ICASSP '99 Proceedings of the Acoustics, Speech, and Signal Processing, 1999. on 1999 IEEE International Conference - Volume 05
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In this chapter, various issues on pulse shaping waveform design for bandwidth efficient digital modulations will be addressed. Here what we concern about the pulse shaping waveforms is the physical appearances or shapes each information data bit or symbol take before carrier modulations. It is well known that the spectral characteristics of a carrier modulated signal can be uniquely determined by its base-band signal before modulation, and thus the waveform shape applied to pre-modulated signals is of ultimate importance to ensure overall bandwidth-efficiency of a wireless communication system. This chapter starts with an overview on the evolution of pulse shaping technologies from early digital modulation schemes to recently emerging new carrier modulations such as quadrature-overlapped modulations. The impact of the pulse shaping technologies on both bandwidth-efficiency and power-efficiency, which are two essential merit parameters of a digital modem, will also be discussed. The majority of the content in this chapter, however, is dedicated to the discussions on shaping pulse design methodology as well as performance analysis of a pulse-shaped digital modem, in which various shaping pulse design methods (including those commonly referred and those recently proposed in the literature) will be presented. To measure the effectiveness of the pulse-shaping techniques, different pulse shaped digital modulations will be evaluated and then compared in terms of their spectral characteristics, the sensitivity of their performance against synchronization timing jitter as well as their bit error rate performance, where the emphasis will be put on the pulse-shaped quadrature-overlapped (QO) modems under bandpass nonlinear channels, which usually exist in satellite and mobile cellular systems. Several new pulse shaped QO modulation schemes, which adopt various novel pulse shaping waveforms generated by time-domain convolution method, wilt be presented and their performance analysis will be carried out in comparison with other traditional digital modems, such as QPSK, OQPSK, MSK and so forth.