US Patent 10999846 Resource allocation in random access procedure

A method, apparatus, and computer program product where a UE receives a RACH configuration, comprising time/frequency resources for each RACH Preamble and a corresponding Msg1 Data Part. The UE selects the RACH preamble, transmits the selected RACH preamble, and ascertains whether the selected RACH preamble is associated with a 2-step RA procedure. The UE determines at least one resource for Msg1 Data Part based on the selected RACH preamble. The UE performs a LBT preceding the Msg1 Data Part at a predetermined point in time and transmits the Msg1 Data Part provided that the channel is unoccupied based on the LBT. Likewise, a gNB sending a RACH configuration to the UE, receiving a RACH preamble back, ascertaining that RACH preamble is associated with a 2-step RACH procedure, and determining at least one resource for Msg1 Data Part based on the received RACH preamble.