Peak-to-Average Power Reduction (PAPR) by Pulse Shaping Using a Modified Raised Cosine Filters

Orthogonal frequency division (OFDM) technologies allow data transmission over band limited channels requires pulse shaping to eliminate or control intesymbol interference (ISI). Nyquist filters provide ISI-free transmission. Here we introduce a new family of modified raised cosine filters is formulated in an effort to reduce the peak-to-average power ratio (PAPR) of the baseband signal over that obtained using the conventional raised cosine filter, while maintaining the same excess bandwidth and the zero intersymbol interference condition. The modified filters contain a new design parameter d, giving an additional degree of freedom to minimize PAPR for a given roll-off factor ¿. It is shown that PAPR can be reduced by more than .5 dB over most of the ¿ range. Closed form expressions for the frequency and impulse responses of the modified raised cosine filters are presented, along with the optimum value of d that yields minimum PAPR as a function of ¿.