Patent ID: 8705658

Claim:
A modulator in a broadcasting and communication system, the modulator comprising: a first quadrature phase shift keying (QPSK) modulating unit QPSK-modulating first data including in-phase (I) data and quadrature (Q) data to generate a first signal; a phase rotating unit rotating a phase of the first signal by a predetermined angle θ to generate a phase rotated signal; a second QPSK modulating unit QPSK-modulating second data different from the first data and including I′ data and Q′ data to generate a second signal; and a layer modulating unit modulating the phase rotated signal and the second signal to output a final signal, wherein the layer modulating unit includes: a detecting unit detecting a value of the phase rotated signal on a real (Re) axis or an imaginary (Im) axis; a binary phase shift keying (BPSK) mapping unit mapping the second signal onto a constellation; and a multiplexer (MUX) multiplexing the phase rotated signal and the second signal mapped onto the constellation in a single signal stream form to output the final signal.