• Managing threats by the use of visualisation techniques

      Viduto, Valentina; Maple, Carsten; Huang, Wei (Inderscience, 2011)
      Identification of threats in networked systems is one of the important risk management processes that should be followed in order to be aware of all risks. In general, risk assessment guidelines for threat analysis propose to use historical organisation's data, thus, novel and unheard threats often are skipped from an analysis. In this paper, we propose a novel onion skin model (OSM) which consists of visualisation techniques, such as attack graphs, often applied for qualitative and quantitative risk assessment analyses. The model can be used to facilitate in threat identification and decision-making process by focusing on attack scenarios that illustrate vulnerable nodes, threats and shortest attack paths to the attacker's goal. The model can be used as part of risk management practices to improve security awareness through different attack scenarios and manage all system risks.
    • Minimum energy wireless sensor networks

      Allen, Ben; Safdar, Ghazanfar Ali; University of Bedfordshire, UK (University of Bedfordshire, 2011)
      Here, on-off keying modulation is used as a means of reducing the transmit energy requirements whilst exploiting inherent channel coding, which sets the scene of this PhD study.
    • Mobile terminal GPS antennas in multipath environment and effects of human body presence

      Ur-Rehman, Masood; Gao, Yue; Chen, Xiaodong; Parini, Clive G.; Ying, Zhinong (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2009)
    • Mode converter optical isolator based on dual negative refraction photonic crystal

      Aroua, Walid; AbdelMalek, Fathi; Haxha, Shyqyri; Tesfa, Sintayehu; Bouchriha, Habib; University of Bedfordshire; El Manar University (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2014)
      A new design of an optical isolator based on photonic transitions in the interbands of a honeycomb structure that generates a dual negative refraction in a photonic crystal is presented. The involved photonic transition is associated to the perturbation of the dielectric constant of the medium. The band structure is determined using the plane wave method where the transmission spectra, field profile, and mode amplitudes are obtained by applying the finite difference time domain method. Due to the time-dependent perturbation of the refractive index of the medium that constitutes the dual negative refraction, asymmetric transmission mechanism is achieved for one of the desired modes, demonstrating optical isolation. Using the dual negative refraction effect in photonic crystal structure, the optical isolation is reported for only one of the desired optical modes. It is anticipated that the proposed mode conversion mechanism can be employed for designing ultrahigh-speed optical interconnections. The proposed optical isolator model is expected to have a significant impact on designing ultrahigh-speed integrated optical platforms.
    • A modified Loo model with partially blocked and three dimensional multipath scattering: analysis, simulation and validation

      Karadimas, Petros; Kotsopoulos, Stavros A.; University of Patras (Springer, 2009)
      This paper presents a novel mobile fading channel model, belonging to the class of Loo models, in which the multipath power arrives both in three dimensions (3-D) and in two angular sectors at the azimuth receiver's plane. Moreover shadowing affects the amplitude of the line of sight (LOS) component, making it time varying and following a lognormal distribution, as required for a Loo model. The Doppler power spectral density (PSD) is analytically calculated, after Fourier transforming the closed form autocorrelation function. Afterwards exact solutions for the probability density function (PDF) of the envelope and phase are presented. What follows are approximate solutions for the second order statistics, i.e. the level crossing rate (LCR) and the average duration of fades (ADF's). A new, appropriate for 3-D scattering cases, deterministic simulation scheme is developed, which implements the analytical model on a digital computer and is used to test the validity of the approximate solutions. Moreover the deterministic model is thoroughly investigated for all the possible cases, in terms of its convergence to the analytical one. Finally a curve fitting of the LCR to real world data, drawn from channel measurements, will demonstrate the flexibility and usefulness of the modified Loo model.
    • Multi objective resource scheduling in LTE networks using reinforcement learning

      Comşa, Ioan-Sorin; Aydin, Mehmet Emin; Zhang, Sijing; Kuonen, Pierre; Wagen, Jean–Frédéric (IGI Global, 2012)
      The use of the intelligent packet scheduling process is absolutely necessary in order to make the radio resources usage more efficient in recent high-bit-rate demanding radio access technologies such as Long Term Evolution (LTE). Packet scheduling procedure works with various dispatching rules with different behaviors. In the literature, the scheduling disciplines are applied for the entire transmission sessions and the scheduler performance strongly depends on the exploited discipline. The method proposed in this paper aims to discuss how a straightforward schedule can be provided within the transmission time interval (TTI) sub-frame using a mixture of dispatching disciplines per TTI instead of a single rule adopted across the whole transmission.
    • Multi-element antenna systems for wireless communications with multi-clustered scattering

      Allen, Ben; Karadimas, Petros; University of Bedfordshire (University of Bedfordshire, 2012)
      the proposed research will focus on analyzing and evaluating MEA systems based on new theoretical, realistic though, multi-clustered scattering models for the directional statistics of the propagating multipath power and using several well-known signal processing techniques (e.g., MRC, SC).
    • Multi-tone frequency shift keying for ultrawideband wireless communications

      Sipal, Vit; Allen, Ben; Edwards, David J. (IET, 2012-07-03)
      The study explores the performance of multi-tone frequency shift keying (MT-FSK) in ultrawideband (UWB) wireless communications as an alternative to the standard modulation techniques. Its advantage is its ability to provide multiple user access even within the recently tightened regulations on UWB communications. Unlike previous works that discussed MT-FSK from the information theory perspective, here the possibility of practical implementation is explored. The basic system parameters such as tone bandwidth, number of frequencies and duty cycle are studied in terms of propagation characteristics, optimum data rate and system complexity. With optimum parameters, the authors show that a system using MT-FSK is capable of data transmission at a data rate of 250 Mbps with bit-error-rate below 10-5 whereas the receiver complexity is lower than for standard methods utilising the UWB spectrum by means of impulse radio or multi-band orthogonal frequency division multiplexing (OFDM).
    • Multiview image coding using depth layers and an optimized bit allocation

      Gelman, Andriy; Dragotti, Pier Luigi; Velisavljević, Vladan (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2012)
      The authors present a novel wavelet-based compression algorithm for multiview images. This method uses a layer-based representation, where the 3-D scene is approximated by a set of depth planes with their associated constant disparities. The layers are extracted from a collection of images captured at multiple viewpoints and transformed using the 3-D discrete wavelet transform (DWT). The DWT consists of the 1-D disparity compensated DWT across the viewpoints and the 2-D shape-adaptive DWT across the spatial dimensions. Finally, the wavelet coefficients are quantized and entropy coded along with the layer contours. To improve the rate-distortion performance of the entire coding method, we develop a bit allocation strategy for the distribution of the available bit budget between encoding the layer contours and the wavelet coefficients. The achieved performance of our proposed scheme outperforms the state-of-the-art codecs for several data sets of varying complexity.
    • Multiview image compression using a layer-based representation

      Gelman, Andriy; Dragotti, Pier Luigi; Velisavljević, Vladan (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2010)
      The authors propose a novel compression method for multiview images. The algorithm exploits the layer-based representation, which partitions the data set into planar layers characterized by a constant depth value. For efficient compression, the partitioned data is decorrelated using the separable three-dimensional wavelet transform across the viewpoint and spatial dimensions. The transform is modified to efficiently deal with occlusions and disparity variations for different depths. The generated transform coefficients are entropy coded. Experimental results show that our coding method is capable of outperforming the state-of-the-art algorithms, like H.264/AVC, for different data sets.
    • Network performance optimization: a case study of enterprise network simulated in OPNET

      Shah, Munam Ali; Safdar, Ghazanfar Ali; Maple, Carsten; Sardar, Khurram (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2011)
    • A new twist on UWB pathloss modelling

      Dohler, Mischa; Allen, Ben; Armogida, A.; McGregor, S.; Ghavami, Mohammad; Aghvami, A.Hamid (IEEE, 2004-05)
      Ultra wideband (UWB) systems facilitate extremely high data rates over fairly short distances. Notwithstanding the short communication distances, a proper powerloss model is required to knowledgably model and adjust the transmission power of such systems. The extremely wide bandwidth prohibits narrowband pathloss models to be applied to the link budget calculation of UWB systems. The contribution of this paper is the derivation of a novel breakpoint within the vicinity of the transmitter, which is shown to influence the UWB link budget considerably.
    • A node discovery service for partially mobile sensor networks

      Dyo, Vladimir; Mascolo, Cecilia (ACM, 2007)
    • Novel authenticated key management framework for ad hoc network security

      McGrath, Clare; Safdar, Ghazanfar Ali; McLoone, Maire (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006)
    • A novel birefrigent photonic crystal fiber surface plasmon resonance biosensor

      Otupiri, R.; Akowuah, Emmanuel K.; Haxha, Shyqyri; Ademgil, H.; AbdelMalek, Fathi; Aggoun, Amar; Kwame Nkrumah University of Science & Technology, Ghana; University of Bedfordshire (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2014)
      A numerical analysis of a novel birefringent photonic crystal fiber (PCF) biosensor constructed on the surface plasmon resonance (SPR) model is presented in this paper. This biosensor configuration utilizes circular air holes to introduce birefringence into the structure. This PCF biosensor model shows promise in the area of multiple detection using HEx11 and HEy11 modes to sense more than one analyte. A numerical study of the biosensor is performed in two interrogation modes: amplitude and wavelength. Sensor resolution values with spectral interrogation yielded 5 × 10-5 RIU (refractive index units) for HEx11 modes and 6 × 10-5 RIU for HEy11 modes, whereas 3 × 10-5 RIU for HEx11 modes and 4 × 10-5 RIU for HEy11 modes are demonstrated for the amplitude interrogation.
    • A novel common control channel security framework for cognitive radio networks

      Safdar, Ghazanfar Ali; O'Neill, M. (Inderscience, 2012)
      Cognitive radio technology makes use of the underutilised spectrum opportunistically without causing interference to the primary users. Cooperatively communicating cognitive radio devices use the common control channel of the cognitive radio medium access control to perform free channel announcements, channel selection and channel reservation before any actual data transmission. Common control channel security is vital in order to ensure security in the subsequent communication among the cognitive radio nodes. Additional to well-known security problems in wireless networks, cognitive radio networks introduce new classes of security threats and challenges, such as misbehaviours in spectrum sensing, licensed user emulation and attacks in the common control channel transactions. This paper presents a novel common control channel security framework (protocol) for cooperatively communicating cognitive radio networks. To the best of the authors knowledge, this is the first paper to address the security requirements of the common control channel. An implementation of the proposed security protocol is discussed illustrating how two cognitive radio nodes can authenticate each other prior to any confidential common control channel negotiations. The protocol is formally validated by GNY logic and a security analysis of the protocol illustrates that it meets the principal security requirements of authentication, confidentiality, integrity and non-repudiation.
    • A novel dynamic Q-learning-based scheduler technique for LTE-advanced technologies using neural networks

      Comşa, Ioan-Sorin; Zhang, Sijing; Aydin, Mehmet Emin; Kuonen, Pierre; Wagen, Jean–Frédéric; University of Bedfordshire (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2012)
      The tradeoff concept between system capacity and user fairness attracts a big interest in LTE-Advanced resource allocation strategies. By using static threshold values for throughput or fairness, regardless the network conditions, makes the scheduler to be inflexible when different tradeoff levels are required by the system. This paper proposes a novel dynamic neural Q-learning-based scheduling technique that achieves a flexible throughput-fairness tradeoff by offering optimal solutions according to the Channel Quality Indicator (CQI) for different classes of users. The Q-learning algorithm is used to adopt different policies of scheduling rules, at each Transmission Time Interval (TTI). The novel scheduling technique makes use of neural networks in order to estimate proper scheduling rules for different states which have not been explored yet. Simulation results indicate that the novel proposed method outperforms the existing scheduling techniques by maximizing the system throughput when different levels of fairness are required. Moreover, the system achieves a desired throughput-fairness tradeoff and an overall satisfaction for different classes of users.
    • A novel lifecycle model for Web-based application development in small and medium enterprises

      Huang, Wei; Li, Ru; Maple, Carsten; Yang, Hong-Ji; Foskett, David; Cleaver, Vince (Springer, 2010)
      Software engineering's lifecycle models have proven to be very important for traditional software development. However, can these models be applied to the development of Web-based applications as well? In recent years, Web-based applications have become more and more complicated and a lot of efforts have been placed on introducing new technologies such as J2EE, PhP, and .NET, etc., which have been universally accepted as the development technologies for Web-based applications. However, there is no universally accepted process model for the development of Web-based applications. Moreover, shaping the process model for small medium-sized enterprises (SMEs), which have limited resources, has been relatively neglected. Based on our previous work, this paper presents an expanded lifecycle process model for the development of Web-based applications in SMEs. It consists of three sets of processes, i.e., requirement processes, development processes, and evolution processes. Particularly, the post-delivery evolution processes are important to SMEs to develop and maintain quality web applications with limited resources and time.
    • Novel method for improving the capacity of optical MIMO system using MGDM

      Baklouti, F.; Dayoub, I.; Haxha, Shyqyri; Attia, R.; Aggoun, Amar; University of Bedfordshire (2014)
      In current local area networks, multimode fibers (MMFs), primarily graded index (GI) MMFs, are the main types of fibers employed for data communications. Due to their enormous bandwidth, it is considered that they are the main channel medium that can offer broadband multiservices using optical multiplexing techniques. Amongst these, mode group diversity multiplexing (MGDM) has been proposed as a way to integrate various services over an MMF network by exciting different groups of modes that can be used as independent and parallel communication channels. In this paper, we study optical multiple-input–multiple-output (O-MIMO) systems using MGDM techniques while also optimizing the launching conditions of light at the fiber inputs and the spot size, radial offset, angular offset, wavelength, and the radii of the segment areas of the detectors. We propose a new approach based on the optimization of launching and detection conditions in order to increase the capacity of an O-MIMO link using the MGDM technique. We propose a (3 $times$ 3) O-MIMO system, where our simulation results show significant improvement in GI MMFs' capacity compared with existing O-MIMO systems.