Although combining Full Duplex (FD) and Cognitive Radio (CR) technologies can provide several benefits, the presence of the residual self-interference (RSI) at the FD transceiver may influence the spectrum sensing capabilities. In particular, focusing on the blind eigenvalue-based detectors (EVDs), this paper shows that operating at mmWave widebands, the RSI is a colored noise strongly affecting the detection performance even when it is characterized by low power. Consequently, we propose here a whitened detector whose novelty consists in the real-time computation of the whitening matrix, differently from previous works which employ an offline computation. The proposed whitening matrix computation uses a sample covariance matrix (SCM) regularization tailored for the FD scenario, instead of the conventional SCM estimator. Particularly, we prove that the proposed whitened detector is robust against RSI power uncertainty, attaining a constant false alarm rate under typical FD operating conditions. Finally, we show that our method provides computational load reduction and faster convergence to the theoretical false alarm probability characteristic of the white noise case. Numerical simulations validate the theoretical analysis confirming the better performance of the proposed whitening approach, particularly when applied to the sphericity test, in comparison to the offline-based approach.

Recently, with the advances in self-interference cancellation, full-duplex (FD) techniques have become a feasible approach to improve the spectrum usage in new generation wireless systems. In particular, in cognitive radio networks, FD allows a secondary user to simultaneously sense the spectrum and transmit, improving the network efficiency. However, the residual self interference (RSI) arising from an imperfect cancellation, represents a bottleneck for the spectrum sensing performance. This paper analytically demonstrates that RSI represents a colored noise which leads to the SNR Wall phenomenon making the typical OFDM signal detectors no longer robust. To overcome this drawback, we propose a generalized likelihood ratio test detector exploiting the multipath correlation due to the primary user’s (PU) channel. It is proven that the proposed method is not affected by the SNR Wall, hence it is robust w.r.t an imperfect self-interference cancellation. Specifically, best detection performance is achieved when an approximated knowledge of the maximum delay spread of the PU channel is available, otherwise it is shown that a limited performance degradation occurs. Moreover, provided results highlight that our approach outperforms the classical alternatives in different scenarios, including when PU employs a mixed numerology OFDM signal, which characterizes the 5G New Radio waveform.

Spectrum sensing plays a key role in cognitive radio technology to acquire information on the occupancy status of the channel. Cyclostationary spectrum sensing is considered one of the most promising approaches. However, its performance is severely degraded by a mismatch between the actual and the nominal cyclic frequency [i.e. cyclic frequency offset (CFO)]. This is particularly true for vehicular networks, due to the high mobility and particularly to the presence of a non‐zero radial acceleration between the transmitter and the receiver that makes the signal filtered out by the Doppler channel chirped, thus introducing the CFO. Consequently, the signal to be detected has to be properly modelled as a generalised almost‐cyclostationary process. The proposed approach performs a maximum‐likelihood estimation of the CFO jointly to the detection exploiting multiple cycles, through a maximisation of the generalised likelihood ratio test. The closed‐form of false alarm probability is derived highlighting that this approach represents a constant false alarm rate detector. Numerical evaluations are provided to show the correctness of the theoretical analysis and that the performance is approximatively constant for a large range of CFO values. Moreover, comparisons with existing algorithms are provided.

Power line communication technology receives today a renewed attention for a wide class of advanced applications and services, thanks to the advantage of using the existing electrical infrastructure, which requires only limited deployment costs. However, wires have been originally designed for power and not for data, and signal propagation is affected by several impairments such as impulsive noise and frequency selectivity. On the other end, new emerging application perspectives-mainly related to the smart grid or Internet of Things paradigms-need reliable unicast and/or multicast information delivery methodologies. This paper deals with an efficient multicast power line communication system based on the use of a decision direct impulsive noise mitigation scheme and of multiple transmissions of symbols in the frequency domain, allowing an efficient exploitation of the communication channel frequency diversity. The performance of the reliable multicast power line communication system is derived by resorting to the application of the absorbing Markov chain theory in terms of mean overall delivery delay and throughput, in relation to different application scenarios. Moreover, a suitable optimization procedure is also proposed here in order to achieve the best performance. The advantages of the proposed optimized reliable multicast power line communication system are finally validated by comparisons with a classical system.

A multiuser detection scheme is presented, which is based on the interference cancellation principle for noncoherent optical direct-sequence code division multiple access (CDMA) systems. The performance of the proposed receiver, in terms of bit error probability, is derived by means of an analytical approach. Simulation results are also reported in order to validate the analytical predictions. Performance comparisons with the classical matched filter receiver and other non-coherent optical CDMA (OCDMA) receivers already proposed in the literature are discussed in order to highlight the good behavior of the receiver scheme under consideration.