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  • Presentation: 2017-09-28 13:00 V3, Stockholm
    Ainomäe, Ahti
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Distributed Detection in Cognitive Radio Networks2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    One of the problems with the modern radio communication is the lack of availableradio frequencies. Recent studies have shown that, while the available licensed radiospectrum becomes more occupied, the assigned spectrum is significantly underutilized.To alleviate the situation, cognitive radio (CR) technology has been proposedto provide an opportunistic access to the licensed spectrum areas. Secondary CRsystems need to cyclically detect the presence of a primary user by continuouslysensing the spectrum area of interest. Radiowave propagation effects like fading andshadowing often complicate sensing of spectrum holes. When spectrum sensing isperformed in a cooperative manner, then the resulting sensing performance can beimproved and stabilized.

    In this thesis, two fully distributed and adaptive cooperative Primary User (PU)detection solutions for CR networks are studied.

    In the first part of this thesis we study a distributed energy detection schemewithout using any fusion center. Due to reduced communication such a topologyis more energy efficient. We propose the usage of distributed, diffusion least meansquare (LMS) type of power estimation algorithms with different network topologies.We analyze the resulting energy detection performance by using a commonframework and verify the theoretical findings through simulations.

    In the second part of this thesis we propose a fully distributed detection scheme,based on the largest eigenvalue of adaptively estimated correlation matrices, assumingthat the primary user signal is temporally correlated. Different forms of diffusionLMS algorithms are used for estimating and averaging the correlation matrices overthe CR network. The resulting detection performance is analyzed using a commonframework. In order to obtain analytic results on the detection performance, theadaptive correlation matrix estimates are approximated by a Wishart distribution.The theoretical findings are verified through simulations.

  • Presentation: 2017-10-19 10:00 Wretlindsalen, Solna
    Lama, Lara
    KTH, School of Biotechnology (BIO), Proteomics and Nanobiotechnology.
    Novel methods for improving rapid paper-based protein assays with gold nanoparticle detection2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This thesis describes methods for improving sensitivity in rapid singleplex and multiplex microarray assays. The assays utilize the optical characteristics of colloidal gold nanoparticles for the colorimetric detection of proteins.

    Multiplexed detection in sandwich immunoassays is limited by cross-reactivity between different detection antibodies. The cross-reactivity between antibodies can contribute to increased background noise - decreasing the Limit-of-Detection of the assay - or generate false positive signals. Paper I shows improved assay sensitivity in a multiplexed vertical flow assay by the application of ultrasonic energy to the gold nanoparticles functionalized with detection antibodies. The ultrasonication of the antibody conjugated gold nanoparticles resulted in a 10 000 fold increase in sensitivity in a 3-plex assay. COMSOL Multiphysics was used to simulate the acoustical energy of the probe used in Paper I for obtaining an indication of the size and direction of the forces acting upon the functionalized gold nanoparticles.

    In Paper II, it was studied if different gold nanoparticle conjugation methods and colorimetric signal enhancement of the gold nanoparticle conjugates could influence the sensitivity of a paper-based lateral flow microarray assay, targeting cardiac troponin T for the rapid diagnostics of acute myocardial infarction.

    Ultrasonication and signal enhancement of the detection gold nanoparticles has the potential of improving the sensitivity of paper based assays and expanding their potential future applications.

  • Presentation: 2017-10-20 16:04
    Ahlin, Jesper
    Philosophy and History, KTH, School of Architecture and the Built Environment (ABE), Philosophy and History of Technology, Philosophy.
    Personal Autonomy and Informed Consent: Conceptual and Normative Analyses2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis is comprised of a “kappa” and two articles. The kappa includes an account of personal autonomy and informed consent, an explanation of how the concepts and articles relate to each other, and a summary in Swedish.

    Article 1 treats one problem with the argument that a patient’s consent to treatment is valid only if it is authentic, i.e., if it is “genuine,” “truly her own,” “not out of character,” or similar. As interventions with a patient’s life and liberties must be justified, the argument presupposes that the authenticity of desires can be reliably determined. If the status of a desire in terms of authenticity cannot be reliably determined, discarding the desire-holder’s treatment decision on the basis that it is inauthentic is morally unjustified. In the article, I argue that no theory of authenticity that is present in the relevant literature can render reliably observable consequences. Therefore, the concept of authenticity, as it is understood in those theories, should not be part of informed consent practices.

    Article 2 discusses the problem of what it is to consent or refuse voluntarily. In it, I argue that voluntariness should be more narrowly understood than what is common. My main point is that a conceptualization of voluntariness should be agent-centered, i.e., take into account the agent’s view of her actions. Among other things, I argue that an action is non-voluntary only if the agent thinks of it as such when being coerced. This notion, which at first look may seem uncontroversial, entails the counterintuitive conclusion that an action can be voluntary although the agent has been manipulated or coerced into doing it. In defense of the notion, I argue that if the agent’s point of view is not considered accordingly, describing her actions as non-voluntary can be alien to how she leads her life. There are other moral concepts available to describe what is wrong with manipulation and coercion, i.e., to make sense of the counterintuitive conclusion. Voluntariness should be reserved to fewer cases than what is commonly assumed.

  • Presentation: 2017-10-26 13:00 Ka-Sal C, Electrum, KTH Royal Institute of Technology, Kista
    Celik, Haris
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    On the Performance of Dynamic TDD in Ultra-Dense Wireless Access Networks2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The appetite for wireless high-data rate services is expected to continue for many years to come and drive the need for more capacity. Ultra-dense networks (UDNs) represent a paradigm shift where each base station (BS) serves only a few user equipments (UEs). By most accounts, most of the traffic will be generated indoor and operate in time-division duplex (TDD). This thesis considers dynamic TDD which has shown to perform well indoor for fluctuating traffic where the shorter communication range enables similar transmit powers to be used in uplink and downlink, but also generates potentially more harmful same-entity interference. Because of the sheer number of cells in UDN, the interference management needs to be both effective and scalable.

     

    In the first part of the thesis, we compare static TDD with non-cooperative dynamic TDD and show that flexible time resource allocation is preferred for indoor UDNs. However, since it only provides a lower bound on performance, additional interference coordination is required. Unfortunately, existing schemes often consider either too few, too many, or simply the wrong interferers. We introduce a scheduling model that relates BS-to-BS interferences measured offline to individual BS activation probability taking into account traffic and propagation environment. Results show that the proposed scheme performs well when interference is high, and optimally when interference is low.

     

    In the second part, we introduce cooperation to utilize the otherwise idle BSs and mitigate same- and other entity interference. Zero forcing (ZF) is employed in the downlink where not only downlink UEs but also uplink BSs are included in the precoding. Since downlink BSs do not know the information to be sent by uplink UEs beforehand, dummy symbols with zero power are transmitted. It shown that both uplink and downlink performance improves at low and medium load. Furthermore, it is possible to trade performance in the two directions at high load.