A digital broadcasting transmission and/or reception system having an improved reception performance and a signal-processing method thereof. A digital broadcasting transmitter comprises a randomizer to input and randomize data streams including a plurality of segments having at least one segment having one or more null packets, a null packet exchanger to create known data having a predetermined pattern and to replace the null packets at positions of the segments having the null packets of the randomized data streams to insert the known ‘data, an encoder to encode the data streams to which the known data is inserted, and a modulation/RF unit to modulate, RF-modulate, and transmit the encoded data streams. A digital broadcasting receiver detects the known data’ from a signal received from the digital broadcasting transmitter and uses the detected known data for synchronization and equalization, so that a digital broadcasting reception performance of the digital broadcasting receiver can be improved at poor multipath channels.