Your settings of TBFULLIMIT and TBFDLLIMIT mean that you PREFER to have a maximum of 2 TBFs per PDCH. This means that your BSC will attempt to allocate more PDCHs for new TBFs when the current number of TBFs per PDCH is 2.
From a user perspective, the effect is relative. Generally, each user will experience a higher throughput when the number of TBFs per PDCH is lower (ie, the lower the settings of TBFULLIMIT and TBFDLLIMIT, the better the throughput per user).
PDCH allocation failures can be caused by:
1. High voice traffic(which does not apply to you)
2. PCU congestion
3. PCU hardware faults
4. PCU parameter settings (ONDEMANDGPHDEV)
4. Faulty TRXs on the cells
If you have the failures occurring on several cells on the same BSC, then it’s definately a PCU problem. Check PCU congestion and the setting of the ONDEMANDGPHDEV parameter(it should not be too low). You can also try resetting the PCU, ‘cos sometimes some RPPs don’t work properly.
Failures in individual cells on different BSCs are caused by problems in the cells themselves (eg TRX or other hardware fault).
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