An efficient constructive e-alignment for onsite-online learning

This paper aims at proposing an efficient constructive electronic-based alignment (CeA) to promote self-learning amongst the students via e-learning environment where e-lectures/e-tutorials are developed followed by e-assessments. The CeA is developed based on behaviourism, cognitivism, humanism and constructivism to ensure the students’ learning does take place in the e-learning environment. Considering engineering related courses at higher education, it has been shown that the decline in mathematical background of the students causes difficulties in accomplishing the quantitative curricula. A well-designed constructive alignment is thus necessary to support active learning of the students having different background. Onsite tutorials and seminars may be helpful; however, they may not be very effective, especially in a large-sized and/or high-diversity class. Therefore, in this paper, the proposed CeA not only helps the onsite students strengthen their knowledge but also provides the offsite students with various kinds of learning supplement. Particularly, a case study is presented to show the potential impact of the CeA on both onsite and online learning of mathematics for postgraduate students in both telecommunications engineering and computer networks

On the optimisation of practical wireless indoor and outdoor microcells subject to QOS constraints

Wireless indoor and outdoor microcells (WIOMs) have emerged as a promising means to deal with a high demand of mobile users for a variety of services. Over such heterogeneous networks, the deployment of WIOMs costs mobile/telecommunications company high capital expenditures and operating expenses. This paper aims at optimising the WIOMs taking into account various network communication environments. We first develop an optimisation problem to minimise the number of cells as well as determining their optimal locations subject to the constraints of the coverage and quality-of-service (QoS) requirements. In particular, we propose a binary-search based cell positioning (BSCP) algorithm to find the optimal number of cells given a preset candidate antenna positions. The proposed BSCP algorithm is shown to not only reduce the number of cells for saving resources but also requires a low computational complexity compared to the conventional approaches with exhaustive search over all available sites. Moreover, EDX SignalPro is exploited as a simulation platform to verify the effectiveness of the proposed BSCP for the WIOMs with respect to various propagation modes and antenna parameters of different types, including isotropic, multiple-input single-output and multiple-input multiple-output

Opportunistic secure transmission for wireless relay networks with modify-and-forward protocol

This paper investigates the security at the physical layer in cooperative wireless networks (CWNs) where the data transmission between nodes can be realised via either direct transmission (DT) or relaying transmission (RT) schemes. Inspired by the concept of physical-layer network coding (PNC), a secure PNC-based modify-and-forward (SPMF) is developed to cope with the imperfect shared knowledge of the message modification between relay and destination in the conventional modify-and-forward (MF). In this paper, we first derive the secrecy outage probability (SOP) of the SPMF scheme, which is shown to be a general expression for deriving the SOP of any MF schemes. By comparing the SOPs of various schemes, the usage of the relay is shown to be not always necessary and even causes a poorer performance depending on target secrecy rate and quality of channel links. To this extent, we then propose an opportunistic secure transmission protocol to minimise the SOP of the CWNs. In particular, an optimisation problem is developed in which secrecy rate thresholds (SRTs) are determined to find an optimal scheme among various DT and RT schemes for achieving the lowest SOP. Furthermore, the conditions for the existence of SRTs are derived with respect to various channel conditions to determine if the relay could be relied on in practice

A lightweight secure image super resolution using network coding

Images play an important part in our daily life. They convey our personal stories and maintain meaningful objects, events, emotions etc. People, therefore, mostly use images as visual information for their communication with each other. Data size and privacy are, however, two of important aspects whilst transmitting data through network like internet, i.e. the time prolongs when the amount of data are increased and the risk of exposing private data when being captured and accessed by irrelevant people. In this paper, we introduce a unified framework, namely Deep-NC, to address these problems seamlessly. Our method contains three important components: the first component, adopted from Random Linear Network Coding (RLNC), to protect the sharing of private image from the eavesdropper; the second component to remove noise causing to image data due to transmission over wireless media; and the third component, utilising Image Super-Resolution (ISR) with Deep Learning (DL), to recover high-resolution images from low-resolution ones due to image sizes reduced. This is a general framework in which each component can be enhanced by sophisticated methods. Simulation results show that an outperformance of up to 32 dB, in terms of Peak Signal-to-Noise Ratio (PSNR), can be obtained when the eavesdropper does not have any knowledge of parameters and the reference image used in the mixing schemes. Various impacts of the method are deeply evaluated to show its effectiveness in securing transmitted images. Furthermore, the original image is shown to be able to downscale to a much lower resolution for saving significantly the transmission bandwidth with negligible performance loss

Beamforming in coexisting wireless systems with uncertain channel state information

This paper considers an underlay access strategy for coexisting wireless networks where the secondary system utilizes the primary spectrum to serve its users. We focus on the practical cases where there is uncertainty in the estimation of channel state information (CSI). Here the throughput performance of each system is limited by the interference imposed by the other, resulting in conflicting objectives. We first analyze the fundamental tradeoff between the tolerance interference level at the primary system and the total achievable throughput of the secondary users. We then introduce a beamforming design problem as a multiobjective optimization to minimize the interference imposed on each of the primary users while maximizing the intended signal received at every secondary user, taking into account the CSI uncertainty. We then map the proposed optimization problem to a robust counterpart under the maximum CSI estimation error. The robust counterpart is then transformed into a standard convex semi-definite programming. Simulation results confirm the effectiveness of the proposed scheme against various levels of CSI estimation error. We further show that in the proposed approach, the trade-off in the two systems modelled by Pareto frontier can be engineered by adjusting system parameters. For instance, the simulations show that at the primary system interference thresholds of -10 dBm (-5 dBm) by increasing number of antennas from 4 to 12, the secondary system throughput is increased by 3.3 bits/s/channel-use (5.3 bits/s/channel-use

A secure network coding based modify-and-forward scheme for cooperative wireless relay networks

This paper investigates the security at the physical layer of cooperative relay communications. Inspired by the principle of physical-layer network coding (PNC), we propose a new secure relaying scheme, namely secure PNC-based modify-and-forward (SPMF). In the proposed scheme, the relay node linearly combines the decoded data from the source node with an encrypted key before conveying the mixed data to the destination node. As both the linear PNC operation and encrypted key at the relay are unknown to the eavesdropper, the SPMF scheme provides a double security level in the system. Particularly, taking into account the practical scenario of the imperfect knowledge shared between the relay and destination, the secrecy outage probability (SOP) of the proposed SPMF scheme is analysed and evaluated in comparison with modify-and-forward, cooperative jamming, decode-and-forward and direct transmission schemes. The proposed scheme is shown to achieve a performance improvement of up to 3 dB when compared to the conventional schemes under imperfect knowledge of shared information between the nodes

A comparative experimental design and performance analysis of Snort-based Intrusion Detection System in practical computer networks

As one of the most reliable technologies, network intrusion detection system (NIDS) allows the monitoring of incoming and outgoing traffic to identify unauthorised usage and mishandling of attackers in computer network systems. To this extent, this paper investigates the experimental performance of Snort-based NIDS (S-NIDS) in a practical network with the latest technology in various network scenarios including high data speed and/or heavy traffic and/or large packet size. An effective testbed is designed based on Snort using different muti-core processors, e.g., i5 and i7, with different operating systems, e.g., Windows 7, Windows Server and Linux. Furthermore, considering an enterprise network consisting of multiple virtual local area networks (VLANs), a centralised parallel S-NIDS (CPS-NIDS) is proposed with the support of a centralised database server to deal with high data speed and heavy traffic. Experimental evaluation is carried out for each network configuration to evaluate the performance of the S-NIDS in different network scenarios as well as validating the effectiveness of the proposed CPS-NIDS. In particular, by analysing packet analysis efficiency, an improved performance of up to 10% is shown to be achieved with Linux over other operating systems, while up to 8% of improved performance can be achieved with i7 over i5 processors