4 research outputs found
Cyclostationary-based jammer detection algorithm for wide-band radios using compressed sensing
A new algorithm for jammer detection is proposed in this work for wide-band (WB) cognitive radio networks. First, the received WB signal, which is comprised of multiple narrow-band (NB) signals, is recovered from sub-Nyquist rate samples using compressed sensing. Compressed sensing allows us to alleviate Nyquist rate sampling requirements at the receiver A/D converter. After the Nyquist rate signal has been recovered, a cyclostationary feature detector is employed on this estimated signal to compute the cyclic features. Finally, the proposed algorithm uses the second order statistics, namely, the spectral correlation function (SCF), to classify each NB signal as a legitimate signal or a jamming signal. In the end, performance of the proposed algorithm is shown with the help of Monte-Carlo simulations under different empirical setups
Data-Driven Approach based on Deep Learning and Probabilistic Models for PHY-Layer Security in AI-enabled Cognitive Radio IoT.
PhD Theses.Cognitive Radio Internet of Things (CR-IoT) has revolutionized almost every eld of life
and reshaped the technological world. Several tiny devices are seamlessly connected in
a CR-IoT network to perform various tasks in many applications. Nevertheless, CR-IoT
su ers from malicious attacks that pulverize communication and perturb network performance.
Therefore, recently it is envisaged to introduce higher-level Arti cial Intelligence
(AI) by incorporating Self-Awareness (SA) capabilities into CR-IoT objects to facilitate
CR-IoT networks to establish secure transmission against vicious attacks autonomously.
In this context, sub-band information from the Orthogonal Frequency Division Multiplexing
(OFDM) modulated transmission in the spectrum has been extracted from the
radio device receiver terminal, and a generalized state vector (GS) is formed containing
low dimension in-phase and quadrature components. Accordingly, a probabilistic method
based on learning a switching Dynamic Bayesian Network (DBN) from OFDM transmission
with no abnormalities has been proposed to statistically model signal behaviors
inside the CR-IoT spectrum. A Bayesian lter, Markov Jump Particle Filter (MJPF),
is implemented to perform state estimation and capture malicious attacks.
Subsequently, GS containing a higher number of subcarriers has been investigated. In
this connection, Variational autoencoders (VAE) is used as a deep learning technique
to extract features from high dimension radio signals into low dimension latent space
z, and DBN is learned based on GS containing latent space data. Afterward, to perform
state estimation and capture abnormalities in a spectrum, Adapted-Markov Jump
Particle Filter (A-MJPF) is deployed. The proposed method can capture anomaly that
appears due to either jammer attacks in transmission or cognitive devices in a network
experiencing di erent transmission sources that have not been observed previously. The
performance is assessed using the receiver
Compressive Sensing of Multiband Spectrum towards Real-World Wideband Applications.
PhD Theses.Spectrum scarcity is a major challenge in wireless communication systems with their
rapid evolutions towards more capacity and bandwidth. The fact that the real-world
spectrum, as a nite resource, is sparsely utilized in certain bands spurs the proposal
of spectrum sharing. In wideband scenarios, accurate real-time spectrum sensing, as an
enabler of spectrum sharing, can become ine cient as it naturally requires the sampling
rate of the analog-to-digital conversion to exceed the Nyquist rate, which is resourcecostly
and energy-consuming. Compressive sensing techniques have been applied in
wideband spectrum sensing to achieve sub-Nyquist-rate sampling of frequency sparse
signals to alleviate such burdens.
A major challenge of compressive spectrum sensing (CSS) is the complexity of the sparse
recovery algorithm. Greedy algorithms achieve sparse recovery with low complexity but
the required prior knowledge of the signal sparsity. A practical spectrum sparsity estimation
scheme is proposed. Furthermore, the dimension of the sparse recovery problem
is proposed to be reduced, which further reduces the complexity and achieves signal
denoising that promotes recovery delity. The robust detection of incumbent radio is
also a fundamental problem of CSS. To address the energy detection problem in CSS,
the spectrum statistics of the recovered signals are investigated and a practical threshold
adaption scheme for energy detection is proposed. Moreover, it is of particular interest to
seek the challenges and opportunities to implement real-world CSS for systems with large
bandwidth. Initial research on the practical issues towards the real-world realization of
wideband CSS system based on the multicoset sampler architecture is presented.
In all, this thesis provides insights into two critical challenges - low-complexity sparse
recovery and robust energy detection - in the general CSS context, while also looks
into some particular issues towards the real-world CSS implementation based on the
i
multicoset sampler