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					                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
 

 

 

 

 



                                 KPI Optimization Process 
                                          Appendix‐3  
         refers to page 15 of Network Performance Monitoring & Optimization Process 


                                                       Huwaei 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
PROCESS for SDCCH Assignment Success Rate Optimization:
Definition:      When From the MS SDCCH Request is sent to Base Station and if MS
successfully gets the SDCCH in response SDCCH Assignment has done successfully.

PROCESS for Optimization:
    1. Identify the Bad performing Cells for SDCCH Assignment Success Rate
    2. Take the detailed report showing (Ex. Total SDCCH Assignment Request, Total SDCCH
       Assignment Successful)
    3. Follow the below mentioned Process after Analyzing detailed report...
    4. From Report Check whether you have Idle SDCCH available in cell or not for SDCCH
       Assignment; because the Main factor for lowering SDCCH Assignment success rate is
       SDCCH congestion.
    5. SDCCH Congestion:

              a. Check The SDCCH Requests (Immediate Assignment Measurement Per Cell
                 Report form M200)
              b. Ex. Call purpose, SMS, Location Update
              c. If you find High SDCCH Request and low TCH utilization Check “SDCCH
                 Dynamic Allocation Allow” feature is enabled or not? if not enable this feature.
              d. If you have very High SDCCH Request for Location Updating; optimize the LAC
                 boundary.
              e. Only For some exceptional cases you can increase the Static SDCCH Time Slots.

    6. Check Hardware/Transmission alarms; Resolve if find any.
    7. Audit for any parameters related discrepancies and define as per standard parameters set.
    8. RF and Environmental Factors:

           a. Low Coverage Areas (Try to reduce low coverage patches with physical
               optimization; New sites)
           b. Interference/ Bad quality/ UL-DL Imbalance;
           c. Check the states for TRx on which SDCCH is configured can be issue of TRx
               also; Change TRx if you found random behavior of TRx.
    9. After all rectification observe the subsequent days report if you still find the problem
       repeat the same process with due care to Pin Point the actual cause.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 




Fish bone diagram for the root cause analysis high SDCCH congestion rate




PROCESS for SDCCH DROP Rate Optimization:
Definition:    When MS is already on SDCCH and in-between communication with Base
station SDCCH channel got disconnected abruptly then SDCCH Drop has occurred.

PROCESS for Optimization:
    1. Identify the Bad performing Cells for SDCCH Drop Rate
    2. Take the detailed report showing (Ex. Total SDCCH Assignment Successful, Total
       SDCCH Dropped)
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
    3. Follow the below mentioned Process after Analyzing detailed report...
    4. The Main Reasons for High SDCCH Drop Rate are improper Parameters Configuration
        and Bad RF & Environmental factors.
    5. First Audit for any parameters related discrepancies and define as per standard
        parameters set.
    6. Check for Neighbor Relations and correct if it is not proper.
    7. For counter level analysis refer “Call Drop Measurement per Cell” report from M2000.
    8. Low Coverage: Through Drive Test Find out the low coverage patched and try to
        improve with physical optimization; New site; coverage enhancement features for some
        cases(Ex. Power Boost Tech, No Combining, TMA/TMB)
    9. Interference: Check for interference from repeaters, Intra-Network interference due to
        aggressive reuse or improper Freq., Inter-Network can also be the case. Find out the
        actual cause and rectify it.
    10. Antenna System: High VSWR due to feeders, Improper antenna configuration(Ex. Sector
        cable Swap)
    11. Check for Hardware Issue and rectify if you found any.
    12. After the activity check the subsequent days report and repeat the procedure for pin
        pointing the actual cause.


 

 

Fish bone diagram for the root cause analysis for high SDCCH drop rate
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 


PROCESS for RACH (Random Access Channel) Success Rate
Optimization:
Definition: Random Access Channel (RACH) is used by the MS on the “uplink” to request
for allocation of an SDCCH. This request from the MS on the uplink could either be as a page
response (MS being paged by the BSS in response to an incoming call) or due to user trying to
access the network to establish a call. For all services there will CH REQ (Channel Request)
from MS and in the response of CH REQ if MS will get the IMM ASS CMD (Signaling Ch)
Access to system is successful. Nature of this Access REQ is random so it is call Random Access
Channel Request.

PROCESS for Optimization:
    1. Identify the Bad performing Cells for RACH Success Rate
    2. Take detailed report and analyze for no of failure of Request and failures.
    3. The main reasons for bad RACH success rate could be access from very distant place
       with very low coverage; Parameters Configuration discrepancies.
    4. First Check for Parameters Configuration discrepancies and correct as per standard
       parameter set.
    5. The main parameters to look for Huawei
           a. “MS MAX Retrans” can set depending upon Traffic and Clutter.
           b. “Tx-Interger” will reduce the RACH collision and can improve RACH success
               rate.
           c. “T3122” waiting time for next network access.
           d. “RACH Min.Access Level(dbm)” very important parameter for low coverage
               rural areas.
           e. “CCCH conf” & “BS_AG_BLKS_RES” check properly defined or not? Because
               if you have overload with AGCH “IMM ASS” can’t be send in the response of
               CH REQ.

    6. Check for Hardware Issues (Ex. BTS sensitivity has very crucial role to play here)
    7. Check for Uplink Interference and quality.
    8. Check for UL-DL imbalance and correct if any problem.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
    9. After the activity check the subsequent days report and repeat the procedure for pin
       pointing the actual cause. 
          
          
         Fish Bone diagram for the root cause analysis of poor Random Access Success
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
PROCESS for TCH Assignment Success Rate Optimization:
Definition:      When From the MS TCH Request is sent to Base Station and if MS successfully
gets the TCH in response TCH Assignment has done successfully.

PROCESS for Optimization:
    1. Identify the Bad performing Cells for TASR( TCH Assignment Success Rate)
    2. Take the detailed report showing (Ex. Total Assignment Request, Total Assignment
       Successful)
    3. Follow the below mentioned Process after Analyzing detailed report...
    4. From Report Check whether you have Idle TCH available in cell or not for Assignment
       and follow the below process.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 


A & B in above Flow chart are measurement Points for TCH Assignment Failures...

    5. As per the Above Process If you have already used “Re-Assignment”, “Directed Retry”
        and “Queuing” features and still you are having issue with TCH Congestion (No Idle
        TCH)... Try to Decrease Half Rate Triggering Thresholds...
    6. Ex. Below Parameters for Huawei System
        “TCH Busy Traffic Threshold (%)”
        “AMR TCH/H Prior Allowed”
        “AMR TCH/H Prior Cell Load Threshold”
    7. Check for discrepancies with Parameter Configuration and set as per Standard Parameters
        set available.
    8. If you find Issue is not with High Traffic and Congestion... Check Hardware Issue (Ex.
        BTS/BSC/MSC hardware / UL-DL Imbalance due to VSWR) resolve if you find any.
    9. Transmission Issues at A-bis/A-ter/A links
    10. If Hardware is Ok check for Bad RF Environment... (Very low Coverage, High
        Interference, Bad Quality, Call from Distant Place (TA).
    11. Follow below Process for Above Points... You can check the counters Report for Pin
        pointing the actual cause. (Ex. Assignment Per Cell Report from M2000)
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 

    12. Correct the affected area (Ex. If call is getting originated from High TA and getting failed
        due improper strength ; Optimize the Site Coverage with Physical Optimization) and
        check the subsequent days Report; If you still find the issue follow the same flow right
        from the starting with due care to PIN Point the Actual cause..

    13. TBF Success Rate
    14. Average GPRS RLC throughput & Average EDGE RLC Throughput
    15. Downlink Multislot Assignment Success Rate
    16. SDCCH Assignment Success Rate
    17. SDCCH DROP Rate
    18. ACH (Random Access Channel) Success Rate
    19. Assignment Success Rate
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                  
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
PROCESS for Rx Quality Optimization:
    •    Definition : Rx Quality is measure of BER of radio link                     between MS and BTS

    •     Poor Speech Quality could be due to

                        •    Patchy Coverage ( holes)

                        •    No Target cell for Handover

                        •    Echo , Audio holes, Voice Clipping

                   Interference ---:

              •    Co-channel

              •    Adjacent channel

              •    External

              •    Multipath

              •    Noise

Speech Quality Parameters
    •    RxQUAL: Measured on the midamble.

    •    Indicates poor speech quality due to radio interface impairments

    •    FER : Measured on the basis of BFI ( Ping -Pong effect on speech )

    •    Preferred under Frequency Hopping situation

    •    Audio holes: Blank period of speech, due to malfunctioning of Transcoder boards or
         PCM circuits.

    •    Mean Opinion Score (MOS) : ITU standard for estimating speech quality

PROCESS for Optimization:
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
1) Physical optimization
2) New cell dependency
3) Overshooting
4) Neighbor list tuning
5) BCCH tuning (Freq plan)
                               ALUMS‐OOMP‐L2‐014 ALU      UMS OPERATIO             MANUAL 
                                                                      ONAL PROCESS M          
                                      2           EFFECTIV
                            EDITION 1.2                                uary  2011 
                                                         VE DATE: 01Janu



 
 




From M2                                   nt          on                   x
         2000 extract Rx Quality measuremen distributio Counters to know Trx –cell wise Rx
Quality.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
PROCESS for HOSR Optimization:
Definition: HO activity is performaed to maintain – Call continuity and        call quality . The
inputs that the BSC uses for making a handover decision, from the received MRs from the MS is
the DL signal strength, DL quality, and the signal strength of the six best reported neighbours.
From the serving BTS, for the same MS the BSC will use UL signal strength, UL quality and
TA.

Handover Process:
         The GSM handover process uses a mobile assisted technique for accurate and fast
         handovers, in order to:

- Maintain the user connection link quality.

- Manage traffic distribution

         The overall handover process is implemented in the MS,BSS & MSC.

         Measurement of radio subsystem downlink performance and signal strengths received
         from surrounding cells, is made in the MS.

         These measurements are sent to the BSS for assessment.

         The BSS measures the uplink performance for the MS being served and also assesses
         the signal strength of interference on its idle traffic channels.

         Initial assessment of the measurements in conjunction with defined thresholds and
         handover strategy may be performed in the BSS. Assessment requiring measurement
         results from other BSS or other information resident in the MSC, may be perform. in
         the MSC.

         The MS assists the handover decision process by performing certain measurements.

         When the MS is engaged in a speech conversation, a portion of the TDMA frame is idle
         while the rest of the frame is used for uplink (BTS receive) and downlink (BTS transmit)
         timeslots.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
         During the idle time period of the frame, the MS changes radio channel frequency and
         monitors and measures the signal level of the six best neighbor cells.

         Measurements which feed the handover decision algorithm are made at both ends of the
         radio link.

Classification By Reason:
    •    Emergency HO

              – Timing advance (TA) Emergency HO

              – Bad quality (BQ) Emergency HO

              – Rx Level Drop Emergency HO

              – Interference emergency HO

    •    load HO

    •    Normal HO

              – Edge HO

              – Layer HO

              – Power budget (PBGT) HO

    •    Fast moving MS HO (Speed-sensitive HO )

PROCESS for Optimization:
    10. Identify the Bad performing Cells for HOSR
    11. Take the detailed report showing cause & target cell
    12. Check congestion; hardware Alarm; Quality; Rx level
    13. Late Handover – Handover margin (like Rx level-Rx Qual etc )need to define properly.
    14. Ping-Pong Handover – A proper Hysteresis is used to prevent the Ping Pong effect. This
        can be caused by fading
    15. Unnecessary Handover – more number of handovers, higher risk of facing quality
        problem and even in call drop
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL           
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
    16. Missing neighbor – Best server is not in there in neighbor list
    17. BCCH Missing
    18. Same BCCH & BSIC combination
    19. one way neighbor handover
    20. Neighbor cell in other BSC- need to define correct CGI,BCCHNO,BSIC
    21. Congestion on other cell




         Fish bone diagram for the root cause analysis for high handover failure rate




PROCESS for TCH drop Optimization:
Definition:           TCH drop (or a dropped call) could be broadly classified into 3 sub classes:

    1. Degradation of the links (Uplink and Downlink): either degradation of Signal Strength
       which falls near or lower than the sensitivity of the base station (around to -110 dBm) or
       that of the mobile (around -104dBm) or degradation of quality of the links (Uplink and
       Downlink) often due to interference.
    2. Excess TA (TA>63 or excess path imbalance due to high TA).
    3. Other Reasons.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                   
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 



PROCESS for Optimization:
           Call drops are identified through SACCH messages. A Radio Link Failure Counter value
           is broadcast on the BCH. The counter value may vary from network to network. At the
           establishment of a dedicated channel, the counter is set to the broadcast value (which will
           be the maximum allowable for the connection). The mobile decrements the counter by 1
           for every FER (unrecoverable block of data) detected on the SACCH and increases the
           counter by 2 for every data block that is correctly received (up to the initial maximum
           value). If this counter reaches zero, a radio link failure is declared by the mobile and it
           returns back to the idle mode.
           If the counter reaches zero when the mobile is on a SDCCH then it is an SDCCH Drop.
           If it happens on a TCH, it is a TCH drop.
           Sometimes an attempted handover, which may in itself have been an attempt to prevent a
           drop, can result in a dropped call.
           When the quality drops, a mobile is usually commanded to perform a handover.
           Sometimes however, when it attempts to handover, it finds that the target cell is not
           suitable. When this happens it jumps back to the old cell and sends a Handover Failure
           message to the old cell. At this stage, if the handover was attempted at the survival
           threshold, the call may get dropped anyway. If on the other hand the thresholds were
           somewhat higher, the network can attempt another handover.
       1                                                              2

                    C hannel R equest                                                  C hannel R equest

                    Im m A s s i g n m e n t                                           Im m A s s i g n m e n t

                    S e rvic e R e q u e s t                                           S e rvic e R e q u e s t

                    S ig n a llin g                                       S D C C H S ig n a llin g
                                 :                                                               :
                    S ig n a llin g                                                 S peech
                                                                          TCH
                    R LT = 0 ; D R O P S                                            R LT = 0 ; D R O P S
                    SDCCH DROP !                                                    TCH DROP !


                3                                          S D C C H / TC H

                                                           H a n d o ve r C o m m a n d

                                               H and A ccess

                                                           H a n d o ve r F a ilu re
                               ALUMS‐OOMP‐L2‐014 ALU      UMS OPERATIO             MANUAL 
                                                                      ONAL PROCESS M          
                                      2           EFFECTIV
                            EDITION 1.2                                uary  2011 
                                                         VE DATE: 01Janu



 
 




      2000 extract Call Drop M
From M2                               nt          o
                             Measuremen counters to know cause.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                             
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
8.3.1 Fish bone diagram for the root cause analysis for high TCH Drop Rate


     E x te r n a l In te r fe r e n c e   L o w S ig n a l S tr e n g th D L   L o w S ig n a l S tr e n g th U L




                                                                                                                     T C H D ro p R a te




    H ig h T A /R F S p illa g e /P a th Im b a le n c e        B a d Q u a lity D L    B a d Q u a lity U L


Figure 1: Fish bone diagram for the root cause analysis for high TCH Drop Rate



                            C LS                    HCS           H ard w are Faults    D rop s due to O ther R eason




                                                                                                                       TC H D rop R ate




    A ssignm ent to another cell           H andover Failures        P ow er C ontrol    S udden L ost C on nection

Figure 2: Fish bone diagram for the root cause analysis for high TCH Drop Rate
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 



PROCESS for SCR:
Definition:           SCR = ((Total Call - INTERNAL_FAILURES)/TOTAL CALLS) x 100%...

Total Call = BSS Originate Call->2G ORG CALL ATTEMPT TIMES
    + Trunk Office Direction Incoming Office Traffic->SEIZURE TIMES

INTERNAL_FAILURES = Failure Reason Traffic-> CAUSE013_switch equipment congestion
+ CAUSE016_temporary failure
+ CAUSE027_switch equipment failure
+ CAUSE061_no CR resource
+ CAUSE062_no CCB resource
+ CAUSE166_network error
+ CAUSE169_temporary error
+ CAUSE170_device congestion
+ CAUSE201_IWF resource unavailable

PROCESS for Optimization:


    1. Identify the Failure reasons count for each internal failure reason.
    2. Check detailed explanation of cause values those contributing the major factor.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
PROCESS for Paging Success Rate:
Definition: Paging Success rate is the percentage of valid page responses received by the
system

PSR = ( CC service first paging response number + CC service repeat paging response number+
SMS service first paging response number + SMS service repeat paging response number) / (CC
service first send paging number + SMS service first send paging number)*100

PROCESS for Optimization:
    1. Removal of non existing Cell site database created in BSCs
    2. Correcting the number of LACs per BSC (Minimizing the number of LAC per BSC)
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                                        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
    3. Standard template of Cell site database in each BSC.
          1 Fish bone diagram for the root cause analysis of poor Paging Success Rate


                                      3 . In c o rre c t M S C P a ra m e te rs     1 . In c o rre c t C e ll P a ra m e te rs




                                                                                                                                 P o o r P a g in g S u c c R a te




              5 . P o o r P a g in g S tra te g y             4. Poor R F         2 . E x c e s s p a g in g D is c a rd s


            Figure 1 : Root Cause for Poor Paging Succ Rate (1)




              10. ABIS , A interface fluctuations, Errors            8. incorrect LAC Dimension         6. SDCCH Congestion




                                                                                                                                      Poor Paging Succ Rate




             11. decrease signalling load on CCCH               9. ABIS , A interface Congestion 7. Combined BCCH


            Figure 2 : Root Cause for Poor Paging Succ Rate (2)
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
         PROCESS for SS7 Signaling Load:
         Definition:

    1. TRANSMITT LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS
       TRANSMITTED + 6 *(MSU TRANSMITTED + MSU RETRANSMITTED) ) /
       (248000 * 3600 * 0.2) ) * 100) -----> HSL
    2. TRANSMITT LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING
       OCTETSTRANSMITTED + 6 *(MSU TRANSMITTED + MSU RETRANSMITTED) )
       / (8000 * 3600 * 0.4) ) * 100) -----> OTHER THAN HSL
    3. RECEIVE LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS RECEIVED
       + 6 *(MSU RECEIVED) ) / (248000 * 3600 * 0.2) ) * 100) -----> HSL
    4. RECEIVE LINK OCCUPANCY (%)= ((( NO. OF SIGNALLING OCTETS RECEIVED
       + 6 *(MSU RECEIVED) ) / (8000 * 3600 * 0.4) ) * 100) -----> OTHER THAN HSL


PROCESS for Optimization:
         1. Identify the signaling links whose utilization is going above 80%.
         2. Prepared Plan for additional signaling links as per requirement…
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
PROCESS for TBF Success Rate Optimization:


Definition:      Temporary Block Flow (TBF) is a physical connection used by the two Radio
Resource entities to support the unidirectional transfer of PDUs on packet data physical
channels. The TBF is allocated radio resource on one or more PDCHs and comprises a number
of RLC/MAC blocks carrying one or more LLC PDU. TBF Success Rate is when during a
data session, TBFs are successfully established on UL and DL.

PROCESS for Optimization:
    22. Identify the Bad performing Cells for TBF Success Rate.
    23. Identify the bifurcation of Poor TBF Success Rate: whether UL or DL is poor or it is poor
        in both directions.
    24. Take the detailed report showing (Ex. Total TBF Requests, Total TBF Success, Failure
        reasons)
    25. Identify the failure reasons after analyzing detailed report and follow the below
        mentioned process. Failure is mainly due to TBF Congestion or MS No response.
    26. TBF Congestion:

              a. Check The Static and Dynamic PDCH definition from BSC Configuration data)
              b. If you find Zero Static or Dynamic PDCH, define the same.
              c. If PDCH definition is sufficient as per the guidelines, then check whether the TBF
                 requests are high. If requests are high, then we need to define more PDCHs in the
                 cell. But before defining more PDCHs, check whether the Voice Utilization is not
                 high and there is no TCH Congestion in the cell..

    27. Check Hardware/TRX alarms; Resolve if find any.
    28. Audit for any parameters related discrepancies and define as per standard parameters set.
    29. MS No Response: RF and Environmental Factors:

              a. Low Coverage Areas (Try to reduce low coverage patches with physical
                 optimization; New sites)
              b. Interference/ Bad quality/ UL-DL Imbalance;
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
              c. Check the states for TRx on which PDCH is configured can be issue of TRx also;
                 Change TRx if you found random behavior of TRx.

After all rectification observe the subsequent days report if you still find the problem repeat the
same process with due care to Pin Point the actual cause.

PROCESS for Optimization of Average GPRS RLC throughput and
Average EDGE RLC Throughput:
Definition:           Throughput is the amount of data uploaded/downloaded per unit of time.

PROCESS for Optimization:
    1. Identify the Bad performing Cells for Poor GPRS/EDGE Throughput.
    2. Identify the bifurcation of Poor Throughput: whether UL or DL is poor or it is poor in
       both directions.
    3. Take the detailed report showing (Ex. Total TBF Requests, Coding Scheme Utilization)
    4. Identify the cells after analyzing detailed report and follow the below mentioned process.
    5. Take the configuration dump of the poor cells:

              a. Check The Static and Dynamic PDCH definition from BSC Configuration data)
              b. If you find Zero Static or Dynamic PDCH, define the same.
              c. If PDCH definition is sufficient as per the guidelines, then check whether the TBF
                 requests are high. If requests are high, then we need to define more PDCHs in the
                 cell. But before defining more PDCHs, check whether the Voice Utilization is not
                 high and there is no TCH Congestion in the cell.
              d. Check whether there are enough Idle TS defined at the site. If not, definition to be
                 done.

    6. Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive
       test to analyze the cell in more detail.

    7. Check Gb Congestion/Utilization at the BSC/PCU.
    8. Check Hardware/TRX alarms; Resolve if find any.
    9. Audit for any parameters related discrepancies and define as per standard parameters set.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL         
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
After all rectification observe the subsequent days report if you still find the problem repeat the
same process with due care to Pin Point the actual cause.




PROCESS for Optimization of Downlink Multislot Assignment
Success Rate:
Definition:       User timeslot request based on traffic types and MS multi-timeslot capability
and the actual timeslot allocated by the system which can also be termed as Downlink Multislot
Assignment Success rate.

PROCESS for Optimization:
    1. Identify the Bad performing Cells for Poor DL Multislot Assignment.
    2. Take the detailed report showing (Ex. Total TBF Requests, Failure in terms of TS
       requests)
    3. Identify the cells after analyzing detailed report and follow the below mentioned process.
    4. Take the configuration dump of the poor cells:

              a. Check The Static and Dynamic PDCH definition from BSC Configuration data)
              b. If you find Zero Static or Dynamic PDCH, define the same.
              c. If PDCH definition is sufficient as per the guidelines, then check whether the TBF
                 requests are high. If requests are high, then we need to define more PDCHs in the
                 cell. But before defining more PDCHs, check whether the Voice Utilization is not
                 high and there is no TCH Congestion in the cell.
              d. Check the multiplexing thresholds and upgrade/downgrade reports.

    5. Check whether it is due to poor radio conditions/interference; check C/I. Perform a drive
       test to analyze the cell in more detail.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL         
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
    6. Check Gb Congestion/PCU-DSP Utilization.
    7. Check Hardware/TRX alarms; Resolve if find any.
    8. Audit for any parameters related discrepancies and define as per standard parameters set.

After all rectification observe the subsequent days report if you still find the problem repeat the
same process with due care to Pin Point the actual cause.
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL          
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
 




                                 KPI Optimization Process 
                                     Appendix‐3 (contd..) 
         refers to page 15 of Network Performance Monitoring & Optimization Process 


                                                Alcatel & ZTE 
                                                                
                                                                
                                                                
 

 

 

                                       




The document covers the TCH Assignment Success rate & SDCCH Congestion optimization process for 
Alcatel  & ZTE GSM Radio Networks to be complaint by Alcatel‐Lucent Managed Solutions India Pvt. Ltd 
Radio Optimization Engineers & associated staff. 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
Contents 


1. PURPOSE………………………………………………………………………………………….4 


2. SCOPE………………………………………………………………………………………………4 


3. INTRODUCTION……………………………………………………………………………….4 


4. DEFINITION……………………………………………………………………………………..5 
4.1 TCH ASSIGNMENT SUCCESS RATE (TASR) 

4.2 SDCCH CONGESTION (SD CONG)  


5. VENDOR WISE COUNTER BASED DESCRIPTION 
5.1 TCH ASSIGNMENT SUCCESS RATE (TASR) 
5.1.1 ALCATEL TASR DESCRIPTION 

5.1.2 ZTE TASR DESCRIPTION 

5.2 SDCCH CONGESTION (SD CONG) 
5.2.1 ALCATEL SD CONG DESCRIPTION 

5.2.2 ZTE SD CONG DESCRIPTION 


6. VENDOR WISE ROOT CAUSE ANALYSIS & OPTIMIZATION STEPS 
6.1 TCH ASSIGNMENT SUCCESS RATE (TASR) 
6.1.1 ALCATEL TASR ANALYSIS 

6.1.2 ZTE TASR ANALYSIS 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
6.2 SDCCH CONGESTION (SD CONG) 
6.2.1 ALCATEL SD CONG ANALYSIS 

6.2.2  ZTE SD CONG ANALYSIS 


7. APPENDIX 
7.1 SDCCH DIMENSIONING 
7.1.1 ALCATEL SD DIMENSIONING METHOD 

7.1.2 ZTE SD DIMENSIONING METHOD 
 


8. Optimization Process for other Radio KPIs 
 

 

 

 

 

 

 

 

 

 

 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
 

 

 

         1. PURPOSE 
                 This document serves as a process guideline for key performance indicator (KPI) 
              optimization  such  as  TCH  Assignment  Success  Rate  (TASR)  and  SDCCH  (SD) 
              Congestion  in  advanced  wireless  GSM  2G  networks  in  multi‐vendor  scenario 
              comprising of Alcatel (B10 version) & ZTE (ZXG10‐2.97) Radio systems.  
          
         2. SCOPE 
                  This document is meant for experienced wireless 2G GSM professionals involved 
              in key performance indicator (KPI) optimization specifically TCH Assignment Success 
              Rate  (TASR)  and  SDCCH  (SD)  Congestion  in  multi‐vendor  scenario  comprising  of 
              Alcatel (B10 version) & ZTE (ZXG10‐2.97) Radio systems. 

                  Also,  the  document  targets  the  internal  customers  of  ALUMS  with  sufficient 
              background in GSM. 

         3. INTRODUCTION 
                   Dynamic  network  configuration  changes,  operation  &  maintenance  activities 
              with  exponentially  rising  curve  of  subscriber  density  for  wireless  services  prompts 
              the radio engineers to be quick & effective to retain the Quality of Services (QoS) in 
              current scenario.  
                   TCH  Assignment  Success  Rate  (TASR)  and  SDCCH  congestion  are  two  critical 
              pointers to quality of network accessibility during busy hours & non busy hours for 
              the subscribers.  
                   Ideally,  cells  in  the  network  needs  to  be  designed  for  0%  SDCCH  congestion  & 
              100% TASR to ensure 100 % error‐free subscriber services initiated from the MS to 
              the MSC. Practically, the real time radio environment (changing clutters), high level 
              of  faults/outages  in  network  elements  (MSC/BSC/TRAU/BTS)  and  higher  subscriber 
              services (Voice/Data) demands destabilizes the designed network capacity to result 
              in degradation of TASR & SDCCH congestion. 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL             
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                 In  order  to  achieve  sustainable  demand,  the  network  resources  are  re‐
              dimensioned periodically with coverage/capacity/KPI optimization as when required 
              basis and TASR / SD Congestion stands prime focus area as to be discussed. 
                  
                  
                  

 

         4. DEFINITION 
              4.1 TCH ASSIGNMENT SUCCESS RATE (TASR) 
                         In  general,  TASR  is  defined  as  percentage  ratio  of  successful  TCH 
                  Attempts  to  TCH  Attempts  over  an  observed  period  of  time.    It  measures  how 
                  often setup message sent from MS for Mobile Originating Call (MOC) or Mobile 
                  Terminating Call (MTC) is successful during TCH allocation procedure from MSC. 
                         General Equation:‐ 
                         TASR (%) = (TCH Attempt seizures/TCH Attempts) *100 
                         GSM Layer 3 Equation:‐ 
                         TASR (%) = (No. of Assignment Complete msg. /Assign Requests.)*100 

                                                Figure 1 Successful TCH Assignment phase 




                                                                                                              
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 


        TCH 

      ASSIGN‐
       MENT 

       PHASE 




                                                                                                        
                          Although, TASR indicates successful TCH seizures for MS connectivity with 
                   the network during call phase. Better way to approach TASR improvement is to 
                   focus on TCH Assignment failure rate which is equally important.  
                           
                          High TCH Assignment failures can be observed for under reasons: 
                              • Hardware faults in Network elements (BTS/BSC/MSC) 
                              • Software & Network configuration database discrepancy 
                              • Low Coverage zone 
                              • Path loss issue  
                              • High Interference from internal/external sources 
                              • Transmission issues in A‐bis/A‐ter links 
                              • CIC mismatches between BSC‐MSC 
                              • BTS wiring diagram issue 
                              • Incorrect Feature, Parameters & Timer usages 
                              • Mismatch in TRX radio timeslots mapping on RSL 
                              • Sector blocking due to clutter issues 
                              • TCH Congestion 
                              • High Traffic Utilization 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                                  •   Wrong antenna type deployments for required clutters 
                                  •   Invalid counter pegging 
                                  •   Incorrect counter selection for failure monitoring 

                           TASR  improvement  based  on  above  mentioned  causes  is  covered  in 
                   Vendor  wise  root  cause  analysis  &  Optimization  steps  section.    Many  internal 
                   system  reports  based  on  measurable  counters  are  required  to  co‐correlate  to 
                   arrive  at  certain  conclusion  for  improvement  action  and  are  covered  in  up‐
                   coming sections. Assignment failure cause points are shown in figure as under: 

                                                 Figure 2 TCH Assignment failure cause points 

                             MS                  BTS                      BSC                  TRAU                        MSC 

                                      Um                    A‐bis                A                       A‐ter 

                                                   

                                                                                       

                                                                                 Legend: 

                                                                                 Assignment failure cause point:‐   

              4.2  SDCCH CONGESTION (SD CONG) 
                          In general, SDCCH Congestion is defined as the percentage ratio of SDCCH 
                  Blocks  to  total  SDCCH  Attempts  over  an  observed  period  of  time.  It  measures 
                  how  often  Mobile  Station  (MS)  is  unable  to  access  the  network  for  various 
                  signaling (MM/CC) procedures to ensure subscriber service establishment. 
                          General Equation:‐ 
                          SD CONG (%) = (SD Blocks/SD Attempts) *100 
                          GSM Layer 3 Equation:‐ 
                          SD CONG (%) = (Immediate Assign. Rejects /Channel Required) *100 
                                                                                    In case of SDCCH 
                                                                                                        Congestion, 
                                                 Figure 3 SDCCH Assignment phase 
                                                                                                        IMMEDIATE 
                                                                                                        ASSIGNMENT 
                                                                                                        REJECT message 
                                                                                                        flows from BTS to 
                                                                                                        MS on AGCH 
                                   ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL             
                                EDITION 1.2           EFFECTIVE DATE: 01January  2011 



     
     




SDCCH 

ASSIGN‐
 MENT 

PHASE




                                                                                                          
               
                             Various  Mobility  Management  (MM)  sub‐layer  and  Connection 
                       Management  (CM)  sub‐layer  procedures  require  usage  of  SDCCH  channel 
                       between MS and MSC. Some of the commonly observed signaling procedures 
                       on SDCCH are as under: 
                                  • Normal Location Update (LU) 
                                  • Periodic Registration 
                                  • IMSI Attach/Detach 
                                  • Call Setup (MOC/MTC) 
                                  • SMS point to point (MO/MT) 
                                  • Fax Setup 
                                  • Supplementary services (USSD) 

                                 Most of the root causes for SD Cong % are listed under: 

                                      •   Improper SDCCH Dimensioning 
                                      •   Incorrect usage of available features,  parameters & timers 
                                      •   High TCH Utilization  
                                      •   Non optimized LAC Borders (Inter cell/Inter BSC/Inter MSC) 
                                      •   Configured but out of service SDCCHs 
                                      •   Phantom RACHs (Co BCCH/BSIC ) 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                      
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                                  •   Overshooting cells inside the clutter 
                                  •   Equipment failure (Cell/TRE/BSC) 
                                  •   Increased  mean  hold  time  of  SDCCH  due  to  large  no.  of  Layer  3 
                                      message flows between MS‐MSC 
                                  •   LAPD congestion in A‐bis interface 
                                       

                             SDCCH Congestion cause points are shown in figure as under: 

                                                 Figure 4 SDCCH Congestion cause points 

                             MS                  BTS                      BSC                  TRAU                        MSC 

                                      Um                    A‐bis                A                       A‐ter 

                                                   

                                                                                       

                                                                                             

                                                                                 Legend: 

                                                                                 SDCCH Congestion cause point:‐   

                           SDCCH Congestion cause points are the locations where probable event 
                   failures are observed due to various reasons mentioned above.  

                          SDCCH  Congestion  improvement  based  on  above  mentioned  causes  is 
                   covered in Vendor wise root cause analysis & Optimization steps section.  Many 
                   internal  system  reports  based  on  measurable  counters  are  required  to  co‐
                   correlate to arrive at certain conclusion for improvement action and are covered 
                   in up‐coming sections. 

 

         5. VENDOR WISE COUNTER BASED DESCRIPTION 
              5.1 TCH ASSIGNMENT SUCCESS RATE (TASR) 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                    
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                   5.1.1 ALCATEL TASR DESCRIPTION 

                         Alcatel BSS system (B10) evaluates the TASR based on certain measurable 
                   counters from NPO with below relation: 

                             TASR (%) = MC718 / [MC140a‐(MC142e+MC142f)*100. 

                             Also, MC142e=C142a+C142c & MC142f=C142b+C142d. 

                          Counters increment or decrement based on various factors governing the 
                   network operator settings and real time operational status. It is important to be 
                   aware  of  TASR  %  value  on  cell  basis  to  visualize  the  impact  &  validity  of  these 
                   counters.  

                               

                   5.1.2 ZTE TASR DESCRIPTION 

                         ZTE  BSS  system  (ZXG10‐V2.97)  evaluates  the  TASR  based  on  certain 
                   measurable counters from OMCR with below relation: 

                         TASR  %  =  {(C11609‐C11696)  ‐  (C11610+C11654+C11658‐C11697‐
                   C116101‐C116133)} * 100 / (C11609‐C11696) 

                            Counter  description  &  details  can  be  found  in  Appendix  section  or  on 
                   click to respective counter in quicker way. 

                              

              5.2 SDCCH CONGESTION (SD CONG) 

                   5.2.1 ALCATEL SD CONG DESCRIPTION 

                         Alcatel  BSS  system  (B10)  evaluates  the  SD  CONG  based  on  certain 
                   measurable counters from NPO with below relation: 

                             SD CONG (%) = [MC04] / [MC04 + MC148]*100 

                            Counter  description  &  details  can  be  found  in  Appendix  section  or  on 
                   click to respective counter in quicker way.  
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL            
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                   5.2.2  ZTE SD CONG DESCRIPTION 

                         ZTE BSS system (ZXG10‐V2.97) evaluates the SD CONG based on certain 
                   measurable counters from OMCR with below relation: 

                             SD CONG % = (C11625 ‐ C11626 + C11697) *100 / (C11625 + C11696) 

                              

                              

         6. VENDOR WISE ROOT CAUSE ANALYSIS & OPTIMIZATION STEPS 
             
              6.1 TCH ASSIGNMENT SUCCESS RATE (TASR) 

                   6.1.1 ALCATEL TASR ANALYSIS 

                        Alcatel (BSS 10 release) TASR analysis requires monitoring of the KPI from 
         BBH report circulated from local\central MIS team on daily basis at cell level. 

                          It  involves  clear  understanding  of  associated  counter  based  internal 
                   system reports from NPO/OMC server as under which reflect the root causes for 
                   poor  TASR  %  values  and  needs  study  of  these  reports  in  following  sequence 
                   based on degradation severity: 

                                  •   Active alarms report  
                                  •   Path balance report 
                                  •   RTCH Assignment report 
                                  •   Quality/Level report 
                                  •   Timing Advance (TA) report 
                                  •   Network parameter checks 

                             Refer Appendix Sample Reports section for screenshot. 

                             Flow‐diagram for TASR improvement report checks: 
                                                          TASR CYCLE
                              
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                         
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                                                                            Active Alarms

                                       
                                                                             Path Balance
                                       

                                                                             RTCH Assign

                                       
                                                                            Quality/Level
                                       

                                                                           Timing advance

                                       
                                                                           N/w parameter 
                                       

                                 Below  Flowchart  1  represents  the  TASR%  improvement  cycle  based  on 
                         trigger condition and root causes: 

                                       
                                                                                    START 

                                                                                                         

                                                                                                         
                                                                        Identify & filter TASR 
                                                                        % from BBH report 
                                       
                                                                        for analysis 
                                       

                                                                                                            
                                                                                TASR %                         No further 
                                                                  Yes                                   No 
                                 Check & clear 
                                                                                <98.75%                        investigation reqd. 
                               active alarms 
                                                                                                
    Check for TRE 
    Path bal.  >5 dB 
                                                                                            
                                                                  BSS problem, check Abis 
    without TMA                                                   media stability with any 
                                       
                                                                  CIC mismatch at Ater 
                                                                  front (GTCNAAFLCPMR) 
    Verify the                         
    Tx/Rx path & 
    rectify it 
                                 ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                    
                              EDITION 1.2           EFFECTIVE DATE: 01January  2011 



   
   
                                                                  MSC/BSC/Cell 
                                                                  Parameters, Timers & 
                                                                              
                                                                  Features audit for fine 
      Check failure                                               tuning purpose  
                                        
      phase in RTCH 
      Assign report                     
                                                                         Check BBH report 
                                                                         for TASR % value 
                                                                         after problem 
                                       No 
     GTCNAFLRR                                                           correction 
      >GTCNAFLBR 
        
                                                                                                   Revisit the 
                 Yes                                                            TASR %             improvement 
                                                                                >=98.75            cycle to START 
Radio problem, check 
                                        
Quality/Level/TA RMS 
                                                                                            Yes 
reports with any TCH 
congestion (GTCNACGR)                                                              STOP

   

                                        

                                        

                                                                            Active Alarms

                                        
                                                                            Path Balance
                                        

                                                                                    IOI

                                        
                                                                            BER (U/L‐D/L)
                                        

                                                                          Timing advance

                                        
                                                                          N/w parameter 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                            
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                                          

                                          

                                          

                                  Below  Flowchart  2  represents  the  TASR%  improvement  cycle  based  on 
                          trigger condition and root causes: 

 
                                                                                       START 

                                                                                                            

                                                                                                            
                                                                           Identify & filter TASR 
                                                                           % from BBH report 
                                          
                                                                           for analysis 
                                          

                                                                                                               
                                                                                TASR %                            No further 
                                                                  Yes                                   No 
                                 Check & clear 
                                                                                   <98.75%                        investigation reqd. 
                                 active alarms 
                                                                                                   
    Check RTFs 
    Path loss <105 
                                                                                               
                                                                     BSS problem, check Abis 
    & >115 no TMA                                                    media stability with any 
                                          
                                                                     CIC mismatch at Ater 
                                                                     front (GTCNAAFLCPMR) 
    Verify the                            
    Tx/Rx path & 
    rectify it 
                                                                     MSC/BSC/Cell 
                                                                     Parameters, Timers & 
                                                                                 
                                                                     Features audit for fine 
                                                                     tuning purpose  
                                          
    Check IOI 
                                         No 
    report for                                                              Check BBH report 
    Uplink Intrf.                                                           for TASR % value 
                                                                            after problem 
                                                                            correction 
                                 ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                             
                              EDITION 1.2           EFFECTIVE DATE: 01January  2011 



   
   
                  Yes 
                                                                                            Revisit the 
                                                                         TASR %             improvement 
                                                                         >=98.75            cycle to START 
                                 
Radio problem, check 
Quality/Level/TA RMS                                                                 Yes 
reports with any TCH 
congestion (GTCNACGR)                                                       STOP

   

               6.1.2  ZTE TASR ANALYSIS 

                                ZTE (ZXG10‐V2.97) TASR analysis requires monitoring of the KPI from BBH 
                         report circulated from local\central MIS team on daily basis at cell level. 

                                It  involves  clear  understanding  of  associated  counter  based  internal 
                         system reports from OMCR as under which reflect the root causes for poor TASR 
                         %  values  and  needs  study  of  these  reports  in  following  sequence  based  on 
                         degradation severity: 

                                      •     Active alarms report  
                                      •     Path Balance report   
                                      •     Basic Measurement report 
                                      •     Timing Advance (TA) report 
                                      •     Network parameter checks 

                                Refer Appendix Sample Reports section for screenshot. 

                                Flow‐diagram for TASR improvement report checks: 
                                                                      TASR CYCLE
                                 

                                                                     Active Alarms

                                 
                                                                     Path Balance
                                 

                                                                             IOI
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                         
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                                       

                                       
                                                                            BER (U/L‐D/L)
                                       

                                                                           Timing advance

                                       
                                                                           N/w parameter 
                                       

                                       

                                       

                                       

                                 Below  Flowchart  3  represents  the  TASR%  improvement  cycle  based  on 
                         trigger condition and root causes: 

 
                                                                                    START 

                                                                                                         

                                                                                                         
                                                                        Identify & filter TASR 
                                                                        % from BBH report 
                                       
                                                                        for analysis 
                                       

                                                                                                            
                                                                                TASR %                         No further 
                                                                  Yes                                   No 
                                 Check & clear 
                                                                                <98.75%                        investigation reqd. 
                               active alarms 
                                                                                                
    Check for TRE 
    Path bal.  >5 dB 
                                                                                            
                                                                  BSS problem, check Abis 
    without TMA                                                   media stability with any 
                                       
                                                                  CIC mismatch at Ater 
                                                                  front (GTCNAAFLCPMR) 
    Verify the                         
    Tx/Rx path & 
    rectify it 
                                 ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                    
                              EDITION 1.2           EFFECTIVE DATE: 01January  2011 



   
   
                                                                  MSC/BSC/Cell 
                                                                  Parameters, Timers & 
                                                                              
                                                                  Features audit for fine 
      Check failure                                               tuning purpose  
                                        
      phase in RTCH 
      Assign report                     
                                                                         Check BBH report 
                                                                         for TASR % value 
                                                                         after problem 
                                       No 
     GTCNAFLRR                                                           correction 
      >GTCNAFLBR 
        
                                                                                                   Revisit the 
                 Yes                                                            TASR %             improvement 
                                                                                >=98.75            cycle to START 
Radio problem, check 
                                        
Quality/Level/TA RMS 
                                                                                            Yes 
reports with any TCH 
congestion (GTCNACGR)                                                              STOP

                                        

               

               

               

               

              6.2 SDCCH CONGESTION (SD CONG) 

                           6.2.1 ALCATEL SD CONG ANALYSIS 

                           Alcatel (BSS 10 release) SD CONG analysis requires monitoring of the KPI 
              from BBH report circulated from local\central MIS team on daily basis at cell level. 

  It  is  highly  critical  to  understand  the  radio  network  configuration  &  spatial  location  of  cells 
  based on which certain implications can be made for high SD Cong %.  
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                           It  is  advised  not  to  confuse  with  OMCR  Counters  &  NPO  Indicators  in 
                   Alcatel (BSS 10 release). NPO Indicators can be direct OMCR Counters or Indirect 
                   Counters based on computation. 

                           Below  Flowchart  4  represents  the  SD  CONG%  improvement  cycle  based 
                   on trigger condition and root causes: 

                                                                           START

                                 

                                                                   Identify & filter SD 
                                                                   CONG   % from BBH 
                                                                   report for analysis 

                                 

                                                                                                                    

                                                 No                                                   Yes   
                Check HW availability                                                                                       
                                                                   SD CONG 
                           
                                                                   %! = 0.00
                                 

                                 

                                 

                                 

                                 

                                 

                                 

                                 

                                 

                                 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                              

                              

                              

                              
                                                                 STOP
                              


7. APPENDIX 
             7.1 SDCCH DIMENSIONING 

                         SDCCH  Dimensioning  is  the  need  for  signaling  resource  optimization 
         based  on  carried  SDCCH  &  TCH  traffic  in  a  cell.    Different  vendors  provide  various 
         solutions  for  dimensioning  based  on  network  settings  &  traffic  requirements.    Two 
         methods available for SD dimensioning are: 

                        •    Automatic ( Load based increase/decrease of SDCCH/8) 
                        •    Manual ( Traffic Estimations and  Cell Statistics) 

                       Automatic SD dimensioning is dependent on feature availability in the system 
              although most of systems have dynamic SDCCH configuration feature to control SD 
              traffic  in  peak  hours.  Dynamic  SDCCH  feature  activation  is  network  operator 
              dependent  &  is  highly  recommended  when  flow  monitoring  of  LAPD  layer  2 
              messages is available. 

                        Manual SDCCH dimensioning is based on two following methods 

                             •    Traffic Estimations:‐ 
                                     Various  Layer‐3  events  (LU/IMSI  ATTACH‐DETACH/Call  set‐
                                     up/SMS/FAX  etc  require  average  mean  holding  time  (seconds) 
                                     based on which SDCCH traffic estimation is done. This method is 
                                     largely  ignored  in  real  networks  due  to  varying  probability  of 
                                     mean holding times of Layer 3 (MM/CM) messages and SD traffic 
                                     estimation. 
                                      
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                                                        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                             •    Cell Statistics:‐ 
                                       Cell  Statistics  based  SD  dimensioning  is  highly  recommended  in 
                                      current  real  time  dynamic  networks  due  to  high  demand  for 
                                      SDCCH resources and forms valid part of discussion in the manual. 
                                       
                                      Cell statistic based approach considers maximum SDCCH channel 
                                      occupancy in 24 hours or peak SD traffic for SD dimensioning as a 
                                      critical  input  besides  configured  total  SDCCH  channels  including 
                                      (SDCCH/4,  SDCCH/8)  with  or  without  CBCH.  SD  carried  traffic  or 
                                      busy  channels  must  be  average  of  minimum  3  weeks  to  capture 
                                      cell behavior on long term basis for effective dimensioning. 
                                       
                                       

                           As  a  Thumb  rule,  Designed  SDCCH  Grade  of  Service  (G.O.S)  can  be 
                   calculated as under: 

                                                       SDCCH G.O.S (%) = ¼* TCH G.O.S (%) 

                                        GSM  wireless  networks  consider  TCH  capacity  dimensioning  at  2 
                                        % G.O.S, hence SD capacity is dimensioned at 0.5% G.O.S. 

                                        Common  flowchart  5  for  SD  dimensioning  based  on  cell  statistic 
                                        approach  is  as  under  and  same  is  applicable  in 
                                        Alcatel/Motorola/ZTE vendors as well. 

                                                                                  START

                              

                                              

                                                
              Check for Counter 
                                                                                   SD 
                                                Yes                                                                     No                                                        
              with max SD traffic 
                                                                           Dimensioning 
              or busy channels  
                                                                              reqd.

                                                                                                                                                  


                   Max SD                                                   Max SD busy 
                   traffic                                                  sub‐channels 
                  available                                                   available
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL                                                                   
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                                                                                                                                               

                                                              No                                                                        No 

                                           

                                    

                                  Yes                                                                      Yes 
                  Compute channels                                                Check for configured 
                                                                           
                  frm carried SD traffic                                          & required SDCCH 
                  using 0.5 % G.O.S 
                                                                                  sub‐channel with 
                  from Erlang B table                                             40% excess addition 
                                                                                                                   

                                                  
                                                  
                                                  
                                                                                                  STOP
Note: 8 SDCCH sub‐channels correspond to one hard coded SDCCH/8 

                                          7.1.1 ALCATEL SD DIMENSIONING METHOD 

                                                  Alcatel  (B10  release)  SD  Dimensioning  is  done  using  NPO 
                                          indicator GSDTRE which gives SD Erlang hourly basis for a day. Minimum 
                                          3  weeks  data  average  with  maximum  SD  Erlang  observed  in  daily  busy 
                                          hour must be taken into account before further analysis. 

                                                         Refer steps as mentioned in Flowchart 5 for SD dimensioning. 

                                                          

                                          7.1.2 ZTE SD DIMENSIONING METHOD 

                                                  ZTE  (ZXG10‐V2.97)  SD  Dimensioning  is  done  using  Basic 
                                          Measurement  report.xls  available  in  OMCR  with  counter  C11627 
                                          (Maximum Number of Busy SDCCH). Minimum 3 weeks data average (If 
                                          available)  with  maximum  SD  busy  channels  in  24  hours  must  be  taken 
                                          into account before further analysis. 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL            
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
                                      Refer steps as mentioned in Flowchart 5 for SD dimensioning. 

                                       
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
 


8. Optimization Process for other Radio KPIs 
 
 
SDCCH Drop Rate 
 
Definition: SDCCH Call Drop Rate indicates the probability of call drops that occur when MSs 
occupy SDCCHs. This KPI reflects the seizure condition of signaling channels. If the value of this 
KPI is high, user experience is adversely affected. 
 
SDCCH Call Drop Rate = Call Drops on SDCCH/ Successful SDCCH seizures 
 
Causes: 

    30. Due to Blind spot, low coverage level, or cross coverage. 
    31. High VSWR due to feeders leads to the reduction in the transmit power and in the 
        receiver sensitivity.  
    32. Poor transmission quality and unstable transmission links over the Abis interface 
    33. Unavoidable inter‐network interference, interference from repeaters, or high and 
        unavoidable intra‐network interference caused by aggressive frequency reuse 
        Interference 
    34. unavailable terrestrial resources or faulty devices 
 
 
Action: 
    1. Reduce Coverage hole, Blind spots by physically optimization. 
    2. By maintaining balance between Uplink Downlink path by achieving less VSWR value, 
       proper tuning of RxLevAccessMin and RachLevAccessMin Parameter. 
    3. Stable Transmission – Minimum LapD failures 
    4. Proper Frequency plan to reduce Inference level by retuning frequency, Maio, HSN, 
       reducing Overshooting. 
    5. Reshuffling of SDCCH Timeslot as per TRX efficiency. Rectification of Faulty TRX’s. 
    6. Timer T200 can be optimized as per transmission efficiency.  
        
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
          
          
          
Handover Success Rate 
         
Definition: The purpose of handover is to ensure the call continuity, improve the speech 
quality, and reduce the cross interference in the network, thus providing better services for the 
subscribers. Success ratio of handover is the ratio of the total number of successful handovers 
to the total number of handover requests. 
 
Success Rate of Handover = Successful Handovers/Handover Requests 
 
HSR is impacted due to 
    1. Blind spot, low coverage level, or cross coverage. 
    2. Unavoidable interference can be the inter‐network interference, interference from 
        repeaters, or intra‐network interference resulting from aggressive frequency reuse.  
    3. Poor transmission quality and unstable transmission links over the Abis interface 
    4. Faulty devices, or asynchronous clocks 
    5. Imbalanced distribution of traffic volume in the network. If the network is congested 
        badly, the handover failures increase because of no available TCHs and the handover 
        success rate decreases. The network congestion does not affect the success rate of radio 
        handover. 
Action 
    1. Proper neighbor definition (1st tier mandatory and 2nd tier definition as per requirement) 
    2. Maintaining proper footprint by physical optimization. 
    3. Reducing Interference level by smooth frequency plan  
    4. Stable error free transmission links 
    5. Avoiding Ping‐pong HO by defining proper HO margin parameter which may be due 
        Level or Quality. 
    6. Providing appropriate time frame for clear msg or Establish msg between BTS’s by T8 
        timer 
    7. For intra Bsc HO, time to receives HO complete msg from BSC should be optimized by 
        T3103 timer 
    8. Maximizing the HO cause due to Power budget. 
    9. Maintaining proper traffic distribution by physically, DR, queuing parameters to avoid 
        HO failure due to neighbor cells congestion 
    10. Clock drift should be avoided. 
 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL        
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
 
 
TCH Call Drop Rate 
 
Call Drop Ratio on TCH indicates the ratio of the number of call drops to the number of 
successful TCH seizures after the BSC successfully assigns TCHs to MSs. 
 
TCH Call drops due to 
    1. Blind spot, low coverage level, or cross coverage. 
    2. Unavoidable interference can be the inter‐network interference, interference from 
        repeaters, or intra‐network interference resulting from aggressive frequency reuse.  
    3. Poor transmission quality and unstable transmission links over the Abis interface 
    4. Faulty devices and high VSWR 
    5. If the target cell involved in the Directed Retry procedure is under another BSC 
    6. During intra Bsc handover 
    7. If preemption is used in MSC  then lower priority MS will face call drop. 
 
Action 
    1. Clean frequency plan viz. achieve minimum interference level by clean BCCH (CO/ADJ), 
        MAL, MAIO, MS Plan. 
    2. Minimizing coverage holes by physical optimization (Orientation, Height, E.Tilt, M.Tilt). 
    3. Setting Radio link timeout parameter as per inter‐site distance viz. for rural sites RLT can 
        be of higher value. 
    4. Similar for Rural site where uplink quality is poor, Rxlev Access min, Rach Access min 
        parameter can be set appropriately. Proper balance should be maintained for this 
        parameter else path imbalance will result and TCH drop will increase. TMA/TMB can be 
        planned appropriately. 
    5. Minimize Ater Abis fluctuation – Link stability plays very vital role. 
    6.  Ater Congestion further results in TCH call drops. Sufficient Ater argument should be 
        maintained. 
    7. Power control used for HO should be properly designed to avoid drop where ever there 
        is sudden RxLev drop. 
    8. During HO to neighbor cells should be having free TCH resources else call drop may 
        increase. For this proper half rate thresholds should be defined as per traffic pattern, 
        decongestion of these cells by capacity argument. 
    9. Queuing length should not made too long/short. 
    10. Drop due to intra Bsc HO, congestion free Ater argument should be maintained 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL          
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
    11. Timer T305 and T308 interval should be well enough to receive the Disconnect and 
        Release message from Msc and Bsc respectively. 
    12. Proper Neighbor definition should be maintained – some handovers cannot be 
        performed and thus call drops. 
    13. By maximizing Power control HO’s reduces the interferences level, which further 
        reduces TCH drop rate. 
    14. By DTX feature further Interference levels are reduced, reducing TCH drop. 
     
     
RACH Success rate 
     
    Def : Random Access Channel (RACH) is used by the MS on the “uplink” to request for
    allocation of an SDCCH. This request from the MS on the uplink could either be as a page
    response (MS being paged by the BSS in response to an incoming call) or due to user trying
    to access the network to establish a call. 
     
     
RACH Failure can be due to :‐ 
    1.  AGCH Overload at Base Station 
    2.  RACH Collisions 
    3.  MS out of Range 
    4.  Poor Uplink quality 
    5.  BTS Receiver Problem 
     
Action 
    1. Appropriate no. of CCCH blocks should be designed as per Traffic pattern. Signaling link 
         should be increased from 16k to 32k as per requirement to avoid overloading. 
    2. Minimum Coverage hole is first requirement for greater RACH success rate. 
    3. Use of DTX mode in Uplink reduces the interference level making less probability for 
         RACH collision 
    4. Hardware alarm like difference in uplink and downlink path balance heavily impacts 
         RACH success rate. H/W alarm should be minimized 
    5. Max. No Of Retransmission parameter allows the MS to retransmit again for AGCH by 
         not incrementing the RACH access failure counter. 
    6. RACH Access min and RACH Busy Threshold parameter can be tuned to restrict the MS 
         in out of range. If this parameter is set to a higher value, the actual coverage area of the 
         network becomes small; if this parameter is set to a lower value; all drops are likely to 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
       occur because of invalid access or too weak access signals, thus decreasing the success 
       rate. 
    7. Fluctuation in transmission media further decreases the success rate. Stable media need 
       to be maintained. 
    8. Uplink quality can be further boosted by TMA/TMB. 
        
       Rx Quality 
 
Samples carried within 0 to 4 Level by sum of samples carried within 0 to 7 Levels, is termed as 
Rx Quality for the TRX/cell. 
 
Poor Speech Quality could be bad due to  
    1. Coverage holes 
    2. No Target cell for Handover 
    3. Interference ‐ 
            • Co‐channel 
            • Adjacent channel 
            • External 
            • Multipath 
            • Noise 
    4. E1 fluctuation – poor FER 
    5. Path balance, VSWR , Hardware issue at BTS 
    6. Poor power budget thresholds 
    7. Half rate penetration  
    8. Repeater used – broadband/narrow/manual 
         
Action 
 
    1. Both Uplink and Downlink good quality, proper uniform coverage patterns are 
        prerequisite. 
    2.  Clean frequency plan viz. achieve minimum interference level by clean BCCH (CO/ADJ), 
        MAL, MAIO, MS Plan 
    3. Overshooting should be avoided by E/M tilt, height reduction and reorientation e.g. cells 
        from high altitude (mountain) are tending to overshoot even with maximum tilt and 
        height. Sector facing towards water (sea, pond) causes reflection and further 
        interference in the surrounding. Proper orientation or isolated frequency plan need to 
        be considered for these sites. 
                               ALUMS‐OMP‐L2‐014 ALUMS OPERATIONAL PROCESS MANUAL      
                            EDITION 1.2           EFFECTIVE DATE: 01January  2011 



 
 
    4. Missing neighbor’s further causes HO due to interference. Proper 1st tier neighbor 
        should be defined 
    5. Poor FER further degrades the quality, by making MS to go to lowest codec supported. 
        Error free E1 link should be maintained. 
    6. Difference in uplink and downlink path causes further quality in uplink and downlink 
        respectively. Call served by faulty/alarmed timeslot/TRX causes quality degradation. 
        Minimum Hardware alarms should be maintained. 
    7. Aggressive Half rate utilization makes MS to use lowest EFR or AMR codec maximum 
        times making subscriber to put their efforts to understand about the clearly of 
        conversation.  
    8. Repeater’s frequencies are not updated automatic whenever an RF engg. changes 
        frequency plan of serving macro site since maximum repeaters are manually tuned 
        repeaters.  
    9. Quality is found poorer at places where external interferences are present viz. close by 
        CDMA sites, restricted zones due to jammers/frequencies used by them. Notch filters 
        can be proposed to reduce CDMA frequency effects. 
    10. TMA/TMB can be used at Highway sites to achieve good uplink path. 
    11. MS should access network with proper uplink and downlink lev which are set by 
        Rxlevaccess min and Rach accesmin parameter. 
 

				
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