S.No Problem

1 SD Drop 1

2

345

2 TC Drop 1

2345

3 SD Blocking 12

34567

84 TC Blocking 1

2345

65 Poor HOSR 1

2

34

6 Poor TSSR 1

23

456

7 BAD DLQ 1

23

45

Timers T3212T100

T31018 Poor RSR 1

23

Ques Factors Affecting CSSR: Diff bw: Antenna with 0 Tilt & other with Inbuilt 6 and uptilted 6 degree

Reasons for Poor HOSRAntenna Vertical Beamwidth: DirectivityClutter Loss for a Commercial BuildingDiff Feeder Loss: 7/8" Cable is 4.5 db per 100 MetreConcentric Cells- C2 Cell reselection with Penalty time; Umbrella Handovers: More level MarginNo calls Established despite good coverage: Accmin: RXP or DMAX:MAXTA:TALIMIT

Formula for Tower Height Calculation

TIMERS1 T32122 T1003 T31014 T7 Frequency of the HANDOVER_REQUIRED message

Possible Reason

Interference

Co-BCCHHardware Problem

Bad Coverage: Bad Signal StrengthVSWRSwap: Sector or CableWrong PER: Should be 4 HoursLess SDCCH TS in Sector

Traffic : SMS or Calls: Wrong no of SDCCHAlarms on SDCCH or TRXHardware ProblemDynamic SDCCH Not working

Hardware ProblemLesser Trx'sWrong Half rate settingsLocked TS or Trx'sOutage of nearby site: high traffic due to that

Co-BCCH BSIC in neghboursCo-BCCH Overlapping coverage in neighbours

Wrong Definitions: More NeighboursLarge LAC with high Traffic

Switch Problem

Wrong MFR Parameter(Default is 4)Paging Timer in MSC 4.5 SecondOvershooting

Bad Coverage: Bad Signal Strength: Overshooting

Wrong DRT Value for Neighbours like -100 etc should be -85

Hardware Problem: Loose or Faulty Cables, Faulty Connections

Interference: on BCCH or hopping, Wrong HSN, MAIO, MS etc

Wrong LAC Boundary or Overlapping Coverage at LAC Boundary

Blocking due to More than 18 Logical Channels in one Trx (with TCHD and SDCCH)

Non-BCCH Trx Lock for a time period when Site on Battery

Congestion on Target cells: BLT is 70 normally: should be changed to 90 when poor HOSR due to congestion

PGCH: AGCH ratio wrong, Ideally 6:3 or 7:2 if needed and if does not impacts CSSR

Coverage holes area; User gets out of coverage many a times so paging failures till user does not gets Detached i.e. 4 Hours( PER time)Solution Decrease PER Timer to 2 or 1 Hours & Monitor

InterferenceHO Problems: due to congestion etc

Wrong MAIO;HSN;MS

Periodic Location updateRLT 20 20*480ms

InterferenceTimerParameters ( RET)

Diff bw: Antenna with 0 Tilt & other with Inbuilt 6 and uptilted 6 degree

Diff Feeder Loss: 7/8" Cable is 4.5 db per 100 MetreConcentric Cells- C2 Cell reselection with Penalty time; Umbrella Handovers: More level MarginNo calls Established despite good coverage: Accmin: RXP or DMAX:MAXTA:TALIMIT

PER 4 hoursRLT 24 20*480=10 SecondsImmediate Assignment Def:

T7 Frequency of the HANDOVER_REQUIRED message

MinIntBetweenUnsuccHoAttempt

Frequent HO: Ping Pong: Coverage; Wrong Handover Margins

4 Hours10Seconds

AGCH, PGCH, SD, Block, SD Drop, Quality, Signal Strength

3Seconds

Decrease by 1 when SAACH is not receivedo        Timer start condition: The timer T3101 starts when the BSC sends an IMMEDIATE_ASSIGNMENT_CMD message to the BTS.

o        Timer stop condition: The timer T3101 stops when an ESTABLISH_IND message is received from the MS.

Resolution:

1 Remove Interference

2 Improve Coverage

3 DRT -854 Remove Co- BCCH5 Remove hardware Problem

1 Remove hardware Problem

2 Check Interference and parameters3 Improve Coverage4 Check VSWR5 Hardware Check1 Dynamic SDCCH2 Right LAC Boundary

3 HYS Value change to 8 db from 6 db but see it does not increases drops4567

1 Proper Half Rate Settings2 TRHO should be enabled with a neighbour level of -853 DRT Should be Enabled

3

LMRG

Check HRI(Tch in handover) Parameter Value

6 0

PMRG QMRG

Increment by 2 when SAACH is received