paging enhancement study

8/10/2019 Paging Enhancement Study

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Paging Enhancement Study

Prepared by Wen Qing5/30/2006


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Background

When it occurs a paging request during locationupdate,the phenomenon no page response takes

place easily. Though it seems that probability isvery low, this phenomenon affects some importantKPI especially for DT.


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Feature introduce

The Paging Enhancement optional featurefurther improves the VLR level paging retry

procedure as it enables the recent locationarea information retrieval before the repetitionof the paging request. With this additionallocation information query, you can avoid the

situation when the paging fails as thesubscriber has already moved to a differentlocation area in the same MSC/VLR. Thus,you can increase the paging success rate.


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VMSC VLR VMSC-AIF RAN MS

1 Paging request

Retrieve recent LAIfrom the database2

3 Page MS (TMSI,LAI1)4a Page

Paging

4b PagePaging5 Page MS NACK

Retrieve recet LAI fromthe database6

7 Page MS (IMSI,LAI2)8 Page

Paging9 L3 message10 Process Access Request

PAR (security procedures)

12

11

Page MS NACK13 Paging response


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Feature trial projectTest tool and areaTEMS , 4 SIM cards (three of four cards are the same paging group),MSC_A( open PE ), MSC_B( not open PE )

4 MS have different purposes .we define MS1,MS2,MS3,M4:Test plan:

MS1: call originalMS2: call terminal ( Paging during LU )MS3: listen to the paging message in old_LACMS4: listen to the paging message in new_LAC

Test one: location update in the boundary of the LAC that are in the sameMSC_A


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MSC_A

MS4MS3

LAC_old LAC_new

MS2 MOVING


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Test two: location update in the boundary of the LAC that comes from thedifferent MSC

MSC_B

MS3

MSC_A

MS4

MS2 MOVING


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Test analyse and conclusionAfter we tested ,the feature carry out its page mechanic. we can draw

a conclusion that the paging enhancement feature can improve paging performance , we can avoid the situation when the paging fails asthe subscriber has already moved to another location area withinthe same MSC/VLR. The paging enhancement can contributelittle profit for KPI about paging.the contribution counts on the

probability the page happing during location update.and thisfeature doesnt affect any other files that are directly visiable tothe opreator. MSC2

PSR(BSS) PSR(MSC) Repage Rate

4 26 0.805 0.971 0.152

4 27 0.800 0.969 0.156

4 28 0.808 0.972 0.149


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The feature s bug

When we tested that MS2 move from MSC_A (open PE) to MSC_Bduring paging ,call original can hear unassign (unallocated) number .

we analyse the wireless link .


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From the upper illustration , we can see that MS1 receive downlinkmessage:Disconnect , and disconnection cause value comes fromUnassigned (unallocated) number


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Then we use the call trace function and compare the abnormal call withnormal call .there exist two type clear codes .

Abnormal callsclear code:0314H

Normal calls clearcode:0012H


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After call trace,we observe the statistics about MSC clear code 0314.

MSC20 CC 0314H

0

50

100

150

200

250

4 -

2 6

4 -

2 6

4 -

2 6

4 -

2 7

4 -

2 7

4 -

2 7

4 -

2 8

4 -

2 8

4 -

2 8

4 -

2 8

4 -

2 8

4 -

2 8

4 -

2 9

4 -

2 9

4 -

2 9

4 -

2 9

4 -

2 9

4 -

3 0

MSC39 CC 0314H

0

50

100

150

200

250

4 -

2 6

4 -

2 6

4 -

2 6

4 -

2 7

4 -

2 7

4 -

2 7

4 -

2 7

4 -

2 8

4 -

2 8

4 -

2 8

4 -

2 8

4 -

2 8

4 -

2 9

4 -

2 9

4 -

2 9

4 -

2 9

4 -

2 9

4 -

2 9

4 -

3 0

From the upper two illustration , clear code 0314 gets higher when MSC open the paging enhancement feature and gets lower when MSC close PE . So we can

judge that the paging enhancement feature brings on the much clear code 0314coming up..


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Solution

We design the three circumstances for checking the features bug. Both the original call and the terminal call are in the same MSC (openPE)

The original call and the terminal call are in the different MSCThe original call the terminal call are in the different NETWORK ( oneis PSTN , the other is PLMN)


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Lets analyse the truth in the clear code 0314:

MSC25 MS1MSC39

MS2

MSC33

CC0314

ISUP MAP

CC0817


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Solution AChange the announcement for the clear code 0314 . After

announcement changed, we can only improve the circumstance thatBoth the original call and the terminal call are in the same MSC .From mapping of the internal clear code to the external clear code,theclear code 0314 has been translated into 0817 through ISUP link.sothis way cannt solute the bug completely.


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Solution Bwe define the clear code 0314 as 0012 in the original MSC , so the

next link step can follow the same situation as 0012 . Then we canreceive the corrcet announcement NO PAGING RESPONSE . Afterwe carry out this trial ,we obtain the ideal result .we receive thecorrect annoucement in all of the circumstances.it doesnt affect otherKPI . So the bug that clear code 0314 lead to the wrong

announcement has been conquered completely.


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paging enhancement study

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