A terminal device , comprising: means for transmitting , at the terminal device , a random access request in a random access procedure to a network device ; means for receiving , during the random access procedure, from the network device an uplink grant for the terminal device ; means for determining whether a size indicated by the uplink grant matches a size of a medium access control, MAC, protocol data unit, PDU, stored in a buffer of the terminal device ; means for, if determining that the size indicated by the uplink grant mismatches the size of the medium access control protocol data unit stored in the buffer, including a medium access control sub-protocol data unit from the medium access control protocol data unit in a subsequent uplink transmission , characterized in that the means for including the medium access control sub-protocol data unit from the medium access control protocol data unit in the subsequent uplink transmission comprise: means for determining whether the random access procedure is successfully completed by receiving the uplink grant; and means for, in response to determining that the random access procedure is considered successfully completed, discarding a cell radio network temporary identifier, C-RNTI, medium access control, MAC, control element, CE, from the medium access control protocol data unit in the subsequent uplink transmission , wherein the means for determining whether the random access procedure is successfully completed comprise means for determining that the uplink grant is addressed to a cell radio network temporary identifier. means for transmitting , at the terminal device , a random access request in a random access procedure to a network device ; means for receiving , during the random access procedure, from the network device an uplink grant for the terminal device ; means for determining whether a size indicated by the uplink grant matches a size of a medium access control, MAC, protocol data unit, PDU, stored in a buffer of the terminal device ; means for, if determining that the size indicated by the uplink grant mismatches the size of the medium access control protocol data unit stored in the buffer, including a medium access control sub-protocol data unit from the medium access control protocol data unit in a subsequent uplink transmission , characterized in that the means for including the medium access control sub-protocol data unit from the medium access control protocol data unit in the subsequent uplink transmission comprise: means for determining whether the random access procedure is successfully completed by receiving the uplink grant; and means for, in response to determining that the random access procedure is considered successfully completed, discarding a cell radio network temporary identifier, C-RNTI, medium access control, MAC, control element, CE, from the medium access control protocol data unit in the subsequent uplink transmission , wherein the means for determining whether the random access procedure is successfully completed comprise means for determining that the uplink grant is addressed to a cell radio network temporary identifier. means for determining whether the random access procedure is successfully completed by receiving the uplink grant; and means for, in response to determining that the random access procedure is considered successfully completed, discarding a cell radio network temporary identifier, C-RNTI, medium access control, MAC, control element, CE, from the medium access control protocol data unit in the subsequent uplink transmission , wherein the means for determining whether the random access procedure is successfully completed comprise means for determining that the uplink grant is addressed to a cell radio network temporary identifier. <EOS>