Day 3-LTE Radio KPI – Mobility Optimization

PowerPoint Presentation

2/25/2015eRAN3.0 Handover Optimization Manual

LTE maintenance performance team 2012-03-10

HUAWEI TECHNOLOGIES CO., LTD.www.huawei.comHuawei Confidential Security Level: :40-47pt :26-30pt: :FrutigerNext LT Medium : Arial

:35-47pt: :24-28pt::

HUAWEI TECHNOLOGIES CO., LTD.Huawei Confidential :32-35pt : R153 G0 B0 :FrutigerNext LT Medium : Arial

:30-32pt : R153 G0 B0:

:20-22pt (2-5) :18pt : :FrutigerNext LT Regular : Arial

:18-20pt(2-5):18pt ::

13

.

1

AbstractPage 2This slide describes the intra-radio access technology (RAT) handover process and principles, symptoms of handover problems, methods of obtaining logs related to handover problems, troubleshooting process and method, and typical problem cases. If a handover problem cannot be solved, related deliverables need to be provided for further analysis at Huawei headquarters.

The first chapter describes the handover process in details to provide reference of some field personnel not familiar with the handover procedure and can be skipped if not required.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

2

ContentHandover Principle and Signaling Procedure

Symptoms of Handover Problems

Related Tools and Data Collection

Handover Fault Location and Troubleshooting

Routine Troubleshooting Operations and Deliverables for Handover ProblemsPage 3


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Overview

Page 4Handover is a process of connection interaction exchanges between the UE and the network when the UE roams, as shown in the following figure.

The whole handover process in the Long-Term Evolution (LTE) system is controlled by the eNodeB, and the eNodeB needs to monitor the radio quality of the environment where the UE is located. In a handover, the eNodeB sends a measurement configuration message to the UE and then the UE sends a measurement report to the eNodeB once conditions for triggering measurement report are met.

Triggering a handover: Currently, Huawei eNodeBs use event A3 to an intra-frequency handover and events A2 and A4 to trigger an inter-frequency handover.

Implementing a handover: The eNodeB sends a handover command to the UE and the UE disconnects from the serving cell and then hands over to the target cell after receiving the handover command.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

4

Handover Type

Page 5Handover in the LTE system Intra-RAT handoverCarrier frequency relationship: Intra-frequency handover Inter-frequency handoverSignaling bearing mode: Intra-eNodeB handoverIntra-MME X2 handover (if the X2 interface is available) Intra-MME S1 handover (if the X2 interface is unavailable) Inter-MME S1 handover over the X2 interface (if the X2 interface is available) Inter-MME S1 handover over the S1 interface (if the X2 interface is unavailable) Inter-RAT handover


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

5

Measurement Event

Page 6


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

6

Parameter Configuration (Intra-Frequency Handover)Handover-related parameters are used to control the reporting time and difficulty level of a handover in the measurement report. For details about handover parameter configuration, see eRAN3.0 Handover-related MML Command Configuration GuideIntra-frequency handover triggering process (event A3)

Mn indicates the measured Reference Signal Received Power (RSRP) and Reference Signal Received Quality (RSRQ) of neighboring cells. Ofn indicates the frequency offset. Ocn indicates the neighboring-cell offset to be configured through the neighboring relationship. Ms indicates the measured RSRP and RSRQ of the serving cell. Ofs indicates the offset of the serving frequency. Ocs indicates the offset of the serving cell. Hys indicates the hysteresis, closely related to the service feature and the mobility speed. Reducing the probability of ping-pong effect. Off a3-Offset Mn, Ms is in units of dBm or dB. Other parameters are in units of dB.

Page 7


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

7

Parameter Configuration (Inter-Frequency Handover) Inter-frequency handover triggering processEvent A2 triggers the GAP measurement. Two GAP modes In a period of 40 ms (default) or 80 ms

Event A4 triggers the inter-frequency handover.

Page 8


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

8

Intra-eNodeB Inter-Cell Handover

The UE sends a measurement report to the eNodeB in the serving cell.The eNodeB sends a Handover Command message after completing cell admission control and radio resource allocation in the target cell. The UE accesses the target cell. After the handover is complete, resources of the serving cell are released. (RRC_CONN_RECFG)(RRC_CONN_RECFG_CMP)Page 9


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

9

Inter-eNodeB X2 Handover (I)

The UE has accessed to the cell and performs services. The source eNodeB sends a measurement configuration message to the UE, instructing the UE to start neighboring-cell measurement. The UE sends a measurement report to the eNodeB after detecting a cell that meets handover conditions. The source eNodeB determines a handover based on the handover algorithm and current state. The source eNodeB sends a Handover Request message to the target eNodeB, starting the handover preparation. The Handover Request message carries the service information and other access layer information (encryption, integrity, and measurement information) of the current UE. The target eNodeB sends a message carrying the admission result and radio resource configuration information to the serving eNodeB, completing the handover preparation. After receiving the Handover Request message from the serving eNodeB, the target eNodeB performs admission control based on the service information and radio resource configuration carried in the message. The source eNodeB forwards the container from the target eNodeB to the UE through the radio message to notify the UE of a handover. Sequence number (SN) information is used to transfer the SN status and hyper frame number (HFN) information of the UE from the source eNodeB to the target eNodeB for the purpose of data retransmission and encryption integrity protection. The SN information only applies to the RLC AM mode in Huawei. Start data forwarding. (RRC_CONN_RECFG)Page 10


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

10

Inter-eNodeB X2 Handover (II)

After completing the random access procedure to access the target eNodeB, the UE sends a Handover Confirm message to the target eNodeB. After receiving the Handover Confirm message from the UE, the target eNodeB initiates a path switch to the MME to complete the user data transmission. After completing the user-plane handover on the S-GW, the MME sends a PathSwitchRsp message to the target eNodeB. After the path switch procedure, the target eNodeB instructs the source eNodeB to release related resources, completing the whole handover procedure. (RRC_CONN_RECFG_CMP)Page 11


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

11

Inter-eNodeB S1 Handover (I)

The source eNodeB sends a Handover Request message to the MME. The MME transfers the Handover Request message to the corresponding target eNodeB for handover preparation. After completing admission control and radio resource configuration, the target eNodeB returns a Handover Ack message to the MME. The MME transfers the Handover ACK message to the source eNodeB. Similar to the handover over the X2 interface, the source eNodeB sends the SN information to the MME and the MME forwards the SN information to the target eNodeB. (RRC_CONN_RECFG)Page 12


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

12

Inter-eNodeB S1 Handover (II)The UE accesses the target eNodeB. The target eNodeB notifies the MME of the handover completion. The MME notifies the source eNodeB of resource release. The source eNodeB returns a resource release completion message. (RRC_CONN_RECFG_CMP)Page 13


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

13

Page 14Querying the Inter-frequency Handover Capability of the UE

To query the UE capability in initial access, view the feature group indicators information element (IE) in the UE CAPABILITY INFO IND message.

Bits 13, 14, and 25 indicate the inter-frequency handover capability of the UE. For details, see 3GPP TS 36.331.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Traffic Measurement Counters for Handovers (Outgoing Handover)Page 15

Counter measurement for intra-eNodeB handoversCounter measurement for inter-eNodeB S1 handoversThe following description of counter measurement uses the intra-eNodeB handover and inter-eNodeB S1 handover as examples.

Point A: measures the number of outgoing handover attempts. This counter is incremented by 1 after the eNodeB receives the measurement report and successfully determines a handover. Point B: measures the number of outgoing handover executions. This counter is incremented by 1 after the eNodeB sends a handover command to the UE. Point C: measures the number of successful outgoing handovers. If an intra-eNodeB handover is performed, this counter is incremented by 1 after the eNodeB receives the handover response message (RRC Reconfiguration completion message) from the UE. If an inter-eNodeB S1 handover is performed, this counter is incremented by 1 after the eNodeB receives the UE release message from the MME (or from the target eNodeB in case of an inter-eNodeB X2 handover).


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Traffic Measurement Counters for Handovers (Incoming Handover)Page 16 Counter measurement for inter-eNodeB X2 handoversCounter measurement for inter-eNodeB S1 handoversThe following description of counter measurement uses the inter-eNodeB S1 handover and inter-eNodeB X2 handover as examples.

Point A: measures the number of incoming handover attempts. This counter is incremented by 1 after the target eNodeB receives a handover request.Point B: measures the number of incoming handover executions. This counter is incremented by 1 after the target eNodeB sends a handover acknowledge. Point C: measures the number of successful incoming handovers. If an inter-eNodeB X2 handover is performed, this counter is incremented by 1 after the target eNodeB sends a UE release message to the source eNodeB. If an inter-eNodeB S1 handover is performed, this counter is incremented by 1 after the target eNodeB sends the handover notification to the MME.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.







:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Symptoms of Handover Problems (1/5) Page 18A handover problem occurs if a UE sends a measurement report based on configurations on the eNodeB but fails in handover based on the handover procedure. By handover failure step, handover problems can be classified as follows: The UE sends a measurement report but does not receive a handover command. The eNodeB fails to receive a measurement report. The serving cell encounters a fault in sending uplink signals or uplink messages. The eNodeB receives a measurement report but does not sends a handover command due to internal admission failure, lost handover messages over the S1 or X2 interface, or handover punishment. This problem must be caused by a system problem and has nothing to do with the UE and the Uu interface. The eNodeB sends a handover command which the UE fails to receive. The serving cell encounters a fault in sending downlink signals or downlink messages. The UE receives a handover command and the eNodeB does not receive a handover completion message. The UE performs random access to the target cell and the eNodeB does not receive message 1. The UE performs random access to the target cell. The eNodeB receives message 1 and the UE does not receive message 2. The UE performs random access to the target cell. The UE receives message 2 and the eNodeB does not receive message 3. The eNodeB receives a handover completion message and the subsequent procedure fails. This problem seldom occurs and must be caused by a system problem, having nothing to do with the UE and the Uu interface.If a handover fails, service drops or RRC connection reestablishment occur in most cases.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Symptoms of Handover Problems (2/5)Page 19

In this example, compare logs between the UE and the eNodeB to analyze symptoms on the UE and the eNodeB in case of a handover failure.

The eNodeB does not receive the measurement report from the UE.

The UE sends a measurement report, which the UE does not receive. Symptoms on the UE and the eNodeB are as follows: Signaling on the UESignaling on the eNodeB


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Symptoms of Handover Problems (3/5)Page 20The UE does not receive a handover command from the eNodeB.

After the UE sends a measurement report, the eNodeB receives the measurement report and sends a handover command, which the UE does not receive. Symptoms on the UE and the eNodeB are as follows:

Signaling on the UESignaling on the eNodeB


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Symptoms of Handover Problems (4/5)Page 21The eNodeB does not receive a handover completion message from the UE.

After the UE sends a measurement report, the eNodeB receives the measurement report and sends a handover command. After the UE receives the handover command and initiates access to the target eNodeB, the target eNodeB does not receive the handover completion message. Symptoms on the UE and the eNodeB are as follows:The UE sends a handover completion message (RRC_Connection_Reconfiguration_Complete) to the eNodeB. However, this message is lost over the Uu interface when transmitting at the lower layer.

Signaling on the UEThe target cell does not receive a handover completion message. The serving cell sends a handover command.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Symptoms of Handover Problems (5/5)Page 22Summary: Problems of the Uu interface causing handover failures have many symptoms on the UE and features a common characteristics, that is, not long (within 2s) after the UE sends a measurement report, the UE resends an RRC_Connection_Request message or an RRC_Connection_Reestablishment_Request message, or directly enters the idle state (capable of receiving paging and system information only).


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.







:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Related Tools and Data CollectionPage 24Some tools are used for problem analysis. For example, the M2000 is used to trace signaling and replay service data of the eNodeB and the Probe is used on the UE side. UEs of other manufacturers also have different analysis tools.

Common tracing tools: standard interface tracing on the Web LMT and Probe

Web LMT interfaceProbe interface


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Related Tools and Data CollectionPage 25

Signaling tracing interface on the M2000Common tracing tool: signaling tracing on the M2000


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Related Tools and Data CollectionPage 26Data analysis tool: Probe

Probe which is used to trace and analyze the data of Huawei UEs Traffic review tool which is used to analyze traced eNodeB data


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Related Tools and Data CollectionPage 27

Confirming the Handover Measurement Configuration and Handover Measurement Reportmessages Use the message query software to display the details. Display the measurement Report message. If the measID in this message is the same as that in the measurement configuration message, the measurement report corresponds to the measurement event and the phyCellId is the physical cell identifier (PCI) of the target cell. Display the RRC_Connection_Reconfiguration message. If there is a measConfig ID, it is a measurement configuration message and the measID corresponding to the ReportConfigIdg is the handover measurement ID.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Related Tools and Data CollectionPage 28Confirming the Handover Command message

Use the message query software to display the last RRC_Connection_Reconfiguration message in the handover measurement report. Use the traced message on the UE as an example.

Display the last RRCConnectionReconfiguration message in the handover measurement report. If the targetPhysCellId IE exists, the RRCConnectionReconfiguration message is a handover command.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.


Confirming the cell sending the Handover completion message

The cell sending the handover completion message can be simply confirmed by viewing the traced file on the network side and by using the message query software on the UE side. On the UE side, the SystemInfomationBlockType1 message in the handover measurement report over the Uu interface can be displayed to view details. Double-click the SIB1 message in the handover measurement report. View the PLMN ID and cell identity (including the eNodeB ID and cell ID included in the MML command on the eNodeB).


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Related Tools and Data CollectionTool NameFunctionApproachLMTUsed to perform X2 tracing, Uu tracing, S1 tracing, and single-UE tracing. http://support.huawei.com/support/TraceViewerUsed to replay signaling messages traced on Web LMT. http://support.huawei.com/support/PROBEUsed to trace information of Huawei UEs, including signaling information, scheduling information, and signal quality. http://support.huawei.com/support/LTE traffic measurement toolUsed to resolve traffic measurement data of the eNodeB. http://support.huawei.com/support/


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.







:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Handover Fault Location and Troubleshooting: Missing Neighboring CellsHandover failures caused by missing neighboring cellsSymptom: As the RSRP and SINR of the serving cell deteriorates, the RSRP of the neighboring cell becomes better. Solution: Manually add neighboring cells.

The UE sends a measurement report but does not receive a handover command. The eNodeB receives the measurement report but does not initiate a Handover (no handover request is sent over the X2 interface and no handover command is sent over the Uu interface). Currently, many E-UTRANs are at the construction stage and the problem of missing neighboring cell occurs seriously, especially because some eNodeBs are not running. As a result, eNodeBs without neighboring cells planned have some neighboring cells. The problem of missing neighboring cells is the top one reason of handover failures. Page 32


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

32

Fault Location and Troubleshooting: Non-Timely Handover (1/2)Handover failures caused by non-timely handoversSymptom: When the radio quality of the neighboring cell meets the handover threshold, the RSRP of the serving cell suddenly drops. Generally, a handover failure is caused by a problem in the serving cell, for example, the eNodeB does not receive the measurement report from the UE or fails to send a handover command. Tracing results of the eNodeB show that, after sending a handover command, the eNodeB does not receive a handover completion message. or the eNodeB does not receive the measurement report from the UE. Tracing results of the UE show that, after receiving the handover command and sending a handover completion message, the UE initiates RRC connection reestablishment, or the UE does not receive a handover command. Page 33The E-UTRAN works in intra-frequency networking mode and does not support soft handovers. The intra-frequency interference forms the largest challenge. Compared with the GERAN and UTRAN, the handover area is much smaller and handover failures easily occur if handovers are not timely completed.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

33

Fault Location and Troubleshooting: Non-Timely Handover (2/2)Solutions

If the interval from the time of neighboring-cell radio quality meeting the handover threshold to the time of sudden dropping of the serving-cell radio quality is excessively short (for example, smaller than 1s), and the interval from the time of neighboring-cell radio quality becoming better than the serving-cell radio quality to the time of sudden dropping of the serving-cell radio quality is excessively long (for example, larger than 2s), modify the CellIndividualOffset between the serving cell and the neighboring cell to a value larger than 0 for an earlier handover (this method is used in most cases).

If the interval from the time of neighboring-cell radio quality becoming better than the serving-cell radio quality to the time of sudden dropping of the serving-cell radio quality is excessively short (for example, smaller than 0.5s), modify the IntraFreqHoA3TimeToTrig for an earlier handover (this method is not recommended).

If the same value of CellIndividualOffset needs to be modified for the serving cell and the neighboring cell, modify the IntraFreqHoA3Hyst and IntraFreqHoA3Offset parameters for an earlier handover (this method is not recommended).

Page 34


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

34

Handover Fault Location and Troubleshooting: Weak CoverageHandover failures caused by weak coverageSymptom: When the radio quality of the neighboring cell meets the handover threshold, the RSRP of the serving cell and the neighboring cell is weak. Solutions: Adjust the power ratio; adjust the antenna tile angle; add eNodeBs or carriers.

Tracing results of the eNodeB show that, after sending a handover command, the eNodeB does not receive a handover completion message. or the eNodeB does not receive the measurement report from the UE. Tracing results of the UE show that, after receiving the handover command and sending a handover completion message, the UE initiates RRC connection reestablishment, or the UE does not receive a handover command. Page 35Weak coverage is another major cause leading to handover failures on the live E-UTRAN. Currently, most E-URTANs are under construction and the coverage is weak.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

35

Handover Fault Location and Troubleshooting: InterferenceHandover failures caused by interferenceSymptom: When the RSRP is satisfactory, the throughput is not as good as expected and problems such as handover failures and service drops occur. For details about how to observe uplink and downlink interference, see LTE RF Channel Test and Check Manual. Solution: Clear interference sources. For details, see LTE RF Channel Test and Check Manual.The Received Signal Strength Indicator (RSSI) of the RB traced on the network side is obviously larger than those of others RBs. The subband channel quality indicator (CQI) reported by the UE is obviously smaller than those of other subbands. Page 36


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

36







:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

Routine Troubleshooting Procedure for Handover Problems Page 38Check network KPIs.Check for topN cells.Check equipment states.Check parameter configurationPerform standard interface tracing. Locate traffic fault points.Check the Uu interface. Check for non-radio- interface faults. Close the problem.Confirm the effect. Perform problem-closing operations (including deliverables collection).Conclusion report and cases

Fault detectionFault locationProblem closing Check a handover problem by following the procedure in the figure on the right and then follow the checklist to check items. Submit related deliverables including required information and data to Huawei headquarters for further analysis if necessary.


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

38

Routing Troubleshooting Operation Checklist 2. Sum up KPIs of a cell to obtain the number of handover attempts, number of handover executions, and number of successful handovers of each type on the entire work. 3. Calculate the intra-eNodeB handover success rate, inter-eNodeB handover success rate, X2 handover success rate, and S1 handover success rate. (Inter-eNodeB handover success rate = X2 handover success rate + S1 handover success rate)4. Check whether the handover success rate of each type meets the KPI standard (generally, 98.5% for type-A sites; can be defined as required). If a handover success rate does not meet the standard, analyze problems of this type of handover (intra-eNodeB handover, X2 handover, or S1 handover).

Output: KPI report, top failed-handover typesPage 39

1. View network KPIs. Formula: Handover success rate = Number of successful outgoing handovers/Number of outgoing handover executions

1. Use the M2000 or PRS to export handover-related KPIs, including:


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

39

Routing Troubleshooting Operation Checklist 2 Check top cells. Verify top cells based on KPIs and inter-specific-cell handover information.

Traffic measurement result of inter-specific-cell handover1. Sort the number f handover failures (Number of outgoing handover executions Number of successful outgoing handovers) in a descending order.2. Select top 5 cells with the handover success rate smaller than the average value. 3 If the field personnel report top n cells of handover failures, include the cells in the top cell list. Output: Top cell list

3. Check the equipment status. 1. Verify that handover-related cells are in the activated state. 2 Query eNodeB and cell alarms to check whether abnormal alarms are cleared (for example, X2 link disconnection alarm and RRU alarm). 3 Check whether the test UE can work properly and supports inter-frequency or inter-RAT reselection and handovers. For details, see P16 Querying the UE Capability.

Page 40


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

40

Routing Troubleshooting Operation Checklist 4. Check eNodeB data configurations. 1. Check the mapping between versions. 2. Check whether the handover switch is turned on. 3. Confirm the neighboring cell configuration and parameter configuration (neighboring relationship, X2 interface configuration, and transport configuration).4. Configure the handover threshold and time-to-trigger settings (for details, see P9 and P10). Note: For details about MML commands, see eRAN3.0 Handover-related MML Command Configuration Guide. 2. Perform cell tracing and standard interface tracing. 1. Perform S1 tracing, Uu tracing, and X2 tracing on the M2000 or Web LMT. 2. Use the test UE to perform drive tests and capture corresponding logs on the Probe. 3. Stop drive tests after sufficient logs are captured and then save corresponding logs. Deliverables: eNodeB standard interface tracing results; drive test results of the Probe6. Determine a fault. 1. Follow the standard handover procedure of the right type to locate the faulty point causing the handover failure. 2. If a fault occurs on the Uu interface, it is a radio-interface fault. 3. If a fault occurs on the S1 or X2 interface, it is a non-radio-interface fault.

Page 41


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

41

Routing Troubleshooting Operation Checklist 7. Check a radio-interface fault or non-radio-interface fault.1. In case of a radio-interface fault, see section 4 of Handover Fault Location and Troubleshooting to check it based on different symptoms. 2. In case of a non-radio-interface fault (X2 interface fault), collect and send BRD logs to the R&D personnel at Huawei headquarters for further analysis. 3. In case of a non-radio-interface fault (S1 interface fault), analyze the problem with the EPC personnel, and then collect and send BRD logs to the R&D personnel at Huawei headquarters for further analysis. 8. Confirm problem-closing operations. 1. For a radio-interface fault, close the problem by referring to Handover Fault Location and Troubleshooting.2. For a fault which cannot be located, collect and send deliverables required in the Handover Fault Deliverables to Huawei headquarters.Deliverables: Handover Fault Deliverables9. Implement problem-closing operations. 1. If parameters need to be modified, back up current configurations. 2. Wait for idle hours on the live network. 3. Implement problem-closing operations.Deliverables: Configuration file that is backed up and operation recordPage 42


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

42

Routing Troubleshooting Operation Checklist 10. Confirm the troubleshooting effect. 1. By using repeated drive tests, check whether handover counters in related areas are optimized. 2. Trace KPI changes of one week and check whether related counters meet standards or faults no longer occur. Simultaneously, no other feature fault occurs. 3. If a fault persists, relocate the problem by following operations at the fault location stage or submit required deliverables to the R&D personnel for further analysis. Deliverables: KPI data

11. Make conclusion reports and provide cases. 1. Organize related materials and, if the operator attends the troubleshooting procedure, provide clarification materials. 2. Conclude the troubleshooting procedure and provide related cases. Deliverables: Clarification material (optional), casesPage 43


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

43

Handover Fault DeliverablesPage 44The field personnel provide required deliverables when reporting handover faults to Huawei headquarters.

Description of handover faults, including fault information in the field, for example, whether upgrades are performed, whether network configurations are modified, whether telephone numbers are released by the operator, or whether a special test is performed.

Network configuration, including network scale, number of eNodeBs, inter-eNodeB distance, site height, eNodeB distribution map, and frequency configuration

Network parameter configurations, configuration files of eNodeBs related to handover faults

BRD logs of eNodeBs, including standard interface logs, CHRs, KPIs, and traffic measurement results of inter-specific-cell handovers

Drive test data recorded by using the Probe if Huawei UEs are used, single-UE tracing data on the network side (The initial single-UE tracing only records standard interface signaling; other data is recorded based on requirements from Huawei headquarters.)


:30-32pt : R153 G0 B0:


:18-20pt(2-5):18pt ::

13

.

44

Thank youwww.huawei.com

2.

A3 Measurement Reports

3RRC Conn. Reconf. incl. mobilityControlinformation

4RRC Conn. Reconf. Complete

UE

Source eNB

Target eNB

1.

A3 Measurement Control

Handover preparation

Random access procedure

Measure RSRP/RSRQ

A3 EventTriger

2.

A2 Report

4A4 Reports

UE

Source eNB

Target eNB

1.

A3/A1/A2 Measurement Control

Handover preparation

Measure RSRP/RSRQ

A2 EventTriger

GAP measurement

3

A4 Control

A4 EventTriger

Legend

3. HO decision

UE

Source Cell

Target Cell

Serving Gateway

Detach from old cell and synchronize to new cell

packet data

Buffer packets from MME

packet data

packet data

L

3

signalling

L

1

/

L

2

signalling

User Data

H

a

n

d

o

v

e

r

C

o

m

p

l

e

t

i

o

n

H

a

n

d

o

v

e

r

E

x

e

c

u

t

i

o

n

H

a

n

d

o

v

e

r

P

r

e

p

a

r

a

t

i

o

n

MME/MMEs

Area Restriction Provided

packet data

packet data

Flush DL buffer, continue delivering in transit packets

1. Measurement Control

packet data

packet data

UL allocation

2. Measurement Reports

DL allocation

4. Handover Command

5. Synchronization

6. UL allocation + TA for UE

7. Handover Confirm

packet data

eNB

Measurement Reports

Handover Command

Handover Confirm

Legend

packet data

packet data

UL allocation

2.

Measurement Reports

3.

HO decision

4.

Handover Request

5.

Admission Control

6.

Handover Request Ack

7.

Handover Command

DL

allocation

Data Forwarding

UE

Source eNB

Target eNB

Serving

Gateway

Detach from old cell and

synchronize to new cell

Deliver buffered and in transit

packets to target eNB

Buffer packets from

Source eNB

9.

Synchronisation

10.

UL allocation

+

TA for UE

L

3

signalling

L

1

/

L

2

signalling

User Data

1.

Measurement Control

H

a

n

d

o

v

e

r

E

x

e

c

u

t

i

o

n

H

a

n

d

o

v

e

r

P

r

e

p

a

r

a

t

i

o

n

MME

0.


SN Status Transfer

8.

11.

Handover Confirm

17.

Release Resource

12.

Path Switch Request

UE

Source eNB

Target eNB

Serving

Gateway

packet data

Data Forwarding

Flush DL buffer,

continue

delivering in

-

transit packets

packet data

16.

Path Switch Request Ack

18.

Release

Resources

H

a

n

d

o

v

e

r

C

o

m

p

l

e

t

i

o

n

MME

13.

User Plane update

request

15.

User Plane update

response

14.

Switch DL path

End Marker

End Marker

Legend

3. HO decision

7. Admission Control

UE

Source eNB

Target eNB

Serving Gateway

Detach from old cell and synchronize to new cell

Deliver buffered and in transit packets to target eNB

Buffer packets from MME

L

3

signalling

L

1

/

L

2

signalling

User Data

H

a

n

d

o

v

e

r

E

x

e

c

u

t

i

o

n

H

a

n

d

o

v

e

r

P

r

e

p

a

r

a

t

i

o

n

MME/MMEs


5. Handover Request

7. Handover Request Acknologe

1. Measurement Control

packet data

packet data

UL allocation

2. Measurement Reports

4. Handover Reauired

8. Handover Command

DL allocation

9. Handover Command

10. eNB SN Status Transfer

Data Forwarding

12. Synchronization

13. UL allocation + TA for UE

11. MME SN Status Transfer

Data Forwarding

UE

Source eNB

Target eNB

Serving Gateway

16. UE Context Release Completed

H

a

n

d

o

v

e

r

C

o

m

p

l

e

t

i

o

n

MME/MMEs

15. Handover Notify

14. Handover Confirm

packet data

16. UE Context Release Command

Day 3-LTE Radio KPI – Mobility Optimization

Documents

Transcript of Day 3-LTE Radio KPI – Mobility Optimization