Signal multiplexing device and signal multiplexing method using layered division multiplexing

A signal multiplexing method, 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;
• reducing power of the multiplexed signal to a power level corresponding to the core layer signal to generate a power-reduced multiplexed signal;
• generating a time-interleaved signal by performing time-interleaving that is applied to both the core layer signal and the power-reduced enhanced layer signal in the power-reduced multiplexed signal, after combining the core layer signal and the power-reduced enhanced layer signal;
• and
• generating a broadcast signal frame using the time-interleaved signal and Layer 1 signaling information,
• wherein the Layer 1 signaling information includes injection level information of an injection level controller, the injection level information corresponds to a scaling factor of the injection level controller, and the scaling factor corresponds to a reduction in the power of the enhanced layer signal, and
• wherein the time-interleaving is shared for both a core layer corresponding to the core layer signal and an enhanced layer corresponding to the enhanced layer signal.