01-18 emlpp

18 eMLPP

About This Chapter

18.1 OverviewEnhanced Multi-Level Precedence and Pre-emption service (eMLPP) is a supplementary serviceoffered by the GSM system.

18.2 AvailabilityThe realization of eMLPP depends on the cooperation of the proper network elements, software,configuration parameters, and license.

18.3 ImpactThe impact of eMLPP mainly refers to the impact on system performance.

18.4 Technical DescriptionWhen a high-priority MS initiates a call, the MSC sets the parameters related to the A interfacebased on the user class information that is received from the HLR. The high-priority call isestablished based on these parameters.

18.5 CapabilitiesNone.

18.6 ImplementationThe eMLPP implementation consists of configuring eMLPP, verifying eMLPP, and disablingeMLPP.

18.7 Maintenance InformationThe eMLPP maintenance information is alarm information and performance counterinformation.

18.8 References

HUAWEI BSC6000 Base Station SubsystemBSS Feature Description 18 eMLPP

Issue 01 (2007-09-05) Huawei Technologies Proprietary 18-1

18.1 OverviewEnhanced Multi-Level Precedence and Pre-emption service (eMLPP) is a supplementary serviceoffered by the GSM system.

Definition

When the eMLPP is available, the MSs with a high priority have obvious advantages in termsof the call setup rate, call completion capability, and service continuity. When TCHs areinsufficient, for example, in peak working hours, the calls with a higher priority can preemptthe resources of the calls with a lower priority.

The eMLPP service consists of the following:

l Fast Call Setup

A call with a certain priority can uses the fast call setup procedure. In the fast call setupprocedure, authentication, encryption, and TMSI reassignment are omitted. This can reducethe call setup time.

l Queuing and preemption

When network resources, including trunk circuits, signaling channels, and traffic channels,are insufficient, the calls with a higher priority are not released, but wait in a queue or evenpreempt the resources of the calls with a lower priority.

Purposes

The eMLPP service is used to classify calls into groups with different priorities. The calls witha higher priority can enjoy better services, such as channel preemption and fast call setup. TheeMLPP service offers a segmentation function for operators. Using this function, operators canprovide different levels of services for users with different priorities.

Terms

Terms Definition

eMLPP enhanced multi-level precedence and preemptionservice

PL Priority level

PCI Preemption capability indicator

PVI Preemption vulnerability indicator

QA Queuing allowed indicator

PREC Preemption recommendation indicator

QRI Queuing recommendation indicator

PIE Priority information element

License License for equipment running

18 eMLPPHUAWEI BSC6000 Base Station Subsystem

BSS Feature Description

18-2 Huawei Technologies Proprietary Issue 01 (2007-09-05)

AbbreviationAbbreviation Full Spelling

eMLPP enhanced Multi-Level Precedence and Pre-emption service

PCI Preemption Capability Indicator

PVI Preemption Vulnerability Indicator

PL Priority Level

QA Queuing Allowed indicator

PIE Priority Information Element

PREC Preemption Recommendation

QRI Queuing Recommendation Indicator

LMT Local Maintenance Terminal

TCH Traffic CHannel

TCHF Traffic CHannel Full rate

TCHH Traffic CHannel Half rate

SDCCH Stand-alone Dedicated Control Channel

18.2 AvailabilityThe realization of eMLPP depends on the cooperation of the proper network elements, software,configuration parameters, and license.

Network Elements InvolvedTable 18-1 lists the network elements involved in eMLPP.

Table 18-1 Network elements involved in eMLPP

MS BTS BSC MSC MGW SGSN GGSN HLR

- √ √ √ - - - √

NOTE

l –: not involved

l √: involved

Software ReleasesTable 18-2 lists the versions of GBSS products that support eMLPP.



Table 18-2 GBSS products and related versions

Product Version

BSC BSC6000 V900R001C01 and laterreleases

BTS BTS3X G3BTS32.30000.01.1130 andlater releases

BTS3002C G3BTS36.30000.03.0820 andlater releases

BTS3001C G3BTS34.30000.07.0301 andlater releases

BTS24 G3BTS24.20000.07.1111 andlater releases

BTS23 No releases

BTS22C No releases

BTS3012 BTS3000V100R001C01 andlater releases

BTS3012AE BTS3000V100R001C04 andlater releases

BTS3006C BTS3000V100R002C01 andlater releases

MiscellaneousIn addition, the eMLPP service is available under the following conditions:

l A proper license for eMLPP is obtained and the license is enabled.

l Among Basic Call Control Parameters, Allow EMLPP is set to Yes, as shown in Figure18-1.




Figure 18-1 Setting Allow EMLPP

18.3 ImpactThe impact of eMLPP mainly refers to the impact on system performance.

Impact on System PerformanceWhen resources are insufficient, the eMLPP service ensures that the MSs with a high priorityuse resources first. If the preempted MSs are not handed over to other channels, for example, ifthe site is an isolated one, the TCH resources in neighbor cells are also insufficient, or thehandovers are timeout, the measurement values of performance counters related to Call DropRatio on TCH increase.

Impact on Other FeaturesNone.



18.4 Technical DescriptionWhen a high-priority MS initiates a call, the MSC sets the parameters related to the A interfacebased on the user class information that is received from the HLR. The high-priority call isestablished based on these parameters.

18.4.1 A Interface Parameters Involved in eMLPPThe A interface parameters that the BSC obtains from the MSC determines the eMLPP.

18.4.2 Call Establishment ProcedureThis topic describes the procedure for assigning a TCH by the BSC. The BSC assigns a TCHwhen an MS with a high priority initiates a call or receives a call in a congested cell.

18.4.1 A Interface Parameters Involved in eMLPPThe A interface parameters that the BSC obtains from the MSC determines the eMLPP.

Table 18-3 lists the A interface parameters involved in eMLPP.

Table 18-3 A interface parameters involved in eMLPP

Parameter Meaning Description

PCI Flag bit of preemption If PCI allows preemption,that is, PCI = 1, the call canpreempt the radio resourcesof the call with a lowerpriority.

PVI Flag bit of being preempted If PVI allows beingpreempted, that is, PVI = 1,the radio resources of the callcan be preempted by the callwith a higher priority.

PL Priority level According to the GSMPHASE2+ protocol, PL has14 levels. Level 1 representsthe highest priority and level14 represents the lowestpriority.

QA Queuing indicator If QA allows queuing, that is,QA = 1, the call can queue.

PIE - PIE consists of PCI, PVI,PL, and QA.

18.4.2 Call Establishment ProcedureThis topic describes the procedure for assigning a TCH by the BSC. The BSC assigns a TCHwhen an MS with a high priority initiates a call or receives a call in a congested cell.




1. The BSC determines whether the cell has an idle TCH.l If the cell has an idle TCH, the BSC assigns the TCH to the high-priority MS. The

procedure is complete.l If the cell does not have an idle TCH, go to 2.

2. The BSC determines the PCI of the high-priority MS.l If PCI = 1, go to 3.

l If PCI is not 1, the procedure is complete.

3. The BSC searches for the lowest-priority MS whose PVI is 1.l If such an MS is found, go to 4.

l If No such MS is found, go to 5.

4. The BSC triggers the handover of the MS with the lowest priority.l If the handover succeeds, go to 6.

l If the handover fails, go to 7.

5. The BSC determines the QA of the high-priority MS.l If QA = 1, the high-priority MS queues. Go to 8.

l If QA is not 1, the high-priority MS cannot queue. The procedure is complete.

6. The high-priority MS seizes the channel released by the MS that is handed over to aneighbor cell. The procedure is complete.

NOTE

After the low-priority MS is handed over to a neighbor cell, it cannot preempt the resources of anMS with an even lower priority in the neighbor cell.

7. The channel used by the low-priority MS is released and the high-priority MS seizes thischannel. The procedure is complete.

8. The high-priority MS waits in the queue for channel assignment.l If an idle channel is available before half of the timing length of the queue timer, the

high-priority MS seizures the channel. The procedure is complete.l If the MS waits in the queue for half of the timing length of the queue timer and the

BSC allows directed retry, a directed retry is triggered. If the directed retry fails, thecall is released. The procedure is complete.

l If the MS waits in the queue for half of the timing length of the queue timer and theBSC does not allow directed retry, the call is released when the queue timer expires.The procedure is complete.

18.5 CapabilitiesNone.

18.6 ImplementationThe eMLPP implementation consists of configuring eMLPP, verifying eMLPP, and disablingeMLPP.

18.6.1 Configuring eMLPP



This topic describes how to enable and configure eMLPP on the BSC6000 Local MaintenanceTerminal.

18.6.2 Verifying eMLPPThis topic describes how to verify eMLPP on the BSC6000 Local Maintenance Terminal.

18.6.3 Disabling eMLPPThis topic describes how to disable eMLPP on the BSC6000 Local Maintenance Terminal.

18.6.1 Configuring eMLPPThis topic describes how to enable and configure eMLPP on the BSC6000 Local MaintenanceTerminal.

Procedure

Step 1 Apply for and activate the license.1. When applying for the eMLPP license, ensure that Support Emlpp under License control

items in BSC6000V900R001 (None) Commercial License Application Template is set to1. Value 1 indicates that this function should be enabled.

2. Enable the license on the BSC6000 Local Maintenance Terminal. For details, refer toActivating License.

After the license is activated, the BSC supports eMLPP, but eMLPP is disabled by default.You have to enable it on the BSC6000 Local Maintenance Terminal.

Step 2 On the BSC6000 Local Maintenance Terminal, right-click a cell on the Management Treetab page, and choose Configure Cell Attributes from the shortcut menu. A dialog box isdisplayed, as shown in Figure 18-2.

Figure 18-2 Selecting a cell




Step 3 Double-click the cell in the Cell view list box to add it to the Selected cells list box.

Step 4 Click Next. A dialog box is displayed, as shown in Figure 18-3.

Figure 18-3 Configuring cell attributes

Step 5 In the Cells to be set column, select the cell and click Set Cell Properties. A dialog box isdisplayed, as shown in Figure 18-4.



Figure 18-4 Set Cells Attributes dialog box

Step 6 Click Call Control. A dialog box is displayed, as shown in Figure 18-5.





Step 7 Set Allow EMLPP to Yes.

Step 8 Click OK. A dialog box is displayed, as shown in Figure 18-6.



Figure 18-6 Check the Compatibility of Parameters and Site Versions dialog box

NOTE

There is no information related to Allow EMLPP in the dialog box shown in Figure 18-6.

Step 9 Click Yes to return to the dialog box shown in Figure 18-4.

Step 10 Click OK to return to the dialog box shown in Figure 18-3.

Step 11 Click Finish. The configuration is complete.

----End

18.6.2 Verifying eMLPPThis topic describes how to verify eMLPP on the BSC6000 Local Maintenance Terminal.

Procedure

Step 1 Check whether the eMLPP license is in use.1. Choose BSC Maintenance > Maintain License > Query License . A dialog box is

displayed, as shown in Figure 18-7.




Figure 18-7 Querying the license usage

2. Click Query. The query result is displayed, as shown in Figure 18-8.



Figure 18-8 Query result of the license usage

3. Check SUPPORT eMLPP.

Step 2 Check Allow EMLPP shown in Figure 18-9. If the value is Yes, the eMLPP function isavailable.





----End

18.6.3 Disabling eMLPPThis topic describes how to disable eMLPP on the BSC6000 Local Maintenance Terminal.

ContextIf you want to disable eMLPP in the entire BSC, apply for the license that does not supporteMLPP. Refer to Activating License to activate the license.

If you want to disable eMLPP in a cell, modify the cell attributes. The procedure is as follows:

Procedure

Step 1 In the dialog box shown in Figure 18-10, set Allow EMLPP to No.




Step 2 Click OK. A dialog box is displayed, as shown in Figure 18-11.




Figure 18-11 Check the Compatibility of Parameters and Site Versions dialog box

Step 3 Click Yes to return to the dialog box shown in Figure 18-12.



Figure 18-12 Set Cells Attributes dialog box

Step 4 Click OK to return to the dialog box shown in Figure 18-13.




Figure 18-13 Configuring cell attributes

Step 5 Click Finish. The eMLPP is disabled.

----End

18.7 Maintenance InformationThe eMLPP maintenance information is alarm information and performance counterinformation.

Alarms

None.

Performance Counters

After eMLPP is enabled, the call drop rate may increase because the high-priority MSs maypreempt the resources of the low-priority MSs. The existing BSC6000 performance counterscover the measurement of preemption and queuing. Table 18-4 lists the counters involved ineMLPP.

Table 18-4 Counters involved in eMLPP

Counter Meaning

R3134: Failed Queuing Attempts due toQueue Overflow

This counter is measured when the queuingfails because the number of calls in the queueexceeds the maximum value supported by theBSC.



Counter Meaning

R3135: Queuing Requests This counter is measured when there is noTCH available and the system supportsqueuing.

R3136: Failed Queuings (Preemption) If there is no TCH available in the cell andboth the call and the BSC support preemption,the preemption starts. This counter ismeasured when the preemption fails.

R3137: Failed Queuings (Queuing TimerExpired)

When there is no TCH available in a cell, callqueuing is triggered if the system does notstart the preemption procedure or the dynamicadjustment procedure and the system supportsqueuing. When call queuing is triggered, therelated time is also triggered to wait for an idleTCH. This counter is measured when thetimer expires.

R3138: Failed Queuings (DynamicAdjustment Timed Out)

When there is no TCH available in a cell, theBSC starts dynamic channel adjustment if thesystem supports dynamic adjustment and therequirements for dynamic adjustment are met.If the system also supports queuing, thequeuing procedure and the related timer aretriggered to wait for an idle TCH. This counteris measured when the timer expires.

H332He: Failed Outgoing External Inter-Cell Handovers (Clear Commands Sent byMSC) (Preemption)

In the outgoing external inter-cell handoverprocedure (including directed retry), thehandover fails if the MSC sends a clearcommand message containing the cause valueof preemption. This counter is measured in theserving cell when the handover fails.

H352He: Failed Outgoing Inter-RAT Inter-Cell Handovers (Clear Commands Sent byMSC) (Preemption)

In the outgoing inter-RAT inter-cell handoverprocedure (including directed retry), thehandover fails if the BSC receives a clearcommand message from the MSC. Thiscounter is measured based on the cause value(preemption) contained in the message whenthe handover fails.

R4110A: Successful Channel Assignmentsin Immediate Assignment Procedure(SDCCH)

After the BSC RR module receives a SDCCHrequest, it searches for an idle SDCCH in thechannel resource table. This counter measuresthe number of times the RR module finds anidle SDCCH, including the number of timesthe RR module preempts an SDCCH.




Counter Meaning

R4117A: Successful Channel Assignmentsin Immediate Assignment Procedure(TCHF)

After the BSC RR module receives a TCHFrequest, it searches for an idle TCHF in thechannel resource table. This counter measuresthe number of times the RR module finds anidle TCHF, including the number of times theRR module preempts a TCHF.

R4118A: Successful Channel Assignmentsin Immediate Assignment Procedure(TCHH)

After the BSC RR module receives a TCHHrequest, it searches for an idle TCHH in thechannel resource table. This counter measuresthe number of times the RR module finds anidle TCHH, including the number of times theRR module preempts a TCHH.

R4117B: Successful Channel Assignmentsin Assignment Procedure (TCHF)

After the BSC RR module receives a TCHFrequest, it searches for an idle TCHF in thechannel resource table. This counter measuresthe number of times the RR module finds anidle TCHF, including the number of times theRR module successfully preempts a TCHF.

R4118B: Successful Channel Assignmentsin Assignment Procedure (TCHH)

After the BSC RR module receives a TCHHrequest, it searches for an idle TCHH in thechannel resource table. This counter measuresthe number of times the RR module finds anidle TCHH, including the number of times theRR module successfully preempts a TCHH.

CR313C: Failed Queuing Attempts This counter measures the number of times thequeuing fails within a granularity period in acell. The queuing failure may be caused bydifferent reasons.

M305: Call Drops due to Forced Handover(SDCCH)

After an MS seizes a channel, the BSC triggersa forced handover. If the handover fails, theBSC triggers a release procedure. Thiscounter measure the number of releaseprocedures triggered by the BSC. The channelinvolved in this counter is the SDCCH.

M345: Call Drops due to Forced Handover(TCHF) (Signaling Channel)

After an MS seizes a channel, the BSC triggersa forced handover. If the handover fails, theBSC triggers a release procedure. Thiscounter measure the number of releaseprocedures triggered by the BSC. The channelinvolved in this counter is the TCHF and theservice type is signaling.



Counter Meaning

M315: Call Drops due to Forced Handover(TCHF) (TCH)

After an MS seizes a channel, the BSC triggersa forced handover. If the handover fails, theBSC triggers a release procedure. Thiscounter measure the number of releaseprocedures triggered by the BSC. The channelinvolved in this counter is the TCHF and theservice type is traffic.

M355: Call Drops due to Forced Handover(TCHH) (Signaling Channel)

After an MS seizes a channel, the BSC triggersa forced handover. If the handover fails, theBSC triggers a release procedure. Thiscounter measure the number of releaseprocedures triggered by the BSC. The channelinvolved in this counter is the TCHH and theservice type is signaling.

M325: Call Drops due to Forced Handover(TCHH) (TCH)

After an MS seizes a channel, the BSC triggersa forced handover. If the handover fails, theBSC triggers a release procedure. Thiscounter measure the number of releaseprocedures triggered by the BSC. The channelinvolved in this counter is the TCHH and theservice type is traffic.

18.8 References

l 3GPP TS 23.067: "enhanced Multi-Level Precedence and Pre-emption service (eMLPP);Stage 2".

l 3GPP TR 21.905: "3G Vocabulary".

l 3GPP TS 22.101: "UMTS Service Principles".

l 3GPP TS 22.067: "enhanced Multi Level Precedence and Pre emption service (eMLPP)Stage 1".

l 3GPP TS 23.011:"Technical realization of supplementary services".

l 3GPP TS 23.068: "Voice Group Call Service (VGCS) Stage 2".

l 3GPP TS 23.069: "Voice Broadcast Service (VBS) Stage 2".

l 3GPP TS 48.008: "Mobile Switching Centre Base Station System (MSC BSS) interfaceLayer 3 specification".

l ITU-T Recommendation Q.85: "Stage 2 description for community of interestsupplementary services (clause 3: Multi-Level Precedence and Pre-emption MLPP)".

l ITU-T Recommendation Q.735: "Stage 3 description for community of interestsupplementary services using SS No. 7 (clause 3: Multi-Level Precedence and Pre-emption(MLPP)".

l 3GPP TS 25,331: "RRC Protocol Specification".

l 3GPP TS 25.431: "UTRAN Iu Interface RANAP Signalling".

l 3GPP TS 24.008: "Core Network Protocols - Stage 3".




01-18 emlpp

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