Spectral efficiency improvement techniques for nonlinearly amplified mobile radio systems
A study is reported of 'double-jump' Nyquist channel filters which lead to reduced spectral spreading and an important bit error rate (BER) performance in nonlinearly amplified (NLA) mobile radio systems. In linearly amplified systems the filter retains the intersymbol-interference free properties of Nyquist filters and has the advantage of lower overshoot than the conventional raised cosine (RCS) filters. This reduced overshoot power (ROP) filter leads to a 1 dB system gain over conventional RCS filtered 16-QAM systems in NLA channels. >
The design of multivariable systems can be approached with many different design objectives. An appealing approach from a mathematical point of view is to describe the dynamics of plant and compensator in state-spaco form, transform the resulting augmented system into a problem involving a system performance index such as pole assignment, and apply optimization techniques to choose compensator parameters. This paper develops a methodology whereby exact or partial pole assignment under variations of plant characteristics is incorporated into the system performance index. Through calculations of the gradients of the performance index with respect to compensator parameters, one is able to apply derivative optimization methods to the design problem. Examples are provided to illustrate the design methodology.