A transmitting apparatus comprising: a packet generator configured to generate a packet comprising a header and payload based on input data; a frame generator configured to generate a frame comprising the packet; a transmitter configured to transmit the frame, characterised in that the header comprises a base header which comprises; a first field for indicating a packet type of the input data, a second field which set to a first value indicates that a variable header is present and which set to a second value indicates that the variable header is not present, and a third field which set to a third value indicates that the base header comprises a length field indicating a length of the payload and set to a fourth value indicates that the length field indicates least significant bits (LSBs) of the length of the payload and that a fourth field in the variable header indicates most significant bits (MSBs) of the length of the payload, wherein the fourth field is connected to the length field to indicate an actual length of the payload, and wherein, if the variable header is present, a fifth field in the variable header is set to a fifth value indicating that an extension header is present or is set to a sixth value indicating that the extension header is not present, and wherein the extension header includes information for processing the packet type of the input data defined in the first field. a packet generator configured to generate a packet comprising a header and payload based on input data; a frame generator configured to generate a frame comprising the packet; a transmitter configured to transmit the frame, characterised in that the header comprises a base header which comprises; a first field for indicating a packet type of the input data, a second field which set to a first value indicates that a variable header is present and which set to a second value indicates that the variable header is not present, and a third field which set to a third value indicates that the base header comprises a length field indicating a length of the payload and set to a fourth value indicates that the length field indicates least significant bits (LSBs) of the length of the payload and that a fourth field in the variable header indicates most significant bits (MSBs) of the length of the payload, wherein the fourth field is connected to the length field to indicate an actual length of the payload, and wherein, if the variable header is present, a fifth field in the variable header is set to a fifth value indicating that an extension header is present or is set to a sixth value indicating that the extension header is not present, and wherein the extension header includes information for processing the packet type of the input data defined in the first field. a first field for indicating a packet type of the input data, a second field which set to a first value indicates that a variable header is present and which set to a second value indicates that the variable header is not present, and a third field which set to a third value indicates that the base header comprises a length field indicating a length of the payload and set to a fourth value indicates that the length field indicates least significant bits (LSBs) of the length of the payload and that a fourth field in the variable header indicates most significant bits (MSBs) of the length of the payload, wherein the fourth field is connected to the length field to indicate an actual length of the payload, and wherein, if the variable header is present, a fifth field in the variable header is set to a fifth value indicating that an extension header is present or is set to a sixth value indicating that the extension header is not present, and wherein the extension header includes information for processing the packet type of the input data defined in the first field.