15 research outputs found
Physical Layer Security for Visible Light Communication Systems:A Survey
Due to the dramatic increase in high data rate services and in order to meet
the demands of the fifth-generation (5G) networks, researchers from both
academia and industry are exploring advanced transmission techniques, new
network architectures and new frequency spectrum such as the visible light
spectra. Visible light communication (VLC) particularly is an emerging
technology that has been introduced as a promising solution for 5G and beyond.
Although VLC systems are more immune against interference and less susceptible
to security vulnerabilities since light does not penetrate through walls,
security issues arise naturally in VLC channels due to their open and
broadcasting nature, compared to fiber-optic systems. In addition, since VLC is
considered to be an enabling technology for 5G, and security is one of the 5G
fundamental requirements, security issues should be carefully addressed and
resolved in the VLC context. On the other hand, due to the success of physical
layer security (PLS) in improving the security of radio-frequency (RF) wireless
networks, extending such PLS techniques to VLC systems has been of great
interest. Only two survey papers on security in VLC have been published in the
literature. However, a comparative and unified survey on PLS for VLC from
information theoretic and signal processing point of views is still missing.
This paper covers almost all aspects of PLS for VLC, including different
channel models, input distributions, network configurations,
precoding/signaling strategies, and secrecy capacity and information rates.
Furthermore, we propose a number of timely and open research directions for
PLS-VLC systems, including the application of measurement-based indoor and
outdoor channel models, incorporating user mobility and device orientation into
the channel model, and combining VLC and RF systems to realize the potential of
such technologies
Visible Light Communication Cyber Security Vulnerabilities For Indoor And Outdoor Vehicle-To-Vehicle Communication
Light fidelity (Li-Fi), developed from the approach of Visible Light Communication (VLC), is a great replacement or complement to existing radio frequency-based (RF) networks. Li-Fi is expected to be deployed in various environments were, due to Wi-Fi congestion and health limitations, RF should not be used. Moreover, VLC can provide the future fifth generation (5G) wireless technology with higher data rates for device connectivity which will alleviate the traffic demand. 5G is playing a vital role in encouraging the modern applications. In 2023, the deployment of all the cellular networks will reach more than 5 billion users globally. As a result, the security and privacy of 5G wireless networks is an essential problem as those modern applications are in people\u27s life everywhere. VLC security is as one of the core physical-layer security (PLS) solutions for 5G networks. Due to the fact that light does not penetrate through solid objects or walls, VLC naturally has higher security and privacy for indoor wireless networks compared to RF networks. However, the broadcasting nature of VLC caused concerns, e.g., eavesdropping, have created serious attention as it is a crucial step to validate the success of VLC in wild. The aim of this thesis is to properly address the security issues of VLC and further enhance the VLC nature security. We analyzed the secrecy performance of a VLC model by studying the characteristics of the transmitter, receiver and the visible light channel. Moreover, we mitigated the security threats in the VLC model for the legitimate user, by 1) implementing more access points (APs) in a multiuser VLC network that are cooperated, 2) reducing the semi-angle of LED to help improve the directivity and secrecy and, 3) using the protected zone strategy around the AP where eavesdroppers are restricted. According to the model\u27s parameters, the results showed that the secrecy performance in the proposed indoor VLC model and the vehicle-to-vehicle (V2V) VLC outdoor model using a combination of multiple PLS techniques as beamforming, secure communication zones, and friendly jamming is enhanced. The proposed model security performance was measured with respect to the signal to noise ratio (SNR), received optical power, and bit error rate (BER) Matlab simulation results
Optical wireless communications for cyber-secure ubiquitous wireless networks
Wireless connectivity is no longer limited to facilitating communications between individuals, but is also required to support diverse and heterogeneous applications, services and infrastructures. Internet of things (IoT) systems will dominate future technologies, allowing any and all devices to create, share and process data. If artificial intelligence resembles the brain of IoT, then high-speed connectivity forms the nervous system that connects the devices. For IoT to safely operate autonomously, it requires highly secure and reliable wireless links. In this article, we shed light on the potential of optical wireless communications to provide high-speed secure and reliable ubiquitous access as an enabler for fifth generation and beyond wireless networks
Secrecy Design of Indoor Visible Light Communication Network under Downlink NOMA Transmission
In this work, we investigate the transmission sum rate as well as the secrecy
sum rate of indoor visible light communication (VLC) networks for mobile
devices with the power domain non-orthogonal multiple access (NOMA)
transmission, where multiple legitimate users are equipped with photodiodes
(PDs). We introduce a body blockage model of the legitimate users as well as
the eavesdropper to focus on the case where the communications from
transmitting light-emitting diodes (LEDs) to receiving devices are blocked by
the bodies of receiving users. Furthermore, in order to improve the secrecy
without any knowledge of the channel state information (CSI) of the
eavesdropper, a novel LED arrangement is introduced to reduce the overlapping
area covered by LED units supporting different users. We also propose two LED
operation strategies, called simple and smart LED linking, and evaluate their
performance against the conventional broadcasting in terms of transmission sum
rate and secrecy sum rate. Through computer simulations, the superiority of our
proposed strategies is demonstrated.Comment: 30 pages, 13 figures. This work has been submitted to the IEEE for
possible publication. Copyright may be transferred without notice, after
which this version may no longer be accessibl
Secure Precoding for Future Wireless Communication Systems
Department of Electrical EngineeringPhysical layer security has emerged a flourishing strategy to protect confidential information from eavesdroppers with lower computational complexity compared to cryptography. Secure precoding is a promising transmission method of physical layer security to improve security by exploiting an intrinsic attribute of wireless communications. The main goal of the secure precoding is to maximize secrecy rate in multi-input and multi-output (MIMO) systems with the presence of eavesdroppers. Unfortunately, there exists no optimal solution, and also solving the secrecy rate maximization problem becomes more challenging as networks involve a multi-user (MU) and multi-eavesdropper (ME) scenario because of its non-smoothness and non-convexity. In this thesis, I proposed a novel secure precoding algorithm for downlink MU-MIMO systems under ME threat to enhance the secrecy rate, and provide subsequent analyses for realizing ultra-reliable low latency communications (URLLC). By incorporating strong security, communication reliability, and latency, a multi-objective optimization problem is investigated in the finite blocklength (FBL) regime. The derived optimization problem aims to maximize the secrecy rate by designing a secure precoder, while simultaneously minimizing both the maximum error probability and the rate of information leakage. The proposed FBL-based optimization algorithm provides the significantly improved tradeoff among the security, the error probability, and information leakage rate. Therefore, the proposed algorithms can offer significantly improved security for future wireless communication systems.clos
Wireless networks physical layer security : modeling and performance characterization
Intrigued by the rapid growth and expand of wireless devices, data security is increasingly playing a significant role in our daily transactions and interactions with different entities. Possible examples, including e-healthcare information and online shopping, are becoming vulnerable due to the intrinsic nature of wireless transmission medium and the widespread open access of wireless links. Traditionally, the communication security is mainly regarded as the tasks at the upper layers of layered protocol stack, security techniques, including personal access control, password protection, and end-to-end encryption, have been widely studied in the open literature. More recently, plenty of research interests have been drawn to the physical layer forms of secrecy. As a new but appealing paradigm at physical layer, physical layer security is based on two pioneering works: (i) Shannonâs information-theoretic formulation and (ii) Wynerâs wiretap formulation.
On account of the fundamental of physical layer security and the different nature of various wireless network, this dissertation is supposed to further fill the lacking of the existing research outcomes. To be specific, the contributions of this dissertation can be summarized as three-fold:(i) exploration of secrecy metrics to more general fading channels; (ii) characterization a new fading channel model and its reliability and security analysis in digital communication systems; and (iii) investigation of physical layer security over the random multiple-input multiple-output (MIMO) α âÎŒ fading channels.
Taking into account the classic Alice-Bob-Eve wiretap model, the first contribution can be divided into four aspects: (i) we have investigated the secrecy performance over single-input single-output (SISO) α âÎŒ fading channels. The probability of non-zero (PNZ) secrecy capacity and the lower bound of secrecy outage probability (SOP) are derived for the special case when the main channel and wiretap channel undergo the same non-linearity fading parameter, i.e., α. Later on, for the purpose of filling the gap of lacking closed-form expression of SOP in the open literature and extending the obtained results in chapter 2 to the single-input multiple-output (SIMO) α â ÎŒ wiretap fading channels, utilizing the fact that the received signal-tonoise ratios (SNRs) at the legitimate receiver and eavesdropper can be approximated as new α âÎŒ distributed random variables (RVs), the SOP metric is therefore derived, and given in terms of the bivariate Foxâs H-function; (ii) the secrecy performance over the Fisher-Snedecor F wiretap fading channels is initially considered. The SOP, PNZ, and ASC are finalized in terms of Meijerâs G-function; (iii) in order to generalize the obtained results over α âÎŒ and Fisher-Snedecor F wiretap fading channels, a more flexible and general fading channel, i.e., Foxâs H-function fading model, are taken into consideration. Both the exact and asymptotic analysis of SOP, PNZ, and average secrecy capacity (ASC), are developed with closed-form expressions; and (iv) finally, motivated by the fact that the mixture gamma (MG) distribution is an appealing tool, which can be used to model the received instantaneous SNRs over wireless fading channels, the secrecy metrics over wiretap fading channels are derived based on the MG approach.
Due to the limited transmission power and communication range, cooperative relays or multi-hop wireless networks are usually regarded as two promising means to address these concerns. Inspired by the obtained results in Chapters 2 and 3, the second main contribution is to propose a novel but simple fading channel model, namely, the cascaded α âÎŒ. This new distribution is advantageous since it encompasses the existing cascaded Rayleigh, cascaded Nakagami-m, and cascaded Weibull with ease. Based on this, both the reliability and secrecy performance of a digital system over cascaded α âÎŒ fading channels are further evaluated. Closed-form expressions of reliability metrics (including amount of fading (AF), outage probability, average channel capacity, and average symbol error probability (ABEP).) and secrecy metrics (including SOP, PNZ, and ASC) are respectively provided. Besides, their asymptotic behaviors are also performed and compared with the exact results.
Considering the impacts of usersâ densities, spatial distribution, and the path-loss exponent on secrecy issue, the third aspect of this thesis is detailed in Chapter 8 as the secrecy investigation of stochastic MIMO system over α âÎŒ wiretap fading channels. Both the stochastic geometry and conventional space-time transmission (STT) scheme are used in the system configuration. The secrecy issue is mathematically evaluated by three metrics, i.e., connection outage, the probability of non-zero secrecy capacity and the ergodic secrecy capacity. Those three metrics are later on derived regarding two ordering scheme, and further compared with Monte-Carlo simulations
Enhancing physical layer security in wireless networks with cooperative approaches
Motivated by recent developments in wireless communication, this thesis aims to
characterize the secrecy performance in several types of typical wireless networks.
Advanced techniques are designed and evaluated to enhance physical layer security in
these networks with realistic assumptions, such as signal propagation loss, random node
distribution and non-instantaneous channel state information (CSI).
The first part of the thesis investigates secret communication through relay-assisted
cognitive interference channel. The primary and secondary base stations (PBS and SBS)
communicate with the primary and secondary receivers (PR and SR) respectively in the
presence of multiple eavesdroppers. The SBS is allowed to transmit simultaneously with
the PBS over the same spectrum instead of waiting for an idle channel. To improve
security, cognitive relays transmit cooperative jamming (CJ) signals to create additional
interferences in the direction of the eavesdroppers. Two CJ schemes are proposed to
improve the secrecy rate of cognitive interference channels depending on the structure of
cooperative relays. In the scheme where the multiple-antenna relay transmits weighted
jamming signals, the combined approach of CJ and beamforming is investigated. In
the scheme with multiple relays transmitting weighted jamming signals, the combined
approach of CJ and relay selection is analyzed. Numerical results show that both these
two schemes are effective in improving physical layer security of cognitive interference
channel.
In the second part, the focus is shifted to physical layer security in a random wireless
network where both legitimate and eavesdropping nodes are randomly distributed. Three
scenarios are analyzed to investigate the impact of various factors on security. In
scenario one, the basic scheme is studied without a protected zone and interference. The
probability distribution function (PDF) of channel gain with both fading and path loss
has been derived and further applied to derive secrecy connectivity and ergodic secrecy
capacity. In the second scenario, we studied using a protected zone surrounding the source
node to enhance security where interference is absent. Both the cases that eavesdroppers
are aware and unaware of the protected zone boundary are investigated. Based on the
above scenarios, further deployment of the protected zones at legitimate receivers is
designed to convert detrimental interference into a beneficial factor. Numerical results
are investigated to check the reliability of the PDF for reciprocal of channel gain and to
analyze the impact of protected zones on secrecy performance.
In the third part, physical layer security in the downlink transmission of cellular network
is studied. To model the repulsive property of the cellular network planning, we assume
that the base stations (BSs) follow the MatÂŽern hard-core point process (HCPP), while
the eavesdroppers are deployed as an independent Poisson point process (PPP). The
distribution function of the distances from a typical point to the nodes of the HCPP is
derived. The noise-limited and interference-limited cellular networks are investigated
by applying the fractional frequency reuse (FFR) in the system. For the noise-limited
network, we derive the secrecy outage probability with two different strategies, i.e. the
best BS serve and the nearest BS serve, by analyzing the statistics of channel gains. For
the interference-limited network with the nearest BS serve, two transmission schemes are
analyzed, i.e., transmission with and without the FFR. Numerical results reveal that both
the schemes of transmitting with the best BS and the application of the FFR are beneficial
for physical layer security in the downlink cellular networks, while the improvement du