A method of processing a digital broadcast signal in a transmitter includes encoding signaling information including a transmission parameter channel, including transmission parameters and a fast information channel (FIC) including cross layer information for mobile service acquisition, and transmitting the broadcast signal including ensembles including the encoded signaling information. The FIC is divided into FIC segments, each FIC segment including a FIC segment header and a FIC segment payload. The FIC segment header includes type information indicating a type of the FIC segment, the FIC further including a first ensemble identifier identifying a specific ensemble including a service map table (SMT). The SMT includes a header including a second ensemble identifier corresponding to the first ensemble identifier, a payload including service acquisition information of the specific ensemble, and IP access information of a mobile service for acquiring an IP datagram of the mobile service from the specific ensemble.