Preamble to demodulation reference signal mapping for random access procedures

A method for wireless communications at a user equipment, comprising:

• receiving, from a base station, an indication of a mapping between an aggregated set of preamble sequences and an aggregated set of demodulation reference signal (DMRS) sequences and physical uplink shared channel (PUSCH) resources of a random access message of a random access procedure;
• determining, based at least in part on the indication of the mapping, a mapping rule between a first group of preamble resources comprising at least a part of the aggregated set of preamble sequences and a second group of resources for payloads of the random access message comprising at least a part of the aggregated set of DMRS sequences and PUSCH occasions, wherein the first group and the second group are associated with a resource mapping period of the random access message;
• and
• transmitting, based at least in part on determining the mapping rule, at least one preamble sequence of the aggregated set of preamble sequences in a preamble occasion and at least one DMRS sequence and at least one payload of the random access message of the aggregated set of DMRS sequences and payloads of the random access message in a PUSCH occasion.

An apparatus for wireless communications at a base station, comprising:

• a processor,
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• identify configuration information for a random access message of a random access procedure, the configuration information being associated with an aggregated set of preamble sequences related to one or more preamble occasions and an aggregated set of demodulation reference signal (DMRS) sequences and physical uplink shared channel (PUSCH) resources of the random access message related to one or more PUSCH occasions;
• determine, based at least in part on the configuration information, a mapping rule between a first group of preamble sequences comprising at least a part of the aggregated set of preamble sequences and a second group of resources for payloads of the random access message comprising at least a part of the aggregated set of DMRS sequences and PUSCH occasions, wherein the first group and the second group are associated with a same resource mapping period of the random access message;
• map, based at least in part on determining the mapping rule, at least some of the aggregated set of preamble sequences in the first group and at least some of the aggregated set of DMRS sequences and PUSCH occasions for the payloads of the random access message in the second group;
• and
• transmit, to a user equipment, an indication of the mapping rule between the preamble sequences and the DMRS sequences and PUSCH occasions for the payloads of the random access message.

An apparatus for wireless communications at a user equipment, comprising:

• a processor,
• memory in electronic communication with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• receive, from a base station, an indication of a mapping between an aggregated set of preamble sequences and an aggregated set of demodulation reference signal (DMRS) sequences and physical uplink shared channel (PUSCH) resources of a random access message of a random access procedure;
• determine, based at least in part on the indication of the mapping, a mapping rule between a first group of preamble resources comprising at least a part of the aggregated set of preamble sequences and a second group of resources for payloads of the random access message comprising at least a part of the aggregated set of DMRS sequences and PUSCH occasions, wherein the first group and the second group are associated with a resource mapping period of the random access message;
• and
• transmit, based at least in part on determining the mapping rule, at least one preamble sequence of the aggregated set of preamble sequences in a preamble occasion and at least one DMRS sequence and at least one payload of the random access message of the aggregated set of DMRS sequences and payloads of the random access message in a PUSCH occasion.