just like it does for the PCell, to avoid situations where UE could cause excess UL interference or be unable to be served by the SeNodeB. The detection of a Radio Link Failure on the PSCell is called Secondary Radio Link Failure (S-RLF). When S-RLF happens, the UE stops receiving and transmitting on the SeNodeB and informs MeNodeB via RRC message that the SeNodeB has failed. The UE still continues measuring the SeNodeB according to its configuration, but to recover use of the SeNodeB, the MeNodeB must restart the dual connectivity. The UCI transmission rules defined in earlier releases are used within cell group to deter- mine which physical channel (PUCCH or PUSCH) is used for UCI transmission and which PUCCH resource or PUSCH cell is used. Also periodic CSI dropping rules, handling of UCI combinations and HARQ-ACK timing and multiplexing are done by applying rules of previous release within cell group. In dual connectivity, scheduling of UE transmissions is more challenging than in carrier aggregation, because scheduling decisions in the SeNodeB and in the MeNodeB cannot instantaneously coordinated. Because of this it can easily happen that uplink grants sent from MeNodeB and SeNodeB result in situation where power resources of the UE are exceeded. In order to avoid this, it is possible to configure guaranteed power levels for transmissions in the MCG and SCG, as shown in Figure 4.7. UE max tx power (Pcmax) Guaranteed Remaining Guaranteed for MeNB power for SeNB P_MeNB P_SeNB Figure 4.7 Guaranteed powers and remaining power Small Cell Enhancements in Release 12/13 PUSCH/PUCCH to MeNB SRS to MeNB [P_MeNB, scheduled Guaranteed for MeNB power] Remaining Pcmax power [P_SeNB, scheduled Guaranteed for SeNB power] PUSCH/PUCCH to SeNB SRS to SeNB Figure 4.8 Power control mode 1 The guaranteed power level of a cell group is configured as the percentage of the maximum UE transmission power. For both MCG and SCG, guaranteed power level values can be selected from the following values: 0%, 5%, 10%, 15%, 20%, 30%, 37%, 44%