Downlink coverage with beam groups for non-terrestrial network communications

A base station (gNB), comprising:

• transmitting circuitry and receiving circuitry, wherein
• the transmitting circuitry is configured to:
• transmit synchronization signal blocks (SSBs) and physical broadcast channels (PBCHs) to provide system information block type 1 (SIB1) information including physical random access channel (PRACH) configurations with different PRACH resources and preamble formats mapped to different random access response (RAR) parameters having different redundancy levels;
• receiving circuitry is configured to:
• monitor for a first preamble transmitted using a first preamble format, a first preamble sequence, and a first PRACH resource based on a PRACH configuration mapped to a first RAR parameter having a default or low redundancy level for an initial preamble transmission;
• the transmitting circuitry is further configured to:
• transmit a random access response (RAR) within a RAR window corresponding to the first preamble in response to receiving the first preamble;
• and receiving circuitry is further configured to:
• monitor for a second preamble transmitted using a second preamble format, a second preamble sequence, and a second PRACH resource based on a PRACH configuration mapped to a second RAR parameter having a higher redundancy level, wherein the second preamble is transmitted by a user equipment (UE) in response to the RAR not being received within the RAR window and a maximum preamble power ramping being reached.

A method by a user equipment (UE), comprising:

• monitoring synchronization signal blocks (SSBs) and physical broadcast channels (PBCHs) to obtain system information block type 1 (SIB1) information including physical random access channel (PRACH) configurations with different PRACH resources and preamble formats mapped to different random access response (RAR) parameters having different redundancy levels;
• determining a first preamble format, selecting a first preamble sequence, and a first PRACH resource based on a PRACH configuration mapped to a first RAR parameter having a default or low redundancy level for an initial preamble transmission;
• transmitting a first preamble using the first preamble format, the first preamble sequence, and the first PRACH resource;
• monitoring downlink (DL) signals for a random access response (RAR) within a RAR window corresponding to the first preamble;
• in response to not receiving the RAR within the RAR window and a maximum preamble power ramping being reached, determining a second preamble format, selecting a second preamble sequence, and a second PRACH resource based on a PRACH configuration mapped to a second RAR parameter having a higher redundancy level;
• and transmitting a second preamble using the second preamble format, the second preamble sequence, and the second PRACH resource.