Performance analysis of noise-based frequency offset modulation in dense frequency-selective fading channels

A frequency-offset transmit-reference system using a noise carrier has been studied in dense frequency-selective fading channels. Neglecting inter-symbol-interference (ISI), a closed-form expression for the signal-to-noise ratio is derived. With the help of numerical examples and simulations, the system is analyzed in environments with and without ISI. The results indicate robustness of the system against frequency-selective fading in certain multipath environments. Further improvement is achieved by using high spreading factors. However, ISI limits the system performance in environments where the delay spread is large.