5 LTE ERAN6.0 Handover Feature ISSUE1.00

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Page0Revision RecordDont Print This PageCourse CodeProductProduct VersionCourse Version ISSUEOEO107060LTEeRAN6.01.00Developer/ModifierTimeApproverNew/UpdateYuan Shuai 2012-3Zhu DianrongUpdate from eRAN3.0Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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What is main difference compare with eRAN3.0?Enhanced A2 event for blind handoverEnhanced algorithm for priority rankingAdd relevant counters descriptionLTE eRAN6.0 Handover FeatureP-0Confidential Information of Huawei. No Spreading Without Permission LTE eRAN6.0 Handover Featurewww.huawei.comCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :40-47pt :26-30pt: :FrutigerNext LT Medium : Arial

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Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission P-1ObjectivesUpon completion of this course, you will be able to:Describe the type of handover in LTEDescribe the feature and parameters for intra-frequency handoverDescribe the feature and parameters for inter-frequency handoverDescribe the feature and parameters for inter-RAT handoverList relevant counters for handoverPage2


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LTE eRAN6.0 Handover FeatureP-2Confidential Information of Huawei. No Spreading Without Permission ContentsTechnical DescriptionIntra-frequency Handover Inter-frequency Handover Inter-RAT Handover Page3


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LTE eRAN6.0 Handover FeatureP-3Confidential Information of Huawei. No Spreading Without Permission Mobility Management OverviewPage4Mobility ManagementIdle StateConnected StateCell ReselectionHandoverIntra-frequencyInter-frequencyInter-RATRedirectionCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-4Confidential Information of Huawei. No Spreading Without Permission Redirection IntroductionRedirection is the substitute solution for handover ,used in the following scenario:UE or network doesnt support handoverThere is no neighbor relation When redirection is triggered, eNodeB sends the UE an RRC Connection Release message which contains information about a neighboring frequency in the LTE system or in another RAT system.Page5Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-5Confidential Information of Huawei. No Spreading Without Permission Handover Procedure & Entities Page6UE MeasurementMeasurement HandlingNeighbor Cell ManagementHandover DecisionHandover ExecutioneNodeBHandoverEntitiesCandidate Cell FilterGap pattern controlMROUE CapabilityUE Capability HandlingXxx Based TriggerBlind HandoverCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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As shown above,the handover process consists of three phases: handover measurement,handover decision, and handover execution. A blind handover does not require handover measurement.In the handover measurement phase, the eNodeB uses the RRC Connection Reconfiguration message to deliver the measurement configuration to the UE and waits for a measurement report from the UE.In the handover decision phase, the eNodeB checks the measurement results reported by the UE and determines whether to initiate a handover.In the handover execution phase, the eNodeB controls the procedure of UE handover to the target cell based on the decision, to perform the handover.LTE eRAN6.0 Handover FeatureP-6Confidential Information of Huawei. No Spreading Without Permission Handover Trigger Scenarios Page7Handover Type Measurement Trigger Coverage basedIntra-frequencyThe measurement configuration is performed when the UE establishes a radio bearer. The UE performs intra-frequency measurements by default.Inter-frequencyInter-RATThe eNodeB delivers the measurement configuration to the UE when the signal quality in the serving cell is lower than the associated threshold.Load basedInter-frequencyInter-RATThe measurements are triggered by the Mobility Load Balancing (MLB) algorithm.Frequency-priority-basedInter-frequencyThe measurements are triggered by A1 eventService basedInter-RATInter-frequencyThe eNodeB triggers the measurements after it finds that only the voice service is running on the UE.UL service quality Based Inter-RATInter-frequencyThe eNodeB triggers the measurement after it detects UL power insufficient at the UEDistance basedInter frequencyInter -RATThe measurements are triggered by distance if it is more than the specific threshold Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-7Confidential Information of Huawei. No Spreading Without Permission Measurement Control InformationeNodeB should deliver all the measurement control parameters to UE via RRC reconfiguration, including measurement object, report configuration, measurement ID and filter configuration .Besides, for inter-frequency/inter-RAT measurement, it also includes gap configuration for gap-assisted measurement.

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RRC Reconfiguration Message


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When a UE establishes a radio bearer, the eNodeB delivers the intra-frequency measurement configuration to the UE through an RRC Connection Reconfiguration message by default. Then, the UE performs intra-frequency measurements by default. When measurement gaps need to be set up, the eNodeB delivers the inter-frequency and/or inter-RAT measurement configuration to the UE. After that, the UE performs gap-assisted inter-frequency and/or inter-RAT measurements. Inter-frequency and inter-RAT measurements can use the same gap pattern, but the eNodeB is able to differentiate between the gap configurations for inter-frequency and inter-RAT measurements.

LTE eRAN6.0 Handover FeatureP-8Confidential Information of Huawei. No Spreading Without Permission Measurement Object FrequencyPage9ParametersDescriptionDlEarfcnIndicates the DL EARFCN of the inter-frequency E-UTRAN cellMeasBandWidthIndicates the measurement bandwidth for inter/intra-frequency neighboring cellsQoffsetFreqIndicates the frequency offset of the inter-frequency neighboring cellneighCellConfigIndicate whether all the neighbor have the same configuration or notPresenceAntennaPort1Indicates whether all of the inter-frequency neighboring cells are configured with the double-TX antenna.High priority neighbor cell list (Optional) If we configure some specific neighbors as high measurement priority, then eNodeB will deliver these cells information as well .(New introduced in eRAN6.0)Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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For intra- frequency neighbor, we dont need defined the frequency information, it will use the same configuration as current cell. For the inter-frequency or inter-RAT frequencies, we must add these frequencies separately. LTE eRAN6.0 Handover FeatureP-9Confidential Information of Huawei. No Spreading Without Permission Event Triggered Report Page10EventsThreshold ActionA1Signal quality in the serving cell is higher than a specified thresholdThe eNodeB stops inter-frequency or inter-RAT measurements.A2Signal quality in the serving cell is lower than a specified threshold The eNodeB starts inter-frequency or inter-RAT measurementsA3Signal quality in at least one intra-frequency/inter-frequency neighboring cell is higher than that in the serving cellSource eNodeB sends an intra-frequency/inter-frequency handover request.A4Signal quality is higher than a specified threshold in at least one inter-frequency neighboring cellSource eNodeB sends an inter-frequency handover request.

A5 A2 + A4 (New events in eRAN3.0)Source eNodeB sends an inter-frequency handover request.B1Signal quality is higher than a specified threshold in at least one inter-RAT neighboring cellsource eNodeB sends an inter-RAT handover request.

B2A2 + B1 source eNodeB sends an inter-RAT handover request.


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eNodeB complies with all 3GGP event to trigger UE report. After an event is reported for the first time, the measurement results associated with the event are reported periodically. This reporting mode is called event-triggered periodical reporting. The UE sends the measurement results to the eNodeB in event-triggered periodical reporting mode. The periodical reporting is stopped when the leaving condition is met or after the UE receives feedback from eNdoeB. Event-triggered periodical reporting has the following benefits:Reduces the impact of loss of measurement reports or failures in internal processing on handovers.Enables retries of access in case of admission rejectionProvides complete measurement results by updating cell information in periodical reports, since a single measurement report may not contain information about all neighboring cells that meet an event triggering condition and neighboring cells meeting the condition may change with UE movement.LTE eRAN6.0 Handover FeatureP-10Confidential Information of Huawei. No Spreading Without Permission Measurement Gap ConfigurationPage11


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A measurement gap is a time period during which the UE performs measurements on a neighboring frequency of the serving frequency. Measurement gaps are applicable to inter-frequency and inter-RAT measurements. The UE performs inter-frequency or inter-RAT measurements only within the measurement gaps. One UE normally has only one receiver, and consequently one UE can receive the signals on only one frequency at a time.When inter-frequency or inter-RAT measurements are triggered, the eNodeB delivers the measurement gap configuration, and then the UE starts gap-assisted measurements accordingly. As shown above, Tperiod denotes the repetition period of measurement gaps, and TGAP denotes the gap width, within which the UE performs measurements. Gap-assisted measurements for the following types of handover may co-exist: coverage-based, load-based, and service-based handovers. When two or all of the preceding types of gap-assisted measurement co-exist, the eNodeB records the measurements based on these types. These different types of measurement are called member gap-assisted measurements. The member gap-assisted measurements can share the measurement gap configuration. A UE releases measurement gaps only when all member measurements are stopped.There are two measurement gap patterns available: pattern 1 and pattern 2. In pattern 1, TGAP is 6 ms and Tperiod is 40 ms. In pattern 2, TGAP is 6 ms and Tperiod is 80 ms. The pattern to be used is specified through the GapPatternType parameter.

LTE eRAN6.0 Handover FeatureP-11Confidential Information of Huawei. No Spreading Without Permission Measurement Filleting Operation A: Measurement value at the physical layerB: Measurement value obtained after L1 filtering. C :Measurement value obtained after L3 filtering.

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Before evaluating the reporting criteria and sending measurement reports, the UE performs layer 1 (L1) filtering and L3 filtering on the measurement results. The L1 filtering is performed by the UE at the physical layer to eliminate the impact of fast fading on the measurement results. No user configuration is required for the L1 filtering. The L3 filtering aims at eliminating the impact of shadow fading and certain fast fading. In this way, better measurement data can be provided for the evaluation of the reporting criteria. Based on the triggering quantity, two L3 filtering coefficients are applicable: one for RSRP measurements and the other for RSRQ measurements.

LTE eRAN6.0 Handover FeatureP-12Confidential Information of Huawei. No Spreading Without Permission eNodeB Neighbor ManagementPage13Neighbor Management

Intra-frequency neighborInter-frequency neighborInter-RATneighborGSMcdma2000LTE2.6GLTE2.6GUMTSLTE 800M

Neighbor Black CellNeighbor Black cellCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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A neighboring relation is a relation between the serving cell and each candidate cell involved in a handover. Neighboring relation management covers the following aspects: Whether to allow automatic removal of a neighboring relation by ANR or notWhether to allow handovers of UEs between two cells or notWhether to allow handovers over an X2 interface or notNeighboring relations are planned in the network design stage. They can be automatically adjusted by ANR. The ANR function reduces the risk of missing neighboring cells and solves the problems of inappropriate neighboring relations caused by collisions of physical cell IDs or by physical positions. In this way, the call drop rate is reduced and the handover success rate is increased.Intra-frequency neighboring cellAn intra-frequency neighboring cell is a neighboring cell whose DL E-UTRA Absolute Radio Frequency Channel Number (EARFCN) is the same as the DL EARFCN of the serving cell. An E-UTRAN cell can be configured with a maximum of 32 intra-frequency neighboring cells.Inter-frequency neighboring cellAn inter-frequency neighboring cell is a neighboring cell whose DL EARFCN is different from the DL EARFCN of the serving cell. An E-UTRAN cell can be configured with a maximum of 64 inter-frequency neighboring cells, which can be located on a maximum of 8 neighboring E-UTRAN frequencies. TDD cells can also be configured as inter-frequency neighboring cells of FDD cells. Huawei eNodeB supports interoperability between LTE FDD and LTE TDD.

LTE eRAN6.0 Handover FeatureP-13Confidential Information of Huawei. No Spreading Without Permission Page14Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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Inter-RAT neighboring cellInter-RAT neighboring cells are neighboring UTRAN cells, neighboring GERAN cells, and neighboring CDMA2000 cells. The maximum configurations of neighboring cells and frequencies for an E-UTRAN cell are as follows: 64 neighboring UTRAN cells and 16 neighboring UTRAN frequencies; 64 neighboring GSM cells and 16 neighboring GSM frequency groups; 32 neighboring CDMA2000 EVDO cells and 32 neighboring CDMA2000 1x cells.Black cell: Blacklisted cells are not considered in event evaluation or measurement reporting.This list should be configured manually and delivered to UE via SIB

LTE eRAN6.0 Handover FeatureP-14Confidential Information of Huawei. No Spreading Without Permission ContentsTechnical DescriptionIntra-frequency HandoverInter-frequency HandoverInter-RAT Handover Page15


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LTE eRAN6.0 Handover FeatureP-15Confidential Information of Huawei. No Spreading Without Permission Intra-frequency Handover ProcedurePage16Measurement Triggers(Coverage Based)Measurement Configuration messageMeasurement RSRP/RSRQEvent A3Black cell listIf criteria is matched, UE sends measurement report.

eNodeB Performs HandoverAdmission ProcedureSignaling Procedure ExecutionRetry Mechanism (attempt to next target cell in measurement report list)MeasurementPhaseDecisionPhaseExecutionHandovereNodeB Makes Decision

Event Triggered Periodical ReportingIntra-eNodeB cell has higher priority to reduce Inter-eNodeB signaling or data forwarding.Via S1 or X2


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LTE eRAN6.0 Handover FeatureP-16Confidential Information of Huawei. No Spreading Without Permission Intra-Frequency Measurement TriggerAfter UE attachment, eNodeB sends RRC reconfiguration message which includes intra-frequency measurement control info which assist UE to perform intra-frequency measurement

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It contains all the intra-frequency measurement and report configuration, including A1(optional), A2(optional) and A3(mandatory) event.Trace from eNodeBCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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If intra-frequency handover switch is set ON, then eNodeB will deliver intra-frequency measurement message by default.Relevant switch: LTE eRAN6.0 Handover FeatureP-17Confidential Information of Huawei. No Spreading Without Permission

Element Introduction Measurement ObjectPage18

Optional partCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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If we configure the specific neighbors as high measurement priority, then eNodeB will deliver theses cells information in measurement control message, and after that UE will prior to measure theses cells Relevant configuration LTE eRAN6.0 Handover FeatureP-18Confidential Information of Huawei. No Spreading Without Permission

Element Introduction Report ConfigurationPage19


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In intra-frequency measurement control message, A3 event configuration will be delivered by default, and A1, A2 events are optional if inter-frequency or inter-RAT handover is enabled.LTE eRAN6.0 Handover FeatureP-19Confidential Information of Huawei. No Spreading Without Permission Element Introduction Measurement ID Based on the object and report configuration, eNodeB creates one or more measurement ID linked with object ID and report ID. And this ID should be also included in the UE report, so eNodeB can differentiate each reports

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LTE eRAN6.0 Handover FeatureP-20Confidential Information of Huawei. No Spreading Without Permission Element Introduction Filter Configuration This filtering is performed by RRC, smoothing measurement to resist fast fading effect. A larger value of this parameter indicates a stronger smoothing effect and higher resistance to fast fading, but it may weaken the tracing capability towards varying signals

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LTE eRAN6.0 Handover FeatureP-21Confidential Information of Huawei. No Spreading Without Permission Event A3 Measurement ReportIntra-frequency handover is triggered by event A3, which is reported in event-triggered periodical reporting mode. Enter condition: Mn + Ofn + Ocn Hys > Ms + Ofs + Ocs + A3OffLeave condition: Mn + Ofn + Ocn + Hys < Ms + Ofs + Ocs + A3Off

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Mn: The measurement result of the neighboring cellOfn: The frequency-specific offset for the frequency of the neighboring cell, it is not valid during intra-frequency handover.Ocn: The cell-specific offset (CIO) for the neighboring cell, related command: MOD EUTRANINTERFREQNCELLMs: The measurement result of the serving cell Ofs: The frequency-specific offset for the serving frequencyOcs: The cell-specific offset for the serving cellHys: The hysteresis for event A3. It is specified through the IntraFreqHoA3Hyst parameter and contained in the delivered measurement configuration.Off: The offset for event A3. It is specified through the IntraFreqHoA3Offset parameter. If the entering condition of the event is continuously met during the time specified through IntraFreqHoA3TimeToTrig, the UE reports event A3 and starts the event-triggered periodical reporting. Then, if the leaving condition of the event is continuously met during the time specified through IntraFreqHoA3TimeToTrig, the UE stops reporting event A3.

LTE eRAN6.0 Handover FeatureP-22Confidential Information of Huawei. No Spreading Without Permission Measurement Report In the measurement report, it shows the ID to indicate the type of report

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How to differentiate each measurement report??Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-23Confidential Information of Huawei. No Spreading Without Permission Handover Decision Filtering ListAfter receive measurement report, eNodeB makes candidate list after filtering the following Neighboring cells that have a different PLMN from the serving cell if the inter-PLMNNeighboring cells with a handover prohibition flagPage24

Measurement ReportObtain candidate listDecide target cell


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After receiving a measurement report from the UE, the eNodeB generates a list of candidate cells, which meet the triggering condition of the specific event. As a second step, the eNodeB filters the candidate cells. If the measurement result of an intra-eNodeB cell is the same as that of an inter-eNodeB cell among the candidate cells, the eNodeB prioritizes the intra-eNodeB cell to prevent signaling and data forwarding required in an inter-eNodeB handover.

LTE eRAN6.0 Handover FeatureP-24Confidential Information of Huawei. No Spreading Without Permission Handover Decision Target Decision After get candidate list, eNodeB will rank the list with the following priority:The best RSRP/RSRQ neighbor cell Intra-eNodeB neighbor cell if reported result is the same Inter-eNdoeB neighbor cell with X2 interface if reported result is the same. The eNodeB then sends a handover request to the target cell at the top of the candidate cell list.If the handover request fails, the eNodeB sends the handover request to the next target cell.

Page25Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-25Confidential Information of Huawei. No Spreading Without Permission Handover Execution S1/X2 AdaptionPage26


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In the handover execution phase, the UE and the eNodeB exchange signaling over the radio interface according to 3GPP TS 36.331. During an inter-eNodeB handover, the source eNodeB and the target eNodeB exchange signaling and data through X2/S1 adaptation. The LTE system uses hard handover, that is, only one radio link is connected to a UE at a time. Therefore, to prevent user data loss at the eNodeB during the handover, data forwarding is performed to ensure eNodeB data integrity. The loss of data may cause a decrease in the data transfer ratio and an increase in the data transfer delay.In the case of an intra-MME inter-eNodeB handover, the source eNodeB checks whether the X2 interface is available between the source and target eNodeBs or not and then automatically selects a path for the handover as follows:If the X2 interface is available, the handover request is sent over the X2 interface. Data forwarding is also performed over the X2 interface. If the X2 interface is unavailable, the handover request is sent over the S1 interface. Data forwarding is also performed over the S1 interface.In the case of an inter-MME inter-eNodeB handover, the handover request is sent over the S1 interface. In addition, the source eNodeB checks whether the X2 interface is available between the source and target eNodeBs or not and then automatically selects a path for data forwarding as follows:If the X2 interface is available, data forwarding is performed over the X2 interface.If the X2 interface is unavailable, data forwarding is performed over the S1 interface.

LTE eRAN6.0 Handover FeatureP-26Confidential Information of Huawei. No Spreading Without Permission Retry and PenaltyIf admission failure with target eNodeB, source eNodeB will try the next target until it gets succeed feedback from it. If all the target are failed for handover preparation, source eNodeB will wait for the next UE report. The eNodeB imposes a penalty on a cell where a non-resource-induced admission failure has occurred. In a handover attempt, the eNodeB does not send a handover request to such a cell. This increases the handover success rate and reduces the number ofdropped calls caused by handover failures.Page27Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-27Confidential Information of Huawei. No Spreading Without Permission Measurement Report This command is used to modify the parameters for measurement report

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Each parameters are described as below:Max report cell number: Indicates the maximum number of cells to be included in the measurement report after an event for the intra- or inter-frequency handover within the E-UTRAN is triggered.Measurement report amount: Indicates the number of periodic measurement reports to be sent after an event for the intra- or inter-frequency handover within the E-UTRAN is triggered. It is used to prevent the impact of measurement report loss and internal processing failure on the handover.A3 measurement trigger quantity: Indicates the quantity used to evaluate the triggering condition for the intra-frequency handover event. The quantity can be RSRP or RSRQ. Recommended value: RSRPA3 measurement report quantity: Indicates the quantity to be included in the measurement report for the intra-frequency handover eventIntrafreq measurement report interval: Indicates the interval between each periodic reportMeasurement A4 report quantity: The same meaning as A3 measurementA1A2 Measurement trigger quantity: The same meaning as A3 measurementInterfreq measurement report interval: The same as itrafreq measurement report interval

LTE eRAN6.0 Handover FeatureP-28Confidential Information of Huawei. No Spreading Without Permission A3 Event Parameters Cell OffsetPage29

Evaluate neighbor cell measurement Evaluate serving cell measurement Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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Specific Cell Individual Offset (CIO) values can be set for the serving cell and its neighboring cells. (Ocs and Ocn described in the subsequent chapters denote the CIO for the serving cell and the CIO for the neighboring cell respectively.) When the quality of signals fluctuates, the probability of triggering handovers to or from a specific cell can be adjusted by changing the value of CIO. This reduces the risk of call drops. The CIO values can be adjusted automatically by the MRO function.

LTE eRAN6.0 Handover FeatureP-29Confidential Information of Huawei. No Spreading Without Permission A3 Event Parameters Service Based Page30


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In LTE, 9 QCI are defined as QoS level. Each QCI is mapped with a series handover group. The related command is : MOD CELLSTANDARDQCI The main parameters for intra-handover decision algorithm are shown as following Intrafreq handover hysteresis: Indicates the hysteresis to be used in the triggering condition for the intra-frequency handover event. This parameter helps reduce the number of times the event is triggered because of radio signal fluctuation. Thus, the probability of ping-pong handovers or wrong handover decisions is reduced.Intrafreq handover offset: Indicates the quality offset of the neighboring cell over the serving cell to be used in the triggering condition of the intra-frequency handover event.Intrafreq handover time to trigger: Indicates the time-to-trigger for intra-frequency handover event A3.When detecting that the signal quality in the serving cell and that in at least one neighboring cell meet the entering condition, the UE does not send a measurement report to the eNodeB immediately. Instead, the UE sends a report only when the signal quality continuously meets the entering condition during the time-to-trigger

LTE eRAN6.0 Handover FeatureP-30Confidential Information of Huawei. No Spreading Without Permission Typical Handover FlowPage31


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The signaling procedure shown in above figure is described as follows:When the UE establishes a radio bearer, the source eNodeB sends the UE an RRC Connection Reconfiguration message that contains the measurement configuration. The measurement configuration is set by the source eNodeB to control the measurements of the UE in connected mode.The UE sends measurement reports to the source eNodeB based on the measurement results.The source eNodeB makes a handover decision based on the measurement reports.After deciding that a handover is preferred, the source eNodeB sends a Handover Request message to the target eNodeB, to request the target eNodeB to prepare for the handover. The target eNodeB makes admission decisions. If resources can be granted by the target eNodeB, the target eNodeB performs admission control depending on the QoS information about the Evolved Packet System (EPS) bearer.The target eNodeB prepares L1/L2 resources for the handover and then sends a Handover Request Acknowledge message to the source eNodeB.The source eNodeB sends the UE an RRC Connection Reconfiguration message that contains the mobilityControlInfo IE, indicating that the handover shall start.


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The UE performs a procedure of random access towards the target eNodeB, to achieve the UL synchronization of the UE with the target eNodeB.After successfully accessing the target cell, the UE sends the target eNodeB an RRC Connection Reconfiguration Complete message, indicating that the handover procedure is complete. At this time, the target eNodeB can start sending data to the UE.The DL data path switching is performed.The target eNodeB sends the source eNodeB a UE Context Release message, to inform the source eNodeB of the success of the handover and to trigger the release of the resources at the source eNodeB.After receiving the UE Context Release message, the source eNodeB releases the radio and control-plane resources associated with the UE context.

LTE eRAN6.0 Handover FeatureP-32Confidential Information of Huawei. No Spreading Without Permission RRC Reestablishment ProcedurePage33

Handover Failure

Cell search

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When a handover fails, the UE performs a cell selection procedure and then initiates a procedure of RRC connection re-establishment towards the selected cell. The eNodeB makes a decision based on whether the context of the UE is present. If the eNodeB accepts the re-establishment request, the UE accesses the selected cell, avoiding a dropped call caused by the handover failure. The eNodeB will the status of UE context, if it exists, the procedure could be proceed, otherwise, eNodeB rejects reestablishment. LTE eRAN6.0 Handover FeatureP-33Confidential Information of Huawei. No Spreading Without Permission ContentsTechnical DescriptionIntra-frequency HandoverInter-frequency Handover Inter-RAT Handover Page34


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LTE eRAN6.0 Handover FeatureP-34Confidential Information of Huawei. No Spreading Without Permission Classification of Inter-frequency HandoverMeasurement based handover: HO must be trigged by inter-frequency measurement report Blind handover: Skip inter-frequency measurement, directly execute HO based on priority configuration

Page35

Measurement report (A2)Inter-frequency measurement activateMeasurement report (A4)Handover command Measurement based HO

Measurement report (A2)Handover command Blind Ho Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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Blind handover switch

Once blind HO is activated, eNodeB directly decide the HO target based on the priority configuration of each neighbor

LTE eRAN6.0 Handover FeatureP-35Confidential Information of Huawei. No Spreading Without Permission

Inter-frequency Handover ProcedureMeasurement Triggers(Coverage Based) UE Reporting Event A2 to trigger inter-frequency measurement based on coverageSingle or both of RSRP/RSRQ monitored to trigger IF measurementStop measuring when Event A1 is met

Measurement

GAP-Assisted Measurement

Event Triggered Periodical Reporting A3/A4/A5

eNodeB Performs HandoverAdmission ProcedureExecutionRetry Mechanism (attempt to next target cell in measurement report list) If Admission or Handover FailureeNodeB Makes DecisionEvent Triggered Periodical Reporting

Single or both of RSRP / RSRQ considered to make decision

Via S1 or X2MeasurementTriggerMeasurementPhaseDecisionPhaseExecutionHandover


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LTE eRAN6.0 Handover FeatureP-36Confidential Information of Huawei. No Spreading Without Permission Measurement TriggerCoverage-based handoverMeasurement trigger : A2 eventMeasurement stop: A1 event Load- based handoverThe triggering and stopping of inter-frequency measurements for load-based handover are determined by the MLB algorithm. When the load of the serving cell reaches the threshold for inter-frequency load balancing, the MLB algorithm selects a number of UEs based on the frequency capabilities of the UEs, ARPs, and resource usage and then instructs the UEs to perform gap-assisted inter-frequency measurements for load-based handovers or blind handover.Frequency priority based handoverMeasurement trigger: A1 eventMeasurement stop: A2 event


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The switch for each scenario eNodeB level switch: coverage based, service based, UL quality based

Cell level switch: frequency priority based and distance based


Measurement Trigger (Con.)Service basedThe eNodeB triggers the measurements after identifying the UE having certain service characteristics.UL quality basedThe eNodeB triggers the measurements after it detects unsatisfactory UL quality for the UE.Distance-basedThe eNodeB triggers the measurements after it detects that the reported TA exceeds a threshold


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LTE eRAN6.0 Handover FeatureP-38Confidential Information of Huawei. No Spreading Without Permission Measurement Object ConfigurationMeasurement object The information on a measurement object includes the frequency, measurement bandwidth , and frequency-specific offset

Page39


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This execution is mandatory to for inter-frequency measurement, must be done by manual configuration. If it is configured, then A1/A2 event parameters will be delivered by eNB by default, thus to trigger inter-frequency measurement.

LTE eRAN6.0 Handover FeatureP-39Confidential Information of Huawei. No Spreading Without Permission Coverage Based Measurement Trigger Enter condition: Ms + Hys < Specific A2 ThresholdLeave condition: Ms Hys > Specific A2 Threshold

Page40

LTEGSM/UMTS Coverage

Intra-LTEInter-RATAccording to radio link condition (LTE: RSRP/RSRQ)Moves to neighbor LTE cellMoves out of LTE coverageCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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In a coverage-based inter-frequency handover, event A2 triggers inter-frequency measurements. The triggering of this event indicates that the signal quality in the serving cell is lower than a specified threshold.Ms: The measurement result of the serving cellHys: The hysteresis for event A2Thresh: The threshold for event A2, it can be defined separately with RSRP or RSRQ


Coverage Based Measurement StopEnter condition: Ms Hys > Specific A1 Threshold Leave condition: Ms + Hys > Specific A1 Threshold Page41Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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A1 event is opposite as A2 event. Note: A1 threshold must be larger than A2 threshold so that there is no overlapping area for UE activate/deactivate measurement. LTE eRAN6.0 Handover FeatureP-41Confidential Information of Huawei. No Spreading Without Permission Enhanced A2 Event for FDD/TDD (eRAN6.0)Application scenario: Used for RAN sharing Benefit: Flexible policy configure for MOCN(Multiple Operator Core Network) operatorPrior to Inter-Freq FDD or TDD cellEvery operator can set different event A2 threshold

Page42Operator A A2_FDD threshold: Trigger Operator As UE FDD Inter-Freq MeasureOperator B A2_FDD threshold: Trigger Operator Bs UE FDD Inter-Freq MeasureOperator A A2_TDD threshold: Trigger Operator As UE TDD Inter-Freq MeasureOperator B A2_TDD threshold: Trigger Operator Bs UE TDD Inter-Freq Measure


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UE has different service experience when stay in FDD or TDD network, and each operators may have respective FDD/TDD resource. So eRAN6.0 offer flexible Inter-Freq A2 configure policy.

LTE eRAN6.0 Handover FeatureP-42Confidential Information of Huawei. No Spreading Without Permission Blind HO A2 Event (eRAN6.0 Enhancement) In coverage based inter-frequency handover, eNdoeB will deliver another A1/A2 threshold to trigger or stop blind handover.In the following case, eNodeB only deliver blind handover A1/A2 threshold, not normal A1/A2 thresholdUE doesnt support inter-frequency or inter-RAT measurement Normal A2 threshold is less than blind handover A2 thresholdPage43A2_measure threshold: Trigger Inter-Freq MeasureA2_Blind threshold: Trigger Blind Redirection


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In coverage-based inter-frequency handovers, the eNodeB delivers a measurement configuration related to event A2 for blind handover if the signal quality of the serving cell deteriorates to a specified level and the UE has not been handed over. In addition to delivering the measurement configuration related to event A2 for blind handover, the eNodeB also delivers the measurement configuration related to event A1 used to stop a blind handover in case that the signal quality in the serving cell further deteriorates. If the eNodeB receives a report of event A1 used to stop a blind handover from the UE before the blind handover starts, the eNodeB will not perform the blind handover.

LTE eRAN6.0 Handover FeatureP-43Confidential Information of Huawei. No Spreading Without Permission Load Based Management TriggerPage44

The procedure of HO Execute is same as coverage based HO

It is typically used for co-site scenarioCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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The triggering and stopping of inter-frequency measurements for load-based handovers are determined by the MLB algorithm. When the load of the serving cell reaches the threshold for inter-frequency load balancing, the MLB algorithm selects a number of UEs based on the frequency capabilities of the UEs, ARPs, and resource usage and then instructs the UEs to perform gap-assisted inter-frequency measurements for load-based handovers. The MLB algorithm also determines the cells on which the measurements need to be performed.After load-based inter-frequency measurements are triggered, the eNodeB does not process the outputs from the MLB algorithm if the eNodeB detects that measurement gaps have been set up among which there are measurement gaps for other types of handover. Otherwise, the eNodeB sets up the measurement gaps for the load-based handovers. When the measurement gaps for load-based handovers are released, the gap-assisted measurements for other types of handover are not affected. The measurement gap configuration stops only when all gap-assisted measurements are stopped.

LTE eRAN6.0 Handover FeatureP-44Confidential Information of Huawei. No Spreading Without Permission Frequency Priority Based Measurement TriggerEnter condition: Ms Hys > Specific A1 ThresholdLeave condition: Ms + Hys < Specific A1 Threshold

Page45

A1 Event

LTE 2600MHzLTE 900MHz

High PriorityLow PriorityMeeting radio thresholdCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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Note: This A1 threshold is dedicated, different from other A1 threshold. Event A1 triggers measurements for frequency-priority-based handover.The FreqPriInterFreqHoA1TrigQuan parameter specifies the event A1 triggering quantity for frequency-priority-based measurement, which can be either RSRP or RSRQ. If the triggering quantity is RSRP, the threshold for this event is specified by the FreqPriInterFreqHoA1ThdRsrp parameter. If the triggering quantity is RSRQ, the threshold for this event is specified by the FreqPriInterFreqHoA1ThdRsrq parameter. Other parameters related to event A1 for frequency-priority-based measurement are the same as those for coverage-based inter-frequency measurement.After receiving an event A1 report from a UE, the eNodeB proceeds as follows:If frequency-priority-based blind handover is enabled,the eNodeB selects the neighboring cell with the highest blind-handover priority to perform a handover. However, if load balancing from that neighboring cell to the serving cell is in progress, the eNodeB selects the neighboring cell with the second highest priority. If the eNodeB traverses all candidate cells but fails to find a cell that fulfills the criteria, the eNodeB will decide not to perform a handover.If frequency-priority-based blind handover is disabled, the eNodeB delivers the inter-frequency measurement configuration to the UE. If the triggering condition of event A4 is fulfilled, the UE sends a frequency-priority-based event A4 report to the eNodeB. (The triggering of event A4 for frequency-priority-based handover is similar to that for coverage-based inter-frequency handover

LTE eRAN6.0 Handover FeatureP-45Confidential Information of Huawei. No Spreading Without Permission Service Based Measurement TriggerPage46Handover voice service when E-RAB established to Inter-freq To improve efficiency and capacity of whole system To save the investment at the beginning of LTEF2F1Handover to dedicate frequency according to service

UEeNBUE initiate service

Only VoIP E-RABE-RAB Initial HOMeasurement

Measurement ConfigurationEvent A4

Measure ReportHO DecisionHO ExecuteYCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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Service-based inter-frequency handovers are applicable to two neighboring E-UTRAN frequencies that cover the same area. Based on the QCIs of the services that are running on a UE, the eNodeB can divert the UE to an appropriate co-coverage E-UTRAN frequency by means of a service-based inter-frequency handover. To implement service-based inter-frequency handovers, operators need to configure service-based inter-frequency handover policies. Each service-based inter-frequency handover policy has an ID (ServiceIfHoCfgGroupId) and specifies the frequency (DlEarfcn) that is preferentially used to carry the services of a specific operator (CnOperatorId). Since the services of each operator are further classified by QCIs, each QCI can be associated with a service-based inter-frequency handover policy so that the frequency specified by the policy preferentially carries the services with this QCI.Service-based inter-frequency handovers are controlled by the corresponding switch under the HoAlgoSwitch parameter. If this switch is turned on, the eNodeB triggers a service-based inter-frequency handover for a UE based on the highest-priority QCI of the services running on the UE. If the highest-priority QCI is associated with a service-based inter-frequency handover policy with the InterFreqHoState parameter set to PERMIT_HO, and there is at least one neighboring cell working on the frequency, the eNodeB delivers the measurement configuration related to event A4 to the UE. The triggering of event A4 in service-based inter-frequency handovers is the same as that in coverage-based inter-frequency handovers.


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Related commands:

LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission

Distance Based Measurement Trigger Page48

Note: The neighbor distance with exceed a threshold is considered as abnormal neighbor which can not be configured in NRT Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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As shown above, F1 and F2 indicate two frequencies: Cell 1 uses F1, and Cells 2, 3, and 4 all use F2. The gray area in the figure (Cell 1) is covered by F1, while Cells 2, 3, and 4 is covered by F2. It is obvious that cell 1 exerts cross-cell coverage to the other three cells. Assume that the UE moves along the direction indicated by the arrow. As the UE moves, F1 provides sustained signal quality and therefore inter-frequency measurements are not triggered for the UE even when the UE has been in the coverage of F2 for a long time. Gradually, the UE enters the overlap coverage between Cell 1 and Cell 4. Considering the long distance between the two cells, it is unlikely that Cell 4 is configured as a neighboring cell of Cell 1. As a result, as soon as the UE leaves the coverage of Cell 1, it experiences a call drop. To prevent such a call drop and ensure service continuity, the UE should have been handed over to F2 earlier.Related command:


UL Quality Based Measurement Trigger1. eNodeB evaluates MCS and IBLER of uplink2. eNdodeB triggers inter-frequency measurement 3. UE report inter-frequency measurement result 4. HO is trigged by eNodeB

Page49Sends target cell and instructs UE to initiate GAP measurement Sends GAP measurement report to the eNodeB

MCS < MCS_threshold (5QPSK 1/3) IBLER > IBLER threshold (20%)Instruct UE to HO

1234F1F2Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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UL-quality-based inter-frequency handovers are triggered based on the UL quality. When the UL quality is unsatisfactory, call drops may occur if handovers are not performed in time. Therefore, UL-quality-based inter-frequency handovers are introduced to reduce call drops caused by poor UL quality. The eNodeB uses the modulation and coding scheme (MCS) and initial block error rate (IBLER) to determine the UL quality.

LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission Measurement Activation/Deactivation After eNodeB receive the report of A2/A1, it will activate or stop inter-frequency measurement via another RRC reconfiguration message.

Page50

Measurement Activate

Measurement DeactivateCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-50Confidential Information of Huawei. No Spreading Without Permission Inter-frequency Handover Report Event For coverage based scenario: A3/A4/A5 can be used to trigger inter-frequency HO, decided by InterFreqHoEventType parameter For the other scenario:Only A4 event can be usedA5 event is recommend to prevent pingpong handover


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Related command:LTE eRAN6.0 Handover FeatureP-51Confidential Information of Huawei. No Spreading Without Permission

Event A3 Event A3 in inter-frequency handovers uses the same set of parameters with that in intra-frequency handovers, except the offset and frequency-specific offset. Enter condition: Mn + Ofn + Ocn Hys > Ms + Ofs + Ocs + A3OffLeave condition: Mn + Ofn + Ocn + Hys < Ms + Ofs + Ocs + A3Off


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LTE eRAN6.0 Handover FeatureP-52Confidential Information of Huawei. No Spreading Without Permission Event A4/A5 A4 enter condition: Mn + Ofn + Ocn Hys > Specific A4 Threshold A4 leave condition: Mn + Ofn + Ocn + Hys < Specific A4 ThresholdA5 enter condition: Mn + Ofn + Ocn Hys > Specific A4 Threshold and Ms + Ofs + Ocs + Hys < Specific A2 ThresholdA5 leave condition: Mn + Ofn + Ocn Hys < Specific A4 Threshold or Ms + Ofs + Ocs + Hys > Specific A1Threshold

Page53


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Mn: The measurement result of the neighboring cell.Ofn: The frequency-specific offset for the frequency of the neighboring cell.Ocn: The cell-specific offset for the neighboring cell.Hys: The hysteresis for event A4 Thresh: The threshold for event A4

LTE eRAN6.0 Handover FeatureP-53Confidential Information of Huawei. No Spreading Without Permission Relevant Configuration Common Parameters Page54


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Each parameters are described as below:Max report cell number: Indicates the maximum number of cells to be included in the measurement report after an event for the intra- or inter-frequency handover within the E-UTRAN is triggered.Measurement report amount: Indicates the number of periodic measurement reports to be sent after an event for the intra- or inter-frequency handover within the E-UTRAN is triggered. It is used to prevent the impact of measurement report loss and internal processing failure on the handover.A3 measurement trigger quantity: Indicates the quantity used to evaluate the triggering condition for the intra-frequency handover event. The quantity can be RSRP or RSRQ. Recommended value: RSRPA3 measurement report quantity: Indicates the quantity to be included in the measurement report for the intra-frequency handover eventIntrafreq measurement report interval: Indicates the interval between each periodic reportMeasurement A4 report quantity: The same meaning as A3 measurementA1A2 Measurement trigger quantity: The same meaning as A3 measurementInterfreq measurement report interval: The same as itrafreq measurement report interval

LTE eRAN6.0 Handover FeatureP-54Confidential Information of Huawei. No Spreading Without Permission Relevant Configuration QCI Based ThresholdPage55

A1/A2 parametersA4 parametersFrequency based A1/A2 configuration Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-55Confidential Information of Huawei. No Spreading Without Permission Relevant Configuration Special A1A2 Threshold Page56

Special A2 threshold for FDD/TDD targetSpecial A1/A2 threshold for coverage based blind handover


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LTE eRAN6.0 Handover FeatureP-56Confidential Information of Huawei. No Spreading Without Permission Parameter DescriptionFddIfHoA2ThdRsrpOffsetIndicates the offset of the RSRP threshold for LTE FDD inter-frequency measurement event A2 relative to the RSRP threshold for inter-frequency measurement event A2 (which is specified by InterFreqHoA2ThdRsrp).TddIfHoA2ThdRsrpOffsetIndicates the offset of the RSRP threshold for LTE TDD inter-frequency measurement event A2 relative to the RSRP threshold for inter-frequency measurement event A2 (which is specified by InterFreqHoA2ThdRsrp). BlindHoA1A2ThdRsrpIndicates the RSRP threshold for events A1 and A2 that are used for inter-frequency and inter-RAT blind handovers based on coverage.BlindHoA1A2ThdRsrqIndicates the RSRQ threshold for events A1 and A2 that are used for inter-frequency and inter-RAT blind handovers based on coverage.ContentsTechnical DescriptionIntra-frequency Handover DescriptionInter-frequency Handover DescriptionInter-RAT Handover DescriptionPage57


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LTE eRAN6.0 Handover FeatureP-57Confidential Information of Huawei. No Spreading Without Permission Inter-RAT Handover ProcedurePage58Measurement Triggers(Coverage Based)UE Reporting Event A2 to trigger inter-frequency measurement based on coverageSingle or both of RSRP / RSRQ monitored to trigger IF measurementStop measuring when Event A1 is met

Measurement

GAP-Assisted Measurement

Event Triggered Periodical Reporting B1/B2 (for U/G/C)

eNodeB Performs HandoverAdmission ProcedureSignaling Procedure ExecutionRetry Mechanism (attempt to next target cell in measurement report list) if admission or handover failureeNodeB Makes DecisionEvent Triggered Periodical ReportingTo be considered to make decision:RSCP or Ec/No for UMTSRx_Level for GSMPilot Strength for CDMA2000

MeasurementTriggerMeasurementPhaseDecisionPhaseExecutionHandover


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LTE eRAN6.0 Handover FeatureP-58Confidential Information of Huawei. No Spreading Without Permission Measurement TriggerCoverage based:The same as inter-frequency handover, use event A2/A1Enhanced A1A2 threshold for UTRAN and GERAN (eRAN6.0 enhancement)Load based/Distance based/UL quality basedThe same as inter-frequency handoverService basedIn a service-based handover, the eNodeB hands over a UE to another system based on the type of the service running on the InterRatHoStateUE. The applicability of handover is set through the parameter, whose values are MUST_HO, NO_HO, and PERMIT_HO.


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If the InterRatHoState parameter is set to MUST_HO for a QCI, the eNodeB delivers the service-based handover measurement configuration to a UE when the UE initiates a service with that QCI.If the InterRatHoState parameter is set to NO_HO for a QCI, the eNodeB does not deliver the service-based handover measurement configuration to a UE on which a service with that QCI is running, even if the UE initiates a service for which InterRatHoState is set to MUST_HOIf the InterRatHoState parameter is set to PERMIT_HO for a QCI, the eNodeB does not deliver the service-based handover measurement configuration to a UE when the UE initiates a service with that QCI. When a service with that QCI isrunning on the UE, the eNodeB delivers the service-based handover measurement configuration to the UE if the UE initiates a service for which InterRatHoState is set to MUST_HO.LTE eRAN6.0 Handover FeatureP-59Confidential Information of Huawei. No Spreading Without Permission Service Based HO ConfigurationPage60


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Assume that an operator plans to use bearers with a QCI of 1 to carry voice over IP (VoIP) services, bearers with a QCI of 5 to carry IMS signaling, and bearers with a QCI of 9 as default bearers. The operator also hopes that UEs performing only VoIP services are served by an inter-RAT system to ensure the service continuity while sparing E-UTRAN resourcesThe value MUST_HO is recommended for QCI 1The value NO_HO is recommended for QCI 2 to QCI 4, and QCI 6 to QCI 8.The value PERMIT_HO is recommended for QCI 5 and QCI 9.LTE eRAN6.0 Handover FeatureP-60Confidential Information of Huawei. No Spreading Without Permission Measurement ObjectPage61System Object ParametersUMTSRSCPInterRATHoUtranB1ThdRSCP for coverage-based handoversLdSvBasedHoUtranB1ThdRSCP for load and service-based handoversEc/NoInterRATHoUtranB1ThdEcN0 for coverage-based handoversLdSvBasedHoUtranB1ThdECN0 for load- and service-based handoversGERANRSSI InterRATHoGeranB1Thd for coverage-based handoversLdSvBasedHoGeranB1Thd for load and service-based handoverscdma2000Pilot Strength InterRATHoCDMAB1ThdPS for coverage-based handoversCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-61Confidential Information of Huawei. No Spreading Without Permission Inter-RAT Handover EventFor coverage based scenario:B1 and B2 can be used and decided by InterRatHoEventTypeFor the other scenario:Only B1 is supported


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LTE eRAN6.0 Handover FeatureP-62Confidential Information of Huawei. No Spreading Without Permission B1/B2 EventB1 enter condition: Mn + Ofn Hys > Specific B1 Threshold B1 leave condition: Mn + Ofn + Hys < Specific B1 Threshold B2 enter condition: Mn + Ofn Hys > Specific B1 Threshold and Ms + Ofs + Ocs + Hys < Specific A2 ThresholdB2 leave condition: Mn + Ofn Hys < Specific B1 Threshold or Ms + Ofs + Ocs + Hys > Specific A2 Threshold

Page63


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Mn: The measurement result of the neighboring cellOfn: The frequency-specific offset for the frequency of the neighboring cellHys: The hysteresis for event B1. The hysteresis values for inter-RAT handovers to UTRAN, GERAN, and CDMA2000

LTE eRAN6.0 Handover FeatureP-63Confidential Information of Huawei. No Spreading Without Permission Inter-RAT HO Common ConfigurationPage64


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LTE eRAN6.0 Handover FeatureP-64Confidential Information of Huawei. No Spreading Without Permission Report Configuration Common A1A2Page65


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LTE eRAN6.0 Handover FeatureP-65Confidential Information of Huawei. No Spreading Without Permission Report Configuration Dedicated A2 For RAT Page66


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LTE eRAN6.0 Handover FeatureP-66Confidential Information of Huawei. No Spreading Without Permission Parameter DescriptionUtranA2ThdRsrpOffsetIndicates the offset of the RSRP threshold for UTRAN inter-RAT handover event A2 relative to the RSRP threshold for inter-RAT handover event A2 (which is specified by InterRatHoA2ThdRsrp). GeranA2ThdRsrpOffsetIndicates the offset of the RSRP threshold for GERAN inter-RAT handover event A2 relative to the RSRP threshold for inter-RAT handover event A2 (which is specified by InterRatHoA2ThdRsrp). Report Configuration GSM & UMTSPage67

GSMUMTSCopyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureP-67Confidential Information of Huawei. No Spreading Without Permission Handover Execution Page68

LTE PS2G(GPRS)/3G PSPS handover

LTE VOIP2G/3G CSSRVCC

LTE PSCCO/NACCGSM PS


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The following inter-RAT handover policies are applicable:PS handover: is applicable to PS services. In PS handover, services are handed over from the PS domain of the source system to the PS domain of the target system to ensure continuous service provision. Single Radio Voice Call Continuity (SRVCC): is applicable to voice services. In the case of SRVCC, the services are handed over from the LTE system to the CS domain of the target system.Cell Change Order with or without Network Assisted Cell Change (CCO/NACC): is specific to the GSM cases. During the CCO/NACC, the UE is ordered to switch to the GERAN idle mode, and consequently it can try to access the GSM network. The procedure is simple but causes a long delay. In GSM, however, the CCO/NACC mode is a substitute for PS handover. For the CCO with NACC, the eNodeB needs to acquire the system information from the target system and then send the information to the UE through a handover command, thereby accelerating the UE access to the target GSM cell.Redirection: It is the simplest method to transfer UEs to an inter-RAT system. The 3GPP protocols stipulate that UEs that can work in another RAT also support redirections to the RAT.

LTE eRAN6.0 Handover FeatureP-68Confidential Information of Huawei. No Spreading Without Permission E-UTRAN to UTRAN CS/PS SteeringApplication scenarios: Multiple frequencies are deployed in UTRAN to separate CS/PS traffic. The function will be applied during inter_RAT handover to UTRAN and CSFB to UTRAN scenarioFeature benefit: We can set the UTRAN frequency priority based on the service type (CS or PS)In case of measurement based handover: eNodeB just deliver the high priority frequency for UE measurement based on service type so that UE doent need to measure all frequencies.In case of blind handover: eNodeB selects the target with high frequency priority based on service type.


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LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission How to Enable the Feature Activate the feature in the license, the control item is E-UTRAN to UTRAN CS/PS Steering Turn on relevant switch:Prerequisite switches should be turned on, including UtranPsHoSwitch and UtranCsfbSwitch ; If blind handover is used, one additional switch BlindHoSwitch should be turned on as wellTurn on the dedicated switch for steering: FreqLayerSwtichPage70Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission Relevant MML Algorithm Switch Page71

CSFB switch for CS steering Generic switch for UTRAN PS handover and blind handover Switch for PS/CS steering Copyright 2013 Huawei Technologies Co., Ltd. All rights reserved. :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

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LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission Relevant MML CS/PS Steering Priority Page72


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LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission LTE-GSM/UMTS PS Handover FlowPage73


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LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission LTE GSM/UMTS SRVCC FlowPage74


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For SRVCC from EUTRAN to UTRAN/GERAN, MME first receives the handover request from EUTRAN with the indication that this is for SRVCC handling, and then triggers the SRVCC procedure with the MSC Server enhanced with SRVCC via the Sv reference point if MME has SRVCC STN-SR information for this UE. MSC Server enhanced for SRVCC then initiates the session transfer procedure to IMS and coordinates it with the CS handover procedure to the target cell. MSC Server enhanced for SRVCC then sends PS-CS handover Response to MME, which includes the necessary CS HO command information for the UE to access the UTRAN/GERAN.

LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission LTE GSM CCO/NACC FlowPage75


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In the case of CCO/NACC to GERAN, the eNodeB directly orders the UE to switch to the GERAN, instead of sending a handover request over the S1 interface. In the procedure shown in the figure, steps 3 to 8 are used to request the system information of the GERAN. They are applicable only to CCO with NACC.

LTE eRAN6.0 Handover FeatureConfidential Information of Huawei. No Spreading Without Permission SummaryThe typical handover application scenarioThe procedure of handoverEvent type used for each handover Relevant parameters

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Course NameP-76Confidential Information of Huawei. No Spreading Without Permission Abbreviations CCO: Cell Change Order CIO: Cell Individual Offset NACC: Network Assistant Cell ChangeSRVCC: Single Radio Voice Call Continuity


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Thank youwww.huawei.comCourse NameP-78Confidential Information of Huawei. No Spreading Without Permission Load Evaluation

Load Balancing Decision

Inter-Freqency HO Based Measurement

Event A4 Triggered

UE

eNB

Measure Report

HO Decision

IF-HO Execute

Measurement GAPEvent A4 Parameters

Blind HO

Y

Blind HO Switch is ON & target cell is in blind HO List?

N

target cell

load transfer

LTE f1

High load

LTE f3

Low load

LTE f2

5 LTE ERAN6.0 Handover Feature ISSUE1.00

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