ns- missions from a UE are supported in one slot. Such configuration flexibility for PUCCH has a number of advantages including support of UEs with smaller bandwidth capabilities, 3 5G System Overview Figure 3.5.9 Short and long PUCCH structures. symbol Long PUCCH more efficient usage of the available physical resources depending on the target coverage, and capacity and/or support of low latency transmissions. There are two PUCCH structures supported by NR: one with short and one with long duration; see Figure 3.5.9 for an illustrative example. More specifically, NR PUCCH with short duration spans one or two symbols in a slot, and can be multiplexed in the time domain with downlink or uplink transmissions. This PUCCH format can be used to sup- port low latency use cases such as URLLC. In such use cases, PUCCH can be transmitted in the last OFDM symbol of a slot to enable fast HARQ-ACK feedback. Similar to LTE, to provide robust transmission and high capacity of UCI, NR also supports PUCCH transmission with long duration, where multiple OFDM symbols are allocated for PUCCH to ensure the desired coverage and size of the UCI payload. In total, NR defines five different formats for PUCCH. The number of bits, PUCCH duration, and the number of PRBs that can be used for PUCCH transmission in NR are summarized in Table 3.5.5. Table 3.5.5 Supported PUCCH formats in 5G NR. Number of Number of Summary of Format Duration bits in UCI Types of UCI key elements Short HARQ, SR Cyclic shift (CS) per UCI UE multiplexing using CS HARQ, SR, CSI TDM of UCI and DM-RS UE multiplexing using CS and OCC Short HARQ, SR, CSI FDM of UCI and DM-RS 1-6, 8-10, HARQ, SR, CSI TDM of DM-RS and UCI 12, 15, 16 UCI using DFT-s-OFDM HARQ, SR, CSI TDM of DM-RS and UCI Pre-DFT OCC multiplexing of UEs 3.5 NR Physical Layer The long PUCCH has variable duration in time domain, that is, the actual number of OFDM symbols for long PUCCH in a slot is configurable and can range from 4 to 14. For short PUCCH formats, the transmission of the UCI is always confine