SHO overhead formula 3G ZTE (V3.09)

[hieuphong]

Hi experts,
I want to caculate KPI "SHO overhead" of 3G ZTE (Version V.3.09). Can you help me the formula for this KPI.
Morever, I have the problem with cells at border LAC. The result of drivetest have many CS call drop, PS call drop and HO failure (RSCP is good), EcNo is normal). The between 2 RNCs have Iur interface. What parameter to check Iur? Thanks so much!

[rumy]

Hi hieuphong,

SHO Overhead is not a very used KPI and it shows you how much overlapping you have between neighboring cells or how much Iub resources are you wasting. In general, SHO Ov. has some desirable values 0.3-0.4 which tells you the time UE is in soft handover [%].
Having the stats with # of (1 cell in AS, 2 cells and 3cells in AS) you can build a formula:
SHO_O=(1*#1_AS+2*#2_AS+3*#3_AS)/(#1_AS+#2_AS+#3_AS)-1

For the drops/ HO failures at the LAC borders you can put some traces on those cells and look after timers as T_reloc_overall_expiry, for eg. I would imagine that the majority of drops occurs especially for HS calls or CS+HS calls.

Press thanks if it helped!