High PDCH allocation failure with low TCH load

[sdineszi]

Hello,

I have seen a strange phenomenon in my network - many cells have a high PDCH allocation failure (80-90%) while having a low TCH load(~30%).
Why does it happen? how come the E******* algorithm can't allocate more PDCHs from the available CSs?

[srilasitha]

check wither dynamic allocation is enabled and maximum PDCH channel configurations

[alert181]

Check your PCU congestion/utilization. If you have congestion or high utilization on the PCU, it would affect your PDCH allocation success rate. Also check your ONDEMANDGPHDEV parameter on the BSCs. If it's too low, it may affect your on demand PDCH allocations.

[sdineszi]

thanks for the replies.
srilasitha (http://www.finetopix.com/member.php?21361-srilasitha) - what is the name of the maximum PDCH channel configurations parameter? Is it per cell or per BSC?
alert181 - what is the parameter for high utilization on the PCU? the ONDEMANDGPHDEV is set to the default level of 20.

[alert181]

PCU congestion and utilization are not shown by parameters, but counters.

The following formulas can be used:
PCU CONGESTION = (ALLPDCHPCUFAIL/ALLPDCHPCUATT)*100%

Other counters that can indicate high utilization/congestion are:
FAILMOVECELL, GSL6180,GSL8190,GSL9100

PCU GSL UTILIZATION = (GSLUTIL/GSLSCAN)*100%

The ONDEMANDGPHDEV parameter value is normal. Leave it as it is.