5G PUCCH and 5G PUSCH

5G PUCCH and 5G PUSCH

PUCCH is used to carry Uplink Control Information (UCI), and following types of UCI are supported in NR:

·         Hybrid automatic repeat request acknowledgement (HARQ-ACK): information to report whether the DL transmission of a TB is successful or not

·         Scheduling request (SR): signal to request UL grant to gNB

·         Channel state information (CSI): information represents channel condition between gNB and UE

The UCI can be carried by PUCCH or PUSCH. The channel coding schemes for different UCI sizes are shown in Table.

Channel coding for uplink control information (UCI)

UCI size including CRC, if present	Channel code
1	Repetition code
2	Simplex code
3-11	Reed Muller code
>11	Polar code

1. For HARQ-ACK feedback of PDSCH with corresponding DCI, PUCCH resource set(s) containing one or more PUCCH resources are configured.
2. One PUCCH resource is determined based on the UCI payload size and the PUCCH resource indicator field in the DL assignment. For HARQ-ACK feedback of PDSCH without corresponding DCI, SR, and CSI report, a PUCCH resource is configured for each.
3. When multiple PUCCHs are overlapped fully or partially in time, the UCIs are multiplexed in a PUCCH.
4. When a PUCCH is overlapped with a PUSCH fully or partially in time, the UCI is multiplexed (i.e. piggybacked) on the PUSCH.
5. Each PUCCH resource is configured with a PUCCH format. Various PUCCH formats are specified as in Figure.
6. Each PUCCH format supports either durations of 1 to 2 symbols, or durations of 4 to 14 symbols.
7. PUCCH formats 0/2 are called as short-PUCCH, which can deliver UCI by 1 or 2 symbols. PUCCH formats 0/2 are beneficial to reduce latency.
8. PUCCH formats 1/3/4 are called as long-PUCCH, which can deliver UCI with any of 4 to 14 symbols. PUCCH formats 1/3/4 are adopted to improve coverage.
9. The frequency/time-domain resources for PUCCH transmissions in NR are flexibly configurable.
10. In PUCCH format 0/1/4, multiple PUCCH resources can be CDMed on the same time/frequency resource.
11. A short-PUCCH can be TDMed with a long-PUCCH or a short PUCCH within a slot.

NR PUCCH formats

PUSCH is used to transmit one TB. A DCI in a PDCCH can schedule a PUSCH transmission with DM-RS (and other RS if any). The PUSCH is transmitted based on the information in the PDCCH, for example, time/frequency-domain resource including frequency-hopping, modulation, and layer. The number of layers for PDSCH transmissions is 4. HARQ re-transmission is supported for PUSCH transmissions as mentioned in Section