ISHO Failure Due to Radio Reasons

[silverstayne]

Hi All,

I just want to ask what else should I check if I have high ISHO failures within the same site. 3G cell failing to handover to its 2G cell
even with correct parameters defined. Can someone help? Please thanks!

[electron]

If it is specific relation try to check interference level in area(Co-BCCH,...) if it is global issue u need to share more information here

cheers
Hi All,

I just want to ask what else should I check if I have high ISHO failures within the same site. 3G cell failing to handover to its 2G cell
even with correct parameters defined. Can someone help? Please thanks!

[kape]

How do you know that it fails due to radio? The IRATHO have two phases, one is relocation preparation where it checks resources on target 2G cell.
If that fails fails you should be checking congestion on target 2G cell or routing/cell definition problems in MSC. (wrong or missing definition of target 2G cell or LAC in MSC)
If thats ok, then comes the second phase it is the Handover .When it fails again two options:
-The call is dropped, this case timers expire in RNC or MSC so IU connection is released
-HO supervision timer expired in UE and UE is able to recover on 3G and send HO fail with /physical channel failure to RNC. This is radio failure
Here you check
-check if HO access is failing already or just HO complete not received (for the later it could be ciphering problem)
-check the target 2G cells triplet (BCCH/NCC/BCC) is uniqe in this area. This will ensure that the target 2G cell lookup is correct.
-check the stats on the target 2G cell. Perhaps the incoming HO failure rate itself is high. Could be wrong TRX/antenna/cabling or need restart
-check 2d/3a/3c thershold settings, perhaps too low. The target cell RSSI threshold should be in the range -99..-95dBm