Multiuser Communication Using Chirp Signals of Equal Chirp Rate

Chirp modulation can be considered as a type of spread spectrum modulation process providing high processing gain, robustness to multipath interference, requirement of low power. The paper presents a multiuser communication system using chirp signals having the same chirp rate and different initial frequencies for different users. The design of the chirp waveforms is discussed, and the correlations between them and the conditions for minimizing interference are derived. Analytical expressions of bit error rate (BER) performance for coherent and noncoherent cases for single user and multiuser systems using the proposed set of linear chirp signals are analyzed in additive white Gaussian noise (AWGN) and Rayleigh fading channels. The performance of the multiuser system is compared with that of reported linear chirp spread spectrum (CSS) systems. Performance of the presented system is also evaluated under Doppler frequency offset scenario.