ated with a small cell on a licensed carrier in the small cell cluster through ideal backhaul. The NR-unlicensed (NR-U) study item has considered different unlicensed bands or shared bands such as 2.4, 3.5, 5, 6, 37, and 60 GHz band. Some bands are available globally whereas others are only regionally available. The NR-U study item does not target sub- gigahertz unlicensed bands due to the lack of sufficient spectrum to support efficient NR-U operation. Five deployment scenarios have been identified for NR-U as follows [12]: Scenario A: Carrier aggregation between licensed-band NR (PCell) and NR-U (SCell) NR-U SCell may have both downlink and uplink or only downlink coverage Scenario B: Dual connectivity between licensed-band LTE (PCell) and NR-U (PSCell) Scenario C: Standalone NR-U Scenario D: An NR cell with a downlink in an unlicensed band and uplink in a licensed band In LTE Rel-10 and Rel-11 carrier aggregation, PUCCH was configured only on the PCell. Therefore, uplink control information, that is, HARQ ACK/NACK, CSI of SCells were transmitted on PUCCH of the PCell, if not multiplexed with SCell's own PUSCH. In LTE dual connectivity, it was determined not suitable to carry UCIs of SeNB in PUCCH of PCell in MeNB due to backhaul latency. Therefore, PUCCH is configured on a special SCell of SeNB called Primary SCell or PSCell. The PSCell is never deactivated and RACH procedure needs to be initiated upon its initial configuration. 856 Chapter 8 Scenario E: Dual connectivity between licensed-band NR (PCell) and NR-U (PSCell) The references to sub-7 GHz bands are intended to include unlicensed bands in 6 GHz region that are under consideration by some regulatory bodies. NR-U is trying to identify additional functionalities that may need a new physical layer design (except channel access procedures) for operation in the unlicensed spectrum that are applicable to a particular fre- quency range (e.g., sub-7 GHz, 7-52.6 GHz, above 52.6 GHz). Optimizations for some fre- quency bands may be necessary due to different re