Spectrally shaped generalized multitone direct-sequence spread spectrum

We propose a new modulation scheme called spectrally shaped generalized multitone direct-sequence spread spectrum (S-MT-DS-SS), with adjustable parameters on each subcarrier. The parameters we adjust are each subcarrier signal´s amplitude, data rate, chip rate, and the frequency separation between subcarriers. By appropriate selection of these parameters, we can obtain moderate shaping of the transmitted signal spectrum, including sidelobe reduction, without pulse shape filtering. The spectral shaping is attained by concentrating energy in the spectral mainlobe, without significantly increasing sidelobe levels. Analysis and simulation results show that by properly choosing signal parameters, we can reduce the level of the spectral sidelobes, while slightly changing the width of mainlobe and simultaneously obtaining error probability performance comparable to that of the conventional MT-DS-SS approach.