A base station device including: a transmitter configured to transmit, for each logical channel, first data of a first type and second data of a second type; and processor circuitry configured to: omit information about a data length of the second data in a MAC protocol data unit (PDU), place a medium access control (MAC) header in front of a MAC service data unit (MSDU) of the second data, and multiplex the first data and the second data, wherein the data length of the second data is omitted from the MAC header and an R bit (reserved bit) is set in the first bit of the first octet in the MAC header.