A broadcast signal transmitter includes a first bit interleaver to bit interleave core layer data of at least one core layer Physical Layer Pipe (PLP) for a core layer; a second bit interleaver to bit interleave enhanced layer data of at least one enhanced layer PLP for an enhanced layer; an injection level controller to control power ratio between the bit-interleaved core layer data and the bit-interleaved enhanced layer data; a combiner to combine the core layer data and the enhanced layer data which the power ratio is controlled and to output Layered Division Multiplexing (LDM) data; a power normalizer to normalize power of the LDM data; a time interleaver to perform time-interleaving on the LDM data which the power is normalized; a framer to generate a signal frame comprising a preamble and the time-interleaved LDM data; and a modulator to perform Orthogonal Frequency Division Multiplexing modulation on the signal frame.