • •
X2-links to Nb-eNBs are established. Neighbor cell configuration information is stored in the eNB. Neighbor Relations are stored in eNB.
Figure 12
UE-based ANR Retrieval by eNB
NbeNB NbeNB NbeNB
NbeNB
NeighborCell
eNB NbeNB
NbeNB NbeNB
NbeNB
eNBdiscovering neighborcells viaUE-based ANR
6.3 LTE783: ANR InterRAT UTRAN 6.3.1 The establishment of NR for Inter-RAT UTRAN This procedure describes the establishment of NR for inter-RAT UTRAN. The procedure is triggered by the operator manually, to establish NR for inter-RAT UTRAN, perform the following steps:
Preconditions: • • •
UTRAN cell information is available. LTE cells and eNBs exist and are under management of the NetAct. The operator has set the desired NetAct policy values for inter-RAT UTRAN cell selection.
Description: The following steps are supported by the NetAct • •
Issue: 04A
The operator selects a set of the eNB or the LTE cells and starts the “ANR for InterRAT UTRAN” algorithm. The NetAct Optimizer identifies for each LTE cell the most suitable neighbor UTRAN cells under consideration of the operator policy and reports all found NRs. The operator is able to modify the found NR.
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• •
Automatic Neighbor Relation (ANR)
Based on the information generated by the NetAct Optimizer, the NetAct updates the existing eNB plan file. The NetAct Configurator downloads and activates the delta plan files.
Post conditions: •
The LTE cells are configured with neighbor UTRAN cells for handover support and other mobility procedures from LTE to UTRAN via S1 interface and the UE idle mode mobility.
6.3.2 New UTRAN neighborship generation during LTE autoconfiguration This procedure describes the establishment of NR for inter-RAT UTRAN cells. The operator can run the process autonomously or define the LTE720: SON LTE Auto Configuration feature break point in-line with the LTE720: SON LTE Auto Configuration feature management. The automatic inter-RAT configuration of the eNB is based on the LTE783: ANR InterRAT UTRAN feature for the given cells of the new/planned eNB. Within the auto configuration process the LTE783: ANR InterRAT UTRAN feature does not support a break point itself. Preconditions The Inter-RAT cell geo-location information is available. The own LTE cells for the new/planned eNB are assigned in the LTE720: SON LTE Auto Configuration process. The operator has set the wanted NetAct policy values for inter-RAT cell selection as preference settings. All features are activated. Description The following steps are supported by the NetAct: 1. The LTE720: SON LTE Auto Configuration process starts the auto-configuration process, that includes the “ANR for Inter-RAT UTRAN” algorithm. 2. Based on the information generated by the NetAct Optimizer, the NetAct updates the eNB configuration plan. At the LTE720: SON LTE Auto Configuration break point the operator can modify the found NR. 3. The NetAct Configurator completes the configuration plan for the impacted eNBs and, within the LTE720: SON LTE Auto Configuration process, downloads and activates the delta plan file Post conditions The LTE cells are configured with neighbor inter-RAT UTRAN cells for support of HO and other mobility procedures from LTE to inter-RAT UTRAN via S1 interface and UE idle mode mobility.
6.4 LTE784: ANR InterRAT GERAN 6.4.1 Establishment of NR for Inter-RAT GERAN This procedure describes the establishment of NR for inter-RAT GERAN. The operator starts manually and interactively steps through the process.
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Preconditions • • •
The GERAN cell information is available. LTE cells and eNBs exist and are under management of the NetAct. The operator has set the wanted NetAct policy values for InterRAT GERAN cell selection.
Description The following steps are supported by the NetAct: • •
• •
The Operator selects or has selected a set of eNB or LTE cells. The Operator starts the “ANR for InterRAT GERAN” algorithm. The NetAct Optimizer identifies for each LTE cell the most suitable neighbor GERAN cells under consideration of the operator policy. The NetAct Optimizer reports all found NRs and the Operator can still modify the found NR. Based on the information generated by the NetAct Optimizer, the NetAct has to update the existing eNB plan file. The NetAct Configurator downloads and activates the delta plan files.
Result The LTE cells will be configured with the neighbor GERAN cells for support of HO and other mobility procedures from LTE to GERAN via S1 interface and the UE idle mode mobility.
6.4.2 New GERAN neighbor ship generation during LTE autoconfiguration This procedure describes the establishment of the NR for inter-RAT GERAN cells. The operator can run the process autonomously or define the LTE720: SON LTE Auto Configuration feature break point in-line with the LTE720: SON LTE Auto Configuration feature management. The automatic inter-RAT configuration of the eNB is based on LTE784: ANR InterRAT GERAN for the given cells of the new/planned eNB. Within the auto configuration process the LTE784: ANR InterRAT GERAN feature does not support a break point itself. Preconditions The inter-RAT cell geo-location information is available. The own LTE cells for the new/planned eNB are assigned in the LTE720: SON LTE Auto Configuration feature process. The operator has set the wanted NetAct policy values for inter-RAT cell selection as preference settings. All features are activated. Description The following steps are supported by NetAct: 1. The LTE720: SON LTE Auto Configuration feature process starts the autoconfiguration process, that includes the “ANR for Inter-RAT GERAN” algorithm. 2. Based on the information generated by the NetAct Optimizer, the NetAct updates the eNB configuration plan. At the LTE720: SON LTE Auto Configuration feature break point the operator can modify the found NR.
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3. The NetAct Configurator completes the configuration plan for the impacted eNBs and, within the LTE720: SON LTE Auto Configuration process, downloads and activates the delta plan file. Post conditions The LTE cells are configured with the neighbor inter-RAT GERAN cells for support of HO and other mobility procedures from LTE to inter-RAT GERAN via S1 interface and the UE idle mode mobility.
6.5 LTE539: Central ANR 6.5.1 Central ANR for New eNBs This use case describes the deployment of a new eNB. The auto-configuration procedure performed in the NetAct is described. To support the immediate feedback to the eNB installation personnel, it is recommended that the eNB configuration is done instantly. Therefore, this use case considers one eNB to be configured. The NetAct Optimizer still has to consider all planned eNBs.
Actors The auto-configuration procedure is running on the NetAct for one new eNB.
Preconditions •
• •
A new eNB has already been deployed and the auto-connection procedure has been executed. This means that the new eNB received M-plane, IP address from the DHCP server. The M-plane connection from the new eNB towards the NetAct exists. The C-plane IP address and the global eNB ID together with the geo-location of the planned and existing eNBs are known.
Description The following steps are supported by the NetAct in the auto-configuration workflow: •
•
•
The workflow engine of Configurator triggers service of the NetAct Optimizer to generate a list of neighbor eNBs. This can be generated up-front based on the data received from the planning tool. The NetAct Optimizer generates a list of bi-directional neighbor relations of eNBs, based on the Operator policy, and the distance of the eNB to the new eNB in the current and planned network deployment. Service of Optimizer enforces bidirectional relationships and enforces the pre-set number of adjacencies. The NetAct Configurator incorporates the neighbor list received from the Optimizer into valid adjEnbIPAddressMaps, or from RL30 on it creates LNADJ instances. The Optimizer configures the global eNB ID of the list of neighboring eNBs in the new eNB's adjEnbIPAddressMap, or from RL30 on it creates LNADJ instances. –
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The Configurator complements the neighbor list of the new eNB with the corresponding IP addresses.
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The Configurator fills the ADIPNO.adjEnbIPAddressMap, or from RL30 on creates LNADJ instances, of all neighbor eNBs with the address information of the new eNB. The NetAct Configurator continues the auto-configuration of the new eNB.
Post conditions •
•
•
Issue: 04A
The configuration of the new eNB has a valid ADIPNO the adjEnbIPAddressMap parameter, or from RL30 on created LNADJ instances, that contains neighbors complying with the criteria and policies as set in the Optimizer. The configurations of the surrounding eNBs have valid ADIPNO the adjEnbIPAddressMaps parameter, or from RL30 on created LNADJ instances, that contains the new eNB as a target. The eNB will automatically set up the X2 links as defined in feature LTE724: Automatic Neighbor Cell Configuration.
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