5G NR PUCCH | contents, function, physical layer processing

This page covers 5G NR PUCCH function, 5G NR PUCCH contents, mapping and physical layer processing of 5G NR PUCCH.

Following channels are supported by 5G NR wireless system.
Downlink channels: PDSCH (DL shared channel), PBCH (Broadcast channel), PDCCH (DL control channel)
Uplink channels: PRACH (Random Access Channel), PUSCH (UL shared channel), PUCCH (UL control channel)

5G NR PUCCH function, contents and mapping


• PUCCH channel is used to transport UCI (Uplink Control Information) e.g. HARQ feedback, CSI (Channel State Information) and SR (Scheduling Request).
• 5G NR PUCCH is flexible in time domain and frequency domain.
• The PUCCH channel utilizes five PUCCH formats.
• PUCCH format 0 and 2 occupies 1 or 2 OFDM symbols. It is known as short PUCCH.
• PUCCH format 1, 3 and 4 occupies 4 to 14 OFDM symbols. It is known as long PUCCH.
• PUCCH format 0 and 1 carry UCI payloads having 1 or 2 bits.
• Other PUCCH formats carry UCI payloads having more than 2 bits.

PUCCH Format Length of OFDM symbols Number of Bits
0 1-2 <=2
1 4 to 14 <=2
2 1 to 2 >2
3 4 to 14 >2
4 4 to 14 >2

• In PUCCH formats 1/3/4, symbols having DMRS are time multiplexed with UCI symbols to achieve low PAPR .
• In PUCCH format 2, DMRS is frequency multiplexed with data subcarriers.
• Multi user multiplexing on same time/frequency resources is supported for PUCCH formats 0/1/4 only with the help of unique cyclic shifts.
• UE can also be configured for CSI reporting or SR with the help of PUCCH resources.
• For transmission of UCI + (HARQ-ACK) , 4 PUCCH resource sets are used based on UCI size. For first set is used for maximum of 2 HARQ-ACK bits (i.e. max. 32 PUCCH resources). The other sets are used for 2 bits of UCI (i.e. max. 8 PUCCH resources).
• 5G NR UE determines set based on UCI size and also indicates PUCCH resource in the set based on DCI's 3 bit field.

5G NR PUCCH physical layer processing

5G NR Physical layer processing for PUSCH channel

The physical layer processing for PUSCH is shown in the figure-1. Refer complete article on 5G NR Physical layer >> for more information. PUCCH channel follows the same modules with modifications as described in the 3GPP TS 38.211, 38.212, 38.213 and 38.214 specifications.


5G NR Numerology | 5G NR Terminology

5G NR Control channels | 5G NR Traffic Channels | 5G NR Reference Signals and sequences

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RF and Wireless Terminologies