Methods and apparatuses for transmitting/receiving control information in a system in which multiple frequencies are used to carry multiple services by means of transmission frames, which are constituted of time resources and/or time-frequency resources. Control information regarding frame configuration information is not transmitted over a separate control channel but over a data channel. The service traffic for each non-primary service traffic may include control information for a primary service. Thus, even when a receiver changes the current service to a target service, control information necessary to detect the location of the target service in a frame and demodulate the target service can be acquired, and thus a service change can be made without reading a separate control channel.