A broadcast signal transmitter includes a first Forward Error Correction (FEC) encoder configured to encode core layer data, a second FEC encoder configured to encode enhanced layer data, an injection level controller configured to control power ratio between the encoded core layer data and the encoded enhanced layer data, a combiner configured to combine the core layer data and the enhanced layer data and to output Layered Division Multiplexing (LDM) data, a power normalizer configured to normalize power of the outputted LDM data, a time interleaver configured to time-interleave the LDM data, a framer configured to generate a signal frame comprising a preamble and the time-interleaved LDM data, the preamble carrying signaling information, and a modulator configured to perform Orthogonal Frequency Division Multiplexing (OFDM) modulation on the generated signal frame.