Wireless multimedia sensor networks, security and key management

Wireless Multimedia Sensor Networks (WMSNs) have emerged and shifted the focus from the typical scalar wireless sensor networks to networks with multimedia devices that are capable to retrieve video, audio, images, as well as scalar sensor data. WMSNs are able to deliver multimedia content due to the availability of inexpensive CMOS cameras and microphones coupled with the significant progress in distributed signal processing and multimedia source coding techniques. These mentioned characteristics, challenges, and requirements of designing WMSNs open many research issues and future research directions to develop protocols, algorithms, architectures, devices, and testbeds to maximize the network lifetime while satisfying the quality of service requirements of the various applications. In this thesis dissertation, we outline the design challenges of WMSNs and we give a comprehensive discussion of the proposed architectures and protocols for the different layers of the communication protocol stack for WMSNs along with their open research issues. Also, we conduct a comparison among the existing WMSN hardware and testbeds based on their specifications and features along with complete classification based on their functionalities and capabilities. In addition, we introduce our complete classification for content security and contextual privacy in WSNs. Our focus in this field, after conducting a complete survey in WMSNs and event privacy in sensor networks, and earning the necessary knowledge of programming sensor motes such as Micaz and Stargate and running simulation using NS2, is to design suitable protocols meet the challenging requirements of WMSNs targeting especially the routing and MAC layers, secure the wirelessly exchange of data against external attacks using proper security algorithms: key management and secure routing, defend the network from internal attacks by using a light-weight intrusion detection technique, protect the contextual information from being leaked to unauthorized parties by adapting an event unobservability scheme, and evaluate the performance efficiency and energy consumption of employing the security algorithms over WMSNs

Dual Band-Notched Microstrip-Fed Vivaldi Antenna Utilizing Compact EBG Structures

We propose an ultra-wideband (UWB) antipodal Vivaldi antenna (AVA) with high-Q stopband characteristics based on compact electromagnetic bandgap (EBG) structures. First, an AVA is designed and optimized to operate over an UWB spectrum. Then, two pairs of EBG cells are introduced along the antenna feed line to suppress the frequency components at 3.6–3.9 and 5.6–5.8 GHz (i.e., WiMAX and ISM bands, resp.). Simulated and measured results show a voltage standing wave ratio (VSWR) below 2 for the entire 3.1–10.6 GHz band with high attenuation at the two selected subbands. This simple yet effective approach eliminates the need to deform the antenna radiators with slots/parasitic elements or comprise multilayer substrates. Furthermore, the flexibility it offers in terms of controlling both the number and locations of the band-reject frequencies is advantageous for antennas with nonuniform flares as in the AVA

Non-uniform transmission line ultra-wideband wilkinson power divider

We propose a technique with clear guidelines to design a compact planar Wilkinson power divider (WPD) for ultra-wideband (UWB) applications. The design procedure is accomplished by replacing the uniform transmission lines in each arm of the conventional power divider with varying-impedance profiles governed by a truncated Fourier series. Such non-uniform transmission lines (NTLs) are obtained through the even mode analysis, whereas three isolation resistors are optimized in the odd mode circuit to achieve proper isolation and output ports matching over the frequency range of interest. For verification purposes, an in-phase equal split WPD is designed, simulated, and measured. Simulation and measurement results show that the input and output ports matching as well as the isolation are below -10 dB, whereas the transmission parameters are in the range of (-3:2 dB, -4:2 dB) across the 3.1 GHz-10.6 GHz band

A Secure Cluster-Based Multipath Routing Protocol for WMSNs

The new characteristics of Wireless Multimedia Sensor Network (WMSN) and its design issues brought by handling different traffic classes of multimedia content (video streams, audio, and still images) as well as scalar data over the network, make the proposed routing protocols for typical WSNs not directly applicable for WMSNs. Handling real-time multimedia data requires both energy efficiency and QoS assurance in order to ensure efficient utility of different capabilities of sensor resources and correct delivery of collected information. In this paper, we propose a Secure Cluster-based Multipath Routing protocol for WMSNs, SCMR, to satisfy the requirements of delivering different data types and support high data rate multimedia traffic. SCMR exploits the hierarchical structure of powerful cluster heads and the optimized multiple paths to support timeliness and reliable high data rate multimedia communication with minimum energy dissipation. Also, we present a light-weight distributed security mechanism of key management in order to secure the communication between sensor nodes and protect the network against different types of attacks. Performance evaluation from simulation results demonstrates a significant performance improvement comparing with existing protocols (which do not even provide any kind of security feature) in terms of average end-to-end delay, network throughput, packet delivery ratio, and energy consumption

An efficient design of 45-nm CMOS low-noise charge sensitive amplifier for wireless receivers

Amplifiers are widely used in signal receiving circuits, such as antennas, medical imaging, wireless devices and many other applications. However, one of the most challenging problems when building an amplifier circuit is the noise, since it affects the quality of the intended received signal in most wireless applications. Therefore, a preamplifier is usually placed close to the main sensor to reduce the effects of interferences and to amplify the received signal without degrading the signal-to-noise ratio. Although different designs have been optimized and tested in the literature, all of them are using larger than 100 nm technologies which have led to a modest performance in terms of equivalent noise charge (ENC), gain, power consumption, and response time. In contrast, we consider in this paper a new amplifier design technology trend and move towards sub 100 nm to enhance its performance. In this work, we use a pre-well-known design of a preamplifier circuit and rebuild it using 45 nm CMOS technology, which is made for the first time in such circuits. Performance evaluation shows that our proposed scaling technology, compared with other scaling technology, extremely reduces ENC of the circuit by more than 95%. The noise spectral density and time resolution are also reduced by 25% and 95% respectively. In addition, power consumption is decreased due to the reduced channel length by 90%. As a result, all of those enhancements make our proposed circuit more suitable for medical and wireless devices

Probabilistic analysis of security attacks in cloud environment using hidden Markov models

© 2020 John Wiley & Sons, Ltd. The rapidly growing cloud computing paradigm provides a cost-effective platform for storing, sharing, and delivering data and computation through internet connectivity. However, one of the biggest barriers for massive cloud adoption is the growing cybersecurity threats/risks that influence its confidence and feasibility. Existing threat models for clouds may not be able to capture complex attacks. For example, an attacker may combine multiple security vulnerabilities into an intelligent, persistent, and sequence of attack behaviors that will continuously act to compromise the target on clouds. Hence, new models for detection of complex and diversified network attacks are needed. In this article, we introduce an effective threat modeling approach that has the ability to predict and detect the probability of occurrence of various security threats and attacks within the cloud environment using hidden Markov models (HMMs). The HMM is a powerful statistical analysis technique and is used to create a probability matrix based on the sensitivity of the data and possible system components that can be attacked. In addition, the HMM is used to provide supplemental information to discover a trend attack pattern from the implicit (or hidden) raw data. The proposed model is trained to identify anomalous sequences or threats so that accurate and up-to-date information on risk exposure of cloud-hosted services are properly detected. The proposed model would act as an underlying framework and a guiding tool for cloud systems security experts and administrators to secure processes and services over the cloud. The performance evaluation shows the effectiveness of the proposed approach to find attack probability and the number of correctly detected attacks in the presence of multiple attack scenarios

Developing a consensus-based scoring rubric to enhance practice-based assessment of student nurses' clinical competence: A Delphi study

This is an accepted manuscript of an article published by Elsevier in Nurse Education Today, available online: https://doi.org/10.1016/j.nedt.2021.104859 The accepted version of the publication may differ from the final published version.Background Concerns about reliability and validity of practice-based assessment of professional competencies are frequently reported in the literature. Difficulty in understanding competency statements or distinguishing different achievement levels has been found to be a major factor. Objectives To develop a consensus-based scoring rubric based on stakeholders' interpretations of level descriptors for student nurses' professional values competencies. Design Two rounds of Classic e-Delphi. Settings This study was conducted in a London based university using Bristol Online Survey website as a host. Participants 100 stakeholders with vested interests in undergraduate pre-registration nurse education were purposefully invited to participate. Method Round one collected free-text interpretations of the United Kingdom Nursing and Midwifery Council professional values competency statements. Round two used a Likert scale questionnaire to measure the level of agreement to the level descriptor statements generated through round one. Responses were analysed through content analysis in round one and consensus measure in round two. A threshold of 70% agreement to determine consensus was set in advance. Results In round one, 47 participants provided their interpretations of the competency statements. In round two, 51 participants completed the questionnaire. All 24 items achieved a strong consensus with 86%–100% of participants agreeing or strongly agreeing with the statements. Conclusions A Delphi study was successfully used to develop a consensus-based scoring rubric with clearly stated descriptors for professional values competency statements. This scoring rubric holds the potential to enhance practice-based assessment across all healthcare professional disciplines.Accepted versio

Exploring mentors' interpretation of terminology and levels of competence when assessing nursing students: An integrative review.

The purpose of this integrative review is to evaluate the empirical and theoretical literature on the challenges mentors face in interpreting and assessing levels of competence of student nurses in clinical practice. An integrative review of the literature. An extensive and systematic literature search was conducted covering the period 1986-September 2016 across twelve databases covering health and education related publications. Grey literature was searched from wide relevant sources. Sources were eligible for review when they referred to mentor's interpretation or assessment of student nurses' level of competence in practice settings. Methodological rigor of the included studies was evaluated with the Mixed Methods Appraisal Tool

Electromagnetics Waveguide Tubes Coated With Inhomogeneous Lossy Materials for Superior Shielding Above and Below Cutoff Frequency

Abstract-A new approach for enhanced electromagnetic interference shielding of metallic waveguide (WG) tubes coated with inhomogeneous lossy materials is proposed based on numerical simulation. Shielding enhancement is achieved by using stepped variations of complex permittivity and complex permeability coating materials along the WG transverse direction. Such variation in the coating layer provides multiple wave reflections below and above the WG cutoff frequency. The underlying principle is applied to a rectangular WG operating in the dominant TE 10 mode. Simulation examples of rectangular WGs coated with uniform and stepped lossy materials are demonstrated. The proposed approach shows remarkably better performance when compared with WGs coated with uniform lossy materials

A Lightweight and Efficient Digital Image Encryption Using Hybrid Chaotic Systems for Wireless Network Applications

Due to limited processing capabilities and other constraints of most wireless networks, many existing security algorithms do not consider the network efficiency. This is because most of these security solutions exhibit intolerable overhead and consider only securing scalar data, which are not suitable for other data types such as digital images, hence affecting the provided security level and network performance. Thus, in this paper, we propose a lightweight and efficient security scheme based on chaotic algorithms to efficiently encrypt digital images. Our proposed algorithm handles digital images in two phases: Firstly, digital images are split into blocks and compressed by processing them in frequency domain instead of Red-Green-Blue (RGB) domain. The ultimate goal is to reduce their sizes to speed up the encryption process and to break the correlation among image pixel values. Secondly, 2D Logistic chaotic map is deployed in key generation, permutation, and substitution stages for image pixel shuffling and transposition. In addition, 2D Henon chaotic map is deployed to change the pixel values in the diffusion stage in order to enhance the required level of security and resist various security attacks. Security performance analysis based on standard test images shows that our proposed scheme overcomes the performance of other existing techniques