gsm parameter optomization

7/31/2019 Gsm Parameter Optomization

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Below mentioned parameters may cause TCH Congestion & also help you to reduce TCH

Congestion:

1. TCH Traffic Busy Threshold(%)

2. RXLEV_ACCESS_MIN

3. SACCH Multi-Frames and Radio Link Timeout4. SDCCH Dynamic Adjustment

5. RACH Min.Access Level

6. Speech Version7. TCH Immediate Assignment

8. Speech Version

9. Fix Abis Prior Choose Abis Load Threshold

10. Assignment Cell Load Judge Enable11. Flex Abis Prior Choose Abis Load Threshold

12. Directed Retry Load Access Threshold

13. Balance Traffic Allowed

14. Load HO Allowed15. Load HO Step Period

16. Load HO Step Level17. Cell Direct Try Forbidden Threshold

18. Direct Retry

19. SDCCH Dynamic Adjustment20. Direct Retry and Cell Direct Try Forbidden Threshold

21. AMR TCH/H Prior Allowed

22. T3103

23. T310724. F2H HO th/ H2F HO th

25. Maximum Ratio Threshold of PDTCH

Here is the some possible solution for Low TCH Assignment Success Rate

Successful assignments show the number of successful TCH allocations at call setup.Atunsuccessful assignment, the Assignment Complete message, sent by the MS, was never

received by the BTS.

Probable Reasons The reason for a low number of successful assignments might be thefollowing items:

1.No Dominant Serving Cell

Action:Check coverage plots, perform drive tests.Solution:Add new base station.

2.Severe Congestion on the TCHAction:Check failed TCH allocation for assignment due to congestion.

Check failed TCH allocation for handover due to congestion .

Check TCH congestion.


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3.Low Signal Strength for Call Access

The signal strength might be higher on the BCCH than on the TCH.

Action:Check signal strength of BCCH and TCH. Perform MTR recordings.Solution: Adjust and increase TCH output power.

4.InterferenceInterference, disturbance on SDCCH or target TCH frequency.

Action:Check Interference.

Solution:Improve frequency plan and decrease interference.

5.Faulty Transceiver

Action:Check BTS Error Log.

Solution:Replace or repair faulty equipment.

6.Low Output Power

Action:Check set output power parameters and the actual transceiver output power.

Solution: Increase output power or replace faulty transceiver.

SDCCH Drop Reasons and Solutions

1)Low Signal Strength on Down or UplinkThe reason for poor coverage could be too few sites, wrong output power, shadowing, no

indoor coverage or network equipment failure.

Action: Check coverage plots.Check output power. Perform drive tests. Check BTS error

logSolution: Add new sites. Increase output power. Repair faulty equipment.

2)Poor Quality on Down or UplinkAction: Check C/I and C/A plots. Check frequency plan. Perform drive tests.

Solution: Change frequency. Use available radio features.

3)Too High Timing Advance

Action: Check if the cell parameter TALIM is < style="font-weight: bold;">Solution: Set

TALIM to a value close to 63. Tilt antenna/reduce antenna height/output power, etc. for

cochannel cells.

4)Mobile Error

Some old mobiles may cause dropped calls if certain radio network features are used.Another reason is that the MS is damaged and not working properly.

Action: Check MS fleet.

Solution: Inform operator.

5)Subscriber Behavior

Poorly educated subscribers could use their handsets incorrectly by not raising antennas,

choosing illadvised locations to attempt calls, etc.


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Action: Check customer complaints and their MS.

6)Battery FlawWhen a subscriber runs out of battery during a conversation, the call will be registered as

dropped call due to low signal strength or others.

Action: Check if MS power regulation is used. Check if DTX uplink is used.

7)Congestion on TCH

The SDCCH is dropped when congestion on TCH.Action: Check TCH congestion

Solution: Increase capacity on TCH or using features like Assignment to another cell, Cell

Load Sharing, HCS, Dynamic Half-Rate Allocation and FR-HR Mode Adaptation etc

HUAWEI only

SDCCH CONGESTIONSDCCH congestion rate = Failed SDCCH seizures due to busy SDCCH/Total requests for

the SDCCH x 100%SDCCH Blocking Rate = SDCCH Blocked Calls/ SDCCH Seizure Requests *100

Check Equipment faulty and transmission Check Improper Data Configration

Check Interference

Check LAC planning( on LAC boundary high pagging occur. So high PSR will gone to

down and Blocking can occur.Parameter Setting

SDCCH Availability

LAC T3101 (the timer used in the immediate assignment procedure)

T3212 (the timer used for periodic updating) range 0 to 255, we adjust 20. 1=6mins

SDCCH DROP RATE

Call Drop Rate on SDCCH = (Call Drops on SDCCH/Successful SDCCH Seizures +

Successful SDCCH Seizures in the signaling channel handover) x 100%

Hardware failureTransmission

Version upgrade

Parameter settingIntra-network and inter-network interference

Poor Coverage

Imbalance between uplink and downlinkHardware Faulty

Parameter Setting

1. SACCH Multi-Frames (SACCH period (480ms)) and Radio Link Timeout(SACCH

period (480ms)) are set to too small values.


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2. RACH Min.Access Level(dBm) is set to a too small value.

3. T200 SDCCH(5ms) and N200 of SDCCH are set to too small values.

4. MAIO is set improperly.

gsm parameter optomization

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