Transfer Learning for Device Fingerprinting with Application to Cognitive Radio Networks

Primary user emulation (PUE) attacks are an emerging threat to cognitive radio (CR) networks in which malicious users imitate the primary users (PUs) signals to limit the access of secondary users (SUs). Ascertaining the identity of the devices is a key technical challenge that must be overcome to thwart the threat of PUE attacks. Typically, detection of PUE attacks is done by inspecting the signals coming from all the devices in the system, and then using these signals to form unique fingerprints for each device. Current detection and fingerprinting approaches require certain conditions to hold in order to effectively detect attackers. Such conditions include the need for a sufficient amount of fingerprint data for users or the existence of both the attacker and the victim PU within the same time frame. These conditions are necessary because current methods lack the ability to learn the behavior of both SUs and PUs with time. In this paper, a novel transfer learning (TL) approach is proposed, in which abstract knowledge about PUs and SUs is transferred from past time frames to improve the detection process at future time frames. The proposed approach extracts a high level representation for the environment at every time frame. This high level information is accumulated to form an abstract knowledge database. The CR system then utilizes this database to accurately detect PUE attacks even if an insufficient amount of fingerprint data is available at the current time frame. The dynamic structure of the proposed approach uses the final detection decisions to update the abstract knowledge database for future runs. Simulation results show that the proposed method can improve the performance with an average of 3.5% for only 10% relevant information between the past knowledge and the current environment signals.Comment: 6 pages, 3 figures, in Proceedings of IEEE 26th International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC), Hong Kong, P.R. China, Aug. 201

Metrics and Algorithms for Processing Multiple Continuous Queries

Data streams processing is an emerging research area that is driven by the growing need for monitoring applications. A monitoring application continuously processes streams of data for interesting, significant, or anomalous events. Such applications include tracking the stock market, real-time detection of diseaseoutbreaks, and environmental monitoring via sensor networks.Efficient employment of those monitoring applications requires advanced data processing techniques that can support the continuous processing of unbounded rapid data streams. Such techniques go beyond the capabilities of the traditional store-then-query Data BaseManagement Systems. This need has led to a new data processing paradigm and created a new generation of data processing systems,supporting continuous queries (CQ) on data streams.Primary emphasis in the development of first generation Data Stream Management Systems (DSMSs) was given to basic functionality. However, in order to support large-scale heterogeneous applications that are envisioned for subsequent generations of DSMSs, greater attention willhave to be paid to performance issues. Towards this, this thesis introduces new algorithms and metrics to the current design of DSMSs.This thesis identifies a collection of quality ofservice (QoS) and quality of data (QoD) metrics that are suitable for a wide range of monitoring applications. The establishment of well-defined metrics aids in the development of novel algorithms that are optimal with respect to a particular metric. Our proposed algorithms exploit the valuable chances for optimization that arise in the presence of multiple applications. Additionally, they aim to balance the trade-off between the DSMS's overall performance and the performance perceived by individual applications. Furthermore, we provide efficient implementations of the proposed algorithms and we also extend them to exploit sharing in optimized multi-query plans and multi-stream CQs. Finally, we experimentally show that our algorithms consistently outperform the current state of the art

Places, Memories and Religious Identity: Muslim Places of Worship in Badakhshan Region of Tajikistan

This study examines the ways in which the Ismailis of the Badakhshan region of Tajikistan understand and relate to their sacred sites. It explores the sacred sites of Badakhshan within the framework of anthropological literature on space and place. Using the concept of chronotope, this study shows that the sacred sites disrupt the materialist and historiographic understanding of and relation to the spaces and places. Through the stories of the miracles of the saints, sacred sites validate and confirm the presence of the transcendent in the lived environment of the people. Beyond the legends about the miracles of the saints, sacred sites are chronotopes that evoke the memory of the Soviet campaigns against these places. Through the retrospective narratives about the Soviet past, people allocate the responsibility for the destruction and desecration of these sites at that period to members of their communities. Although these retrospective narratives are about recent events, they include transcendent intervention; that is, they show how these sites punished those that were involved in the Soviet campaigns against them. Moreover, through these discources and through their visitations to the sacred sites, people unconsciously attribute certain agency to them, which emerges in the relationship between people and these places. People seek the help of these sites to grant their wishes. In most cases, these wishes are about curing the seriously ill family member or curing infertility problems. In that sense, sacred sites help people to recapture the sense of agency in situations where they experience its loss. Therefore, sacred sites are chronotopes, the physical sites in the inhabited space of the community that incorporate and evoke the legends about the miracles of the saints, the stories about the recent Soviet past of these sites and the discourses about their current status in the life of the community. The stories and discources associated with the sacred sites affect and shape people’s perceptions and articulations of their inhabited spaces and places

Performance of Venture-Backed Firms in an Emerging Market Context

Entrepreneurs have trouble funding their businesses, from traditional finance sources. These entrepreneurs bring to the market innovative ideas and technical skills vital for firm success. Yet they may lack managerial advice and/or business expertise, which Venture capital (VC) firms are able to provide for them, along with funding. Nonetheless, not all VC-backed firms succeed. Therefore, an understanding of the determinants of success of these firms is crucial. This study contributes to the literature; by combining the characteristics of entrepreneurs and VC firms, and their relationship, to assess their impact on VC-backed firms’ performance. There is a sufficient amount of literature testing these determinants separately. However, studying them together as they co-exist in the market produces more reliable results. Additionally, emerging economies are still developing their VC markets, thus research on these markets is relatively recent. Hence, this study is timely and crucial, as it generate key insights to help leverage successful industries. This is achieved by combining two survey responses. One distributed to 14 VC firms in Egypt, and another to 79 of their portfolio firms. The research data is analysed using t-tests, ordinary least square regression and ordered probit regression. Supported by the Institutional Theory, the findings of this study emphasise the importance of entrepreneur networks in Egypt. As they have a positive and significant impact on performance of VC-backed firms. The resource-based capabilities of portfolio firms, matched to their firms’ strategies, have a significant impact on the performance of VC-backed firms. Finally, the VC-E relationship shows that contracts have a significant negative impact on VC- backed firms’ performance. However, when legal environment factors are considered, their impact becomes insignificant. Instead, the strength of the VC-E relationship has a positive impact on sales growth. Hence, trust is more crucial than contracts, in weak legal environments. This study provides recommendations to entrepreneurs, VCs and policy makers in Egypt.Arab Academy for Science Technology and Maritime Transport