16.14.9 Support for NR NTN coverage enhancements

To improve NR uplink coverage in NTN, the following enhancements are supported:

• PUCCH repetition for Msg4 HARQ-ACK configured in system information or dynamically in DCI for Msg4 when multiple repetition factors are configured in the system information:
• UEs reports the capability of PUCCH repetition for Msg4 HARQ-ACK in Msg3 PUSCH;
• When Msg4 HARQ-ACK is repeated, PUCCH repetition is applied for all PUCCH transmission before dedicated PUCCH resource is provided.
• Improved channel estimation by NTN-specific PUSCH DMRS bundling enhancement that enables DMRS bundling in presence of timing drift, where the UE maintains phase continuity by considering effects of transmission delay variation between the UE and the uplink time synchronization reference point.

To improve NR downlink coverage in NTN, the following enhancements are supported for NTN operating in FR1-NTN bands:

• Repetition of PDCCH in common search space;
• Repetitions of PDSCH carrying Msg4:
• UEs reports the capability of PDSCH repetition for Msg4 in Msg3 PUSCH.
• Repetitions of PDSCH carrying SIB1 in two consecutive slots as specified in TS 38.214 [56].

To extend the NR downlink coverage for NTN operating in, for FR1-NTN and FR2-NTN bands: extended periodicity of 160 ms (apart from the existing 20ms value) for the half frames with SS/PBCH blocks is assumed by UE during initial cell selection.