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Belajar KPI

VIEWS: 356 PAGES: 14

									OJT KPI Sumalirja
By : Robertus Pekujawang

Contoh Kasus:

1. SDSR decrease on Sawangan Sector 2 and 3 cause traffic drop (20 August 2007)
       BSC:33 / BTSM:23

       If SDSR decrease, there are 3 possibilities reason why : caused by blocking (SDCCH
       addition), hardware problem, or interferrence.
       Check on Batrana what makes SDSR decrease.
       By checking on Batrana, SD blocking is zero and by checking on Map info there is no
       interference, so temporary conclusion, this problem was caused by hardware problem.
       Ask to scan alarm by OMC.
            (cari log alarm dari OMC) (gambar Mapinfo tgl itu) (gambar Batrana)

2. DCR increase on Sinon Sayang (20 August 2007)

       By checking on MapInfo, sector 2 has no adjacent to site Motoling, so when MS go far
       away from Sinon Sayang, signal strength from Sinon Sayang decreases and there is no
       adjacent to handover to, or available adjacent too weak (compare to handover treshold)
       for MS to handover to. When signal strength goes to minimum value, drop call occur.
       By checking on Batrana, most failed happen due to Radio Link Failure and T200.
       Considering MS condition on hilly area RDLNKTO then set to 15 (default : 7, max : 15) to
       give more chance for MS to try (more failure before decide to drop). RDLNKTO and
       PCRLFTH also set to a value in relation to RDLNKTBS based on formula. T200 set to a
       higher value.
       Every time check a site, make sure that neighbourhood already complete.

   070820_Sumal_Aldo_101

 Cell Name    BSC   BTSM   BTSN    Object   No   Parameter          New Value                 Old Value
 Sinon
 Sayang        57     6      1      BTS          RDLNKTO                15                        12
                             1     PWRC     0    RDLNKTBS               64                        52
                             1     PWRC     0     PCRLFTH               60                        48
                             1      BTS             T200      145-31-38-90-70-29-168   88-62-62-180-180-90-135
                             2      BTS          RDLNKTO                15                        12
                             2     PWRC     0    RDLNKTBS               64                        52
                             2     PWRC     0     PCRLFTH               60                        48
                             2      BTS             T200      145-31-38-90-70-29-168   88-62-62-180-180-90-135

       (gambar dari MapInfo) (gambar dari Batrana) (gambar dari KPI Tool)

T200 = LapDm Timer 200 (BTS timer , unit= 5 ms and 10 ms)
Parameter format: sdcchSAPI0 - facchTCHF - facchTCHH -sacchTCHSAPI0 - sacchSDCCH
sdcchSAPI3 -sacchTCHSAPI3.
Should be set in correspondence with the channel mapping and channel characteristics on the
radio interface. When the BTS transmits a DL layer-2 frame on the air the BTS starts the timer
T200 and waits for the acknowledgement frame from the MS. If the acknowledgement from the
MS is not received within T200 the transmission of the layer 2 frame is repeated and T200
restarted. The total number of repetitions is restricted to N200, a fixed value specified by GSM
which depends on the control channel types:
         N200(SDCCH)=23, N200(SACCH)=5,
         N200(FACCH/FR)=34, N200(FACCH/HR)=29
If T200 expires after the last layer 2 frame repetition the BTS sends
an ERROR INDICATION with cause .T200 expired N200+1 times. (followed by a RELEASE
INDICATION) message to the BSC, which releases the associated resources (Call Drop).



RDLNKTBS = Radio Link Time Out BS (Radio link counter BS) (Downlink)
Define initial value of counter S within the BTS. Every time the BTSM/MS unable to decode a
SACCH message on the uplink/downlink, S counter is decrement by 1, vice versa incremented
by 2. As soon as the counter S in the BTS reaches 0, a Connection Failure Indication message
with cause ‘radio link failure’ is sent to BSC and the BSC initiates a release of the concerned
connection (Call Drop).

RLF Counter S



                                           RADIO_LINK_TIMEOUT = 8


                                             Radio Link Failure Warning
                                             Power Command


                                                                    Radio Link Failure
            PC_TIMEOUT = 2




                                                                          SACCH Frames

          decoded SACCH message

          not decoded SACCH message

RDLNKTO = Radio link timeout MS (counter) (Uplink)
Similar to RDLNKTBS but for MS. If S reaches 0, the connection is released and MS return to idle
mode (This action caused Call Drop).

Relationship between RDLNTBS and RDLNKTO =
        S = 4 + 4 x RDLNKTO
        S= RDLNKTBS               so RDLNKTBS = 4 + 4 x RDLNKTO or vice versa

PCRLFTH = Power control radio link failure threshold
If the RDLNKTBS decrease and reach PCRLFTH value (that’s why RDLNKTBS > PCRLFTH),
the BTS immediately increases the BS and MS transmit power to the maximum.
Note : this parameter only relevant if if the parameter related to power control set to true.
         EPWCRLFW = TRUE

Addition:
        EMSPWRC = (Adaptive, Classic, or Disable)
        EBSPWRC = (Adaptive, Classic, or Disable)

        BBHOP => EBSPWRC = Disable atau Adaptive
        SFH   => EBSPWRC = Classic atau Adaptive
        EMSPWRC selalu aktif.
3. High DCR and TCHB on Wakal Sector 1, Drop HOSR on another sector (20 August 2007)

      Configuration of this site is 2/4/4 (BSC:58/BTSM:12)
      Because TCHB on Sector 1 is very high, maybe one TRX down on this sector. This
      conclusion     taken      by     calculating  the   erlang use     erlang calculator
      (www.erlang.com/calculator/erlb)
      Because one TRX on Sector 1 is down thus it caused HOSR drop on another Sector
      because MS on another sector can not perform handover to sector 1.
      Ask to scan alarm by OMC.
      (cari log alarm dari OMC) (Cari data get kpi tanggal ini) (contoh kalkulator erlang)
   (gambar batrana)
4. Drop HOSR on Sawangan (21 August 2007)

       By checking on DbTree all adjacent already complete, but by tracking using MapInfo we
       found out that adjacent to surround site suddenly vanish. This problem was caused by
       rehoming of surround site of Sawangan by unknown party without LAC update on
       TGTBTS.
       Ask RDP to update TGTBTS.
               (gambar Mapinfo)

5. DCR increase on Sinon Sayang (27 August 2007) BSC:57, BTSM:6

       By checking CTRX report on Batrana, the visualization of RXLEV to RXQUAL and
       RXLEV to TA on sector 2 and 3 look weird, thus possibility reason for this case is
       hardware problem.
       Ask to scan alarm by OMC.
               (cari log alarm dari OMC) (cari gambar Batrana)



RXLEV vs TA
RXLEV vs RXQUAL
6. DCR increase on Sinon Sayang (28 August 2007) BSC:57, BTSM:6

        Justification: Contour (use Google Earth and Global Mapper).
                       Attempt and Drop comparison on Batrana (low traffic, so even small drop, in
                       Percentage become big).
        CU perftest on OMC to find out the condition of CU.
        RDLNKTO and T200 set to maximum value.
                 (cari action list) (cari getKPI)

070829_SuLutMalGo_Maya_101

 Cell name            BSC       BTSM       BTSN     Object        No        Parameter       New Value     Old Value
 Sinon Sayang
 GSM                  57         6          0       HAND          0      ENAQUALEVHOM         TRUE         FALSE
                      57         6          0       HAND          0        MAXFAILHO            3            2
                      57         6          0       HAND          0         HOAVLEV            6-2          4-2
                      57         6          0       ADJC          0       QUALLEVHOM           70            69
                      57         6          0       ADJC          1       QUALLEVHOM           70            69

070830_SuLutMalGo_Maya_101

Cell Name       BSC    BTSM          BTSN       Object       No        Parameter           New Value                   Old Value
Sinon Sayang
GSM              57         6          0         BTS                  RDLNKTO                  15                          12
                 57         6          0        PWRC         0        RDLNKTBS                 64                          56
                 57         6          0        PWRC         0         PCRLFTH                 60                          52
                 57         6          0         BTS                     T200      175-100-100-175-175-90-175   88-62-62-180-180-90-135



7. Drop HOSR on Sawangan Sector 3 and 1 (4 Sept 2007) BSC:33 / BTSM: 23

         Check on Handover report at Batrana and find out on what adjacent more handover
         failure happen.
         On sector 1 it seem that failure happen on it’s adjacent no. 1 and 2 on table Uplink
         Strength (UL).
         Parameter setting in relation to strength or level (HOLTHVDL,HOLTHQUUL) >
         parameter set to be higher => so it need more time before condition for HO reached
         On sector 1 handover failed due to better cel = 0 (Handover failure commonly happen
         due to Quality and Level => very small on Quality because even on low level, quality is
         good => failure on quality commonly caused by interferrence). So handover is planned it
         hard to handover due to level but easier due to better cell. In this case ELEVHOM set to
         TRUE, LEVHOM set to a bigger value, and HOM set to a smaller value.
         On sector 3 SDSR value so close to acceptance value. By checking on Batrana, it
         caused by T200, so T200 then set to a bigger value.
         HOSR on sector 3 also bad. By checking on Batrana, the problem almost equal to sector
         1, thus action taken equal to sector 1.
                  (cari gambar Batrana) (cari action list)

070904_Sulutmalgo_Aldo_101

 Cell name      BSC    BTSM          BTSN       Object   No            Parameter         New Value                    Old Value
 Sawangan
 GSM            33         23         0         HAND       0       HOLTHQUDL                  6                          5
                                      0         ADJC       0        LEVHOM                   71                          69
                                      0         ADJC       0          HOM                    63                          69
                                      0         ADJC       1        LEVHOM                   71                          69
                                      0         ADJC       1          HOM                    63                          69
                                2       BTS             T200        145-31-38-90-70-29-168   88-62-62-180-180-90-135
                                2      HAND     0     ELEVHOM               TRUE                     FALSE
                                2      ADJC     0     LEVHOM                  71                        69
                                2      ADJC     0       HOM                   63                        69
                                2      ADJC     1     LEVHOM                  71                        69
                                2      ADJC     1       HOM                   63                        69

HOLTHQUDL = Handover lower threshold quality downlink (5= 3,2% to 6,4%; 6= 6,4% to 12,8%)
In this case will give more tolerance to higher BER.
Defines the receive signal quality threshold on the downlink for inter-cell quality handover decision.

ELEVHOM = Enable level handover margin (FALSE/TRUE)

LEVHOM = Level handover margin (unit:1db, 69 = 6 dB, 71 = 8dB)
The level handover is triggered if the UL or DL receive level of the serving cell falls short of the
thresholds HOLTHLVUL resp. HOLTHLVDL. (In case of Handover due to Level/Strength)
        If ELEVHOM = FALSE
                the target cell only has to fulfil the handover minimum condition
                          RXLEV_NCELL(n) > RXLEVMIN(n) + Max(0,Pa).
                to be included in the target cell list of the INTERCELL HANDOVER CONDITION
                INDICATION with the cause values uplink strength or downlink strength.
        If ELEVHOM = TRUE
                also the level difference between the serving cell and the neighbour cell (power
                budget PBGT) is considered. In this case the neighbour cell only appears in the
                target cell list if its power budget exceeds the entered level handover margin:
                          PBGT(n) > LEVHOM(n)
                in addition to the handover minimum condition. (Better Cell)

HOM = Handover margin (unit:1db, 63 = 0 dB, 69 = 6dB)
This parameter defines a threshold for the power budget handover (handover to another cell if this cell
offers a higher transmission level (irrespective of whether the power level of the actual cell is above the
minimum)) In this case PBGTHO must be true.
Handover triggered if the power budget of a specific neighbour cell exceeds the handover margin set
for the ADJC object representing this cell.

8. Drop HOSR on Sinon Sayang sector 1 (4 Sept 2007)

        DCR already good but HOSR getting worse on sector 1.
        By checking database using DbTree, RACHBT had set to 114 by unknown party thus set
        to it default value 109.
        By checking on Batrana there are a lot of failed caused by BC and Strength.
        ELEVHOM set to true, HOM set to a bigger value (handover due to better cell will be
        more difficult), LEVHOM set to a bigger value.
070904_Sulutmalgo_Aldo_101

 Cell name     BSC   BTSM   BTSN    Object   No   Parameter         New Value             Old Value
 Sinonsayang    57     6      0      BTS           RACHBT              109                   114
                              1      BTS           RACHBT              109                   114
                              2      BTS           RACHBT              109                   114
                              0     HAND     0    ELEVHOM             TRUE                 FALSE
                              0     ADJC     0      HOM                 69                    66
                              0     ADJC     0    LEVHOM                71                    69
                              0     ADJC     1      HOM                 69                    66
                              0     ADJC     1    LEVHOM                71                    69

RACHBT = RACH busy threshold
This attribute defines a threshold for the received signal level during network access and
handover access. A signal level exceeding this threshold is interpreted as a busy RACH or a busy
FACCH (when transmitting CHANNEL REQUEST (RACH) or Handover ACCESS (FACCH)).
Minimum signal level threshold an MS can use RACH.

Dilapangan biasanya setting RXLevAmi bersamaan dengan setting RACHBT dimana apabila
RxlevAmi diperbesar maka semakin mudah MS untuk mengakses channel sehingga walaupun
Rx Levelnya besar apabila RxLevAmi dan RACHBTnya belum mencapai sesuai dengan yang
disetting maka MS tidak akan dapat mengakses channel . RXLEVAMI dapat mengurangi jumlah
handover.
Adalah threshold untuk level signal RACH. Tujuan utama dari parameter ini adalah untuk
menghindari beban SDCCH yang tidak perlu. BTS akan mengukur level signal tiap timeslot
RACH dan menentukan apakah signal request diterima atau tidak. Jika signal terima lebih besar
atau sama dengan nilai RACHBT maka RACH burst akan diindikasikan BUSY (ada satu atau
lebih MS yang mengakses jaringan)



KPI Value

SDSR (SDCCH Successfull Rate)

Stand-alone Dedicated Common Control Channel (SDCCH) is a signalling used for call
initialization, sms, and location update. SDSR is a ratio between total successfull SDCCH to total
attempt by MS to get SDCCH.
Acceptance value by Telkomsel for SDSR :

For GSM/Stand Alone DCS : Urban = 93.00 %
                          Sub Urban = 92.50 %
                          Rural = 91.50 %

For Co-Located DCS :          Urban = 97.40 %
                              Sub Urban = 98.10 %
                              Rural = 95.80 %

For Indoor Coverage :         Indoor Stand Alone = 98.30 %
                              Indoor Collocated = 97.00 %
Checking Step:

    1. Check a site on KPI Monitooring tool if SDSR decrease.
    2. Check on Batrana what make SDCCH failed or blocked (high traffic) e.g.
       SD_Drop_Radiolink_failure, SD_Drop_T200, SD_Drop_unidentified, then set related
       parameter.
    3. Also check on MapInfo if interferrence happen, and ask RNP to retune if needed.
    4. Ask OMC to scan alarm to check hardware status.

HOSR (Handover Successfull Rate)

Handover that monitored by KPI team are only outgoing and intra BSC handover.
HOSR is a ratio between successfull handover to total handover attempt.
Acceptance value by Telkomsel for HOSR :

For GSM/Stand Alone DCS : Urban = 92.00 %
                          Sub Urban = 90.00 %
                          Rural = 87.00 %

For Co-Located DCS :          Urban = 95.00 %
                              Sub Urban = 94.00 %
                              Rural = 95.10 %

For Indoor Coverage :         Indoor Stand Alone = 93.00 %
                              Indoor Collocated = 94.50 %

There are four reason for MS to do handover :
    1. Quality
           Handover due to quality occur when quality (BER or FER) of sinyal received by MS
       fall to a value below treshold. If value for treshold set to a higher value it mean that
       system will be more tolerance to signal quality so it will need more time before treshold
       reached (handover occur) and vice versa for a smaller value. Failure on handover due to
       quality generally very small, because even on low level or low strength signal, quality still
       good enough. Main reason for failure on handover due to quality is interferrence because
       it make quality go very bad.

    2. Level or strength
           Handover due to level or strength occur when level of sinyal received by MS fall to a
       value below treshold. If value for treshold set to a smaller value it mean that system will
       be more tolerance to signal level so it will need more time before treshold reached
       (handover occur) and vice versa for a higher value. This kind of handover can combined
       to handover due to better cell by applied another parameter i.e ELEVHOM, LEVHOM and
       HOM. If ELEVHOM = TRUE, also the level difference between the serving cell and the
       neighbour cell (power budget PBGT) is considered. In this case the neighbour cell only
       appears in the target cell list if its power budget exceeds the entered level handover
       margin:
       PBGT(n) > LEVHOM(n)
       in addition to the handover minimum condition.

    3. Distance
          Handover due to distance occur when MS reach treshold define how far a MS can go.
       This treshold closely related to Timing Advance (TA).

    4. Better Cell
          Handover due to better cell occur when signal level received by MS from neighbour
       site is better than serving site.

Checking Step:

    1. Check a site on KPI Monitooring tool if HOSR decrease.
    2. Check on Batrana handover report what make handover failed based on handover kind :
       Quality, Strength or Level, Power Budget, and Better Cell. Set related parameter to repair
       a handover type or to combine those kind of handover type to get better HOSR. Failed
       handover on quality generally caused by interferrence, and ask RNP to retune.
    3. Check on database if there are parameter set or change to not recommended value and
       repair it to a recomended value.
    4. Check neighbourhood and interferrence on MapInfo.

DCR (Drop Call Rate)

There are three reason for Drop Call :
       1. Full
       2. Radio Link Failure
       3. Interferrence

DCR is a ratio between drop call to total call made by subscriber.
Acceptance value by Telkomsel for HOSR :

For GSM/Stand Alone DCS : Urban = 0.70 %
                          Sub Urban = 0.95 %
                          Rural = 1.15 %

For Co-Located DCS :           Urban = 0.50 %
                           Sub Urban = 0.40 %
                           Rural = 0.65 %

For Indoor Coverage :      Indoor Stand Alone = 0.4 %
                           Indoor Collocated = 0.3 %

Checking Step:

   1. Check a site on KPI Monitooring tool if DCR increase.
   2. Check on Batrana what make a call to drop e.g. TCH_Drop and TCH_Attempt,
      TCH_Drop_Radio_Link_Failure,                                     TCH_Drop_T200,
      TCH_Drop_Remote_Transcoder_Failure. Set related parameter to repair DCR.

TCHB (Traffic Channel Blocking)

BHT (Busy Hour Traffid)

								
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