Using hypergraph theory to model coexistence management and coordinated spectrum allocation for heterogeneous wireless networks operating in shared spectrum

Electromagnetic waves in the Radio Frequency (RF) spectrum are used to convey wireless transmissions from one radio antenna to another. Spectrum utilisation factor, which refers to how readily a given spectrum can be reused across space and time while maintaining an acceptable level of transmission errors, is used to measure how efficiently a unit of frequency spectrum can be allocated to a specified number of users. The demand for wireless applications is increasing exponentially, hence there is a need for efficient management of the RF spectrum. However, spectrum usage studies have shown that the spectrum is under-utilised in space and time. A regulatory shift from static spectrum assignment to DSA is one way of addressing this. Licence exemption policy has also been advanced in Dynamic Spectrum Access (DSA) systems to spur wireless innovation and universal access to the internet. Furthermore, there is a shift from homogeneous to heterogeneous radio access and usage of the same spectrum band. These three shifts from traditional spectrum management have led to the challenge of coexistence among heterogeneous wireless networks which access the spectrum using DSA techniques. Cognitive radios have the ability for spectrum agility based on spectrum conditions. However, in the presence of multiple heterogeneous networks and without spectrum coordination, there is a challenge related to switching between available channels to minimise interference and maximise spectrum allocation. This thesis therefore focuses on the design of a framework for coexistence management and spectrum coordination, with the objective of maximising spectrum utilisation across geographical space and across time. The amount of geographical coverage in which a frequency can be used is optimised through frequency reuse while ensuring that harmful interference is minimised. The time during which spectrum is occupied is increased through time-sharing of the same spectrum by two or more networks, while ensuring that spectrum is shared by networks that can coexist in the same spectrum and that the total channel load is not excessive to prevent spectrum starvation. Conventionally, a graph is used to model relationships between entities such as interference relationships among networks. However, the concept of an edge in a graph is not sufficient to model relationships that involve more than two entities, such as more than two networks that are able to share the same channel in the time domain, because an edge can only connect two entities. On the other hand, a hypergraph is a generalisation of an undirected graph in which a hyperedge can connect more than two entities. Therefore, this thesis investigates the use of hypergraph theory to model the RF environment and the spectrum allocation scheme. The hypergraph model was applied to an algorithm for spectrum sharing among 100 heterogeneous wireless networks, whose geo-locations were randomly and independently generated in a 50 km by 50 km area. Simulation results for spectrum utilisation performance have shown that the hypergraph-based model allocated channels, on average, to 8% more networks than the graph-based model. The results also show that, for the same RF environment, the hypergraph model requires up to 36% fewer channels to achieve, on average, 100% operational networks, than the graph model. The rate of growth of the running time of the hypergraph-based algorithm with respect to the input size is equal to the square of the input size, like the graph-based algorithm. Thus, the model achieved better performance at no additional time complexity.Electromagnetic waves in the Radio Frequency (RF) spectrum are used to convey wireless transmissions from one radio antenna to another. Spectrum utilisation factor, which refers to how readily a given spectrum can be reused across space and time while maintaining an acceptable level of transmission errors, is used to measure how efficiently a unit of frequency spectrum can be allocated to a specified number of users. The demand for wireless applications is increasing exponentially, hence there is a need for efficient management of the RF spectrum. However, spectrum usage studies have shown that the spectrum is under-utilised in space and time. A regulatory shift from static spectrum assignment to DSA is one way of addressing this. Licence exemption policy has also been advanced in Dynamic Spectrum Access (DSA) systems to spur wireless innovation and universal access to the internet. Furthermore, there is a shift from homogeneous to heterogeneous radio access and usage of the same spectrum band. These three shifts from traditional spectrum management have led to the challenge of coexistence among heterogeneous wireless networks which access the spectrum using DSA techniques. Cognitive radios have the ability for spectrum agility based on spectrum conditions. However, in the presence of multiple heterogeneous networks and without spectrum coordination, there is a challenge related to switching between available channels to minimise interference and maximise spectrum allocation. This thesis therefore focuses on the design of a framework for coexistence management and spectrum coordination, with the objective of maximising spectrum utilisation across geographical space and across time. The amount of geographical coverage in which a frequency can be used is optimised through frequency reuse while ensuring that harmful interference is minimised. The time during which spectrum is occupied is increased through time-sharing of the same spectrum by two or more networks, while ensuring that spectrum is shared by networks that can coexist in the same spectrum and that the total channel load is not excessive to prevent spectrum starvation. Conventionally, a graph is used to model relationships between entities such as interference relationships among networks. However, the concept of an edge in a graph is not sufficient to model relationships that involve more than two entities, such as more than two networks that are able to share the same channel in the time domain, because an edge can only connect two entities. On the other hand, a hypergraph is a generalisation of an undirected graph in which a hyperedge can connect more than two entities. Therefore, this thesis investigates the use of hypergraph theory to model the RF environment and the spectrum allocation scheme. The hypergraph model was applied to an algorithm for spectrum sharing among 100 heterogeneous wireless networks, whose geo-locations were randomly and independently generated in a 50 km by 50 km area. Simulation results for spectrum utilisation performance have shown that the hypergraph-based model allocated channels, on average, to 8% more networks than the graph-based model. The results also show that, for the same RF environment, the hypergraph model requires up to 36% fewer channels to achieve, on average, 100% operational networks, than the graph model. The rate of growth of the running time of the hypergraph-based algorithm with respect to the input size is equal to the square of the input size, like the graph-based algorithm. Thus, the model achieved better performance at no additional time complexity

Managing Shared Access to a Spectrum Commons

The open access, unlicensed or spectrum commons approach to managing shared access to RF spectrum offers many attractive benefits, especially when implemented in conjunction with and as a complement to a regime of marketbased, flexible use, tradable licensed spectrum ([Benkler02], [Lehr04], [Werbach03]). However, as a number of critics have pointed out, implementing the unlicensed model poses difficult challenges that have not been well-addressed yet by commons advocates ([Benjam03], [Faulhab05], [Goodman04], [Hazlett01]). A successful spectrum commons will not be unregulated, but it also need not be command & control by another name. This paper seeks to address some of the implementation challenges associated with managing a spectrum commons. We focus on the minimal set of features that we believe a suitable management protocol, etiquette, or framework for a spectrum commons will need to incorporate. This includes: (1) No transmit only devices; (2) Power restrictions; (3) Common channel signaling; (4) Mechanism for handling congestion and allocating resources among users/uses in times of congestion; (5) Mechanism to support enforcement (e.g., established procedures to verify protocol is in conformance); (6) Mechanism to support reversibility of policy; and (7) Protection for privacy and security. We explain why each is necessary, examine their implications for current policy, and suggest ways in which they might be implemented. We present a framework that suggests a set of design principles for the protocols that will govern a successful commons management regime. Our design rules lead us to conclude that the appropriate Protocols for a Commons will need to be more liquid ([Reed05]) than in the past: (1) Marketbased instead of C&C; (2) Decentralized/distributed; and, (3) Adaptive and flexible (Anonymous, distributed, decentralized, and locally responsive)

Critical Programming: Toward a Philosophy of Computing

Beliefs about the relationship between human beings and computing machines and their destinies have alternated from heroic counterparts to conspirators of automated genocide, from apocalyptic extinction events to evolutionary cyborg convergences. Many fear that people are losing key intellectual and social abilities as tasks are offloaded to the everywhere of the built environment, which is developing a mind of its own. If digital technologies have contributed to forming a dumbest generation and ushering in a robotic moment, we all have a stake in addressing this collective intelligence problem. While digital humanities continue to flourish and introduce new uses for computer technologies, the basic modes of philosophical inquiry remain in the grip of print media, and default philosophies of computing prevail, or experimental ones propagate false hopes. I cast this as-is situation as the post-postmodern network dividual cyborg, recognizing that the rational enlightenment of modernism and regressive subjectivity of postmodernism now operate in an empire of extended mind cybernetics combined with techno-capitalist networks forming societies of control. Recent critical theorists identify a justificatory scheme foregrounding participation in projects, valorizing social network linkages over heroic individualism, and commending flexibility and adaptability through life long learning over stable career paths. It seems to reify one possible, contingent configuration of global capitalism as if it was the reflection of a deterministic evolution of commingled technogenesis and synaptogenesis. To counter this trend I offer a theoretical framework to focus on the phenomenology of software and code, joining social critiques with textuality and media studies, the former proposing that theory be done through practice, and the latter seeking to understand their schematism of perceptibility by taking into account engineering techniques like time axis manipulation. The social construction of technology makes additional theoretical contributions dispelling closed world, deterministic historical narratives and requiring voices be given to the engineers and technologists that best know their subject area. This theoretical slate has been recently deployed to produce rich histories of computing, networking, and software, inform the nascent disciplines of software studies and code studies, as well as guide ethnographers of software development communities. I call my syncretism of these approaches the procedural rhetoric of diachrony in synchrony, recognizing that multiple explanatory layers operating in their individual temporal and physical orders of magnitude simultaneously undergird post-postmodern network phenomena. Its touchstone is that the human-machine situation is best contemplated by doing, which as a methodology for digital humanities research I call critical programming. Philosophers of computing explore working code places by designing, coding, and executing complex software projects as an integral part of their intellectual activity, reflecting on how developing theoretical understanding necessitates iterative development of code as it does other texts, and how resolving coding dilemmas may clarify or modify provisional theories as our minds struggle to intuit the alien temporalities of machine processes

Security Policies That Make Sense for Complex Systems: Comprehensible Formalism for the System Consumer

Information Systems today rarely are contained within a single user workstation, server, or networked environment. Data can be transparently accessed from any location, and maintained across various network infrastructures. Cloud computing paradigms commoditize the hardware and software environments and allow an enterprise to lease computing resources by the hour, minute, or number of instances required to complete a processing task. An access control policy mediates access requests between authorized users of an information system and the system\u27s resources. Access control policies are defined at any given level of abstraction, such as the file, directory, system, or network, and can be instantiated in layers of increasing (or decreasing) abstraction. For the system end-user, the functional allocation of security policy to discrete system components, or subsystems, may be too complex for comprehension. In this dissertation, the concept of a metapolicy, or policy that governs execution of subordinate security policies, is introduced. From the user\u27s perspective, the metapolicy provides the rules for system governance that are functionally applied across the system\u27s components for policy enforcement. The metapolicy provides a method to communicate updated higher-level policy information to all components of a system; it minimizes the overhead associated with access control decisions by making access decisions at the highest level possible in the policy hierarchy. Formal definitions of policy often involve mathematical proof, formal logic, or set theoretic notation. Such policy definitions may be beyond the capability of a system user who simply wants to control information sharing. For thousands of years, mankind has used narrative and storytelling as a way to convey knowledge. This dissertation discusses how the concepts of storytelling can be embodied in computational narrative and used as a top-level requirements specification. The definition of metapolicy is further discussed, as is the relationship between the metapolicy and various access control mechanisms. The use of storytelling to derive the metapolicy and its applicability to formal requirements definition is discussed. The author\u27s hypothesis on the use of narrative to explain security policy to the system user is validated through the use of a series of survey instruments. The survey instrument applies either a traditional requirements specification language or a brief narrative to describe a security policy and asks the subject to interpret the statements. The results of this research are promising and reflect a synthesis of the disciplines of neuroscience, security, and formal methods to present a potentially more comprehensible knowledge representation of security policy

Unmet goals of tracking: within-track heterogeneity of students' expectations for

Educational systems are often characterized by some form(s) of ability grouping, like tracking. Although substantial variation in the implementation of these practices exists, it is always the aim to improve teaching efficiency by creating homogeneous groups of students in terms of capabilities and performances as well as expected pathways. If students’ expected pathways (university, graduate school, or working) are in line with the goals of tracking, one might presume that these expectations are rather homogeneous within tracks and heterogeneous between tracks. In Flanders (the northern region of Belgium), the educational system consists of four tracks. Many students start out in the most prestigious, academic track. If they fail to gain the necessary credentials, they move to the less esteemed technical and vocational tracks. Therefore, the educational system has been called a 'cascade system'. We presume that this cascade system creates homogeneous expectations in the academic track, though heterogeneous expectations in the technical and vocational tracks. We use data from the International Study of City Youth (ISCY), gathered during the 2013-2014 school year from 2354 pupils of the tenth grade across 30 secondary schools in the city of Ghent, Flanders. Preliminary results suggest that the technical and vocational tracks show more heterogeneity in student’s expectations than the academic track. If tracking does not fulfill the desired goals in some tracks, tracking practices should be questioned as tracking occurs along social and ethnic lines, causing social inequality

9th International Conference on Business, Technology and Innovation 2020

Welcome to IC – UBT 2020 UBT Annual International Conference is the 9th international interdisciplinary peer reviewed conference which publishes works of the scientists as well as practitioners in the area where UBT is active in Education, Research and Development. The UBT aims to implement an integrated strategy to establish itself as an internationally competitive, research-intensive university, committed to the transfer of knowledge and the provision of a world-class education to the most talented students from all background. The main perspective of the conference is to connect the scientists and practitioners from different disciplines in the same place and make them be aware of the recent advancements in different research fields, and provide them with a unique forum to share their experiences. It is also the place to support the new academic staff for doing research and publish their work in international standard level. This conference consists of sub conferences in different fields like: Security Studies Sport, Health and Society Psychology Political Science Pharmaceutical and Natural Sciences Mechatronics, System Engineering and Robotics Medicine and Nursing Modern Music, Digital Production and Management Management, Business and Economics Language and Culture Law Journalism, Media and Communication Information Systems and Security Integrated Design Energy Efficiency Engineering Education and Development Dental Sciences Computer Science and Communication Engineering Civil Engineering, Infrastructure and Environment Architecture and Spatial Planning Agriculture, Food Science and Technology Art and Digital Media This conference is the major scientific event of the UBT. It is organizing annually and always in cooperation with the partner universities from the region and Europe. We have to thank all Authors, partners, sponsors and also the conference organizing team making this event a real international scientific event. Edmond Hajrizi, President of UBTUBT – Higher Education Institutio

Global Political Leadership

Global Political Leadership explores contemporary shifts in leadership, and the related leadership crisis, in the global world. Globalization is now perceived as a threatening and hostile force, with many of its advocates and political supporters turning away from it, but its processes cannot be reversed. New powers emerge, old ones re-emerge, and uncertainty about the future global order is increasing. This book tells the inside stories of global power games and asks important questions about the leadership crisis in the western world. The author provides an interpretative framework for contemporary shifts within the western political sphere based on the concept of global leadership. This framework presents the nature of the transformation caused by global processes, as part of which force and coercion have ceased to be the main modus operandi of the international realm. The issue of global political leadership has often been neglected in international relations literature, while being widely exploited by managerial and organizational studies. However, all social organizations have ‘gone global’ within the last several decades; they are more interconnected and more dependent on global processes, so the question of effective leadership strategies matching these new realities is highly necessary, even – or especially – at a time when globalization is no longer seen as a leading political programme. This book will be of great interest to students and scholars of global affairs, politics and international relations, leadership and development, and diplomatic studies

Thumb Culture: The Meaning of Mobile Phones for Society

Mobile communication has an increasing impact on people's lives and society. Ubiquitous media influence the way users relate to their surroundings, and data services like text and pictures lead to a culture shaped by thumbs. Representing several years of research into the social and cultural effects of mobile phone use, this volume assembles the fascinating approaches and new insights of leading scientists and practitioners. The book contains the results of a first international survey on the social consequences of mobile phones. It provides a comprehensive inventory of today's issues and an outlook in mobile media, society and their future study

Spaces of imagination : associational life and the state in post-war, urban Liberia

This ethnography explores social imaginaries in post-war, urban Liberia – a physical and social context dominated by intricacies of past oligarchic rule, dictatorship, brutal civil war and post-war reconstruction. Against this challenging backdrop, this thesis asks: How do Liberians imagine the social to be and how do such imaginaries translate into social practice? Embedded in a political anthropology of the state and conceptually drawing on agency as defined by the interrelated temporal-structural dimensions of the past, present and future (Emirbayer and Mische 1998), this ethnography analyses three political associations and their interrelations with the state. Based on twelve months of empirical field research between 2009 and 2012 in urban Liberia, this thesis shows how ordinary people engage in meticulous social practices of “hustling”, “trying”, studying and maintaining social relations to economically or politically influential persons to forge a living in this insecure, unpredictable setting. Associations create social spaces in which imaginaries are uttered and shared, and inform individual and collective action. The first association, the Unconstitutionally Disbanded Armed Forces of Liberia (UDAFOL), is a particular group with claims towards the central and sensitive post-war issue of national security. UDAFOL represents the grievances of soldiers that have been disbanded in the implementation of the Security Sector Reform. They consider their disbandment unconstitutional and a political decision. The disgruntled ex-servicemen regularly take to the streets, and address specific state images and practices in various forms of collective action. The second association is the Concerned Mandingo Society of Liberia (COMASL), a group representing the temporally and situationally marginalized and instrumentalized ethnic group of Liberian Mandingo. As traders and late comers in Liberia, their belonging to the nation-state is contested. Though lawfully placed in the field of formal citizenship according to the constitution, in everyday life, their participation is challenged by discursively formed social boundaries. These boundaries are countered by COMASL on the basis of claims of belonging. The third association is the West Point Women for Health and Development Organization (WPHD), a women’s association in a Monrovian slum. The association presses for political action in regards to the delivery of public goods and services such as security, justice, sanitation or health care. This association flexibly navigates the donor-sphere as a quite formalized NGO, directly addresses some of the neighborhoods’ problems, and situatively works in cooperation with state actors or mounts pressure on them. These three associations highlight some particularities and complexities of post-war intricacies and how social spaces create an environment for collective action in response these problems. As the three case studies show, the state plays a central role and is ascribed major responsibility. The associations make claims towards political actors to initiate and catalyze change. This ethnography shows that state and civil society are not monolithic black boxes but composed of individual actors with various experiences, knowledge and interests, and are very closely interwoven into a “state in society”(Migdal 2001), formed and shaped by multifaceted relationships of claims and state responses. Often overlooked, and highlighted in this thesis, is the existence of official norms that underlie the expectations towards the powerful political leaders that give the state a concrete imagery (Olivier de Sardan 2008). These norms do not emerge randomly, but from the political history of the Liberian state, and through experiences from other states. From the social actor’s point of view, hence, the Liberian state is not a failed, weak or absent state. Quite to the contrary, it is considered strong, yet its actors are considered to lack political will to meet the needs and to work in the interest of the ordinary people and implement policies that make a change