A Comparison Study For Psd Performance In Ofdm Systems Based On Using Autocorrelation Techniques

Cooperative wireless communication relay networks in OFDM-based systems have been shown to improve performance in various systems using digital modulation techniques as a form of spatial diversity, OFDM, a multicarrier modulation technique, is widely adopted because of its many advantages. Most of the time, in-band spectrum of the multicarrier signal is assumed to be flat. A recent literature analyzes the PSD and concludes that the assumption of flat spectrum is not completely correct. This paper analyzes the PSD with different approach. The modulated carriers are cropped in an interval of symbol length and viewed as a modulated pulse. An expression for the PSD with the necessary and sufficient conditions is revealed. The validity of the flat PSD assumption of multicarrier signals is also suggested. This method indeed improves the performance in comparison in various aspects of PSD with fixed and random values of input applied on functions on FFT, IFFT etc. to existing when filtering is necessary for band limited conditions.