Improved Chirp Modulation Spread Spectrum Receiver Based on Fractional Fourier Transform for Multiple Access

The fractional Fourier transform (FRFT) is one among the most efficient techniques for digital signal processing of linear frequency modulated (LFM) signal applications. Chirp (or LFM) modulation spread spectrum (CMSS) with FRFT technique is employed for demodulation of the multiple access System. The concept of multiple access is based on the use of multiple chirp signals, with different chirp rate, as carrier signal for transmission. Corresponding receiver is designed with optimal ordered FRFT block with multiplicative filter to reduce the interference. Additive white Gaussian noise (AWGN) is considered as a channel noise for evaluation of performance. Bit error rate (BER) is taken as a measure of performance with different signal to noise ratio and the results are compared with those reported in literatures. The details of the simulation techniques employed and the results of the novel receiver are presented and discussed.