Coverage enhancement for initial access with feedback via PRACH sequence

A base station, comprising:

• a processor configured with processor executable instructions to:
• transmit Remaining Minimum System Information (RMSI) Downlink Control Information (DCI) indicating that a Channel State Indicator-Reference Signal (CSI-RS) will be transmitted, wherein the RMSI DCI includes time and frequency resources for an RMSI, and wherein the time and frequency resources for the RMSI indicate time and frequency resources for the CSI-RS;
• transmit the CSI-RS according to the time and frequency resources for the CSI-RS;
• receive from a wireless device an indication of a selected sub-beam of a beam associated with a synchronization signal block (SSB) in a Physical Random Access Channel (PRACH) message;
• and
• perform an initial access procedure with the wireless device using the selected sub-beam indicated in the PRACH message.

A method performed by a processor of a wireless device for enhancing coverage for initial access, comprising:

• receiving from a base station Remaining Minimum System Information (RMSI) Downlink Control Information (DCI);
• determining time and frequency resources for a Channel State Indicator-Reference Signal (CSI-RS) based on the RMSI DCI, wherein determining time and frequency resources for the CSI-RS based on the RMSI DCI comprises:
• determining time and frequency resources for an RMSI based on the RMSI DCI;
• and
• determining time and frequency resources for the CSI-RS based on the time and frequency resources for the RMSI;
• receiving the CSI-RS using the determined time and frequency resources;
• selecting a sub-beam of a beam associated with a synchronization signal block (SSB) based on the CSI-RS;
• and
• sending to the base station an indication of the selected sub-beam associated with the SSB in a Physical Random Access Channel (PRACH) message.

A wireless device, comprising:

• a processor configured with processor-executable instructions to:
• receive from a base station Remaining Minimum System Information (RMSI) Downlink Control Information (DCI);
• determine time and frequency resources for a Channel State Indicator-Reference Signal (CSI-RS) based on the RMSI DCI, wherein the processor is further configured with processor-executable instructions to:
• determine time and frequency resources for an RMSI based on the RMSI DCI;
• and
• determine time and frequency resources for the CSI-RS based on the time and frequency resources for the RMSI;
• receive the CSI-RS using the determined time and frequency resources;
• select a sub-beam of a beam associated with a synchronization signal block (SSB) based on the CSI-RS;
• and
• send to the base station an indication of the selected sub-beam associated with the SSB in a Physical Random Access Channel (PRACH) message.