Wednesday, November 9, 2011

SDCCH Congestion Reason

---Low Availability

Action: Check SDCCH Availability. Check if the channels are manual, control or automatic blocked.

---Increasing Traffic Demand
The high traffic could be related to an occasional event or due to a long term growth.

Action: Check if short term traffic growth. Make trend comparisons. Check if combined SDCCH is used. Check SDCCH dimensioning.

---Bad use of Adaptive configuration of Logical Channels

By using the Adaptive configuration of logical channels feature, the basic SDCCH configuration in a cell will be under-dimensioned. If this feature is not used correctly, it will cause SDCCH congestion.

Action: Check if ACSTATE is on. Check parameters related to Adaptive configuration of logical channels


---Long Mean Holding Time

If the mean holding time is long, this generates a higher traffic load.

Action: Check SDCCH Mean Holding Time

---Too Frequent Periodic Registration

Action: Check Random Access Distribution. Check the timer T3212 in the BSC and the parameters

---BTDM and GTDM in the MSC

Solution: Decrease the periodic registration.

---Location Area Border Cell

If the cell is situated on a misplaced Location Area border, this means that unnecessary many normal LUs are performed.

Action: Check site position and location area border. Check Location Update Performance. Check parameter CRH etc.


---Extensive SMS Usage

Extensive SMS usage increases the SDCCH traffic and could cause congestion if badly dimensioned SDCCH channels.

Action: Check SMS activity.

---Cell Broadcast Used

Action: Check if Cell Broadcast is active. .If active, check if it is used by the operator.

---IMSI Attach/Detach in Use.

An introduction of IMSI attach/detach will increase the traffic on SDCCH. However, the benefits are that the paging success rate will increase. The recommendation is to use Attach/Detach.


---Cell Software File Congestion

Action: Check SAE setting. High Ratio of Random Accesses

Action: Check Random Access performance

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