How to optimize Handover at LAC border

[dmg123]

I got a problem with cell at LAC border, good incoming but bad outgoing handover, could any guy show me the way to fix this :)

[khurrambilal01]

Bad outgoing handover is normaly due to some issue at the Target cell, If there is congestion on target side outgoing HSR will be degraded.
You should reduce ping pong ahndovers to reduce inter BSC handovers.

[dmg123]

Well, no congestion, neighbor list is OK, but just one way is OK, the other way not good, anyone got this case?

[usama0795]

check for issue on neighbring cell meaning hradware issue (check the BTS E1 clock is synchorinized with the BSC).....check for UL quality sample or UL Quality Handover % if high then definitely a hradware issue check for VSWR and send for operation team to check the RF module.....from soft side either soft reset the destination cell / delete and re-create all neoghbors / check for ciphering algorithm settings if both cells support the same algorithm / check for Co-BSIC and BCCH on the neighboring sites / increae rxlevel_min_access level from source to destination making it harder to go to neihgboring cell.....

[ftabasum]

as its a LAC border it would mostly involve different BSCs/RNCs. you need to check
1. configurations of external cells.
2. are they of same or different vendors. if problem of HO happen between BSC/RNC of different vendors it is usually related to timers in BSC.
3. you may increase the cell to cell PBGT and BQ Hysterysis to discourage ping pong HOs. if logical HOs will happen when the level is consistenlty better they would have more chance of getting successful.
4. Check for Alarms/ specially clock synchronization alarms on border.
5. you may also like to check trend when this problem started happening. its also adivsable to cehck neighbor to neighbor stats to pin it down to problematic neighbor relations across the LAC.

Lastly please add to my reputation, i'm dying without it :)

[dmg123]

As the drive test result, mobile sends many measurement report, but BSC triggers nothing, even I can see full neighbors. This one-way handover between LAC (different BSC) is an interesting case

[ftabasum]

As the drive test result, mobile sends many measurement report, but BSC triggers nothing, even I can see full neighbors. This one-way handover between LAC (different BSC) is an interesting case

this is no mystery. its quite normal.

check for configuration of external cell, it must be having wrong definition. it can also be target cell congestion or transmission issue.

if its inter-MSC than you must also get the MSC definitions checked. the best way is to put trace on BSC and MSC and than analyze it. you can than easily see from where the failure is coming. you will see Handover Request and it will be rejected due to certain reasons or config issues.

[dmg123]

Well, we'll reset BSC, and check data between bsc, omc, msc to see any inconsistency :)

[ftabasum]

reset a BSC, are you serious :P

I am even scared at the thought of it, this is no critical problem to reset entire BSC. If i do this i will get fired :P

anyways please help me with reputation :)

[Shakeel_15]

Check DB discrepancies if any.

You can do trial of COBSCMSCadj parameter, Priority of neighboring cell, HOM, Mincell as well.

Also check if no ABIS Clock problem.

BR


I got a problem with cell at LAC border, good incoming but bad outgoing handover, could any guy show me the way to fix this :)

[wola44]

Try to get Material on LAC.

[magno22]

Anyone have document WCDMA lac border optimization parameters? Please share.

[chefo]

if the target cells belong to different BSC or MSC, increase the HO supervision timers, just to make sure the timers don't expire before the HO ready message arrives from the target BSC/MSC.

Depending on the vendor, there are different performance counters which are triggered by each timer expiry, check them - you will notice some increased values if your timers are too short.

[alert181]

To add to chefo, also make sure that the ciphering algorithm on the BSCs/MSCs are the same if the cells are on different BSCs/MSCs.

[Syed Fahad]

DMG, at adjacency level, If the Incoming HSR of the LAC Border cell is 0% from an external Neighbor , then we can be sure that the defintion might be a problem, if its only low, like IHSR is 25 % etc, than we need to HO Failures per TRX Level and causes of HO Failures. In some vendors like Alcatel Lucent, BTS Clock Syn Activity might be done to resolve the issue. From the HO Statistics, it can be seen that if there is no HO Command against HO Request, the reason can be HO Congestion / Definition Related.
CO-BCCH / BSIC on nearby cells is a definate possibility. can you specify the Vnedour Name. Also it can be check that weather HO Failure is between AMR - AMR or Non AMR to AMR and Vice Versa.

[FrankPintor]

posted in wrong topic

[dmg123]

Oh, thanks guys, after comparing database with MSC team, we found that they did not update our BSC change for some sites, and now the problem is gone :D