 3.50 shows a scenario where three different BWPs are configured: BWP1 = 50 MHz and subcarrier spacing of 15 kHz; BWP2 = 10 MHz and subcarrier spacing of 15 kHz; and BWP3 = 25 MHz and subcarrier spacing of 60 kHz [19]. Note that at each time, only one BWP is active. An initial active downlink BWP is defined by its location, number of contiguous PRBs, subcar- rier spacing, and CP, for the control resource set corresponding to TypeO-PDCCH common search space. For operation on the primary cell, a UE is provided by higher layer parameter initial-UL-BWP an initial uplink BWP to perform random-access procedure. If the UE is con- figured with a secondary carrier on the primary cell, it can also be configured with an initial BWP for random-access procedure on the secondary carrier [14,15]. A UE can be provided with a timer value by RRC parameter BWP-InactivityTimer for the primary cell. The UE sub- sequently starts the timer each time that it detects a DCI format 1_1 indicating an active down- link BWP, other than the default downlink BWP, for paired spectrum operation or each time the UE detects DCI format 1_1 or DCI format 0_1 indicating an active downlink or uplink BWP, other than the default downlink/uplink BWP, for unpaired spectrum operation. The UE increments the timer every 1 ms for sub-6 GHz carrier frequencies or every 0.5 ms for carrier frequencies above 6 GHz, if it does not detect a DCI format 1_1 for paired spectrum operation 396 Chapter 3 or if it does not detect a DCI format 1_1 or DCI format 0_1 for unpaired spectrum operation. The timer expires when the value is equal to the BWP-InactivityTimer. Upon expiration of the timer, the UE switches from the active BWP to the default BWP [14,15]. In conjunction with an UL/DL carrier pair for an FDD band, or a bidirectional carrier for a TDD band, a UE may be configured with an additional SUL. The SUL differs from the aggregated uplink in the sense that the UE may be scheduled to transmit either on the SUL or on the uplink of the carrier being supplemented, but n