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The Next Generation 5G Networks can greatly benefit from the synergy between virtualization paradigms, such as the Network Function Virtualization (NFV), and service provisioning platforms such as the IP Multimedia Subsystem (IMS). The NFV concept is evolving towards a lightweight solution based on containers that, by contrast to classic virtual machines, do not carry a whole operating system and result in more efficient and scalable deployments. On the other hand, IMS has become an integral part of the 5G core network, for instance, to provide advanced services like Voice over LTE (VoLTE). In this paper we combine these virtualization and service provisioning concepts, deriving a containerized IMS infrastructure, dubbed cIMS, providing its assessment through statistical characterization and experimental measurements. Specifically, we: $\textit {i)}$ model cIMS through the queueing networks methodology to characterize the utilization of virtual resources under constrained conditions; $\textit {ii)}$ draw an extended version of the Pollaczek-Khinchin formula, which is useful to deal with bulk arrivals; $\textit {iii)}$ afford an optimization problem focused at maximizing the whole cIMS performance in the presence of capacity constraints, thus providing new means for the service provider to manage service level agreements (SLAs); $\textit {iv)}$ evaluate a range of cIMS scenarios, considering different queuing disciplines including also multiple job classes. An experimental testbed based on the open source platform Clearwater has been deployed to derive some realistic values of key parameters (e.g., arrival and service times).

In wireless sensor networks, routing protocols with immutable network policies lacking the flexibility are generally incapable of maintaining desired performance due to the complicated and changeable environment situations and application requirements. The proposed “Flexible Routing Computing Approach (FRCA)” is a novel distributed and probabilistic computing approach capable of modifying or upgrading routing policies on the fly with low cost, which effectively enhances the flexibility of routing protocols. FRCA models the routing metric as a forwarding probability distribution for routing decisions. This model depends on three elements, the physical quantities collected at sensor nodes, the built-in base math functions, and the routing parameters. These elements are all user-oriented and can be specified to implement multifarious complicated network policies meeting different performance requirements. More significantly, through distributing routing parameters from the sink to end nodes, operators are allowed to adjust network policies on the fly without the interruption of network services. Through extensive performance evaluation studies and simulations, the results demonstrated that routing protocols designed based on FRCA could achieve better performance compared to its state-of-the-art counterparts regarding network lifetime, energy consumption, and duplicate packets as well as ensure high flexibility during network policies modification or upgrade.

Putting trust in the world of the Internet of Things, where served and serving entities are often unknown, is very hard especially when personal and business information is often being exchanged for providing and consuming services. Moreover, the issues of interoperability and scalability of billions of heterogeneous things in the IoT systems require more attention. A user-centric model of complex interconnected things must be designed in a way that not only makes things trustworthy for common people but it also provides the solution for interoperability and scalability. ARCA-IoT is such a system which not only identifies the attributes (including quality of service) essential for trust but also presents a user-centric model that is robust enough to tackle the attacks made by dishonest entities to manipulate the trustworthiness. For scalability and interoperability, a cloud-assisted environment is introduced in the ARCA-IoT. An intuitive Naive Bayes approach is used to train the ARCA-IoT in a way that it calculates the probabilities of the trustworthiness of the entities and then identifies various types of attacks with the support of three proposed algorithms. The approach is validated with a specifically designed simulated environment. Based on our simulation results, the ARCA-IoT demonstrates the effectiveness in term of performance metrics such as accuracy, sensitivity, specificity, and precision. Besides this, the system outperforms the existing related approaches in terms of a qualitative analysis based on different parametric metrics such as interoperability, scalability, context-awareness, and a human-like decision.

In RPL routing protocol, the destination advertisement object (DAO) control messages are announced by the child nodes to their parents to build downward routes. A malicious insider node can exploit this feature to send fake DAOs to its parents periodically, triggering those parents, in turn, to forward the fake messages upward to the root node. In this letter, we show how this behavior can have a detrimental side effect on the performance of the network, increasing power consumption, latency, and reducing reliability. To address this problem, a new scheme is introduced to mitigate significantly the effect of the DAO attack on network performance.

Simultaneous localization and environment mapping (SLAM) is the core to robotic mapping and navigation as it constructs simultaneously the unknown environment and localizes the agent within. However, in millimeter wave (mmWave) research, SLAM is still at its infancy. This paper consists a first of its kind in mapping an indoor environment based on the RSS, Time-Difference-of-Arrival, and Angle-of-Arrival measurements. We introduce MOSAIC as a new approach for SLAM in indoor environment by exploiting the map-based channel model. More precisely, we perform localization and environment inference through obstacle detection and dimensioning. The concept of virtual anchor nodes (VANs), known in literature as the mirrors of the real anchors with respect to the obstacles in the environment, is explored. Then, based on these VANs, the obstacles positions and dimensions are estimated by detecting the zone of paths obstruction, points of reflection, and obstacle vertices. Then, extended Kalman filter is adapted to the studied environment to improve the estimation of the points of reflection hence the mapping accuracy. Cramer-Rao lower bounds are also derived to find the optimal number of anchor nodes. Simulation results have shown high localization accuracy and obstacle detection using mmWave technology.

The ubiquity of mobile devices together with its potential to bridge classroom learning to real-world has added a new angle to contextualising mathematics learning. This study investigated the effects of using mobile technologies to students’ attitudes and achievement. A quasi-experimental mixed method design was adopted. Participants were 52 Primary 6 and 7 students. The experimental group participated in a weekly mobile-supported, collaborative learning activities spanning over three months. A no treatment control group was adopted. The experimental group have positive perception of the activities evidenced by student interviews and end activity evaluations. Students’ attitude to mathematics, as assessed by a mathematics attitude inventory, found no significant change for both groups except for the significant decline in enjoyment for the control group. A t test of the gain score between group showed a significant difference, t(43) = 4.57, p = 0.005, ES = 0.89 which indicates that the experimental group had higher gains than the control group. These results indicate that the use of mobile technologies elicit positive responses from students both in terms of how they perceive the mobile activities and how it improved their performance but its’ effect on students attitudes towards mathematics will need to be further investigated. Some implications of the findings are discussed.

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. The enormous developments in the field of wireless communication technologies have made the unlicensed spectrum bands crowded, resulting uncontrolled interference to the traditional wireless network applications. On the other hand, licensed spectrum bands are almost completely allocated to the licensed users also known as Primary users (PUs). This dilemma became a blackhole for the upcoming innovative wireless network applications. To mitigate this problem, the cognitive radio (CR) concept emerges as a promising solution for reducing the spectrum scarcity issue. The CR network is a low cost solution for efficient utilization of the spectrum by allowing secondary users (SUs) to exploit the unoccupied licensed spectrum. In this paper, we model the PU’s utilization activity by a two-state Discrete-Time-Markov Chain (DTMC) (i.e., Free and busy states), for identifying the temporarily unoccupied spectrum bands,. Furthermore, we propose a Cognitive Radio Sense-and-Wait assisted HARQ scheme, which enables the Cluster Head (CH) to perform sensing operation for the sake of determining the PU’s activity. Once the channel is found in free state, the CH advertise control signals to the member nodes for data transmission relying on Stop-and-Wait Hybrid- Automatic Repeat-Request (SW-HARQ). By contrast, when the channel is occupied by the PU, the CH waits and start sensing again. Additionally, the proposed CRSW assisted HARQ scheme is analytical modeled, based on which the closed-form expressions are derived both for average block delay and throughput. Finally, the correctness of the closed-form expressions are confirmed by the simulation results. It is also clear from the performance results that the level of PU utilization and the reliability of the PU channel have great influence on the delay and throughput of CRSW assisted HARQ model.

Medium Access Control (MAC) protocols based on Time Division Multiple Access (TDMA) can improve the reliability and efficiency of WBAN. However, traditional static TDMA techniques adopted by IEEE 802.15.4 and IEEE 802.15.6 do not sufficiently consider the channel status or the buffer requirements of the nodes within heterogeneous contexts. Although there are some solutions that have been proposed to alleviate the effect of the deep fade in WBAN channel by adopting dynamic slot allocation, these solutions still suffer from some reliability and energy efficiency issues and they do not avoid channel deep fading. This paper presents two novel and generic TDMA based techniques to improve WBAN reliability and energy efficiency. Both techniques synchronize nodes adaptively whilst tackling their channel and buffer status in normal and emergency contexts. Extensive simulation experiments using various traffic rates and time slot lengths demonstrate that the proposed techniques improve the reliability and the energy efficiency compared to IEEE 802.15.4 and IEEE 802.15.6 in both situations, the normal and emergency contexts. This improvement has been achieved in terms of packet loss, up to 90% and energy consumption, up to 13%, confirming the significant enhancements made by the developed scheduling techniques.

Traffic management in roads is one of the major challenges faced in developing efficient intelligent transportation systems. Recently, wireless networks have received significant attention for tackling this challenge. However, wireless technologies face the well-known spectrum scarcity problem due to the explosive demand for radio resources. To overcome this challenge, this study presents a novel intelligent traffic control system, utilizing the unused spectrum. Unlike existing works, the spectrum owners in this study hire free spectrum to drivers. The hired spectrum is deployed to build a short-range cost-effective wireless communication for monitoring traffic and enabling drivers to exchange warning messages, and thus enhancing road safety. Our objectives include minimizing crash probability, utilizing unused spectrum, and enabling spectrum owners to generate extra revenue. Numerical analysis demonstrates the capability of our approach to minimize the crash probability among vehicles under different operating road conditions.

Generalized few-mode-fiber (FMF) transmission uses N coherent receivers for mode detection, where N scales with the number of fiber modes. Multiple coherent receivers increase the cost of optical network units (ONUs) in access networks, specifically for intra- and inter data center applications. We have experimentally evaluated a cost effective low-complexity receiver architecture based on mode-division multiplexing (MDM) to mode frequency-division multiplexing (MFDM) conversion for data center connectivity. A single coherent receiver is used to efficiently detect 10 Gbit/s QPSK Nyquist signals over 2.8 km 4-LP mode graded index fiber reducing the ONUs complexity to N/4. All the transmitted modes are successfully detected below the forward error correction (FEC) limit, i.e. 1×10^−3 BER.

Recent advances in technology provided the ground for highly dynamic, mobile, infrastructure-less networks, namely, ad-hoc networks. Despite their enormous benefits, the full potential cannot be reached unless certain issues are resolved. These mainly involve routing, as the lack of an infrastructure imposes a heavy burden on mobile devices that must maintain location information and route data packets in a multi-hop fashion. Specifically, typical adhoc routing devices, such as Personal Digital Assistants (PDAs), are limited in respect to the available throughput, life-time, and performance, that these may provide, as routing elements. Thus, there is a need for metric-driven ad-hoc routing, that is, devices should be utilised for routing according to their fitness, as different device types significantly vary in terms of routing fitness. In addition, a concrete agent-based approach can provide a set of advantages over a non-agent-based one, which includes: better design practice; and automatic reconfigurability.This research work aims to investigate the applicability of stationary and mobile agent technology in multi-hop ad-hoc routing. Specifically, this research proposes a novel hybrid, metric-driven, agent-based routing protocol for multi-hop ad-hoc networks that will enhance current routing schemes. The novelties that are expected to be achieved include: maximum network performance, increased scalability, dynamic adaptation, Quality of Service (QoS), energy conservation, reconfigurability, and security. The underlying idea is based on the fact that stationary and mobile agents can be ideal candidates for such dynamic environments due to their advanced characteristics, and thus offer state of the art support in terms of organising the otherwise disoriented network into an efficient and flexible hierarchical structure, classifying the routing fitness of participating devices, and therefore allow intelligent routing decisions to be taken on that basis.

Organisational information systems development (OISD) projects have long been associated with failure. Not surprisingly, the cost of these failures is enormous. Yet, despite numerous studies, understanding of real-world projects is limited. In particular, little is known about the way in which various factors affect the success of OISD projects. Prior research has focussed on OISD projects from an in-house or client perspective, and the views of the supplier have largely been ignored. By investigating OISD project success factors from the supplier perspective, this doctoral study helps address this gap.Based on an empirical investigation drawn from data collected from Scottish IS/IT solution suppliers, this research identifies and analyses 20 success factors for supplier-based OISD projects, and a range of more detailed, inter-related sub-factors related to each of the twenty. The work confirms the importance of many factors identified in the extant literature. A number of additional factors not previously identified are also exposed. Important differences between supplier and client perspectives are revealed. The findings also develop a variety of factors that have merited scant treatment in the OISD project success factor literature. The means by which OISD project success factors propagate their influences to affect project success was also investigated. This is revealed to be a complex phenomenon comprising billions of causal chains interacting with a few million causal loops. The propagation process is performed by a sizeable network of factors, the topology of which seems to reflect the complexities of real-world OISD projects. Hence, the network is used to propose a new theory for success factors that contributes new insight into the behaviour of these projects.The research also reveals that supplier-based OISD projects are oriented more towards project success than project management success and that OISD project success criteria are far more than simply measures of success. Indeed, the overall conclusion of this thesis is that the concept of OISD project success factors is far more complicated than has been previously articulated.

This research reported in this thesis explores job search networking amongst 16-24 year olds living in Scotland, and the role of social media platforms (i.e. Facebook, Twitter, and LinkedIn) during this process. Networking is treated as an information behaviour; reflecting this, the study is underpinned by a prominent model from the domain of information science. A sequential, mixed methods approach was applied to gather data. This included the use of interviews, focus groups, and a survey questionnaire. The interviews incorporated ego-centric network methods to develop a relational perspective of job search networking.The findings show that young people accrue different types of information from network contacts which can be useful for all job search tasks. Indeed, frequent networking offline and on social media is associated with positive job search outcomes. This is especially true of engaging with family members and acquaintances, and frequent use of Facebook for job search purposes. However, demographic and other contextual factors have a substantial impact on the nature of networking behaviours, and the extent to which they can influence outcomes. Additionally, young jobseekers face a range of barriers to networking, do not always utilise their networks thoroughly, and are more likely to use social media platforms as supplementary tools for job search.A key contribution of this work is that it provides a detailed insight into the process of networking that has been neglected in previous studies. Its focus on social media also reveals a new dimension to the concept which has received little attention in the job search literature. Given its focus on young jobseekers living in Scotland, the findings have also been used to create a detailed list of recommendations for practitioners.