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Paging strategy & LAC optimization

3

July 13, 2010 by Isybel Harto

Summary

There are several kinds of paging strategy in MSC , in order to get the high page successful rate , choose one of the page strategy is very important and necessary. Whatever page strategy need the LAC group , so setting the right LAC group is advantaged to improve the page successful rate .

Paging strategy in MSC

There are three times paging function in MSC ,it should be chose with different page strategy in every time page .the page strategy include muti-LAI page-LAI set page-BSC page-All BSC page and Intersystem page .

1. Introduce the page strategy

muti-LAI page: MSC will send the page message to those LAC which mobile register in last three times .LAI set page: MSC will send the page message to those LAC which be composed as a LAC group in MSC .BSC page: MSC will send the page message to the all of sites in a BSC which mobile register .All BSC page: MSC will send the page message to the all of the BSC that belong to the MSC which mobile register .Intersystem page: the page message will be sent to different sites which belong to different MSC at the same time .

2. How to choose the different page strategy

Actually  the page strategy is flexible ,engineer should chose the page strategy as different network topology configuration .the picture about page strategy in MSC is as follow

If the BSC that belong to same MSC are not nearby ,then this page strategy should be used as below:

First time — muti-LAI page

Second time —-LAI set page

Third time—–BSC page

If the BSC that belong to same MSC are neighbor , then this page strategy should be used as below:

First time — muti-LAI page

Second time —-LAI set page

Third time—–all BSC page

If there are some border site that belong to different MSC ,we can add one more page strategy in third times when it is necessary :

Third time—–all BSC page or BSC page and intersystem page

Note :once we use the intersystem page ,the border cell should be defined in MSC .

3. Configure the LAC group in MSC

Setting the LAC group is complex work ,which LAC should be composed as one LAC group ,we have to consult the rule as below:

  • Those LAC which is near a small town should be one LAC group with town LAC together Example as below picture , the LAC1 and LAC2 should be composed as one LAC group, because there are so many border cell in this tow LAC area
  • In one LAC, if all of the sites are not in border ,in other word the sites belong to different LAC have long distance each other, one LAC one LAC group is much better.

4. Step of optimize the LAC group in MSC

First step : export the data of LAC group from MSC like the table below

Second step: make a map with LAC code and BTS information in mapinfo like the map below

Third step : add or delete the LAC from LAC group by map with the rule of configure the LAC group .please consult the table below

Forth step : modify the LAC group with new LAC group in MSC.

5. Check the LAC&CI

After add the new site or rehome site ,we have to check the number of LAC & CI in MSC and BSC ,because the LAC & CI must be same in MSC and BSC. So two table that include LAC&CI should be exported from MSC and BSC,the detail is below :

1. Cell parameter table from BSC
BSC BSSID SYSTEM CELLID SID NID LAC CI PILOT_PN
Asansol1 0 2 0 14655 65535 43840 21 81
Asansol1 0 2 1 14655 65535 43840 22 249
Asansol1 0 2 2 14655 65535 43840 23 417
Asansol1 0 3 0 14655 65535 43840 31 162
Asansol1 0 3 1 14655 65535 43840 32 330
Asansol1 0 3 2 14655 65535 43840 33 498
Asansol1 0 4 0 14655 65535 43777 41 105
Asansol1 0 4 1 14655 65535 43777 42 273
2. Globe cell table from MSC
BSC MCC MNC CI LAC Protocol Type Border Id
Asansol BSC 404 0 51 43777 IS20001X 0
Asansol BSC 404 0 52 43777 IS20001X 0
Asansol BSC 404 0 53 43777 IS20001X 0
Asansol BSC 404 0 61 43777 IS20001X 0
Asansol BSC 404 0 62 43777 IS20001X 0
Asansol BSC 404 0 63 43777 IS20001X 0
Asansol BSC 404 0 71 43777 IS20001X 0
3. If the site has already rehomed or handovered to other MSC , delete it’s CI in “Globe cell table from MSC” is necessary .

Observe the kpi of page

We can compare with the kpi of page after optimization , generally there are three KPI we can collect in MSC and BSC ,then we can get the result .

1. Paging success ratio (%)

we can get the KPI directly in MSC and export the table as follow

Paging statistical data query template
Begin Time Paging success ratio (%)
2008-02-07 19:00:00 83.2986
2008-02-08 19:00:00 81.9061
2008-02-09 19:00:00 84.1396
2008-02-10 19:00:00 84.2749
2008-02-11 19:00:00 84.7602
2008-02-12 19:00:00 84.3345
2008-02-13 19:00:00 84.6874
2008-02-14 19:00:00 84.5274
2008-02-15 19:00:00 84.0037
2008-02-16 19:00:00 83.865
2008-02-17 19:00:00 83.057
2008-02-18 19:00:00 83.8845
2008-02-19 19:00:00 84.2285
2008-02-20 19:00:00 82.6549

2. Paging success ratio (%)

we can get the original data(2155_1X  Global Voice Paging) in BSC ,and then calculate it by manually.

Formal : paging success ratio=( Common Call MS Paging Response Num+ Assign Soft Handoff Paging Response Num)/ Common Call MS Paging Num *100

Begin Time Node BSS Common Call MS Paging Num Common Call MS Paging Response Num Assign Soft Handoff Paging Response Num Paging success ratio (%)
2008-02-20 16:00:00 100001 0 106019 58349 27241 80.73
2008-02-21 16:00:00 100001 0 101009 54555 27443 81.18
2008-02-22 16:00:00 100001 0 101500 55729 27695 82.19
2008-02-23 16:00:00 100001 0 97956 53097 26682 81.44
2008-02-24 16:00:00 100001 0 93177 49552 25591 80.65
2008-02-25 16:00:00 100001 0 105300 57755 27687 81.14
2008-02-26 16:00:00 100001 0 93726 55876 27788 89.26

3. Usage ratio of page channel (%)

we can get the original data(2892_1X  Cell Control Channel Usage) in BSC ,and then calculate it by manually like the table below.

Formal : page channel usage ratio= Actual Transmit Bits of Paging Channel/Can Transmit Bits of Paging Channel*100

Begin Time Node BSS BTS Actual Transmit Bits of Paging Channel Can Transmit Bits of Paging Channel page channel usage ratio(%)
2008-02-27 19:00:00 100001 0 2 80556251 311011200 25.90
2008-02-27 19:00:00 100001 0 3 61616015 207331200 29.72
2008-02-27 19:00:00 100001 0 23 64030554 207340800 30.88
2008-02-27 19:00:00 100001 0 24 62790615 207331200 30.29
2008-02-27 19:00:00 100001 0 25 84347813 311040000 27.12
2008-02-27 19:00:00 100001 0 26 108424699 414662400 26.15
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3 thoughts on “Paging strategy & LAC optimization

  1. mhd says:

    nice info thx.
    keep share dont stop, some one just start learning 😛

    BR//mhd

  2. mampet says:

    bagaimana dengan NSN version gan? MSC dan BSC nya..paging ini apakah ada pengaruh dari jauhnya BSC? atau transmisi quality?
    tks sharenya

  3. Isybel Harto says:

    pada dasarya untuk semua Vendor mempunyai parameter yang sama dalam hal paging.
    ada 4 hal utama yang di setting untuk masalah paging ini,
    1. paging interval (5s, 6s, or 7s)
    2. paging time/global time (2 times, 3 times)
    3. type of paging (IMSI, IMSI, TMSI or IMSI, TMSI, IMSI)
    4. IMSI/TMSI detach time (120 mnt or 150 mnt)
    semuanya ini berlaku sesuai dengan konturnya. Jadi pengaruh jauhnya BSC sangat menentukan kesuksesan paging.

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