Traffic modelling in WLANs and cellular networks.

Over the past several years there has been a considerable amount of research in the field of traffic modelling for WLANs and Cellular Networks as well as the integration of these networks. To date, the focus of published work has been largely on the operation of delay sensitive calls. Because the voice calls are no longer the only service in wireless and cellular systems, multi-service traffic networks now consist of integrated services with distinctive Quality of Service (QoS) requirements. Therefore, a number of different schemes have been proposed to deal with this problem. Most of these schemes only consider mobility and multi-service traffic characteristics. However, few studies have considered the impact of buffering of voice calls in integrated voice and data services. Therefore, we aim to make a critical investigation of existing traffic models and offer generic traffic schemes for WLAN and Cellular networks in order to analyse the impact of buffering of voice calls in hybrid networks. For this purpose, an analytical model for performance evaluation of a single server network with voice and data traffic is considered. In this system, voice is given priority but can be buffered in a limited way. The analysis shows that this approach can be used in fast mobile systems

A study of the effectiveness of Edmodo on Preservice classroom teachers' views of web-assisted collaborative learning environments, sense of community of classroom, and perceived learning

This study explored the effectiveness of using web-assisted collaborative learning (COL) environments on the sense of classroom community and perceived learning (PL) using a learning platform Edmodo to enhance face-to-face learning within the framework of a community of inquiry. This study utilized pre-experimental quantitative research approaches based on a single group, pre-, and post-test model. To establish the effectiveness of the intervention, pre- and post-tests were conducted. To support the findings, independent sample t-test was used to compare the differences within groups such as gender. The findings of this study underline the importance of fostering the interaction of students with each other as well as content and instructors in online COL environments to enhance traditional classroom teaching and learning. The results show the effectiveness of the deployment of web-assisted COL environments on a sense of community of classroom and PL

Exploring a new Markov chain model for multiqueue systems.

Traditionally, Markov models have been used to study multiserver systems using exhaustive or gated service. In addition, exhaustive-limited and gate-limited models have also been used in communication systems to reduce overall latency. Recently the authors have proposed a new Markov Chain approach to study gate-limited service. Multiqueue systems such as polling systems, in which the server serves various queues have also been extensively studied but as a separate branch of queueing theory. This paper proposes to describe multiqueue systems in terms of a new Markov Chain called the Zero-Server Markov Chain (ZSMC). The model is used to derive a formula for the waiting times in an exhaustive polling system. An intuitive result is obtained and this is used to develop an appoximate method which works well over normal operational ranges

An analytical approach for performance analysis of handoffs in the next generation integrated cellular networks and WLANs

The main feature of the next generation wireless communication systems is the ability to establish ubiquitous and seamless access to various radio access technologies (RATs) and standards. For this reason the integration of cellular and wireless local area networks (WLANs) and performance evaluation of the interaction between these technologies is now an important research area. Modelling such systems for performance evaluation is essential to improve the architecture according to the quality ofbservice (QoS) requirements and performance characteristics. In this paper, an analytical model for performance evaluation of an integrated cellular network and a WLAN is considered. WLAN is deployed inside of the cellular network to support handoffs between cellular networks with higher bandwidth. Such an integrated system can be modelled as a two stage open network. An analytical model is proposed together with an exact solution technique in order to evaluate the performance of an integrated system consisting of a cellular network and a WLAN. A two stage queuing system is considered for this purpose. Numerical results are presented for mean queue length values of cellular system as well as the WLAN

A smart sensor grid to enhance irrigation techniques in Jordan using a novel event-based routing protocol

Due to rapid changes in climatic conditions worldwide, environmental monitoring has become one of the greatest concerns in the last few years. With the advancement in wireless sensing technology, it is now possible to monitor and track fine-grained changes in harsh outdoor environments. Wireless sensor networks (WSN) provide very high quality and accurate analysis for monitoring of both spatial and temporal data, thus providing the opportunity to monitor harsh outdoor environments. However, to deploy and maintain a WSN in such harsh environments is a great challenge for researchers and scientists. Several routing protocols exist for data dissemination and power management but they suffer from various disadvantages. In our case study, there are very limited water resources in the Middle East, hence soil moisture measurements must be taken into account to manage irrigation and аgriculturаl projects. In order to meet these challenges, a Smart Grid that supports a robust, reactive, event-based routing protocol is developed using Ad hoc On-Demand Multipath Distance Vector (AOMDV) as a starting point. A prototype WSN network of 5 nodes is built and a detailed simulation of 30 nodes is also developed to test the scalability of the new system

A phase-shift technique for intermodulation cancellation.

In a multi-carrier transmission system, intermodulation distortion (IMD) is generated because of amplifier non-linearities. The presence of IMD degrades the performance of such systems. In this paper, an IMD cancellation technique based on phase shift is presented. The technique depends on applying pre-determined phase shifts to each carrier signal before they are combined. Then, an increased number of amplifiers are used to enable the cancellation of chosen IMD components. The amount of phase shift depends on the frequency components to be cancelled. Simulation results are presented to show the effectiveness of the technique proposed

An active tangible user interface framework for teaching and learning artificial intelligence

Interactive and tangible computing platforms have garnered increased interest in the pursuit of embedding active learning pedagogies within curricula through educational technologies. Whilst Tangible User Interface (TUI) systems have successfully been developed to edutain children in various research, TUI architectures have seen limited deployment in more complex and abstract domains. In light of these limitations, this paper proposes an active TUI framework that addresses the challenges experienced in teaching and learning artificial intelligence (AI) within higher educational institutions. The proposal extends an aptly designed tabletop TUI architecture with the novel interactive paradigm of active tangible manipulatives to provide a more engaging and effective user interaction. The paper describes the deployment of the proposed TUI framework within an undergraduate laboratory session to aid in the teaching and learning of artificial neural networks. The experiment is assessed against currently adopted educational computer software and the obtained results highlight the potential of the proposed TUI framework to augment students’ gain in knowledge and understanding of abstracted threshold concepts in higher education

Explaining multi-threaded task scheduling using tangible user interfaces in higher educational contexts

Endorsing the advantages of computer-based interaction within the educational domain, this study analysis the potential for tangible interactive technology to mitigate the challenges faced by higher educational institutes in explaining abstracted technical concepts. Implemented within a novel within the educational domain, this paper evaluates the efficacy of adopting a tangible user interface (TUI) to aid in the conceptual understanding of multi-threaded task scheduling and programming by undergraduate IT students. Making use of physical object representations, a description is provided for the distinctive development of a collaborative system that allows students to interact with and visualize the scheduling of multiple software threads onto a computer processes. The paper quantitatively studies the usefulness of the proposed TUI system with respect to traditional lectures by deploying the system within a university computing degree. Evaluation analysis of the obtained results highlight a significant improvement in the students' abilities to grasp the abstract and complex notions of multi-threading, thus validating the potential of the proposed study

The aptness of tangible user interfaces for explaining abstract computer network principles

The technological deployment of Tangible User Interfaces (TUI) with their intrinsic ability to interlink the physical and digital domains, have steadily gained interest within the educational sector. As a concrete example of Reality Based Interaction, such digital manipulatives have been successfully implemented in the past years to introduce scientific and engineering concepts at earlier stages throughout the educational cycle. With difference to literature, this research investigates the suitability and effectiveness of implementing a TUI system to enhance the learning experience in a higher education environment. The proposal targets the understanding of advanced computer networking principles by the deployment of an interactive table-top system. Beyond the mere simulation and modelling of networking topologies, the design presents students the ability to directly interact with and visualise the protocol execution, hence augmenting their ability to understand the abstract nature of such algorithms. Following deployment of the proposed innovate prototype within the delivery of a university undergraduate programme, the quantitative effectiveness of this novel methodology will be assessed from both a teaching and learning perspective on its ability to convey the abstract notions of computer network principles

Performance analysis of cooperative transmission for cognitive wireless relay networks

In this paper, we consider cooperative transmission in cognitive wireless relay networks (CWRNs) over frequency-selective fading channels. We propose a new distributed space-time-frequency block code (DSTFBC) for a two-hop nonregenerative CWRN, where a primary source node and multiple secondary source nodes convey information data to their desired primary destination node and multiple secondary destination nodes via multiple cognitive relay nodes with dynamic spectrum access. The proposed DSTFBC is designed to achieve spatial diversity gain as well as allow for low-complexity decoupling detection at the receiver. Pairwise error probability is then analysed to study the achievable diversity gain of the proposed DSTFBC for different channel models including Rician fading and mixed Rayleigh-Rician fading