00021-faf102516_en_a_msword2003

Ericsson Internal1 (24)

Prepared (also subject responsible if other) No.

Joe Mammolito 000 21-FAF 102 516Approved Checked Date Rev Reference

2011-12-31 A

Service Delivery Instruction - LTE Interworking




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Contents

1 Introduction.................................................................................................................31.1 Purpose...........................................................................................................31.2 Service Description.........................................................................................31.3 Document Scope.............................................................................................5

2 LTE IW Service Delivery.............................................................................................62.1 Resource Requirements.................................................................................62.2 Operator Inputs...............................................................................................72.3 Responsibility Matrix.......................................................................................72.4 Phase 1 – Solution Definition and High Level Design.....................................82.5 Phase 2 (Optional) – Production deployment...............................................12

3 Interworking Design Considerations......................................................................133.1 Interworking Overview and Objectives..........................................................133.2 Interworking modes.......................................................................................143.3 Operator Band Plans.....................................................................................203.4 Test and Verification Methodology................................................................213.5 Licences and feature activation....................................................................22

4 References.................................................................................................................23

5 Appendices................................................................................................................245.1 Customer Engagement Workshop Example.................................................245.2 High level design example............................................................................245.3 Introduction to LTE cell reselection...............................................................245.4 Test Object List.............................................................................................245.5 LTE IRAT Mobility Guideline.........................................................................24




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1 Introduction

This document is the Service Delivery Instruction (SDI) for the design and implementation of LTE to 3G/2G Interworking (IW).

1.1 Purpose

The purpose of this document is to provide a guide for the delivery of LTE Interworking to customer networks. It provides recommendations for deployment options, key parameters, test methodology and performance metrics.

1.2 Service Description

The LTE Interworking service is one of the LTE Radio Network Optimisation (RNO) suite of services. The LTE Interworking service draws upon Ericsson’s LTE technical experts to deliver a highly specialized service for the delivery of an interworking solution that can be tailored to meet the specific requirements of individual operators. The LTE Radio Network Service Suite is shown in Figure 1-1.

Figure 1-1 Ericsson’s LTE Radio Network Service Suite




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1.2.1 Benefits of LTE Interworking

As 3G networks evolve to 4G, a key requirement for operators will be to provide a seamless experience for their customers.

It is likely that LTE will be initially deployed as an overlay on existing 3G/2G networks. Operators will aim to provide cost effective services with higher data rates and capacity in strategic locations.

A well optimized IW design will enable service continuity for mobile users moving from LTE to WCDMA coverage areas, whilst maintaining the best possible service integrity independent of the radio access technology (RAT) used. This may also provide an important point of differentiation for operators in a competitive market environment.

IW can also provide a means to most efficiently leverage the increased capacity of LTE for higher traffic areas, and alleviate congestion on 3G and 2G networks. Figure 1-2 provides a high level conceptual example of RAT interworking.




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Figure 1-2 Interworking High Level Architecture Example

1.3 Document Scope

This document covers RAN considerations for LTE Interworking only, based on L11B/W11B/G10B software releases.

Interworking between LTE and 2G/3G in L11B is limited to session continuity and idle mode cell reselection.

EPC and Packet core considerations and future releases (e.g. 12A) are out of scope.

Existing interworking and capacity management strategies, if applicable

Highest Priority

Lowest Priority

Pri

ori

ty

WCDMA F13

WCDMA F12

WCDMA F11

LTE

WCDMA F23

WCDMA F22

WCDMA F21’

WCDMA Band 1 WCDMA Band 2

GSM Band 1 GSM Band 2

GSM GSM

Idle Mode Cell Reselection

Session Continuity




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2 LTE IW Service Delivery

The service delivery prerequisites and phased delivery approach for the LTE IW Service are described in sections 2.1 to 2.5.

Figure 2-3 Service Delivery Approach

2.1 Resource Requirements

The estimated duration of this service is approximately 4 weeks (or 6 weeks where laboratory testing is proposed).

The change management processes of the customer should be taken into account at the planning and proposal stage. For example, the notification period for any production network parameter changes may be 10 business days.

The competence requirements are as follows to facilitate the end to end implementation of the IW functionality defined by the Ericsson competence framework.

Senior Solution Architect (RF)/project manager

Senior Service Engineer (E-Utran)

Experienced Services Engineer (RF) – Post processing and reports

Drive test team

- Driver (ASP)

Phase 1 Solution Definition and HLD

- Customer Engagement

- Data Collection

- HLD

- Solution verification and recommendation

Phase 2 (Optional)

- Implementation

- Post implementation




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- Assessed/Experienced Services Engineer (RF)

Additional drive test equipment is assumed to be provided. However if this not the case then a more detailed resource requirement for the drive test equipment can be found in the optimization service delivery documentation.

2.2 Operator Inputs

In order to ensure the successful execution of the IW service delivery, the customer may be requested to provide the following inputs:

A representative to act as the primary contact during the execution of the service

A representative authorized to approve the necessary changes during the service period

A complete list of RAN site configurations and status

Coverage data for existing 2G and 3G network layers

A complete list of the RAN parameter settings for LTE and WCDMA networks

Permission to access the Network Management System and run measurement programs

Subscription to the network (free airtime required) for all test UEs and activation of UEs prior to the service execution

2.3 Responsibility Matrix

A suggested responsibility matrix for the provision of the service is shown in Table 2-1.

Table 2-1 Responsibility Matrix

Responsibility Operator EricssonAgreement on responsibility for change implementation

Permission to access OSS-RC/Network Management System and to run measurement program

Measurements All necessary radio network design documents

Post-processing and analysis of measurement data




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Test measurement equipment Approval of changes prior to implementation

Implementation of changes at site Implementation of radio/transport network parameter changes

Overall project management Responsible to secure resources from Ericsson by issuing Purchase Orders

Provide temporary workspace and LAN connectivity to Ericsson’s engineers

Provide access to buildings/switch sites for Ericsson’s RF engineers

Access to key nodes and interfaces

EPC, LTE traces

2.4 Phase 1 – Solution Definition and High Level Design

2.4.1 Initial customer engagement

Initial engagement with the customer is carried out to determine:

The customer’s requirements and objectives for the introduction of LTE IW into their networks.

The customers view of the scope of service to be provided by Ericsson.

2.4.1.1 Workshop

An initial customer workshop may be conducted. The primary purpose of the workshop is to discuss with the customer their requirements for LTE IW and understand their priorities. These may include;

Managing RAN capacity – for example, maximizing LTE utilization where available to alleviate WCDMA congestion.

Providing the best possible user experience in terms of data rates, without an RAT preference.




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Enabling data session continuity between a “hot spot” or in-building LTE deployment and a macro 3G/2G network, or between an LTE macro-to-2G/3G in-building configuration.

Enabling LTE to 3G/2G IW only at the fringe of LTE coverage to minimize the frequency of handing down to 3G/2G.

Improving the performance of an existing IW design.

The initial customer engagement process may also include a technical briefing to introduce Ericsson’s IW functionality. Appendix 5.1 provides a generic example of this, based on LTE and WCDMA software releases L11B and W11B.

2.4.2 Data Collection

In addition to the above items and as set out in 2.2, collection of key data from the customer may include;

Coverage mapping data for existing LTE, WCDMA and GSM network layers – this may form an input to the overall IW strategy to be implemented. it should be noted that the usefulness of this data is dependent on the accuracy of the tuning model and network data used.

Identification of suitable test sites and locations

Identification of suitable drive test routes

The operators’ current UE IW capability and future UE roadmap – UE vendor statements for interworking

2.4.3 High Level Design (HLD)

Following identification of customer objectives and data collection, solution definition and high level design is then developed. This forms the main deliverable of the IW service provided by Ericsson.

The solution definition included in the HLD may consist of mobility procedures and strategy, parameter settings, licencing requirements and recommendations.

An example of a HLD document and recommended parameters is provided in Appendix 5.2.




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2.4.3.1 Definition of IW KPIs

A number of Key Performance Indicators (KPIs) may be defined as acceptance criteria for the IW implementation. Suitable KPI targets may include:

LTE to WCDMA session continuity success rate (e.g. 99.8%)

LTE to WCDMA session continuity interruption time (e.g. 600ms)

WCDMA to LTE cell reselection success rate

WCDMA to LTE cell reselection interval

LTE to WCDMA to LTE reselection success rate

WCDMA to LTE reselection interval

2.4.3.2 Trial design and test case development

Verification testing for IW implementation will generally consist of field testing, with an option for preliminary laboratory testing. Where laboratory testing is proposed, an additional period of two or more weeks may be incorporated into the overall service delivery plan. An example of a Test Object List (TOL) is provided in Appendix 5.4.

2.4.3.3 Laboratory Testing

Laboratory test cases to verify performance and functionality should be designed with consideration for:

continuity of data transfer during active mode session continuity (i.e. full buffer),

the ability for the UE to transition to idle mode to enable cell reselection testing,

the control and measurement of UE signal levels to model the transition from LTE to WCDMA coverage,

the measurement of active mode session continuity interruption time (for example, between specific Layer 3 message events for the Control Plane, and application layer data interruption for the User Plane, or both).

2.4.3.4 Field testing

Field testing for IW verification will be conducted as a drive survey. The design of the drive survey testing should consider:

a drive route to maximize the number of active mode session continuity events based on coverage predictions




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TEMS Discovery scripting to cause UE to transition to idle and subsequent reselection to LTE following each WCDMA session continuity event

the impact of WCDMA state transition timer settings on test duration and ability to collect a satisfactory event sample size.

Idle mode UE for cell reselection testing in conjunction with session continuity testing above

continuity of data transfer during active mode session continuity (i.e. full buffer),

the measurement of active mode session continuity interruption time (for example, between specific Layer 3 message events for the Control Plane, and application layer data interruption for the User Plane, or both).

comparative WCDMA data performance (via a UE locked to WCDMA)

the impact of commercial traffic on user throughput measurements

network alarms that are active at the time of testing

An example of a field test object list for LTE IW is provided in the Appendix 5.4.

2.4.4 Solution Verification and Recommendation

The results of verification testing, recommendations and parameters for production deployment are presented to the customer in a final report.

2.4.5 Ericsson Deliverables

2.4.5.1 Workshop slidepack and technical briefing

2.4.5.2 HLD document

2.4.5.3 Test object list (TOL)

2.4.5.4 Solution Verification Report and Recommendations

2.5 Phase 2 (Optional) – Production deployment

Where the solution proposed in the preceding stage is accepted by the customer, the Service Delivery scope may also include implementation of the IW solution into the customers production network.




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2.5.1 Change management procedure

All of the operators change management procedures should be adhered to when implementing any network changes.

2.5.2 Monitoring of Network Statistics

Following implementation of the IW design, a period of monitoring of network statistics should take place to quantify performance improvements and identify any unintended negative impacts. These may include –

Minutes Per Release-Redirect to WCDMA

Release Redirect WCDMA per Intra LTE HO (%)

Session Continuity per System Release




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3 Interworking Design Considerations

3.1 Interworking Overview and Objectives

In the implementation of IW, the operator is seeking to enable users to maintain connectivity at the edge of LTE coverage. The high level objectives of the operator will generally be comprised of one or more of the following:

Maximize data throughput for the user – i.e. retain users on LTE service in locations where it provides superior data service to that which would be provided by the underlying 2G/3G layer. Where this is an operator objective, the WCDMA network is set to a lower priority than the LTE network to promote the camping of LTE capable devices in the LTE network.

Minimise the frequency of inter-RAT handover and improve the user perception of network stability – i.e. ensure sufficient system hysteresis to prevent ping-pong transitioning

Manage network capacity through additional control of traffic between IRAT network layers – i.e. prioritise lightly loaded network layers over those which are highly loaded to soak up traffic.

In an LTE on WCDMA overlay network, coverage areas may be broadly defined as LTE core (central, contiguous LTE coverage where IW is not expected), and the LTE fringe areas where interworking with WCDMA is expected and desirable. As such, different parameter sets for core and fringe LTE areas may be considered. The example given in the Appendix (refer to 5.1) employs a -115dBm minimum RSRP threshold for LTE to WCDMA cell reselection in core areas, and a -110dBm threshold for fringe areas.

Since user experience metrics are not included in the set of triggers for user mobility procedures such as idle mode cell reselection and session continuity, an estimate mapping of user-experience to the available set of triggers (e.g. RSRP or RSRQ), may be used where applicable.

3.1.1 Design Methodology

IW design strategies for UE behaviour at the edge of the LTE network are discussed in the Appendix in Section 5.5.

Such strategies can be either to accept a release of the session, leaving the customer with no service, or activating fallback to their legacy network with the session continuity feature.

In this latter case, the parameters must be tuned to optimize the transition. If the trigger parameters are set too high, releases may occur. If they are set too low, the session is too early transferred to the legacy network.




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Key parameters subject to tuning are those specifying at what signal level the A2 event (serving cell becomes worse than threshold) is triggered.

3.2 Interworking modes

The following modes of IW mobility are available for the software revisions listed in 1.3.

1 Cell Reselection – LTE to WCDMA (Idle mode)

2 Cell Reselection – WCDMA to LTE (Idle Mode)

3 WCDMA Session Continuity, Coverage Triggered

GSM to LTE Cell reselection is not discussed in this document.

3.2.1 Cell Reselection – LTE to WCDMA (Idle Mode)

Cell reselection from LTE to WCDMA in idle mode is a basic feature available for all compliant UE and Ericsson LTE network equipment. This allows a UE camped on LTE to reselect a WCDMA cell where the requisite conditions are met.

The UE can perform cell reselection only in the LTE_idle state. A detailed description of the criteria for E-UTRAN interfrequency and inter-RAT UTRAN cell reselection is set out in [3], section 4.2.

In most cases, the recommendation to the operator will be to set WCDMA cells to a lower priority than LTE in order to maximize the number of devices camping on LTE. This is achieved via the following WCDMA and LTE cell reselection priority parameters:

UtranFrequencyRelation.cellReselectionPriority

EUtranFreqRelation.cellReselectionPriority

Further detail is given in the Appendix in section 5.1.

3.2.2 Cell Reselection – WCDMA to LTE (Idle Mode)

Cell reselection from WCDMA to LTE (FAJ 121 1474) is an optional feature allowing a UE camped on WCDMA to reselect an LTE cell.

Cell reselection from WCDMA to LTE is supported by E-UTRA capable UEs in idle mode and in state URA_PCH. The LTE frequencies and the parameters for cell reselection are sent on the broadcast channel in System Information Block type 19 (SIB19).




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Cell reselection is based on priority, whereby each LTE and WCDMA frequency layer is assigned a priority from 0 to 7. Where a UE detects a neighboring LTE cell with higher priority than the serving WCDMA cell it will attempt a cell reselection even if the measured signal strength is lower for the LTE cell compared to the WCDMA cell. The signal strength of the neighboring LTE cell must however be above a minimum threshold.

As above, the recommendation in most cases will be to set WCDMA to a lower priority that LTE. The UE will always perform measurements on LTE frequencies with higher priority than the service WCDMA cell.

The functionality is discussed on more detail in [3].

3.2.2.1 Device controlled cell reselection

Where the SIB19 message is not sent (for example in SW release W10B), pre-programming of UE parameters QrxlevminEUTRA and cell reselection priority may be employed for device controlled cell reselection.

3.2.3 WCDMA Session Continuity

The WCDMA session continuity function enables a user to move from relatively poor LTE coverage to improved WCDMA coverage with minimal interruption to data flow and without the need to re-establish a data session. Where WCDMA session continuity is not enabled, the users LTE performance would degrade to a point where session continuity is lost, and necessitate session re-establishment from idle mode.

WCDMA Session Continuity (FAJ 121 0493) is an optional feature that allows a UE in RRC_Connected mode in the requisite coverage conditions to be released from LTE and redirected to WCDMA. When signal strength and/or quality levels are below the defined thresholds (triggering Event A2), the UE will send a measurement report to the eNodeB, which will determine whether redirection to WCDMA will take place.

No direct connections between LTE and WCDMA networks are required. However, an improved user experience (i.e. shorter session continuity interruption time) may be expected where PGW and GGSN functions are served in the same node.

Information about the WCDMA network carrier frequencies must be configured in the LTE eNodeB.

As in the above cases, most operators will desire a higher prioritization of LTE to WCDMA, settable with the following parameters:

EUtranFreqRelation.connectedModeMobilityPrio




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UtranFreqRelation.connectedModeMobilityPrio

3.2.4 High level state/call flow diagram

The attachment below contains signalling flow diagrams for the following scenarios:

LTE to WCDMA Idle Mode Reselection

LTE to WCDMA Session Continuity

WCDMA to LTE Idle Mode reselection

3.2.5 Key parameters and thresholds

3.2.5.1 Idle Mode Cell reselection LTE to WCDMA

WCDMA carrier frequencies must be defined as UtranFrequency managed objects in the LTE eNodeB, each with the LTE parameter UtranFrequency.arfcnValueUtranDl set to the downlink UARFCN of the WCDMA carrier.

When the measurement of IRAT cells is active, cell reselection to a cell on a lower priority WCDMA frequency is performed when

No LTE intra-frequency neighbour meets the intra-frequency cell reselection criteria (outside the scope of this document), and

LTE SServingCell < Threshserving, low, and

WCDMA SnonServingCell,x > Threshx, low during a time interval TreselectionRAT, and

More than 1 second has elapsed since the UE camped on the current LTE serving cell.

Table 3-2 provides the parameters relevant to LTE to WCDMA cell reselection. Further detail and a description of the default values of these parameters and measurement rules are available in [3].




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Table 3-2 Idle Mode Cell reselection LTE to WCDMA parameters

Parameter MO Description

pMaxServingCell EUtranCellFDD Limits UE uplink transmission power in the serving cell and calculates the parameter Pcompensation defined in 3GPP TS 36.304 for cell selection. The attribute is broadcast in SIB1. Value 1000 means the parameter is not included in system information.

qRxLevMin EUtranCellFDD The required minimum received Reference Symbol Received Power (RSRP) level in the EUTRA frequency for cell reselection. Corresponds to parameter Qrxlevmin in 3GPP TS36.304. This attribute is broadcast in SIB1.

qRxLevMinOffset EUtranCellFDD The offset applied to the signalled Qrxlevmin. Corresponds to parameter Qrxlevminoffset in 3GPP TS 36.304. Value 1000 means it is not sent and the UE sets Qrxlevminoffset=0dB.

cellReselectionPriority

UtranFreqRelation

The absolute priority of the carrier frequency used by the cell reselection procedure. Corresponds to parameter priority in 3GPP TS 36.304. Value 0 means lowest priority. The UE behavior when the field is empty if applicable, is specified in 3GPP TS 36.304.

pMaxUtra UtranFreqRelation

Used to calculate the parameter Pcompensation (defined in 3GPP TS 36.304) at cell reselection to a UTRAN cell. Value 1000 means the parameter is not included in system information.

qQualMin UtranFreqRelation

Minimum required quality level in the cell (dB). Corresponds to parameter Qqualmin in 3GPP TS 25.304

qRxLevMin UtranFreqRelation

The required minimum received Rx level in the UTRAN frequency used in cell reselection. Corresponds to parameter Qrxlevmin in 3GPP TS 36.304.

threshXHigh UtranFreqRelation

The threshold used by the UE when reselecting towards a higher priority frequency from thecurrent serving frequency. Each UTRAN frequency may have a specific threshold. The threshold is specified as parameter Thresx,high in 3GPP TS 36.304.

threshXLow UtranFreqRelation

The threshold used in reselection towards a lower frequency priority from a higher priority frequency. Each frequency of UTRAN may have a specific threshold. The threshold is specified as parameter Thresx,low in 3GPP TS 36.304.

tReselectionUtra EUtranCellFDD Cell reselection timer value TreselectionRAT for UTRAN. Transmitted in SIB 6

threshServingLow EUtranCellFDDThreshold for the signal strength of the serving cell, below which the UE performs cellreselection towards a lower priority inter-frequency or inter-RAT frequency (threshServingLow in SIB type 3). Corresponds to parameter Threshserving,low in the document 3GPP TS 36.304.




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3.2.5.2 Idle Mode Cell Reselection WCDMA to LTE

WCDMA feature ‘LTE Cell Reselection’ enables LTE-capable devices to perform priority-based cell reselection from WCDMA to LTE. The LTE frequencies and the parameters for priority based cell reselection are sent on the broadcast channel in System Information Block type 19 (SIB19).

Cell reselection to LTE is supported by E-UTRA capable UEs in Idle mode and in state URA_PCH.

If the device detects a neighbouring LTE cell with higher priority than the serving WCDMA cell it will attempt a cell reselection even if the measured signal strength is lower for the LTE cell compared to the WCDMA cell. The signal strength must however be above a minimum threshold. This will ensure that LTE-capable devices maximise the time spent in the LTE1800 network.

Table 3-3 provides the parameters relevant to WCDMA to LTE cell reselection. Further detail and a description of the default values of these parameters and measurement rules are available in [3].

Table 3-3 Idle Mode Cell Reselection WCDMA to LTE Parameters

RNC Parameter MO

cellReselectionPriority Utrancell Serving Utran cell priority.

cellReselectionPriority EutranfreqRelation Target EUtran cell priority.

threshServingLow Utrancell Specifies the limit for Srxlev in the Utran serving cell below which the UE may perform cell reselection to a E-UTRAN cell belonging to a lower absolute priority layer.

blacklistedcell EutranFreqRelation List of up to 16 cells not considered for cell reselection.

qRxLevMin EutranFreqRelation Minimum required RSRP of LTE target cell

threshHigh EutranFreqRelation Srlev based threshold for a UE to perform absolute priority based cell reselection to an E-UTRAN cell that has a higher priority than the Utran serving cell.

threshLow EutranFreqRelationSrlev based threshold for a UE to perform absolute priority based cell reselection to an E-UTRAN cell that has a lower priority than the Utran serving cell




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3.2.5.3 WCDMA Session Continuity, Coverage Triggered

The Coverage Triggered WCDMA Session Continuity feature requires no direct connections between an LTE network and 2G/3G. However, there is an improvement in the end-to-end user experience if the P-GW and GGSN functionalities are served by the same network element due to the retention of the IP address in the device despite having to re-establish a packet call in the WCDMA network.

Table 3-4 provides the parameters relevant to LTE to WCDMA session continuity. Further detail and a description of the default values of these parameters and measurement rules are available in [3].

Table 3-4 Session Continuity Parameters

Parameter MO Description

badCoverageMeasSelection

UeMeasControl Specifies whether primary, secondary, both primary and secondary or no EventA2 measurement thresholds should be used. The option to use two measurements for eventA2 is needed since the UE is not always able to use both RSRP and RSRQ measurement quantities when moving in a cell. The primary measurements default to RSRP and secondary measurements default to RSRQ. Both primary and secondary measurements can use the same measurement quantity.

a2ThresholdRsrpPrim ReportConfigEUtraBadCovPrim

The primary RSRP threshold value for EventA2. Used only when triggerQuantityA2Prim is set to RSRP.

a2ThresholdRsrpSec ReportConfigEUtraBadCovSec

The secondary RSRP threshold value for EventA2. Used only when triggerQuantityA2Sec is set to RSRP.

a2ThresholdRsrqPrim ReportConfigEUtraBadCovPrim

The primary RSRQ threshold value for EventA2. Used only when triggerQuantityA2Prim is set to RSRQ.

a2ThresholdRsrqSec ReportConfigEUtraBadCovSec

The secondary RSRQ threshold value for EventA2. Used only when triggerQuantityA2Sec is set to RSRQ.

hysteresisA2Prim ReportConfigEUtraBadCovPrim

The hysteresis value for the primary EventA2 measurement.

hysteresisA2Sec ReportConfigEUtraBadCovSec

The hysteresis value for the secondary EventA2 measurement.

reportAmountA2Prim ReportConfigEUtraBadCovPrim

Indicates the number of reports to send when Primary EventA2 is triggered. A value of 0 means that reports are sent at regular intervals for as long as the event is fulfilled.

reportAmountA2Sec ReportConfigEUtraBadCovSec

Indicates the number of reports to send when Secondary EventA2 is triggered. A value of 0 means that reports are sent at regular intervals for as long as the event is fulfilled.




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reportIntervalA2Prim ReportConfigEUtraBadCovPrim

The interval for event triggered periodic measurement reports for the Primary EventA2.

reportIntervalA2Sec ReportConfigEUtraBadCovSec

The interval for event triggered periodic measurement reports for the Secondary EventA2.

reportQuantityA2Prim ReportConfigEUtraBadCovPrim

Indicates whether to include RSRP or RSRQ measurements, or both, in the measurement reports for the Primary EventA2.

reportQuantityA2Sec ReportConfigEUtraBadCovSec

Indicates whether to include RSRP or RSRQ measurements, or both, in the measurement reports for the Secondary EventA2.

timeToTriggerA2Prim ReportConfigEUtraBadCovPrim

The time that the Primary EventA2 criterion has to be fulfilled before the first measurement report is sent.

timeToTriggerA2Sec ReportConfigEUtraBadCovSec

The time that the Secondary EventA2 criterion has to be fulfilled before the first measurement report is sent.

triggerQuantityA2Prim ReportConfigEUtraBadCovPrim

The quantity that triggers the Primary EventA2. The trigger can be set for either RSRP or RSRQ.

triggerQuantityA2Sec ReportConfigEUtraBadCovSec

The quantity that triggers the Secondary EventA2. The trigger can be set for either RSRP or RSRQ.

sMeasure UeMeasControlServing cell quality threshold controlling whether the UE is required to perform measurements. This is the same measurement threshold that is used to begin cell measurements for Intra-LTE Handover. Value 0 disables s-Measure.

filterCoefficientEUtraRsrp

UeMeasControlThe filtering coefficient used to filter RSRP measurements before eventevaluation. The measurement filter averages a number of measurement values to filter out the impact of large scale fast fading. This is the same measurement filter that is used for Intra-LTE Handover measurements.

filterCoefficientEUtraRsrq

UeMeasControlThe filtering coefficient used to filter RSRQ measurements before event evaluation. The measurement filter averages a number of measurement values to filter out the impact of large scale fast fading. This is the same measurement filter that is used for Intra-LTE Handover measurements.

3.3 Operator Band Plans

Interworking may be applied between the following frequency band combinations. The design approach will depend on the specific operator band plan, radio access technology deployment approach and comparative coverage footprints.




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Where a 1:1 deployment methodology has been adopted (that is, LTE deployment at all WCDMA sites within an area), the following basic frequency combinations listed in Table 3-5 may result.

Table 3-5 Operating Band Combination for LTE Interworking

LTE Band WCDMA Band Comments

High (e.g. 2.3/2.6GHz)

High (e.g. 2.1GHz) No significant difference in RAT coverage due to operating band.

High (e.g. 2.1GHz) Low (e.g. 900 MHz)

For a 1:1 site deployment, WCDMA coverage may be expected to be better in a given location than LTE. There may be areas where LTE coverage does not exist, but WCDMA has acceptable coverage (especially in-building).

Evaluation of lower thresholds for reselection from WCDMA to LTE may be warranted.

Low (e.g. 900MHz)

High (e.g. 2100MHz)

For a 1:1 site deployment, LTE coverage may be expected to be better in a given location than WCDMA. There may be areas where LTE coverage exists and WCDMA does not provide coverage.

In general, there should not be a reason for being on WCDMA in the core coverage area due to better coverage of LTE. Evaluation of lower threshold for reselection from LTE to WCDMA may be considered.

Low (e.g. 850MHz)

Low (e.g. 900MHz)

No significant difference in RAT coverage due to operating band.

3.4 Test and Verification Methodology

3.4.1 PM counters

Appendix 5.3, section 4.1 provides a summary of PM counters used to provide an indication of the number of RRC connection setups attributable to IRAT.




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3.5 Licences and feature activation

3.5.1 LTE

A license key needs to be activated for the dual purposes of operating the coverage triggered WCDMA session continuity feature and the activation of SIB6 which is necessary for LTE to WCDMA idle mode cell reselection. The license is called WcdmaSessionContinuity and has the attributes shown below

ManagedElement SystemFunctions Licensing OptionalFeatures WcdmaSessionContinuity

licenseStateWcdmaSessionContinuity

featureStateWcdmaSessionContinuity

serviceStateWcdmaSessionContinuity

First, the value of the read-only attribute licenseStateWcdmaSessionContinuity must be verified as being 1 [Enabled] to confirm that the license for the feature has been preloaded to the eNodeB through the OSS.

The parameter featureStateWcdmaSessionContinuity must be set to 1 [Activated].

The value of the read-only attribute serviceStateWcdmaSessionContinuity must be verified as being 1 [Operable] to confirm that the feature has been activated .

3.5.2 WCDMA

It is necessary to order and install FAJ 121 1474: LTE Cell Reselection with license key CXC 403 0077 in the RNC.

It is also required to verify that the value of the read-only licenseState attribute for the LteCellReselection instance of RncFeature is 1 [Enabled].

The feature is activated by setting the RNC parameter featureState for the LteCellReselection to 1 [Activated].

Verify that the value of the read-only attribute serviceState for the LteCellReselection instance of RncFeature is 1 [Operable] to confirm that the feature has been activated.




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4 References

[1] Introduction to LTE Cell Reselection EAB/FJW-11:0722 Rev B

[2] LTE CPI, Coverage-Triggered WCDMA Session Continuity, 23/1553-HSC105 50/1

[3] Interworking between WCDMA and LTE 36/221 03-FGC 101 0109

[4] Refer to 3GPP Release 8 E-UTRAN specifications 36.304 and 36.331 and UTRAN specifications 25.133, 25.304, and 25.331 for more details

[5] 3GPP 36.331-8d0

[6] 3GPP 25.331-8e0




2011-12-31 A

5 Appendices

5.1 Customer Engagement Workshop Example

<Interworking Functionality.ppt>

5.2 High level design example

5.3 Introduction to LTE cell reselection

5.4 Test Object List

5.5 LTE IRAT Mobility Guideline

00021-faf102516_en_a_msword2003

Documents

lte interworking service

delivery of lte interworking

benefits of lte interworking

lte iw service delivery

implementation of lte

interworking solution

service description

service continuity