A multiple-access noise-based frequency offset modulation (N-FOM) system is studied in the context of near-far problem. A closed-form expression for the signal-to-noise ratio is derived and the bit error rate (BER) is evaluated. The result shows that the near-far problem compromises the performance of the multiple-access N-FOM system. Performance comparison with a standard spread-spectrum system indicates that the nearfar problem has an inherently different effect on the N-FOM communication. The error rate of a node in the N-FOM system increases at a much higher rate as the number of simultaneous communication links increases. However for small number of simultaneous links, an adaptive power control scheme can help minimize the threat of the near-far problem.

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.

A noise-based frequency offset modulation (N-FOM) system is considered, employing a wideband noise carrier, transmit reference modulation and a self-correlation receiver. The performance of such a system in the presence of in-band interference is studied by modeling the interference as a Gaussian random bandpass process and deriving a closed-form expression for the bit error rate (BER). A numerical example shows that the in-band interference has a significant impact on the performance and that the BER decreases with increasing bandwidth of the interference. The performance degradation can be reduced by a suitable choice of the frequency offset.

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A noise-based frequency offset modulation (N-FOM) system is studied in the presence of a single-tone interferer. A closed-form expression for the signal-to-noise ratio is derived and the asymptotic limit of the performance is calculated. The results show that by choosing a suitable value of the frequency offset, the N-FOM system can have an acceptable performance in the presence of single-tone interference, particularly in comparison with modulated interference. However, due to the self-correlation operation of the N-FOM receiver, many interference cross-terms are produced. This increases the overall noise which can restrict N-FOM communication in a high-interference regime.