An apparatus for generating a broadcast signal frame, comprising: an injection level controller configured to generate a power-reduced enhanced layer signal by reducing power of an enhanced layer signal; a combiner configured to generate a multiplexed signal by combining a core layer signal and the power-reduced enhanced layer signal; a power normalizer configured to reduce power of the multiplexed signal to a power level corresponding to the core layer signal for generating a power-reduced multiplexed signal; a time interleaver configured to generate a time-interleaved signal by performing interleaving that is applied to both the core layer signal and the power-reduced enhanced layer signal in the power-reduced multiplexed signal; and a frame builder configured to generate a broadcast signal frame including a bootstrap and a preamble using the time-interleaved signal, wherein the injection level controller reduces the power of the enhanced layer signal corresponds to a scaling factor, and the power normalizer reduces the power of the multiplexed signal corresponds to a normalizing factor, the normalizing factor applied to both the core layer signal and the power-reduced enhanced layer signal, wherein the scaling factor decreases as a power reduction of the injection level controller becomes larger, and the normalizing factor increases as the power reduction of the injection level controller becomes larger, wherein the time interleaver is shared for both a core layer corresponding to the core layer signal and an enhanced layer corresponding to the power-reduced enhanced layer signal, wherein the bootstrap is located at the beginning of the broadcast signal frame and includes a symbol representing a structure of the preamble, and the symbol corresponds to a fixed-length bit string representing a combination of a modulation scheme/code rate, a FFT size, a guard interval length and a pilot pattern of the preamble. an injection level controller configured to generate a power-reduced enhanced layer signal by reducing power of an enhanced layer signal; a combiner configured to generate a multiplexed signal by combining a core layer signal and the power-reduced enhanced layer signal; a power normalizer configured to reduce power of the multiplexed signal to a power level corresponding to the core layer signal for generating a power-reduced multiplexed signal; a time interleaver configured to generate a time-interleaved signal by performing interleaving that is applied to both the core layer signal and the power-reduced enhanced layer signal in the power-reduced multiplexed signal; and a frame builder configured to generate a broadcast signal frame including a bootstrap and a preamble using the time-interleaved signal, wherein the injection level controller reduces the power of the enhanced layer signal corresponds to a scaling factor, and the power normalizer reduces the power of the multiplexed signal corresponds to a normalizing factor, the normalizing factor applied to both the core layer signal and the power-reduced enhanced layer signal, wherein the scaling factor decreases as a power reduction of the injection level controller becomes larger, and the normalizing factor increases as the power reduction of the injection level controller becomes larger, wherein the time interleaver is shared for both a core layer corresponding to the core layer signal and an enhanced layer corresponding to the power-reduced enhanced layer signal, wherein the bootstrap is located at the beginning of the broadcast signal frame and includes a symbol representing a structure of the preamble, and the symbol corresponds to a fixed-length bit string representing a combination of a modulation scheme/code rate, a FFT size, a guard interval length and a pilot pattern of the preamble. <EOS>