Quasi-Orthogonal Multi-Carrier CDMA

It is believed that the dimension of the signal space with interval T and bandwidth W is 2WT, while we cannot make the out-of-band and out-of-time energies of any waveform zero. We propose a Gaussian pulse shaping for multi-carrier CDMA systems to utilize the time and frequency resources effectively. Gaussian pulses have ICI and ISI; they are not orthogonal. Markovity of spreading codes save the drawback of ICI and ISI. Overlapped Gaussian pulses increase the spectral efficiency.