This paper proposes a new modulation technique that doubles the transmission rate of data symbols in digitally modulated systems. The rate is doubled without any changes in the used signal constellation or the modulated signal bandwidth. The proposal doubles the transmission rate by using Complex-Exponential-Basic-Functions (CEBFs) instead of Real-Sinusoidal-Basic-Functions (RSBFs) in synthesizing of digitally modulated signal. If CEBFs are used as carriers, the time-domain samples of the modulated signals will be complex. Two orthogonal pulses reshape the real and imaginary parts of the complex-modulated symbols. The reshaped symbols are added to form one real-modulated signal. The reshaping pulses are chosen to be Hilbert-Transform pair. The paper shows that the canonical form of the modulated symbol in the proposed system looks like the canonical form of the Single-Side-Band modulation. The bandwidth efficiency of the proposed scheme is double the bandwidth efficiency in systems use RSBFs. |
