Dissertations / Theses on the topic 'Access sharing'
To see the other types of publications on this topic, follow the link: Access sharing.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Access sharing.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Beiter, Bernd Michael. "Secret sharing schemes on general access structures /." Aachen : Shaker, 2008. http://d-nb.info/991819993/04.
Full text
2
Sleeper, Manya. "Everyday Online Sharing." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/881.
Full textAbstract:
People make a range of everyday decisions about how and whether to share content with different people, across different platforms and services, during a variety of tasks. These sharing decisions can encompass complex preferences and a variety of access-control dimensions. In this thesis I examine potential methods for improving sharing mechanisms by better understanding the everyday online sharing environment and evaluating a potential sharing tool. I first present two studies that explore how current sharing mechanisms may fall short on social networking sites, leading to suboptimal outcomes such as regret or self censorship. I discuss the implications of these suboptimal outcomes for the design of behavioral nudging tools and the potential for improving the design of selective-sharing mechanisms. I then draw on a third study to explore the broader “ecosystem” of available channels created by the services and platforms people move between and combine to share content in everyday contexts. I examine the role of selective-sharing features in the broader audience-driven and task-driven dynamics that drive sharing decisions in this environment. I discuss the implications of channel choice and dynamics for the design of selective-sharing mechanisms. Using insights from current shortfalls and ecosystem-level dynamics I then present a fourth study examining the potential for adding topic-driven sharing mechanisms to Facebook. I use design mockups and a lab-based interview to explore participants’ hypothetical use cases for such mechanisms. I find that these mechanisms could potentially be useful in a variety of situations, but successful implementation would require accounting for privacy requirements and users’ sharing strategies.
3
Kaskaloglu, Kerem. "Some Generalized Multipartite Access Structures." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/2/12611965/index.pdf.
Full textAbstract:
In this work, we study some generalized multipartite access structures and linear secret sharing schemes for their realizations. Given a multipartite set of participants with m compartments (or levels) and m conditions to be satisfied by an authorized set, we firstly examine the intermediary access structures arousing from the natural case concerning that any c out of m of these conditions suffice, instead of requiring anyone or all of the m conditions simultaneously, yielding to generalizations for both the compartmented and hierarchical cases. These are realized essentially by employing a series of Lagrange interpolations and a simple frequently-used connective tool called access structure product, as well as some known constructions for existing ideal schemes. The resulting schemes are non-ideal but perfect. We also consider nested multipartite access structures, where we let a compartment to be defined within another, so that the access structure is composed of some multipartite substructures. We extend formerly employed bivariate interpolation techniques to multivariate interpolation, in order to realize such access structures. The generic scheme we consider is perfect with a high probability such as 1-O(1/q) on a finite field F_q. In particular, we propose a non-nested generalization for the conventional compartmented access structures, which depicts a stronger way of controlling the additional participants.
4
Kayem, Anne Voluntas dei Massah. "Adaptive Cryptographic Access Control for Dynamic Data Sharing Environments." Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1557.
Full text
5
He, Kun. "Content privacy and access control in image-sharing platforms." Thesis, CentraleSupélec, 2017. http://www.theses.fr/2017CSUP0007.
Full textAbstract:
Au cours de ces dernières années, de plus en plus d’utilisateurs choisissent de diffuser leurs photos sur des plateformes de partage d’images. Ces plateformes permettent aux utilisateurs de restreindre l’accès aux images à un groupe de personnes, afin de donner un sentiment de confiance aux utilisateurs vis-à-vis de la confidentialité de ces images. Malheureusement, la confidentialité ne peut être garantie sachant que le fournisseur de la plateforme a accès aux contenus de n’importe quelle image publiée sur sa plateforme. En revanche, si les images sont mises en ligne chiffrées, seules les personnes ayant la possibilité de déchiffrer les images, auront accès aux images. Ainsi, la confidentialité peut être assurée. Trois principales spécificités sont à prendre en compte lors du chiffrement d’une image : le schéma de chiffrement doit être effectué en respectant le format de l’image (e.g. format JPEG), garantir l’indistinguabilité (l’adversaire ne doit obtenir de l’information sur le contenu de l’image à partir de l’image chiffrée), et doit être compatible avec les traitements des images spécifiques à la plateforme de partage d’images. L’objectif principal de cette thèse a été de proposer un tel schéma de chiffrement pour les images JPEG. Nous avons d’abord proposé et implémenté un schéma de chiffrement garantissant la conservation de l’image et l’indistinguabilité. Malheureusement, nous avons montré que sur Facebook, Instagram, Weibo et Wechat, notre solution ne permettait de maintenir une qualité d’images suffisante après déchiffrement. Par conséquent, des codes correcteurs ont été ajoutés à notre schéma de chiffrement, afin de maintenir la qualité des imagesIn recent years, more and more users prefer to share their photos through image-sharing platforms. Most of platforms allow users to specify who can access to the images, it may result a feeling of safety and privacy. However, the privacy is not guaranteed, since at least the provider of platforms can clearly know the contents of any published images. According to some existing researches, encrypting images before publishing them, and only the authorised users who can decrypt the encrypted image. In this way, user’s privacy can be protected.There are three challenges when proposing an encryption algorithm for the images published on image-sharing platforms: the algorithm has to preserve image format (e.g. JPEG image) after encryption, the algorithm should be secure (i.e. the adversary cannot get any information of plaintext image from the encrypted image), and the algorithm has to be compatible with basic image processing in each platform. In this thesis, our main goal is to propose an encryption algorithm to protect JPEG image privacy on different image-sharing platforms and overcome the three challenges. We first propose an encryption algorithm which can meet the requirements of the first two points. We then implement this algorithm on several widely-used image-sharing platforms. However, the results show that it cannot recover the plaintext image with a high quality after downloading the image from Facebook, Instagram, Weibo and Wechat. Therefore, we add the correcting mechanism to improve this algorithm, which reduces the losses of image information during uploading the encrypted image on each platform and reconstruct the downloaded images with a high quality
6
Brahma, Swastik Kumar. "Spectrum sharing and service pricing in dynamic spectrum access networks." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4854.
Full textAbstract:
Traditionally, radio spectrum has been statically allocated to wireless service providers (WSPs). Regulators, like FCC, give wireless service providers exclusive long term licenses for using specific range of frequencies in particular geographic areas. Moreover, restrictions are imposed on the technologies to be used and the services to be provided. The lack of flexibility in static spectrum allocation constrains the ability to make use of new technologies and the ability to redeploy the spectrum to higher valued uses, thereby resulting in inefficient spectrum utilization (23, 38, 42, 62, 67). These limitations have motivated a paradigm shift from static spectrum allocation towards a more 'liberalized' notion of spectrum management in which secondary users can borrow idle spectrum from primary spectrum licensees, without causing harmful interference to the latter- a notion commonly referred to as dynamic spectrum access (DSA) or open spectrum access (3), (82). Cognitive radio (30, 47), empowered by Software Defined Radio (SDR) (81), is poised to promote the efficient use of spectrum by adopting this open spectrum approach. In this dissertation, we first address the problem of dynamic channel (spectrum) access by a set of cognitive radio enabled nodes, where each node acting in a selfish manner tries to access and use as many channels as possible, subject to the interference constraints. We model the dynamic channel access problem as a modified Rubinstein-Stahl bargaining game. In our model, each node negotiates with the other nodes to obtain an agreeable sharing rule of the available channels, such that, no two interfering nodes use the same channel. We solve the bargaining game by finding Subgame Perfect Nash Equilibrium (SPNE) strategies of the nodes. First, we consider finite horizon version of the bargaining game and investigate its SPNE strategies that allow each node to maximize its utility against the other nodes (opponents).; We then extend these results to the infinite horizon bargaining game. Furthermore, we identify Pareto optimal equilibria of the game for improving spectrum utilization. The bargaining solution ensures that no node is starved of channels. The spectrum that a secondary node acquires comes to it at a cost. Thus it becomes important to study the 'end system' perspective of such a cost, by focusing on its implications. Specifically, we consider the problem of incentivizing nodes to provide the service of routing using the acquired spectrum. In this problem, each secondary node having a certain capacity incurs a cost for routing traffic through it. Secondary nodes will not have an incentive to relay traffic unless they are compensated for the costs they incur in forwarding traffic. We propose a path auction scheme in which each secondary node announces its cost and capacity to the routing mechanism, both of which are considered as private information known only to the node. We design a route selection mechanism and a pricing function that can induce nodes to reveal their cost and capacity honestly (making our auction truthful), while minimizing the payment that needs to be given to the nodes (making our auction optimal). By considering capacity constraint of the nodes, we explicitly support multiple path routing. For deploying our path auction based routing mechanism in DSA networks, we provide polynomial time algorithms to find the optimal route over which traffic should be routed and to compute the payment that each node should receive. All our proposed algorithms have been evaluated via extensive simulation experiments. These results help to validate our design philosophy and also illustrate the effectiveness of our solution approach.ID: 030422691; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 161-166).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
7
Fu, Kevin E. (Kevin Edward) 1976. "Group sharing and random access in cryptographic storage file systems." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80534.
Full textAbstract:
Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Vita.
Includes bibliographical references (p. 79-83).
by Kevin E. Fu.
M.Eng.
8
Lee, Haeyoung. "Dynamic spectrum sharing by opportunistic spectrum access with spectrum aggregation." Thesis, University of Surrey, 2015. http://epubs.surrey.ac.uk/807078/.
Full textAbstract:
The rapid growth of wireless services and the breakneck proliferation of wireless devices continue to strain limited spectrum resource. While the need for efficient spectrum sharing mechanisms has been emphasized, opportunistic spectrum access has been considered as a promising mechanism for dynamic spectrum sharing. However, although the idle spectrum could exist, it is usually rather fragmented and distributed, and hence the secondary network users would face the difficulty in finding required contiguous spectrum. Spectrum aggregation can be exploited to provide effective wide bandwidth communication but at the cost of complexity and overhead. When a primary network uses spectrum dynamically, from the nature of opportunistic spectrum access, collisions can occur between primary and secondary transmissions and spectrum handoff can be utilised to provide reliable communication. However, collision occurrence results in spectrum handoff delay in a secondary network user (SU) along with short-term interference to a primary network user (PU). As a SU accesses more spectrum for higher data rates by spectrum aggregation, collisions can occur more frequently and frequent spectrum handoff will be required. While spectrum aggregation will allow the SU to have high flexibility in spectrum use and spectrum handoff can help improve the reliability of secondary transmissions, the SU faces a new spectrum allocation problem: How wide and which parts of spectrum opportunities should be aggregated while considering the complexity and the overhead for aggregation and for spectrum handoff? This thesis addresses the key challenge of opportunistic spectrum access, focusing on efficient spectrum sharing considering the fragmentation of spectrum opportunities in frequency and time domains. First, considering complexity and overhead for aggregation, the spectrum aggregation approach is investigated and guidelines are derived how to reduce spectrum fragmentation for the efficient spectrum utilisation based on simulation results. Second, the relationship between collision occurrence and spectrum aggregation is analysed. Collision probabilities between primary and secondary transmissions are derived and the impacts of spectrum aggregation on data rates and spectrum handoff are investigated. Then, a spectrum aggregation algorithm is proposed to maximise data rates for a given collision probability threshold. Third, when considering spectrum handoff, the impacts of spectrum aggregation on spectrum handoff and short-term interference to PUs are analysed. Then, the spectrum aggregation algorithm is designed with the aim to minimise collision. Finally, the results of this study are summarised, conclusions are presented and a number of future research topics are proposed.
9
Tercero, Vargas Miurel. "Topics in Dynamic Spectrum Access : Market Based Spectrum Sharing and Secondary User Access in Radar Bands." Licentiate thesis, KTH, Kommunikationssystem, CoS, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-33791.
Full textAbstract:
The steady growth in demand for spectrum has increased research interest in dynamic spectrum access schemes. This thesis studies some challenges in dynamic spectrum access based on two strategies: open sharing and hierarchical access. (1) In the open sharing model, the channels are allocated based on an auction process, taking into account the propagation characteristics of the channels, termed as channel heterogeneity. Two distributed dynamic spectrum access schemes are evaluated, sequential and concurrent. We show that the concurrent accessmechanismperforms better in terms of channel utilization and energy consumption, especially in wireless cellular network with an energy constraint. (2) In the hierarchical model, we assess the opportunities for secondary access in the radar band at 5.6GHz. The primary user is a meteorological radar and WLANs are the secondary users. The secondary users implement an interference protection mechanism to protect the radar, such that the WLAN’s transmission is regulated by an interference threshold. We evaluate the aggregate interference caused to the radar from multiple WLANs transmitting. We derive a mathematicalmodel to approximate the probability distribution function of the aggregate interference at the primary user, considering two cases: when secondary users are homogeneously distributed, and when they are heterogeneously distributed. The heterogeneous distribution of secondary users is modeled using an annulus sector with a higher density, called a hot zone. Finally, we evaluate opportunities for secondary access when WLANs employ an interference protection mechanism that considers the radar’s antenna pattern, such that temporal opportunities for transmission exist. The analytical probability distribution function of the interference is verified showing a good agrement with a Monte Carlo simulation. We show that the aggregate interference is sensitive to the propagation environment, thus in the rural case interference is more severe when compared to the urban case. In the evaluation of the hot zonemodel, we observe that the heterogenous distribution of secondary users has impact on the aggregate interference if the hot zone is near to the radar. The mathematical framework presented in this thesis can easily be adapted to assess interference to other types of primary and secondary users.QC 20110523
10
Attia, Tarek. "Band sharing and satellite diversity techniques for CDMA." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/842977/.
Full textAbstract:
High levels of interference between satellite constellation systems, fading and shadowing are a major problem for the successful performance of communication systems using the allocated L/S frequency bands for Non-Geostationary Earth Orbit (NGEO) satellites. As free spectrum is nonexistent, new systems wishing to operate in this band must co-exist with other users, both satellite and terrestrial. This research is mainly concerned with two subjects. Firstly, band sharing between different systems Code Division Multiple Access (CDMA) and Time Division Multiple Access (TDMA) has been evaluated for maximizing capacity and optimising efficiency of using the spectrum available. For the case of widened channel bandwidth of the CDMA channel, the overlapping was tested under different degrees of channel overlap and different orders of filters. The best result shows that at the optimum degree of channel overlap, capacity increases by up to 21%. For the case of fixed channel bandwidth, the optimum overlapping between CDMA systems depends on the filtering Roll-off factor and achieves an improvement of the spectrum efficiency of up to 13.4%. Also, for a number of narrowband signal users sharing a CDMA channel, the best location of narrowband signals to share spectrum with a CDMA system was found to be at the edge of the CDMA channel. Simulation models have been constructed and developed which show the combination of DS- CDMA techniques, forward error correction (FEC) code techniques and satellite diversity with Rake receiver for improving performance of interference, fading and shadowing under different environments. Voice activity factor has been considered to reduce the effect of multiple access interference (MAI). The results have shown that satellite diversity has a significant effect on the system performance and satellite diversity gain achieves an improvement up to 6dB. Further improvements have been achieved by including concatenated codes to provide different BER for different services. Sharing the frequency band between a number of Low Earth Orbit (LEO) satellite constellation systems is feasible and very useful but only for a limited number of LEOS satellite CDMA based constellations. Furthermore, satellite diversity is an essential factor to achieve a satisfactory level of service availability, especially for urban and suburban environments.
11
MacPherson, Lesley. "Grey Level Visual Cryptography for General Access Structures." Thesis, University of Waterloo, 2002. http://hdl.handle.net/10012/1126.
Full textAbstract:
Visual cryptography, first introduced by Naor and Shamir, allows a secret (black and white) image to be encoded and distributed to a set of participants such that certain predefined sets of participants may reconstruct the image without any computation. In 2000, Blundo, De Santis, and Naor introduced a model for grey-level visual cryptography which is a generalization of visual cryptography for general access structures. Grey-level visual cryptography extends this model to include grey-scale images. Decoding is done by the human visual system. In this thesis we survey known results of grey-level visual cryptography and visual cryptography for general access structures. We extend several visual cryptography constructions to grey-level visual cryptography, and derive new results on the minimum possible pixel expansion for all possible access structures on at most four participants.
12
Mazurek, Michelle L. "A Tag-Based, Logical Access-Control Framework for Personal File Sharing." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/325.
Full textAbstract:
People store and share ever-increasing numbers of digital documents, photos, and other files, both on personal devices and within online services. In this environment, proper access control is critical to help users obtain the benefits of sharing varied content with different groups of people while avoiding trouble at work, embarrassment, identity theft, and other problems related to unintended disclosure. Current approaches often fail, either because they insufficiently protect data or because they confuse users about policy specification. Historically, correctly managing access control has proven difficult, timeconsuming, and error-prone, even for experts; to make matters worse, access control remains a secondary task most non-experts are unwilling to spend significant time on.
To solve this problem, access control for file-sharing tools and services should provide verifiable security, make policy configuration and management simple and understandable for users, reduce the risk of user error, and minimize the required user effort. This thesis presents three user studies that provide insight into people’s access-control needs and preferences. Drawing on the results of these studies, I present Penumbra, a prototype distributed file system that combines semantic, tag-based policy specification with logicbased access control, flexibly supporting intuitive policies while providing high assurance of correctness. Penumbra is evaluated using a set of detailed, realistic case studies drawn from the presented user studies. Using microbenchmarks and traces generated from the case studies, Penumbra can enforce users’ policies with overhead less than 5% for most system calls. Finally, I present lessons learned, which can inform the further development of usable access-control mechanisms both for sharing files and in the broader context of personal data.
13
Dursun, Mustafa. "Data Sharing And Access With A Corba Data Distribution Service Implementation." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607681/index.pdf.
Full textAbstract:
Data Distribution Service (DDS) specification defines an API for Data-Centric Publish-Subscribe (DCPS) model to achieve efficient data distribution in distributed computing environments. Lack of definition of interoperability architecture in DDS specification obstructs data distribution between different and heterogeneous DDS implementations. In this thesis, DDS is implemented as a CORBA service to achieve interoperability and a QoS policy is proposed for faster data distribution with CORBA features.
14
Hultell, Johan. "Cooperative and non-cooperative wireless access : Resource and infrastructure sharing regimes." Doctoral thesis, KTH, Kommunikationssystem, CoS, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9680.
Full textAbstract:
Future wireless networks will combine multiple radio technologies and subsystems, possibly managed by competing network providers. For such systems it may be advantageous to let the end nodes (terminals) make some or all of the resource management decisions. In addition to reducing complexity and costs, increasing redundancy, and facilitating more timely decisions; distributed resource sharing regimes can decouple the individual subsystems. Decoupled subsystems could be desirable both because competing operators can be business-wise separated and because it allows new technologies to be added (removed) in a modular fashion. However, distributed regimes can also lead to “selfish” wireless nodes who only try to maximize their own performance. The first part of this dissertation studies if selfish nodes can make efficient use of wireless resources, using multiaccess and network layers as examples. The related problems are formulated as noncooperative games between nodes. To maintain tractability nodes are confined to simple strategies that neither account for future payoffs nor allow for coordination. Yet, it is demonstrated that selfish nodes can achieve comparable performance to traditional protocols. These results should be interpreted as an argument in favor of distributed regimes. The second part of this dissertation evaluates the effects of multi-provider network architectures where users can roam freely across all networks. From a supply side perspective the benefits are improved path gain statistics and the fact that different networks may have non-overlapping busy hours. Several network configurations are analyzed and it is shown that cooperation between symmetric providers can yield significant capacity gains for both downlink and uplink; even if the providers have nearly collocated sites. When the providers have different site densities the gains from cooperation are reduced and the provider with a sparse network always gains more from cooperating. This suggests that initially, voluntary cooperation may be limited to some special cases. Lastly, the architecture is analyzed in a context where the providers compete for users on a per session basis by offering access at different prices. Although such architectures currently only exist in a few special cases, they could emerge in domestic markets where the costs to switch and search for new networks are low. Based on a game theoretic formulation it is shown that a competitive market for wireless access can be advantageous for both users and providers. The results presented suggest that the advantages of cooperation of competing providers occur in more than just a few cases.QC 20100812
15
Gonzalez, Sanchez Dina Pamela. "Resource Sharing and Network Deployment Games : In Open Wireless Access Markets." Licentiate thesis, KTH, Kommunikationssystem, CoS, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-39480.
Full text
16
Bany, Salameh Haythem Ahmad Mohammed. "Channel Access Mechanisms and Protocols for Opportunistic Cognitive Radio Networks." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193865.
Full textAbstract:
High traffic load over the unlicensed portion of the radiospectrum (a.k.a., ISM bands) along with inefficient usage of thelicensed spectrum gave impetus for a new paradigm in spectrumallocation, whose main purpose is to improve spectrum efficiencythrough opportunistic access. Cognitive radios (CRs) havebeen proposed as a key enabling technology for such paradigm.Operating a CR network (CRN) without impacting the performance oflicensed (primary) users requires new protocols for informationexchange as well as mathematical tools to optimize thecontrollable parameters of the CRN. In this dissertation, wetarget the design of such protocols. First, we develop adistributed CRN MAC (COMAC) protocol that enables unlicensed usersto dynamically utilize the spectrum while limiting theinterference they inflict on primary (PR) users. The main noveltyin COMAC lies in not assuming a predefined CR-to-PR power mask andnot requiring coordination with PR users. Second, we propose anovel distance-dependent MAC protocol for CRNs in whicheach CR is equipped with multiple transceivers. Our protocol(called DDMAC) attempts to maximize the CRN throughput byfollowing a novel probabilistic channel assignment mechanism. Thismechanism exploits the dependence between the signal's attenuationmodel and the transmission distance while considering the trafficprofile. We show that through its distance- and traffic-aware,DDMAC significantly improves network throughput. Finally, weaddress the problem of assigning channels to CR transmissions,assuming one transceiver per CR. The main goal of our design is tomaximize the CRN throughput with respect to both spectrumassignment and transmission power. Specifically, we presentcentralized and distributed solutions that leverage the uniquecapabilities of CRs. Compared with previously proposed protocols,our schemes are shown to significantly improve network throughput.
17
Morrison, Heather. "The dramatic growth of open access : implications and opportunities for resource sharing." Haworth Press, 2006. http://hdl.handle.net/2429/953.
Full textAbstract:
The Open Access movement seeks to make scholarly, peer-reviewed journal articles freely available to anyone, anywhere over the World Wide Web. There were some very significant developments in the area of Open Access (OA) in 2004, including statements by major funders in support of Open Access. There are now so many Open Access scholarly journal articles freely available, that, in the author’s opinion, being aware of, and using, the resources and related tools is now essential for libraries. Libraries can provide more resources faster for users by supplementing paid resources with ones that are Open Access.
Library resources, such as link resolvers, are beginning to incorporate Open Access materials and web searches for Open Access materials. For example, the reSearcher software suite includes Open Access collections along with subscription-based resources in the CUFTS journals knowledgebase, and a web search for an Open Access copy of an article in the GODOT link resolver. SFX also incorporates Open Access journals. After exhausting more traditional resources, interlibrary loans staff are beginning to include Google searching in their workflow.
This article will discuss what Open Access is, the dramatic growth of Open Access, and major collections, resources and tools. Implications, issues, and leadership opportunities for resource sharing specialists will be explored.
18
Koppenhafer, Leslie. "Accounting for the Social Element in Access-Based Consumption." Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18511.
Full textAbstract:
This dissertation examines how the inclusion of the social element in access-based consumption can influence affective and behavioral responses. The first essay builds upon the dimensions proposed by Bardhi and Eckhardt, who found that market mediation, anonymity, temporality, consumer involvement, type of accessed object and political consumerism are key dimensions on which to study access-based consumption. A reconceptualization of these dimensions is proposed in the current work to incorporate the social element. Foremost, a separation of renting and sharing based on the presence or absence of economic exchange is proposed. The implications for the remaining dimensions of anonymity, temporality, consumer participation, type of accessed object, political consumerism and governance are then discussed. Finally, key outcome variables of community, cooperation, loneliness and contagion are reviewed.
In Essay 2, the guiding theory of social distance is used to empirically test the impact of the social element on evaluations of a rental service on the outcomes of satisfaction, attitude, disgust and community. In the rental context examined, users are interpersonally anonymous indicating that there is no relationship between the current user and other users. In addition, users must engage in extra-role behaviors because no intermediaries are present. In three experiments, it is shown that encounters with other users can lead to increased feelings of disgust and decreased satisfaction and attitude towards the rental service. Having information about other users, provided in the form of avatar images, can enhance feelings of community, as can certain types of communication between users. Given the benefits that emerge from feelings of community, Essay 3 explores factors that can enhance or detract from sense of community. Factors such as apathetic participation and similarity are considered. In addition, positive outcomes that emerge from feelings of community, such as sign-up likelihood and care behaviors, are measured.2015-04-17
19
Rakshit, Sudipta. "ACCESS GAMES: A GAME THEORETIC FRAMEWORK FOR FAIR BANDWIDTH SHARING IN DISTRIBUTED SYSTEMS." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2444.
Full textAbstract:
In this dissertation, the central objective is to achieve fairness in bandwidth sharing amongst selfish users in a distributed system. Because of the inherent contention-based nature of the distributed medium access and the selfishness of the users, the distributed medium access is modeled as a non-cooperative game; designated as the Access Game. A p-CSMA type medium access scenario is proposed for all the users. Therefore, in the Access Game, each user has two actions to choose from: "transmit" and "wait". The outcome of the Access Game and payoffs to each user depends on the actions taken by all the users. Further, the utility function of each user is constructed as a function of both Quality of Service (QoS) and Battery Power (BP). Various scenarios involving the relative importance of QoS and BP are considered. It is observed that, in general the Nash Equilibrium of the Access Game does not result into fairness. Therefore, Constrained Nash Equilibrium is proposed as a solution. The advantage of Constrained Nash Equilibrium is that it can be predicated on the fairness conditions and the solution will be guaranteed to result in fair sharing of bandwidth. However, Constrained Nash Equilibrium is that it is not self-enforcing. Therefore, two mechanisms are proposed to design the Access Game in such a way that in each case the Nash Equilibrium of the Access Game satisfies fairness and maximizes throughput. Hence, with any of these mechanisms the solution of the Access Game becomes self-enforcing.Ph.D.
School of Computer Science
Arts and Sciences
Computer Science
20
Sacramento, Junior Luiz Claudio Ferreira. "More than words: broader information sharing and access to the formal credit market." reponame:Repositório Institucional do FGV, 2017. http://hdl.handle.net/10438/18293.
Full textAbstract:
Submitted by Luiz Claudio Ferreira Sacramento Junior (luizclaudiosacramento@hotmail.com) on 2017-05-22T23:07:02Z
No. of bitstreams: 1
Dissertation_final version.docx: 377515 bytes, checksum: c5d360cbf921b7c3982e47f2705d59f4 (MD5)Approved for entry into archive by ÁUREA CORRÊA DA FONSECA CORRÊA DA FONSECA (aurea.fonseca@fgv.br) on 2017-05-23T19:21:16Z (GMT) No. of bitstreams: 1 Dissertation_final version.docx: 377515 bytes, checksum: c5d360cbf921b7c3982e47f2705d59f4 (MD5)
Made available in DSpace on 2017-05-30T18:56:11Z (GMT). No. of bitstreams: 1 Dissertation_final version.docx: 377515 bytes, checksum: c5d360cbf921b7c3982e47f2705d59f4 (MD5) Previous issue date: 2017-03-28
This paper shows how information sharing mechanisms might enable Micro and Small Enterprises (MSEs) to increase their access to formal credit markets. Using a unique dataset provided by the Brazilian Central Bank and Ministry of Labor, a change is applied in the threshold of loans that must be reported and shared by all active financial institutions as a gradual increase in the available information on MSEs. Results suggest that borrowers that benefited by this change obtained more loans and smaller interest rates, and by building a good client pool ended up receiving smaller maturities. Firms were also less likely to delay repayments and present smaller loan losses. This evidence sheds light on information asymmetry and literature on financial inclusion by showing that information sharing mechanisms can improve the decision to offer credit, and MSEs can become less dependent of relationship lending to obtain loans.
Esse estudo mostra como mecanismos de compartilhamento de informação podem permitir Micro e Pequenas Empresas (MPEs) podem melhorar seu acesso a mercados de crédito formais. Utilizando uma base de dados única obtida junto ao Banco Central do Brasil e Ministério do Trabalho, uma mudança é aplicada no limite do valor de empréstimos que precisam ser reportados e compartilhados por todas as instituições financeiras ativas como uma mudança gradual na informação disponível sobre MPEs. Os resultados indicam que tomadores de empréstimo que se beneficiaram dessa mudança obtiveram mais empréstimos e menores taxas de juros, e por constituir um bom grupo de clientes acabam por receber menores vencimentos. As empresas são ainda menos prováveis de atrasar seus pagamentos e apresentam menores perdas aos bancos. As consequências desse estudo lançam luz sobre a literatura de assimetria de informação e inclusão financeira ao mostrar que mecanismos de compartilhamento de informação podem auxiliar na decisão de oferecer crédito e MPEs podem se tornar menos dependentes de empréstimos de relacionamento para obter empréstimos.
21
Low, Marie Rose. "Self defence in open systems : protecting and sharing resources in a distributed open environment." Thesis, University of Hertfordshire, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241623.
Full text
22
Oyediran, David. "Spectrum Sharing: Overview and Challenges of Small Cells Innovation in the Proposed 3.5 GHz Band." International Foundation for Telemetering, 2015. http://hdl.handle.net/10150/596402.
Full textAbstract:
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NVSpectrum sharing between Federal and commercial users is a technique proposed by the FCC and NTIA to open up the 3.5 GHz band for wireless broadband use and small cell technology is one of the candidates for its' realization. The traffic on small cells is temporal and their chances of interfering with other services in shared spectrum are limited. DoD has a documented requirement of 865 MHz by 2025 to support telemetry but only 445 MHz is presently available. DoD is conducting researches to realize test and evaluation spectrum efficient technology with the aim to develop, demonstrate, and evaluate technology components required to enable flight and ground test telemetry operations. This paper will provide an overview on spectrum sharing using small cell technology for LTE-Advanced and dynamic spectrum access would be briefly described. Research challenges for protocols and algorithms would be addressed for future studies.
23
Bennis, M. (Mehdi). "Spectrum sharing for future mobile cellular systems." Doctoral thesis, University of Oulu, 2009. http://urn.fi/urn:isbn:9789514260582.
Full textAbstract:
Abstract
Spectrum sharing has become a high priority research area over the past few years. The motivation behind this lies in the fact that the limited spectrum is currently inefficiently utilized. As recognized by the World radio communication conference (WRC)-07, the amount of identified spectrum is not large enough to support large bandwidths for a substantial number of operators. Therefore, it is paramount for future mobile cellular systems to share the frequency spectrum and coexist in a more efficient manner.
The present dissertation deals with the problem of spectrum scarcity by examining spectrum sharing paradigms where a migration from fixed to flexible resource allocation is investigated. First, a radio resource management (RRM) architecture is proposed where advanced spectrum functionalities accounting for the short-term variations of the spectrum are examined. The achievable gains are shown in a multi-cell, multi-network environment with realistic traffic patterns from a European operator, enhancing thereby spectrum utilization. Second, inter-operator resource sharing in a broadband network is considered where a packet-based cellular network is developed. It is shown that the obtained gains in terms of quality-of-service (QoS), number of operators and different data rates requirements improve the overall efficiency of the network. Besides and in order to cope with the stringent data rate requirements, direct terminal-to-terminal (T2T) communication is examined in which a realistic algorithm is proposed advocating resource reuse in a cellular system with simultaneous communications between mobiles. Numerical results confirm the advantages of resource reuse in terms of throughput, average frame delays and power consumption.
In this thesis, a proposal is made as how to enhance spectrum sharing. The concept of hierarchy is proposed in which wireless competitive operators share the same spectrum band. The decentralized hierarchical approach is shown to bridge the gap between the selfish and centralized approach.
Interference avoidance is studied for point-to-point communication in a selforganized network where different optimal power allocation strategies are examined along with the impact of frequency reuse on the ergodic capacity of the network.
24
Sohul, Munawwar Mahmud. "Spectrum Opportunity Duration Assurance: A Primary-Secondary Cooperation Approach for Spectrum Sharing Systems." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/88018.
Full textAbstract:
The radio spectrum dependent applications are facing a huge scarcity of the resource. To address this issue, future wireless systems require new wireless network architectures and new approaches to spectrum management. Spectrum sharing has emerged as a promising solution to address the radio frequency (RF) spectrum bottleneck. Although spectrum sharing is intended to provide flexible use of the spectrum, the architecture of the existing approaches, such as TV White Space [1] and Citizen Broadband Radio Services (CBRS) [2], have a relatively fixed sharing framework. This fixed structure limits the applicability of the architecture to other bands where the relationship between various new users and different types of legacy users co-exist. Specifically, an important aspect of sharing that has not been explored enough is the cooperation between the resource owner and the opportunistic user. Also in a shared spectrum system, the users do not have any information about the availability and duration of the available spectrum opportunities. This lack of understanding about the shared spectrum leads the research community to explore a number of core spectrum sharing tasks, such as opportunity detection, dynamic opportunity scheduling, and interference protection for the primary users, etc. This report proposes a Primary-Secondary Cooperation Framework to provide flexibility to all the involved parties in terms of choosing the level of cooperation that allow them to satisfy different objective priorities. The cooperation framework allows exchange of a probabilistic assurance: Spectrum Opportunity Duration Assurance (SODA) between the primary and secondary operations to improve the overall spectrum sharing experience for both the parties. This capability will give the spectrum sharing architectures new flexibility to handle evolutions in technologies, regulations, and the requirements of new bands being transitioned from fixed to share usage.
In this dissertation we first look into the regulatory aspect of spectrum sharing. We analyze the Federal Communications Commission's (FCC) initiatives with regards to the commercial use of the 150 MHz spectrum block in the 3.5 GHz band. This analysis results into a Spectrum Access System (SAS) architecture and list of required functionalities. Then we address the nature of primary-secondary cooperation in spectrum sharing and propose to generate probabilistic assurances for spectrum opportunities. We use the generated assurance to observe the impact of cooperation from the perspective of spectrum sharing system management. We propose to incorporate primary user cooperation in the auctioning and resource allocation procedures to manage spectrum opportunities. We also analyze the improvement in spectrum sharing experience from the perspective of the primary and secondary users as a result of cooperation. We propose interference avoidance schemes that involve cooperation to improve the achievable quality of service.
Primary-secondary cooperation has the potential to significantly influence the mechanism and outcomes of the spectrum sharing systems. Both the primary and secondary operations can benefit from cooperation in a sharing scenario. Based on the priorities of the primary and secondary operations, the users may decide on the level of cooperation that they are willing to participate. Also access to information about the availability and usability of the spectrum opportunity will result in efficient spectrum opportunity management and improved sharing performance for both the primary and secondary users. Thus offering assurances about the availability and duration of spectrum opportunity through primary-secondary cooperation will significantly improve the overall spectrum sharing experience. The research reported in this dissertation is expected to provide a fundamental analytical framework for characterizing and quantifying the implications of primary-secondary cooperation in a spectrum sharing context. It analyzes the technical challenges in modeling different level of cooperation and their impact on the spectrum sharing experience. We hope that this dissertation will establish the fundamentals of the spectrum sharing to allow the involved parties to participate in sharing mechanisms that is suitable to their objective priorities.PHD
25
Padaki, Aditya V. "Fundamentals of Efficient Spectrum Access and Co-existence with Receiver Nonlinearity." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/81958.
Full textAbstract:
RF front-ends are nonlinear systems that have nonlinear frequency response and, hence, can impair receiver performance by harmful adjacent channel interference in non-intuitive ways. Next generation wireless networks will see unprecedented diversity across receiver and radio technologies accessing the same band of spectrum in spatio-temporal proximity. Ensuring adjacent channel co-existence is of prime importance for successful deployment and operations of next generation wireless networks. Vulnerabilities of receiver front-end can have a severe detrimental effect on network performance and spectrum co-existence. This dissertation addresses the technological challenges in understanding and accounting for receiver sensitivities in the design of next generation wireless networks. The dissertation has four major contributions.
In the first contribution, we seek to understand how receiver nonlinearity impacts performance. We propose a computationally efficient framework to evaluate the adjacent channel interference in a given radio/spectrum environment. We develop novel tractable representation of receiver front-end nonlinearity to specify the adjacent channel signals that contribute to the interference at the desired channel and the total adjacent channel interference power at a given desired channel.
In the second contribution, we seek to understand how the impact of receiver nonlinearity performance can be quantified. We quantify receiver performance in the presence of adjacent channel interference using information theoretic metrics. We evaluate the limits on achievable rate accounting for RF front-end nonlinearity and provide a framework to compare disparate receivers by forming generalized metrics.
In the third contribution, we seek to understand how the impact of receiver nonlinearity can be managed at the network level. We develop novel and comprehensive wireless network management frameworks that account for the RF nonlinearity, impairments, and diversity of heterogeneous wireless devices. We further develop computationally efficient algorithms to optimize the proposed framework and examine network level performance. We demonstrate through extensive network simulations that the proposed receiver-centric frameworks provide substantially high spectrum efficiency gains over receiver-agnostic spectrum access in dense and diverse next generation wireless networks.
In the fourth contribution, we seek to understand how scalable interference networks are with receiver nonlinearity. We propose practical achievable schemes for interference avoidance and assess the scalability of the next generation wireless networks with interference due to receiver nonlinearity. Further, we develop an algorithmic scheme to evaluate the upper bound on scalability of nonlinear interference networks. This provides valuable insights on scalability and schemes for nonlinear adjacent channel interference avoidance in next generation shared spectrum networks.Ph. D.
26
Bhattarai, Sudeep. "Spectrum Efficiency and Security in Dynamic Spectrum Sharing." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/82872.
Full textAbstract:
We are in the midst of a major paradigm shift in how we manage the radio spectrum. This paradigm shift in spectrum management from exclusive access to shared access is necessitated by the growth of wireless services and the demand pressure imposed on limited spectrum resources under legacy management regimes. The primary constraint in any spectrum sharing regime is that the incumbent users (IUs) of the spectrum need to be protected from harmful interference caused due to transmissions from secondary users (SUs). Unfortunately, legacy techniques rely on inadequately flexible and overly conservative methods for prescribing interference protection that result in inefficient utilization of the shared spectrum.
In this dissertation, we first propose an analytical approach for characterizing the aggregate interference experienced by the IU when it shares the spectrum with multiple SUs. Proper characterization of aggregate interference helps in defining incumbent protection boundaries, a.k.a. Exclusion Zones (EZs), that are neither overly aggressive to endanger the IU protection requirement, nor overly conservative to limit spectrum utilization efficiency. In particular, our proposed approach addresses the two main limitations of existing methods that use terrain based propagation models for estimating the aggregate interference. First, terrain-based propagation models are computationally intensive and data-hungry making them unsuitable for large real-time spectrum sharing applications such as the spectrum access system (SAS). Second, terrain based propagation models require accurate geo-locations of SUs which might not always be available, such as when SUs are mobile, or when their locations are obfuscated for location privacy concerns.
Our second contribution in this dissertation is the novel concept of Multi-tiered Incumbent Protection Zones (MIPZ) that can be used to prescribe interference protection to the IUs. Based on the aforementioned analytical tool for characterizing the aggregate interference, we facilitate a framework that can be used to replace the legacy notion of static and overly conservative EZs with multi-tiered dynamic EZs. MIPZ is fundamentally different from legacy EZs in that it dynamically adjusts the IU's protection boundary based on the radio environment, network dynamics, and the IU interference protection requirement. Our extensive simulation results show that MIPZ can be used to improve the overall spectrum utilization while ensuring sufficient protection to the IUs.
As our third contribution, we investigate the operational security (OPSEC) issue raised by the emergence of new spectrum access technologies and spectrum utilization paradigms. For instance, although the use of geolocation databases (GDB) is a practical approach for enabling efficient spectrum sharing, it raises a potentially serious OPSEC problem, especially when some of the IUs are federal government entities, including military users. We show that malicious queriers can readily infer the locations of the IUs even if the database's responses to the queries do not directly reveal such information. To address this issue, we propose a perturbation-based optimal obfuscation strategy that can be implemented by the GDB to preserve the location privacy of IUs. The proposed obfuscation strategy is optimal in the sense that it maximizes IUs' location privacy while ensuring that the expected degradation in the SUs' performance due to obfuscated responses does not exceed a threshold.
In summary, this dissertation focuses on investigating techniques that improve the utilization efficiency of the shared spectrum while ensuring adequate protection to the IUs from SU induced interference as well as from potential OPSEC threats. We believe that this study facilitates the regulators and other stakeholders a better understanding of mechanisms that enable improved spectrum utilization efficiency and minimize the associated OPSEC threats, and hence, helps in wider adoption of dynamic spectrum sharing.Ph. D.
27
Johansson, Klas. "Cost efficient provisioning of wireless access : infrastructure cost modeling and multi-operator resource sharing." Licentiate thesis, KTH, Skolan för elektro- och systemteknik (EES), 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-580.
Full text
28
Zhang, Jie. "Impact of disk access on the performance of load sharing policies in distributed systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq36882.pdf.
Full text
29
Chennells, Roger Scarlin. "Equitable access to human biological resources in developing countries : benefit sharing without undue inducement." Thesis, University of Central Lancashire, 2014. http://clok.uclan.ac.uk/10634/.
Full textAbstract:
The main research question of this thesis is: How can cross-border access to human genetic resources, such as blood or DNA samples, be governed to achieve equity for developing countries? Access to and benefit sharing for human biological resources is not regulated through an international legal framework such as the Convention on Biological Diversity, which applies only to plants, animals and micro-organisms as well as associated traditional knowledge. This legal vacuum for the governance of human genetic resources can be attributed (in part) to the concern that benefit sharing might provide undue inducements to research participants and their communities. This thesis shows that: (a) Benefit sharing is crucial to avoiding the exploitation of developing countries in genomic research. (b) With functioning research ethics committees, undue inducement is less of a concern in genetic research than in other medical research (e.g. clinical trials). (c) Concerns remain over research involving indigenous populations and some recommendations are provided. In drawing its conclusions, the thesis resolves a highly pressing topic in global bioethics and international law. Originally, it combines bioethical argument with jurisprudence, in particular reference to the law of equity and the legal concepts of duress (coercion), unconscionable dealing, and undue influence.
30
Yu, Shucheng. "Data Sharing on Untrusted Storage with Attribute-Based Encryption." Digital WPI, 2010. https://digitalcommons.wpi.edu/etd-dissertations/321.
Full textAbstract:
"Storing data on untrusted storage makes secure data sharing a challenge issue. On one hand, data access policies should be enforced on these storage servers; on the other hand, confidentiality of sensitive data should be well protected against them. Cryptographic methods are usually applied to address this issue -- only encrypted data are stored on storage servers while retaining secret key(s) to the data owner herself; user access is granted by issuing the corresponding data decryption keys. The main challenges for cryptographic methods include simultaneously achieving system scalability and fine-grained data access control, efficient key/user management, user accountability and etc. To address these challenge issues, this dissertation studies and enhances a novel public-key cryptography -- attribute-based encryption (ABE), and applies it for fine-grained data access control on untrusted storage. The first part of this dissertation discusses the necessity of applying ABE to secure data sharing on untrusted storage and addresses several security issues for ABE. More specifically, we propose three enhancement schemes for ABE: In the first enhancement scheme, we focus on how to revoke users in ABE with the help of untrusted servers. In this work, we enable the data owner to delegate most computation-intensive tasks pertained to user revocation to untrusted servers without disclosing data content to them. In the second enhancement scheme, we address key abuse attacks in ABE, in which authorized but malicious users abuse their access privileges by sharing their decryption keys with unauthorized users. Our proposed scheme makes it possible for the data owner to efficiently disclose the original key owner's identity merely by checking the input and output of a suspicious user's decryption device. Our third enhancement schemes study the issue of privacy preservation in ABE. Specifically, our proposed schemes hide the data owner's access policy not only to the untrusted servers but also to all the users. The second part presents our ABE-based secure data sharing solutions for two specific applications -- Cloud Computing and Wireless Sensor Networks (WSNs). In Cloud Computing cloud servers are usually operated by third-party providers, which are almost certain to be outside the trust domain of cloud users. To secure data storage and sharing for cloud users, our proposed scheme lets the data owner (also a cloud user) generate her own ABE keys for data encryption and take the full control on key distribution/revocation. The main challenge in this work is to make the computation load affordable to the data owner and data consumers (both are cloud users). We address this challenge by uniquely combining various computation delegation techniques with ABE and allow both the data owner and data consumers to securely mitigate most computation-intensive tasks to cloud servers which are envisaged to have unlimited resources. In WSNs, wireless sensor nodes are often unattendedly deployed in the field and vulnerable to strong attacks such as memory breach. For securing storage and sharing of data on distributed storage sensor nodes while retaining data confidentiality, sensor nodes encrypt their collected data using ABE public keys and store encrypted data on storage nodes. Authorized users are given corresponding decryption keys to read data. The main challenge in this case is that sensor nodes are extremely resource-constrained and can just afford limited computation/communication load. Taking this into account we divide the lifetime of sensor nodes into phases and distribute the computation tasks into each phase. We also revised the original ABE scheme to make the overhead pertained to user revocation minimal for sensor nodes. Feasibility of the scheme is demonstrated by experiments on real sensor platforms. "
31
Jiang, Xueyuan. "Dynamic spectrum sharing for future wireless communications." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:d0ce0b24-9f97-476a-bf87-dc34f1a8154e.
Full textAbstract:
The spectrum has become one of the most important and scarce resources for future wireless communications. However, the current static spectrum policy cannot meet the increasing demands for spectrum access. To improve spectrum efficiency, dynamic spectrum access (DSA) attempts to allocate the spectrum to users in an intelligent manner. Cognitive radio (CR) is an enabling technology for DSA, and can maximize spectrum utilization by introducing unlicensed or secondary users (SUs) to the primary system. The key component of DSA is dynamic spectrum sharing (DSS), which is responsible for providing efficient and fair spectrum allocation or scheduling solutions among licensed or primary users (PUs) and SUs. This thesis focuses on the design of efficient DSS schemes for the future wireless communication networks. Firstly, based on the coordinated DSS model, this thesis proposes a heterogeneous-prioritized spectrum sharing policy for coordinated dynamic spectrum access networks. Secondly, based on the uncoordinated DSS model, a novel partial spectrum sharing strategy and the cross-layer optimization method have been proposed to achieve efficient spectrum sharing between two licensed networks. Then, a hybrid strategy which combines the overlay and underlay schemes is proposed under uncoordinated DSS model. The proposed analytical methods can provide efficient and accurate modeling to predict the behaviors of the PUs and SUs in DSS systems. This thesis presents the performance prediction of the proposed novel DSS schemes that achieve efficient spectrum sharing for coordinated and uncoordinated future wireless networks.
32
Morelli, Vincenzo. "APostrophe WiFi Sharing." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14419/.
Full textAbstract:
Negli ultimi anni il tema dell’economia della condivisione ha assunto un piano sempre più attuale, lo sviluppo delle tecnologie mobile, contempora- neamente, è in continua ed esponenziale crescita, le applicazioni necessitano sempre più di un accesso alla rete internet sicuro ed efficiente.
Questa tesi è incentrata sullo sviluppo di un’applicazione per sistemi An- droid che consenta la creazione di un network di utenti e permetta loro di condividere il proprio router casalingo.
I dispositivi condivisi saranno collocati sulla mappa tramite un algoritmo di posizionamento che abbina le meccaniche di geolocalizzazione a quelle del WiFi Manager presente sui dispositivi.
Selezionando l’hotspot più vicino sarà quindi possibile richiedere la con- nessione per un periodo limitato di tempo così da avere accesso ai servizi Facebook, Instagram, Maps e YouTube.
Per la progettazione e l’implementazione di Apostrofe sono stati affron- tati e approfonditi argomenti riguardanti: l’implementazione di un algorit- mo di posizionamento , l’implementazione di un web service , cifratura e trasmissione dati tramite protocollo HTTP .
33
Lawrence-Kuether, Maureen Anne. "Beyond the Paywall: Examining Open Access and Data Sharing Practices Among Faculty at Virginia Tech Through the Lens of Social Exchange." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78236.
Full textAbstract:
The movement towards open access has allowed academic researchers to communicate and share their scholarly content more widely by being freely available to Internet users. However, there are still issues of concern among faculty in regards to making their scholarly output open access. This study surveyed Virginia Tech faculty (N = 264) awareness and attitudes toward open access practices. In addition, faculty were asked to identify factors that inhibited or encouraged their participation in open access repositories. Findings indicate that while the majority of Virginia Tech faculty are seeking to publish in open access, many are unaware of the open access services provided by the university and even less are using the services available to them. Time, effort, and costs were identified as factors inhibiting open access and data sharing practices. Differences in awareness and attitudes towards open access were observed among faculty ranks and areas of research. Virginia Tech will need to increase faculty awareness of institutional open access repositories and maximize benefits over perceived costs if there is to be more faculty participation in open access practices.Master of Arts
34
Farhat, Soha. "Access Selection and Pricing in Multi-operator Wireless Networks." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S029/document.
Full textAbstract:
Notre travail se situe dans le contexte de partage de réseau mobile actif, ou un nombre d'opérateurs partagent leur accès radio, afin de former un système multi-technologie multi-opérateur. Le but de notre étude est de montrer les avantages de la coopération entre les opérateurs, principalement en ce qui concerne les revenus. De plus, nous cherchons des stratégies pour surpasser les conséquences négatives du partage des ressources, surtout celles touchant la performance des réseaux des opérateurs coopérants. Nous avons montré que les bénéfices de la coopération dépendent fortement du choix de partenaires, la tarification de service ( cout de transfert) entre les partenaires, et combien un opérateur partage de ses ressources. Notre travail consiste, en premier temps, à proposer un algorithme de sélection d'accès applicable dans un réseau multi-opérateurs. Cet algorithme devrait garantir la satisfaction en QoS de l'utilisateur et celle en profit de son opérateur d'accès à l'Internet. Ainsi, un algorithme adoptant une décision hybride, NP-BPA (Nearest Performance and Best Profit Algorithm), est proposé. En deuxième temps, nous étudions la tarification de service entre les opérateurs partenaires, précisément le coût de transfert d'un utilisateur. Ce dernier paye juste le prix du service que son opérateur d'accès à l'Internet détermine, il est inconscient du transfert. Les modèles de tarification proposés relient le coût de transfert d'un opérateur au prix adopté pour le service des clients. Le premier modèle, ACAG (As Client As Guest), suggère que le coût de transfert d'un opérateur soit égal à son prix de service. Le deuxième modèle, MIWC (Maximum Income When Cooperating), suggère que les coûts de transfert des opérateurs coopérants soient identiques, et égaux au prix de service le plus élevé des partenaires. Et, le troisième modèle, MCWC (Minimum Cost When Cooperating), suggère que les coûts de transfert des opérateurs coopérants soient identiques et égaux au plus petit prix de service des partenaires. La décision du meilleur modèle à adopter lors de la coopération, intervient une interaction entre les différents partenaires. Nous avons modélisé cette interaction à l'aide de la théorie de jeux. Nous avons exploité un jeu Stackelberg à deux niveaux, TPA (Transaction Pricing and Access Selection), où les opérateurs de service agissent comme Leaders et les opérateurs d'accès à l'Internet des utilisateurs à transférer agissent comme Followers. Finalement, nous avons considéré le mode d'accès hybride pour la coopération. Ce mode d'accès est proposé comme solution surtout pour les opérateurs partageant la plus grande capacité. La performance du réseau de ces opérateurs est relativement affaiblie suite à la coopération. Nous avons vérifié que le pourcentage de blocage diminue quand l'opérateur, ayant une capacité élevée, réduit le pourcentage de ressources partagées. Pour un même pourcentage de partage, le profit d'un opérateur diffère avec le modèle de tarification adopté. Ainsi, une bonne décision doit être prise, concernant le pourcentage de partage et le modèle de tarification, tout en tenant compte de l'effet de cette décision sur les autres partenaires du système. C'est pourquoi que nous avons proposé un nouvel jeu séquentiel à deux niveaux, afin de modéliser l'interaction entre les opérateurs, pour le partage de ressources et la tarification du coût de transfertWe consider a roaming-based infrastructure sharing system, where multiple operators share their radio access in a multi-operator environment. Indeed, when the home operator of a user is unable to satisfy its constraints, because of lack of resources or QoS, a transaction event is triggered. It consists in transferring the considered user to another operator in order to access the service. Moreover, when there are more than two operators sharing their access, the user transfer process includes an access selection decision in order to choose the best operator for service. Furthermore, when a user is transferred, its home operator must pay some transaction cost as cooperation fees for the new service operator. This transaction is seamless to the user. Therefore, the inter-operators sharing agreement set for cooperation must include three important issues: the selection decision algorithm, the transaction cost pricing scenario, and the percentage of resources shared by each operator. In the first part, we introduce our selection decision algorithm in a multi-operator environment, NP-BPA (Nearest Performance and Best Profit Algorithm). It is based on a multi-criteria cost function which groups the different parameters that enable a satisfying selection decision, for the operators and users. In the second part, we study the transaction cost. We find rational that an operator sets its transaction cost as a function of its service price. We consider a sharing system of three partners, interacting to decide the best transaction cost. Taking into account that the service of a guest user may affect the probability of acceptance of a client, an operator looks for preserving the expected revenue from its client. Therefore, we propose the first pricing scenario, ACAG (As Client As Guest) that aims to set the transaction cost of an operator equal to its service price. However, every operator seeks to maximize its revenue; therefore it is expected to set a higher transaction cost. How much higher? This must respect the sharing agreement between different partners and the service prices they adopt. To be optimistic, we propose a second pricing scenario MIWC (Max In When Cooperating). With this scenario all partners agree to have a transaction cost equal to the highest service price announced in the system. But, this scenario may cause losses in some cases where an operator setting a low service price performs a lot of transactions. To be fair, we propose a third pricing scenario MCWC (Min Cost When Cooperating). With this scenario all partners agree to have a transaction cost equal to the lowest service price announced in the system. In order to decide the best pricing scenario to adopt in the sharing system, a two stage Stackelberg game, TPA (Transaction Pricing and Access Selection) game, is formulated. In this game, the operators are the players; the service operators are the leaders and the home operator of a transferred user is a follower. In the third part, we consider a three operator sharing system with hybrid access mode. In this system partners decide to share a restricted amount of their capacity. We show how the sharing factor affects the blocking rates and affect the global profits. Further, the achieved profit does not depend only on the sharing factor, but also on the adopted pricing scenario. Therefore an economic framework based on game theoretical analysis is proposed. It models the interaction between the sharing system operators for resource sharing and pricing, in addition to the access selection. A sequential game is formulated, where the players are the operators. In the first stage, the sharing partners decide the proportion of resources they will share and the transaction pricing scenario in order to maximize their own profits. In the second stage, the home operator of a transferred user selects the suitable service operator. A bi-level optimization problem is solved and equilibrium is found
35
Gao, Bo. "Coexistence of Wireless Networks for Shared Spectrum Access." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/50525.
Full textAbstract:
The radio frequency spectrum is not being efficiently utilized partly due to the current policy of allocating the frequency bands to specific services and users. In opportunistic spectrum access (OSA), the ``white spaces'' that are not occupied by primary users (a.k.a. incumbent users) can be opportunistically utilized by secondary users. To achieve this, we need to solve two problems: (i) primary-secondary incumbent protection, i.e., prevention of harmful interference from secondary users to primary users; (ii) secondary-secondary network coexistence, i.e., mitigation of mutual interference among secondary users. The first problem has been addressed by spectrum sensing techniques in cognitive radio (CR) networks and geolocation database services in database-driven spectrum sharing. The second problem is the main focus of this dissertation. To obtain a clear picture of coexistence issues, we propose a taxonomy of heterogeneous coexistence mechanisms for shared spectrum access. Based on the taxonomy, we choose to focus on four typical coexistence scenarios in this dissertation.
Firstly, we study sensing-based OSA, when secondary users are capable of employing the channel aggregation technique. However, channel aggregation is not always beneficial due to dynamic spectrum availability and limited radio capability. We propose a channel usage model to analyze the impact of both primary and secondary user behaviors on the efficiency of channel aggregation. Our simulation results show that user demands in both the frequency and time domains should be carefully chosen to minimize expected cumulative delay.
Secondly, we study the coexistence of homogeneous CR networks, termed as self-coexistence, when co-channel networks do not rely on inter-network coordination. We propose an uplink soft frequency reuse technique to enable globally power-efficient and locally fair spectrum sharing. We frame the self-coexistence problem as a non-cooperative game, and design a local heuristic algorithm that achieves the Nash equilibrium in a distributed manner. Our simulation results show that the proposed technique is mostly near-optimal and improves self-coexistence in spectrum utilization, power consumption, and intra-cell fairness.
Thirdly, we study the coexistence of heterogeneous CR networks, when co-channel networks use different air interface standards. We propose a credit-token-based spectrum etiquette framework that enables spectrum sharing via inter-network coordination. Specifically, we propose a game-auction coexistence framework, and prove that the framework is stable. Our simulation results show that the proposed framework always converges to a near-optimal distributed solution and improves coexistence fairness and spectrum utilization.
Fourthly, we study database-driven OSA, when secondary users are mobile. The use of geolocation databases is inadequate in supporting location-aided spectrum sharing if the users are mobile. We propose a probabilistic coexistence framework that supports mobile users by locally adapting their location uncertainty levels in order to find an appropriate trade-off between interference mitigation effectiveness and location update cost. Our simulation results show that the proposed framework can determine and adapt the database query intervals of mobile users to achieve near-optimal interference mitigation with minimal location updates.Ph. D.
36
Furuskär, Anders. "Radio resource sharing and bearer service allocation for multi-bearer service, multi-access wireless networks." Doctoral thesis, KTH, Signals, Sensors and Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3502.
Full textAbstract:
Two expected characteristics of future wireless networks aresupport for multiple bearer services, which in turn enablemultiple end-user services, and the parallel use of multipleradio access technologies. This dissertation discusses radioresource management principles to improve capacity for suchmulti-bearer service, multi-access networks.
More specifically, it is first focused on how to mostefficiently share the radio resource between bearer servicegroups within one access technology. A general principle forsharing resources in interference limited systems is proposed,and its expected performance estimated. The proposedinterference balancing principle maximizes capacity byadjusting the power budgets per bearer service group so thatthe maximum tolerable interference levels are equal for allbearer services. To verify its validity, the interferencebalancing principle is applied to the 3rd generation cellularsystems GSM/EDGE and WCDMA in a set of multi-bearer servicecase studies. It is seen that interference balancing maystraightforwardly be introduced in these systems, and thatsignificant capacity gains over non-balanced scenarios can beachieved.
Secondly, how to best share traffic load between thedifferent sub-systems in a multi-access scenario isinvestigated. The capability to handle bearer services, andthereby also end-user services, typically differs betweensub-systems. The overall multi-access system capacity istherefore affected by the allocation of bearer services on tosub-systems. Based on this, a simple principle for findingfavorable, under certain constraints near-optimum, sub-systembearer service allocations is derived. It is seen that for agiven service mix combined capacities beyond the sum of thesub-system capacities may be achieved by using the favorablebearer service allocations. Significant capacity gains are alsoseen in a case study in which the bearer service allocationprinciple is applied to a combined GSM/EDGE and WCDMAmulti-access system. The bearer service type may be said toreflect an expected radio resource cost for supporting a userin each sub-system. By taking into account the actual radioresource cost, which may differ from the expected cost, whenassigning users to subsystems, further capacity gains areachievable.
37
Bian, Kaigui. "Medium Access Control in Cognitive Radio Networks." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/37591.
Full textAbstract:
Cognitive radio (CR) is seen as one of the enabling technologies for realizing a new regulatory spectrum management paradigm, viz. opportunistic spectrum sharing (OSS). In the OSS paradigm, unlicensed users (a.k.a. secondary users) opportunistically operate in fallow licensed spectrum on a non-interference basis to licensed users (a.k.a. incumbent or primary users). Incumbent users have absolute priority in
licensed bands, and secondary users must vacate the channel where incumbent user signals are detected. A CR network is composed of secondary users equipped with CRs and it can coexist with incumbent users in licensed bands under the OSS paradigm. The coexistence between incumbent users and secondary users is referred to as incumbent coexistence, and the coexistence between CR networks of the same type is referred to as self-coexistence.
In this dissertation, we address three coexistence-related problems at the medium access
control (MAC) layer in CR networks: (1) the rendezvous (control channel) establishment
problem, (2) the channel assignment problem in an ad hoc CR network, and (3) the spectrum sharing problem between infrastructure-based CR networks, i.e., the 802.22 wireless regional area networks (WRANs). Existing MAC layer protocols in conventional wireless networks fail to adequately address the key issues concerning incumbent and self coexistence that emerge in CR networks. To solve the rendezvous establishment problem, we present a systematic approach, based on quorum systems, for designing channel hopping protocols that ensure a pair of CRs to "rendezvous" within an upper-bounded time over a common channel that is free of incumbent user signals. In a single radio interface, ad hoc CR network, we propose a distributed channel assignment scheme that assigns channels at the granularity of "segments" for minimizing the channel switching overhead. By taking into account the coexistence requirements, we propose an inter-network spectrum sharing protocol that enables the sharing of vacant TV white space among coexisting WRANs. Our analytical and simulation results show that these proposed schemes can effectively address the aforementioned MAC layer coexistence problems in CR networks.Ph. D.
38
Srinivas, Preethi. "Private Key Allocation based Access Control Scheme for Social Networks." Miami University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=miami1281839737.
Full text
39
Katsouraki, Athanasia. "Sharing and Usage Control of Personal Information." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLV089/document.
Full textAbstract:
Nous vivons une véritable explosion du volume des données personnelles numériques qui sont générés dans le monde chaque jour (ex. capteurs, web, réseaux sociaux, etc.). En conséquence, les particuliers se sentent exposés tandis qu'ils partagent et publient leurs données. Ainsi, il est clair que des outils et des méthodes sont nécessaires pour contrôler la façon dont leurs données sont collectées, gérées et partagées. Les défis sont principalement axées sur le manque d'applications ou de solutions techniques qui assurent la gestion et le partage sécurisés de données personnelles. Le défi principal est de fournir un outil sécurisé et adaptable qui peut être utilisé par tout utilisateur, sans formation technique. Cette thèse fait trois contributions importantes dans le domaine de la protection de la vie privée : (i) Une implémentation du model UCONABC, un modèle de contrôle d'usage, appliqué à un scénario de réseau social, (ii) une extension algébrique de UCON pour contrôler des partages complexes de données (en transformant des données personnelles en données partageable et/ou publiables), et (iii) la conception, l'implémentation et le déploiement sur le terrain d'une plateforme pour la gestion de données sensibles collectées au travers de formulaires d'enquêtesWe are recently experiencing an unprecedented explosion of available personal data from sensors, web, social networks, etc. and so people feel exposed while they share and publish their data. There is a clear need for tools and methods to control how their data is collected managed and shared. The challenges are mainly focused on the lack of either applications or technical solutions that provide security on how to collect, manage and share personal data. The main challenge is to provide a secure and adaptable tool that can be used by any user, without technical background. This thesis makes three important contributions to the field of privacy: (i) a prototype implementation of the UCONABC model, a usage control model, applied to an online social networks scenario, (ii) an algebraic extension to UCON to control the complex sharing of data (by transforming personal data into sharable and publishable data) and (iii) the design, implementation and field testing of a secure platform to manage sensitive data collected through online forms
40
Hermansson, Rickard, and Johan Hellström. "Discretionary Version Control : Access Control for Versionable Documents." Thesis, KTH, Skolan för teknik och hälsa (STH), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-152815.
Full textAbstract:
A common problem in the workplace is sharing digital documents with coworkers. Forsome companies the problem extends to wanting the documentskept internally backedup and controlling which people in the company has rights to read and revise certaindocuments.This paper shows different systems and models for access control, version control,and distribution of the documents that can be used to create asystem that solves theseproblems.One requirement for this system was a user interface where users can upload, down-load and manage access to their documents. Another requirement was a service thathandles version control for the documents, and a way to quickly connect and distributethe documents. The system also needed to be able to handle access control of the ver-sioned documents on document level, referred to as "fine grained access control" in thispaper.These models and systems were evaluated based on aspects of the access control mod-els, version control systems, and distribution systems andprotocols. After evaluating,appropriate selections were made to create a prototype to test the system as a whole.The prototype ended up meeting the goals that Nordicstationset for the project butonly with basic functionality. Functionality for retrieving any version from a docu-ments history, controlling access for the documents at document level, and a simpleweb based user interface for managing the documents.Att enkelt dela dokument med arbetskollegor är något alla företag har ett behov utav.Ofta är dessa dokument interna och skall hållas inom företaget. Även inom företagetkan det finnas behov av att styra vem som har rätt att läsa ellerrevidera dokumenten.Denna examensarbetesrapport beskriver olika tekniker ochmodeller för accesskon-troll, versionshantering och distribution som kan användas för att implementera ettsystem som kan lösa de nämnda problemen.Ett av kraven för systemet var ett användargränssnitt där användare kan ladda upp ochned sina dokument. Ytterligare krav var att systemet skulleversionshantera dokumenetenoch att användare skall kunna komma åt de olika versionerna.Systemet skulle ocksåkunna hantera åtkomstkontroll på dokumentnivå, något denna examensrapport definerarsom "fine grained access control".För att designa ett sådant system så utredes och utvärderades olika tekniker kringåtkomstkontroll och versionshantering samt distributionav dokumenten. För att testasystemet så utvecklads en prototyp baserad på de valda lösningsmetoderna.Den resulterande prototypen uppfyllde de mål som Nordicstation satte för projektet,dock endast med grundläggande funktionalitet. Stöd för atthämta olika versioner avdokument, kontrollera access till dokumentet nere på dokument nivå och ett webbaseratgränssnitt för att administrera dokumenten.
41
Houghton, David Michael. "To Have or to Hold: The Role of Psychological Ownership in the Perceived Value of Owned and Accessed Goods." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/dissertations/1155.
Full textAbstract:
Whether they are renting a neighbor’s used tools, using a bike sharing program to get to work rather than owning a car, or streaming a movie online through Netflix, consumers are forgoing traditional ownership of goods in favor of gaining mere access to them. This behavior reflects a change in the way consumers view possession and ownership. While it is known that consumers become attached to possessions and that possessions mean a great deal to the identities and lives of consumers, it is unclear how consumers feel about goods which they can possess and use but do not own. Specifically, it is unknown whether consumers perceive and become attached to accessed goods in the same way they do owned goods. The answer to this question has strong implications for marketing theory and practice. This study found no significant difference in the perceived value of the good or the perceived value of the possession experience between owned and accessed goods. However, psychological feelings of ownership were found to affect these measures both directly and as a mediating factor between the method of possession and the perceptions of value. This relationship was not found to behave in the same way for both hedonic and utilitarian goods. Utilitarian goods appeared to benefit slightly more than hedonic goods from feelings of ownership. This research has strong implications for theory, including the development of a new conceptual model that ties together disparate research areas, the lack of differences in ownership effects between owned and accessed goods, and the important role played by psychological ownership in shaping consumer perceptions. This research also has strong implications for managers relating to consumer perceptions of owned vs. accessed goods, the importance of generating feelings of psychological ownership within customers, and the differential effect this process has on the perception of utilitarian products.
42
Kelly, Justin. "On the Benefit of Cooperation of Secondary Users in Dynamic Spectrum Access." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/76835.
Full textAbstract:
For the past 70 years, the Federal Communications Commission (FCC) has been the licensing authority for wireless spectrum. Traditionally, spectrum was commercially licensed to primary users with defined uses. With the growth of personal communication systems in the 1990''s, unallocated spectrum has become a scarce commodity. However, since most primary users are active only at certain times and places, much of the allocated spectrum remains underutilized. Substantial holes exist in the spatio-temporal spectrum that could be opportunistically used by unlicensed secondary users. As a result, the FCC is considering allowing secondary users to opportunistically use frequencies that are not being used by primary users. If multiple secondary users are present in the same geographical area, the concept of Dynamic Spectrum Sharing (DSS) allows these users to share the opportunistic spectrum.
If several secondary users want to use a limited set of frequency resources, they will very likely interfere with each other. Sensing is a distributed technique where each transmitter/receiver pair senses (both passively and actively) the available channels and uses the channel that provides the best performance. While sensing alone allows sharing of the spectrum, it is not the optimal method in terms of maximizing the capacity in such a shared system. If we allow the secondary users to collaborate and share information, optimal capacity might be reached. However, collaboration adds another level of complexity to the transceivers of the secondary users, since they must now be able to communicate (Note that in general, the secondary users may have completely different communication protocols, e.g., Wi-Fi and Bluetooth). Additionally, optimizing the capacity of the available spectrum could have other negative side effects such as impacting the fairness of sharing the resources. Our primary goal is to explore the benefit of this cost-benefit tradeoff by determining the capacity increase obtainable from collaboration. As a secondary goal, we also wish to determine how this increase in capacity affects fairness. To summarize, the goal of this work is to answer the question: Fundamentally, what is the benefit of collaboration in Dynamic Spectrum Sharing?Master of Science
43
Short, Patricia Margaret. "Association, reciprocity, sharing and dependency : conditions of access and forms of inequality beyond the market state /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18178.pdf.
Full text
44
Alemu, Getaneh Agegn. "The Role of Open Access in Fostering Knowledge Sharing and Collaboration in Ethiopia: a case study." Thesis, Tallinn University, 2009. http://hdl.handle.net/10919/71501.
Full textAbstract:
This study adopts a qualitative approach and uses the case study method. Fourteen researchers and librarians were interviewed in four organizations in Addis Ababa, Ethiopia.The responses based on the semi-structured interviews provide information about the current status of scholarly communication, the awareness of researchers and librarians about open access and the actual and potential challenges in implementing open access strategies in Ethiopia. This research is believed to illuminate the practicalities and procedures of how open access scholarly communication models could foster and support knowledge sharing and collaboration among Ethiopian researchers.The results of the study show that Ethiopian researchers suffer from lack of adequate access to scholarly literature. There is also lack of scholarly communication outlets to publish and disseminate their research results. This study reveals that the current scholarly communication system in Ethiopia is faced with technological and social challenges. Open access is proposed as a viable alternative for Ethiopia. The research indicates that if Ethiopianuniversities and research institutions adopt open access policies and strategies, it would help them improve the access and dissemination of scientific research results. A concerted effort is required from administrators, librarians, researchers, funding agencies and government to implement and fully harness open access in Ethiopia.
45
Lowman, Michael. "The effectiveness of access and benefit-sharing legislation in South Africa: practical considerations for national regimes." Master's thesis, University of Cape Town, 2012. http://hdl.handle.net/11427/12090.
Full textAbstract:
Includes abstract.Includes bibliographical references.
The Convention on Biological Diversity provides an international regulatory framework for countries to develop their own access and benefit-sharing (ABS) legislation. This international convention governs the utilization of a country's genetic resources and associated traditional knowledge. Due to increased capabilities and demand from industry for these resources, a market is created over which ABS legislation is to govern. This is based on the realization of the objectives of the convention that provide for state sovereignty over a country's indigenous biological resources. This dissertation presents the results from an evaluation of ABS legislation and its implementation within South Africa. Key objectives are to analyze the implementation of regulations and procedures governing access to indigenous biological resources and traditional knowledge, and associated institutional arrangements.
46
Changyan, Yi. "Auction-based Spectrum Sharing in Multi-Channel Cognitive Radio Networks with Heterogeneous Users." IEEE Transactions on Vehicular Technology, 2014. http://hdl.handle.net/1993/23943.
Full textAbstract:
Dynamic spectrum access based on cognitive radio has been regarded as a prospective
solution to improve spectrum utilization for wireless communications. By considering
the allocation efficiency, fairness, and economic incentives, spectrum marketing has been
attracting more and more attentions in recent years. In this thesis, we focus on one of
the most effective spectrum marketing methods, i.e., auction approach, in multi-channel
cognitive radio networks. After presenting some fundamentals and related works, we
begin our discussion in a recall-based auction system where buyers have various service
requirements and the seller could recall some sold items after the auction to deal with
a sudden increase of its own demand. Both single-winner and multi-winner auctions
are designed and analyzed. In addition, we also consider the heterogeneity of radio
resource sellers and formulate a framework of combinatorial spectrum auction. With
theoretical analyses and simulation results, we show that our proposed algorithms can
improve spectrum utilization while satisfy the heterogeneous requirements of different
wireless users.
47
Örn, Sagrelius Lizzie. "Fair and Equitable Participation? : A case study of access and benefit sharing processes in India and Samoa." Thesis, Uppsala universitet, Statsvetenskapliga institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-305362.
Full textAbstract:
The third main objective of the Convention on Biological Diversity aims to guarantee that the process of using traditional knowledge in research and development of new products is fair and equitable. The framework put in place for implementing this third objective, access and benefit sharing, is supposed to enable and ensure the participation of traditional knowledge holders. Using a qualitative study to examine two cases of access and benefit sharing, the TBGRI-Kani case and the Samoan-Mamala case, this thesis seeks to develop an understanding of how power structures affect these processes. Drawing on theories of participation, deliberation and social dominance the findings show that access and benefit sharing runs the risk of being an empty space controlled by the strongest actor, which in most cases are the receivers of traditional knowledge. Rather than celebrating the mere inclusion of traditional knowledge holders in the access and benefit sharing process, attention should be given to the hierarchies within the process as such.
48
Popov, Aleko Ivaylov, and Yashaswini Ravi. "Conceptualization of service loyalty in access-based services in micromobility : A case of e-scooter sharing services." Thesis, Linköpings universitet, Företagsekonomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166570.
Full textAbstract:
Background: Provide insights on the potential drivers of service loyalty in access-based services, especially when the consumers have the option to switch between owning a product or accessing a product through a service. By examining service loyalty in access-based services in the context of e-scooter sharing services, the researchers contribute to the service research field. Aim: Conceptualize service loyalty by considering the ownership dilemma in access-based services in micromobility. More specifically, the study aims to find what are potential drivers of service loyalty, what effects does ownership advantage have on service loyalty and what variables mediate the customer satisfaction – service loyalty relationship in said services. Methodology: A quantitative study, in which a survey method is chosen to gather empirical data. The survey was distributed as an online questionnaire via online platforms. In addition, an e-scooter sharing service company, Helbiz, shared the survey on their official Twitter and Facebook handles. A total of 249 responses was received. Findings: PLS-SEM was used as a statistical analysis tool to analyse the gathered data. Data suggests that customer satisfaction, service image, affective commitment and relative advantage are drivers of service loyalty in access-based services in micromobility. Furthermore, the effect of ownership advantage on service loyalty proved to be inconclusive as the result was not statistically significant. Finally, data indicates that service image, affective commitment and relative advantage mediate the customer satisfaction – service loyalty relationship.
49
Giang, Truong Minh Triet, and trietgiang@yahoo com. "Efficient Admission Control Schemes in Cellular IP Networks." RMIT University. Electrical and Computer Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20060829.113000.
Full textAbstract:
The thesis reviews current admission control schemes in cellular IP networks. It proposes an improved version of Threshold Access Sharing and a new scheme: weight-based scheme. Finally, an admission control scheme for hierarchical cellular network is introduced.
50
Bahrak, Behnam. "Ex Ante Approaches for Security, Privacy, and Enforcement in Spectrum Sharing." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/24720.
Full textAbstract:
Cognitive radios (CRs) are devices that are capable of sensing the spectrum and using its free portions in an opportunistic manner. The free spectrum portions are referred to as white spaces or spectrum holes. It is widely believed that CRs are one of the key enabling technologies for realizing a new regulatory spectrum management paradigm, viz. dynamic spectrum access (DSA). CRs often employ software-defined radio (SDR) platforms that are capable of executing artificial intelligence (AI) algorithms to reconfigure their transmission/reception (TX/RX) parameters to communicate efficiently while avoiding interference with licensed (a.k.a. primary or incumbent) users and unlicensed (a.k.a. secondary or cognitive) users.
When different stakeholders share a common resource, such as the case in spectrum sharing, security, privacy, and enforcement become critical considerations that affect the welfare of all stakeholders. Recent advances in radio spectrum access technologies, such as CRs, have made spectrum sharing a viable option for significantly improving spectrum utilization efficiency. However, those technologies have also contributed to exacerbating the difficult problems of security, privacy and enforcement. In this dissertation, we review some of the critical security and privacy threats that impact spectrum sharing. We also discuss ex ante (preventive) approaches which mitigate the security and privacy threats and help spectrum enforcement.Ph. D.