Random access channel procedure selection scheme

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

• receiving, via a control channel, an order message instructing the UE to perform a random access channel (RACH) procedure;
• determining a preamble preparation time gap between the order message and an occasion for transmitting a RACH preamble;
• determining a payload preparation time gap between the order message and an occasion for transmitting a RACH payload;
• and
• selecting to perform a first RACH procedure instead of a second RACH procedure based at least in part on both the preamble preparation time gap providing sufficient margin for the UE to transmit a RACH preamble in the occasion for transmitting the RACH preamble and the payload preparation time gap providing sufficient margin for the UE to transmit the RACH payload in the occasion for transmitting the RACH payload.

A method for wireless communication by a base station, comprising:

• transmitting, via a control channel, an order message instructing a user equipment (UE) to perform a random access channel (RACH) procedure;
• selecting to perform a first RACH procedure or a second RACH procedure based at least in part on a preamble preparation time gap between the order message and a first occasion for receiving a RACH preamble, or a payload preparation time gap between the order message and an occasion for receiving a RACH payload, or both;
• and
• monitoring for the RACH preamble during the first occasion for receiving the RACH preamble or a second occasion for receiving the RACH preamble based at least in part on the selected RACH procedure.

An apparatus for wireless communication by a user equipment (UE), comprising:

• a processor of the UE,
• memory in electronic communication with the processor, the memory and the processor configured to:
• receive, via a control channel, an order message instructing the UE to perform a random access channel (RACH) procedure;
• and
• select to perform a first RACH procedure or a second RACH procedure based at least in part on:
• a preamble preparation time gap between the order message and a first occasion for transmitting a RACH preamble, or
• a payload preparation time gap between the order message and an occasion for transmitting a RACH payload, or
• both.