Medium access control protocol data unit in a message 3 buffer

A method at a user equipment (UE), the method comprising:

• receiving a random access response message including an uplink grant;
• obtaining a medium access control (MAC) protocol data unit (PDU) from a message 3 (Msg3) buffer based at least in part on that the uplink grant is received in the random access response message;
• determining that an uplink grant size is different than a size of the obtained MAC PDU;
• and
• outputting an indication to include one or more MAC sub-protocol data units (subPDUs) carrying one or more MAC service data units (MAC SDUs) from the obtained MAC PDU based at least in part on the determination that the uplink grant size is different than a size of the obtained MAC PDU.

A processor comprising:

• means for receiving a random access response message including an uplink grant;
• means for obtaining a medium access control (MAC) protocol data unit (PDU) from a message 3 (Msg3) buffer based at least in part on that the uplink grant is received in the random access response message;
• means for determining that an uplink grant size is different than a size of the obtained MAC PDU;
• and
• means for outputting an indication to include one or more MAC sub-protocol data units (subPDUs) carrying one or more MAC service data units (MAC SDUs) from the obtained MAC PDU based at least in part on the determination that the uplink grant size is different than a size of the obtained MAC PDU.