RF KPIs Description

7/30/2019 RF KPIs Description

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RF KPI’s OPTIMIZATION PROCESS

KPI’s monitoring

Alarms check





KPI’s to be monitor

SD Blocking

SD Drop

TCH Blocking

TCH Assignment

TCH DropHOSR





Reasons for SD Blocking

High Utilization of SD.

Signaling load at LAC boundary.

Time slot faulty.

Site location ( Airport, etc).





Solutions for removal of SD Blocking

Check the No. of SDCCH channel Available, if less thenincrease SD channel taking care that there is no TCH Blocking.

Check LAC boundary, If location update is more then changethe LAC of that site.

Use of Dynamic SDCCH (It is a BSC parameter and will beapplied on whole BTS).

Hardware check / shift SD to new time slot





Reasons of SD Drop

Wrong Parameter Planning.

Hardware Fault.

External Interference.Overshooting

High TCH utilization





Check for Wrong Parameter Planning.

Check the BCCH Plan (C/I or C/A).

Co-BSIC & Co BCCH.

LAC Planning.

If a cell is picking call from long distance, Check the sample logaccording to TA .

Cell orientation need to be define according to clutter.

Check the Timer T 3101, It should be 3.5 sec.

Check the Timer T 200, It should be 780 ms.





Cure for SD Drops due to Low Signal Strength

If the drop call is due to low signal strength uplink, check the

receive path of this particular TRX. Check receiver sensitivity,VSWR, feeder connection and etc. Drops due to Low SignalStrength

If the drop call reason is due to low signal strength downlink,then, check the transmit path.

It is also possible to have a high percentage of drops onSDCCH but a low percentage of drops on TCH this couldhappen, for example, if the SDCCH were put on the BCCHfrequency, and the frequency plan were different for the BCCH

than for non-BCCH frequencies It is possible that theinterference situation is worse on the BCCH, thereby causingrelatively high percentage of drops on SDCCH compared toTCH, To reduce this Shifting of SDCCH can also be done.





SD Drop due to excessive TA

Cell Overshooting

For Example----

• A% of Cell picking call from Distance Y------And MeetingKPI’s. (% of A should be >95)

• (100-A%) of Cell picking call beyond Distance Y----NotMeeting KPI’s

Therefore Distance Y will confirms the Criteria of Distance of Overshoot of a cell.

This can be considered for coverage confinement .





Hardware Fault

Check Path Imbalance.

VSWR of the Cell.

Connector Connection.

TRX condition

Mount position and Effective Tilt.





External Interference

May be due to CDMA or External/Unwanted resource.

Use BPF (Band pass filter).





TCH Blocking

Implement half rate or Dual rate.

If Dual rate implemented already then change the value of FRLand FRU.

Add another TRX.

If TRX addition not possible, try to share the traffic of that cellwith the neighboring cell by changing tilt or orientation.





TCH Assignment

For improving assignment, remove TCH Blocking.

Check TRX condition.

Path Imbalance.

VSWR.

Connection from CDU and TRX.Connector connection.





TCH attempt=TCH Block+TCH Allocated.

TCH Allocated=TCH miss (may be block or SD Drop) +TCH Assigned.

It is not necessary that total TCH allocated will be assigned.

See…





Reasons for TCH Drop


Hardware Fault.

External Interference.






Check the BCCH Plan (C/I or C/A).

Co-BSIC & Co BCCH.

Check Co-BCCH.

If a cell is picking call from long distance, Check the sample logaccording to TA.

Check the Timer T 100(RLT). It should be 20.

Check the Neighbor Plan.

Site Orientation and Tilt.





TCH Drop Reason, Low SS DL (%)

If the drop call reason is due to low signal strength downlink,

then, check the transmit path.

Check the proper coverage of the cell, may be far off villagegetting the week coverage. Avoid week coverage area.

Coverage of the cell should be limited at the point where thereis no population.





TCH Drop Reason, Low SS UL (%)

If the drop call is due to low signal strength uplink, check the

receive path of this particular TRX. Check receiver sensitivity,VSWR, feeder connection and etc. Drops due to Low SignalStrength.

Check whether main lobe of the cell is not out of clutter, changethe orientation.

Use of TMA, while installing TMA it should be properly check

whether the cabling of Bias Injector is done properly at BTSend.





Drop Reason, Bad Quality DL (%)

Go for BCCH and TCH Plan check.

Site covered area…may be the populated area is suffering for High C/I or C/A.

Check the Hopping plan.

Check VSWR, Path imbalance.





Drop Reason, Suddenly Lost Connections (%)

If drops are only on one site, then go for a check for that

particular even attach with that site.

If drops are on all sites connected to a single link, then checkthe slip or interference on that Abis interface.

If Drops are distributed on all site of the BSC, then check the

slips on Ater.Down Time of the cell.

TRX condition.

BTS should not getting the temperature alarm continuously.





Drop Reason, Excessive TA (%)

Proper tilting required considering all hot spots are covered.

Effective tilt should be check…

Mount position should be check.





Drop Reason, Other (%)

Check Path Imbalance.

VSWR of the Cell.

Connector Connection.

TRX condition

Mount position or Effective Tilt.





HOSR

Neighbor Planning should be good.

In city neighbor should be planned to 2nd layer, But in newtown try to restrict to 1st layer.

If reversion rate is high, check the hardware condition, qualityand Congestion on target cell.

If handover failure is due to low signal strength, change thehandover margin and also check the VSWR of source andtarget cell.

If handover failure is due to bad signal quality, check the C/A or

C/I. In addition to this please check the hardware fault of thatsite.

If there is lot of Ping-pong handover in the cell avoidoverlapping cell by tilting the cell.





Attention….

If Intra Handover failure is occurring, Check the hardware and

Blocking of all the sec.

Case I- If there is Path Imbalance in sec B, then there ispossibility that there will be handover failure from A-B and C-B. And there will be also intra cell handover failure in sec B

whenever call will be transfer to Faulty TRX.

Case II- If there is Blocking in sec B, then there is possibilitythat there will be handover failure from A-B and C-B.

Please check Co-BSIC & Co-BCCH.

And Co-BCCH during Neighbor Planning.





CBCH Impact on Data & SDCCH Utilization

Check for SDCCH Utilization, proper re-dimensioning should bedone for effective SDCCH use, though it will be helpful for reducing SDCCH Congestion, if any but at the same time if SDCCH are getting hanged then you will not be short to

SDCCH

If you use CBCH, change to SDCCH/8 config, since GPRS hasmore system information to transmit over BCCH and it isadvisable to keep like this.





High RACH Failures

Other reasons look for Random access statistics, if there is a lotof random access failures try to check hardware too.





Concluding

Optimization start at very basic level, so the ground things need

to be check.Drive test to be done with proper guidance of OptimizationEngg.





ND Reports Needed On Daily Basis

S.No ND Reports

Daily Basis Report Description

1 ND Report 23 Outage Report

2 ND Report 51 GPRS

3 ND Report 60 Adjacency Descrepincies

4 ND Report 61 One way Neigh

5 ND Report 67 Sync Report

6 ND Report 74 Adjacency List

7 ND Report 111 Freq Plan

8 ND Report 130 Cells having SD Cong

9 ND Report 135 Cells having TCH Cong

10 ND Report 150 High HO Fail

11 ND Report 153 Ho Fail and Attempts

12 ND Report 154 HO Causes

13 ND Report 163 TCH Drop

14 ND Report 166 SD Drop

15 ND Report 190 UL Interference

16 ND Report 196 TRX UL DL Quality

17 ND Report 204 Network Benchmark

18 ND Report 208 TRX Path Imbalance

19 ND Report 216 BTS Analyser

20 ND Report 232 Overshooting




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RF KPIs Description