 into the radio link recovery time in case of advanced RRC connection re-establishment procedures are implemented. Radio link problem indication detection parameter tuning can also improve the dropped call rate. Figure 12.32 shows the number of consecutive missed periodical CQI reporting based radio link problem detection parameter tuning impact on E-RAB drop rate (note that the cluster is different compared to Figure 12.31). In case more periodical CQI reports are allowed to be missed the E-RAB drop rate is improved. However, it is not recommended to extend the radio link recovery timer too long or try to avoid any radio link problem detection, as if the problematic radio link is not released it just would reserve resources unnecessarily from the eNodeB and end user would experience poor performance. As shown in Figure 12.32, increasing the amount of missed periodical CQI reports improves the dropped call rate. The periodical CQI report is sent typically using PUCCH and therefore the PUCCH power control (explained in Section 12.4) also plays an important role when Radio recovery timer extended Figure 12.31 E-RAB drop rate improvement by radio link recovery timer increase LTE Small Cell Optimization Figure 12.32 Amount of consecutive missed periodical CQI reporting impact on E-RAB drop rate optimizing the E-RAB drop rate. As a general rule the PUCCH power control strategy should follow the PUSCH power control strategy. The PUCCH is not used as often as PUSCH and therefore the PUCCH closed-loop power control commands from eNodeB are not sent as frequently as for PUSCH. Therefore, the PUCCH closed-loop power control decision windows (RSSI and SINR) should be narrower compared to PUSCH and in general lower compared to PUSCH. Figure 12.33 shows the gain in E-RAB drop rate in terms of percentage point improvement compared to before change when RSSI and SINR decision windows are narrowed for conservative PUCCH (and PUSCH) closed-loop power control strategy. 12.6 Handover and Mobility Optimization As mentioned in Sectio