on and the applicable Feature Set combination in the supported MR-DC or NR band combinations. The RLC RTT for NR cell group corresponds to the smallest subcarrier spacing (SCS) numerology sup- ported in the band combination and the applicable Feature Set combination. The NR New Radio Access Layer 2/3 Aspects and System Operation 255 specifications specify X2/Xn delay + Queuing in SN = if SCG is NR, and 55 ms if SCG is LTE. The NR specifications define X2/Xn delay + Queuing in MN = 25 ms, if MCG is NR, and 55 ms if MCG is LTE. They further specify RLC RTT for LTE cell group as 75 ms and the RLC RTT for NR cell group ranging from 20 to 50 ms depending on the subcarrier spacing [13]. The maximum supported data rate for integrity-protected DRBs (see Section 2.2.3.3) is a UE capability indicated at NAS layer, with a minimum value of 64 kbps and a maximum value of the highest data rate supported by the UE. In case of failed integrity check (i.e., due to a faulty or missing MAC-I) the corresponding PDU is discarded by the receiving PDCP entity. 2.4 Discontinuous Reception and Power-Saving Schemes The UE monitors physical downlink control channel (PDCCH) while in RRC_CONNECTED state. This activity is controlled by the DRX and bandwidth adaptation schemes configured for the UE. When bandwidth adaptation is configured, the UE only has to monitor PDCCH on the active BWP, that is, it does not have to monitor PDCCH on the entire downlink frequency of the cell. A BWP inactivity timer (independent from the DRX inactivity timer) is used to switch the active BWP to the default one. The latter timer is restarted upon successful PDCCH decoding and the switching to the default BWP happens when it expires. When DRX is configured, the UE is not required to continuously monitor the PDCCH. The DRX mechanism is characterized by the following parameters [8]: On-duration: The time interval during which the UE would expect to receive the PDCCH. If the UE successfully decodes the PDCCH, it stays awake and starts the inac- tivity timer. Inact