1. A method of demodulating a modified dual carrier modulation (MDCM) signal using hard decision, the method comprising: generating real symbol vector candidates and imaginary symbol vector candidates that correspond to an MDCM signal pair; calculating a first norm between the real part of the MDCM signal pair and each of the real symbol vector candidates and selecting from among the real symbol vector candidates a real symbol vector candidate that has the minimum first norm as the real symbol vector; and calculating a second norm between the imaginary part of the MDCM signal pair and each of the imaginary symbol vector candidates and selecting from among the imaginary symbol vector candidates an imaginary symbol vector candidate that has the minimum second norm as the imaginary symbol vector.