Comparative analysis of wideband communication techniques: Chirp spread spectrum and direct sequence spread spectrum

This paper provides a comparative performance analysis of the direct sequence spread spectrum (DSSS) and the chirp spread spectrum (CSS) for a multi-nodes connectivity over a flat fading channel. The DSSS has strong rejection ability against multi-path propagation interference and has lower power spectral density, while CSS modulated signal is spread by the linear chirps of variable chirp rates and phases which creates pseudo-orthogonal spreading codes and makes it resilient and robust against channel noise and Dopplers spread even at very low power. A simulation model for both techniques with transmission channel noise and frequency and time offsets has been developed in MATLAB and bit error rates (BER) of demodulated signals have been compared. Simulation results show that DSSS technique requires a comparatively difficult demodulation than CSS, as it requires a strong synchronization of transmitter and receiver. On the same transmitting power, CSS outperforms the DSSS.