Spectrally shaped generalized multitone direct sequence spread spectrum.

摘要

In the work of this dissertation, we propose a new modulation scheme called spectrally-shaped generalized multitone direct-sequence spread spectrum (SSG-MT-DS-SS) which is the generalized multitone/multicarrier-DS-SS (MC/MT-DS-SS) scheme. With SSG-MT-DS-SS, we can shape the spectrum of the transmitted signal with out using any kind of pulse shape filter. The spectral shaping is achieved via allowing the data rate, bit energy, processing gain, and carrier frequency of each subcarrier to be adjustable. Specifically, the parameters of each subcarrier are not constrained to be identical as conventional MC/MT-DS-SS schemes. By varying these parameters, we alter the energy distribution of the SSG-MT-DS-SS signal, and, hence, the spectrum of the transmitted signal. In this dissertation, we investigate the spectral shaping mechanism and the shaping capabilities of SSG-MT-DS-SS. We provide a general form of the power spectrum density of SSG-MT-DS-SS with arbitrary parameters on each subcarrier, and develop a numerical method to select the parameters of SSG-MT-DS-SS according to some given design requirements. We derive the general form of the bit error probability SSG-MT-DS-SS in additive white Gaussian noise channel and the dispersive channel. In addition, we also investigate the error performance of SSG-MT-DS-SS with sinusoidal chip waveforms on each subcarrier. It is shown that with the properly selected sinusoidal chip waveform and the dual sidebands combining scheme, we can improve the error performance of SSG-MT-DS-SS in the dispersive channel. The use of error correction code, e.g., Hamming code, and the peak to average power ratio of the SSG-MT-DS-SS are also investigated in this dissertation.