Broadcast signal frame generating apparatus and broadcast signal frame generating method using bootstrap and preamble

A method of generating a broadcast signal frame, comprising:

• generating a power-reduced enhanced layer signal by reducing power of an enhanced layer signal;
• generating a multiplexed signal by combining a core layer signal and the power-reduced enhanced layer signal;
• generating a power-reduced multiplexed signal by reducing power of the multiplexed signal;
• generating a time-interleaved signal by performing time interleaving corresponding to the power-reduced multiplexed signal;
• and
• generating a broadcast signal frame including a bootstrap and a preamble using the time-interleaved signal,
• wherein the preamble includes L1-Basic and L1-Detail, and the bootstrap includes a symbol representing a structure of the L1-Basic, and
• wherein the symbol corresponds to a fixed-length bit string signaling a signaling protection mode of the L1-Basic along with OFDM parameters corresponding to the L1-Basic.