timer Connected longer DRX opportunity period setup transmit/ NR DRX receive Connected Connected Data/signaling transmit/receive Connected shorter DRX opportunity period Figure 1.83 DRX concept and comparison of LTE and NR DRX schemes (example) 16,82]. among all the data bearers are followed. This solution is simple and effective for non-CA sce- narios. In CA scenarios, the UE may operate over several component carriers and supports separate RF transceivers for each RF carrier. The baseline UE-specific DRX mechanism is no longer suitable to achieve higher energy-saving gains since the same DRX setting has to be configured for all component carriers according to the delay requirement of all applications running on the UE. The UE has to wake up the RF circuitries for all RF carriers at the same time to monitor possible downlink allocations. When bandwidth adaptation is configured in NR, the UE only has to monitor the downlink control channel on the [single] active band- width part, thus it does not have to monitor downlink control channels on the entire downlink frequency bands used in the cell. A bandwidth part inactivity timer (independent of DRX inactivity-timer described earlier) is used to switch the active bandwidth part to the default one, that is, the timer is restarted upon successful downlink control channel decoding and switching to the default bandwidth part occurs upon its expiration (see Fig. 1.83). 5G Network Architecture 171 The percentage of time spent in the connected and idle states depends on a number of parameters controlled by the network including paging occasions, DRX cycles, user- inactivity timer, etc. The user-inactivity timer determines how long the UE stays in the connected state after it receives or transmits the last data packet. When the timer expires, the gNB releases the RRC connection and the UE immediately transitions to the idle state. The shorter the user-inactivity timer, the longer the UE battery life. However, if a new packet arrives the gNB queue shortly after the UE transi