A method at a user equipment, the method comprising: receiving a random access channel configuration including a MsgA physical uplink shared channel configuration; determining an association between a physical random access channel preamble of a plurality of physical random access channel preambles and a physical uplink shared channel of a plurality of physical uplink shared channels; randomly selecting a particular physical random access channel preamblefrom the plurality of physical random access channel preambles; transmitting the particular physical random access channel preamble and a physical uplink shared channel associated with the particular physical random access channel preamble, wherein the physical uplink shared channel is transmitted according to the MsgA physical uplink shared channel configuration; and receiving a physical downlink shared channel in response to transmission of the particular physical random access channel preamble and the physical uplink shared channel, wherein a medium access control protocol data unit of the physical downlink shared channel comprises a plurality of random access responses of a plurality of different random access response formats, each of the plurality of random access responses corresponding to a medium access control-subprotocol data unit of the medium access control protocol data unit, wherein the random access channel configuration further comprises a configuration of a plurality of reserved physical random access channel preambles, where the plurality of physical random access channel preambles does not include any of the plurality of reserved physical random access channel preambles. receiving a random access channel configuration including a MsgA physical uplink shared channel configuration; determining an association between a physical random access channel preamble of a plurality of physical random access channel preambles and a physical uplink shared channel of a plurality of physical uplink shared channels; randomly selecting a particular physical random access channel preamblefrom the plurality of physical random access channel preambles; transmitting the particular physical random access channel preamble and a physical uplink shared channel associated with the particular physical random access channel preamble, wherein the physical uplink shared channel is transmitted according to the MsgA physical uplink shared channel configuration; and receiving a physical downlink shared channel in response to transmission of the particular physical random access channel preamble and the physical uplink shared channel, wherein a medium access control protocol data unit of the physical downlink shared channel comprises a plurality of random access responses of a plurality of different random access response formats, each of the plurality of random access responses corresponding to a medium access control-subprotocol data unit of the medium access control protocol data unit, wherein the random access channel configuration further comprises a configuration of a plurality of reserved physical random access channel preambles, where the plurality of physical random access channel preambles does not include any of the plurality of reserved physical random access channel preambles.