A novel bandwidth efficient orthogonal frequency division multiplexing scheme

In this paper, a novel spectrum efficient orthogonal signal multiplexing system based on trigonometric transform is presented. In this system, one half of the complex data is multiplexed using orthogonal real subcarrier signals (i.e., cosw₁t, cosw₂t,..., sinw₁t, sinw₂t,...) and transmitted on one carrier signal (i.e., cosw_ct) and similarly the other half is multiplexed and transmitted on another carrier (i.e., sinw_ct). In this way, the number of subcarriers will be reduced by half of the conventional OFDM systems and as a consequent; (i): the occupied bandwidth will be reduced by about half, (ii): the maximum value of the peak to average power ratio of transmitted signal will be also reduced by half, and it is more robust against the Doppler effect. Also, it is shown that the proposed signaling scheme has cyclic convolutional property such that the channel equalization in a multipath fading channel can be accomplished as simple as in OFDM systems by pointwise multiplication.