A method of transmitting broadcast signals, the method including: generating plural input streams, wherein each of the plural input streams include plural input packets, wherein the input packets correspond to compressed IP packets; link layer processing the input packets in the plural input streams to generate link layer packets, wherein the link layer processing the input packets comprising: encapsulating the input packets into the link layer packets, and delivering the link layer packets to physical layer; physical layer processing the link layer packets in the physical layer to generate the broadcast signals; and transmitting the generated broadcast signals, wherein the link layer packet includes a link layer payload generated by using either a segment of one input packet or concatenated input packets, wherein the link layer packet includes a link layer header including a base part, the base part having a packet configuration field indicating whether the link layer payload includes either the segment or the concatenated input packets, wherein when the link layer payload includes the concatenated input packets, the base part is followed by a first additional part having length fields, each of the length fields indicating length of each of the concatenated input packets and being arranged in an order of the concatenated input packets included in the link layer payload. generating plural input streams, wherein each of the plural input streams include plural input packets, wherein the input packets correspond to compressed IP packets; link layer processing the input packets in the plural input streams to generate link layer packets, wherein the link layer processing the input packets comprising: encapsulating the input packets into the link layer packets, and delivering the link layer packets to physical layer; physical layer processing the link layer packets in the physical layer to generate the broadcast signals; and transmitting the generated broadcast signals, wherein the link layer packet includes a link layer payload generated by using either a segment of one input packet or concatenated input packets, wherein the link layer packet includes a link layer header including a base part, the base part having a packet configuration field indicating whether the link layer payload includes either the segment or the concatenated input packets, wherein when the link layer payload includes the concatenated input packets, the base part is followed by a first additional part having length fields, each of the length fields indicating length of each of the concatenated input packets and being arranged in an order of the concatenated input packets included in the link layer payload. encapsulating the input packets into the link layer packets, and delivering the link layer packets to physical layer; physical layer processing the link layer packets in the physical layer to generate the broadcast signals; and transmitting the generated broadcast signals, wherein the link layer packet includes a link layer payload generated by using either a segment of one input packet or concatenated input packets, wherein the link layer packet includes a link layer header including a base part, the base part having a packet configuration field indicating whether the link layer payload includes either the segment or the concatenated input packets, wherein when the link layer payload includes the concatenated input packets, the base part is followed by a first additional part having length fields, each of the length fields indicating length of each of the concatenated input packets and being arranged in an order of the concatenated input packets included in the link layer payload.