| Summary: | Power amplifiers are nonlinear devices that traditionally have been tried linearized by means of predistortion. The nonlinear impact can be identified by sidelobes in the frequency domain. By accepting a certain sidelobe level, this implies that we also accept a somewhat nonlinear characteristic on the resulting cascade of our transmitter. The main question raised in this thesis is: How is the optimal nonlinear cascade that maximizes transmitted power defined when some given out-of-band spectral requirements are fulfilled? The problem has been limited such that examinations have been done on a single carrier system seen in context to a chosen set of out-of-band spectral requirements. The different nonlinear characteristics have been represented by means of B-splines. Thus, the results obtained are only the best set of parameters in the model utilized, and hence, only a sub-optimal solution to the problem. Results are presented for different spectral restrictions. Simulations performed suggest that a linear characteristic is the optimal, when restrictions are placed within the sidelobe level close to the mainlobe. When the first sidelobe is allowed to grow unlimited, a parameter set using 2-segments B-spline have proved to give the highest average transmitted
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