1,720,988 research outputs found
Relay cooperation in multiaccess networks
No full textCooperation in communication networks results when terminals use their energy and bandwidth resources to mutually enhance their transmissions. Cooperation can be induced in many ways and each approach entails a different tradeoff of power, bandwidth, complexity, and costs to achieve spatial diversity gains characteristic of antenna arrays. In this dissertation, we study a specific cooperative network - a multiaccess relay channel (MARC) where cooperation is induced via a dedicated relay node in a network where multiple users communicate with one destination.
We extend the relaying strategies of decode-and-forward (DF), compress-and-forward (CF), and amplify-and-forward (AF) to the MARC. Specifically, for DF we show that real-time decoding at the destination using a sliding-window incurs a rate loss relative to an offline backward decoding technique. We develop an offset encoding technique that improves sliding window decoding and achieves the corner points of the backward decoding rate region with significantly smaller delay.
Next we compare two approaches to inducing cooperation in a multiaccess channel. In one approach we allow the users to cooperate while in the other we induce cooperation via a relay when the users cannot or do not cooperate. Using the total transmit and processing power consumed at all nodes as a cost metric, we compare the DF and AF sum-rates and outage probabilities for the two networks. Our results show that cooperation is most desirable in the regime where processing power is significantly smaller than the transmit power. We also show that relay cooperation is on average more energy efficient than user cooperation.
Finally, we develop a capacity result for the MARC. The MARC belongs to a class of multi-terminal networks whose capacity is, in general, not known. For a degraded Gaussian K-user MARC, we use max-min optimization techniques to show that DF achieves the K-user sum-capacity.Ph.D.Includes bibliographical references (p. 162-167)
Designing Incentive Schemes For Privacy-Sensitive Users
No full textBusinesses (retailers) often wish to offer personalized advertisements (coupons) to individuals (consumers), but run the risk of strong reactions from consumers who want a customized shopping experience but feel their privacy has been violated. Existing models for privacy such as differential privacy or information theory try to quantify privacy risk but do not capture the subjective experience and heterogeneous expression of privacy-sensitivity. We propose a Markov decision process (MDP) model to capture (i) different consumer privacy sensitivities via a time-varying state; (ii) different coupon types (action set) for the retailer; and (iii) the action-and-state-dependent cost for perceived privacy violations. For the simple case with two states ("Normal" and "Alerted"), two coupons (targeted and untargeted) model, and consumer behavior statistics known to the retailer, we show that a stationary threshold-based policy is the optimal coupon-offering strategy for a retailer that wishes to minimize its expected discounted cost. The threshold is a function of all model parameters; the retailer offers a targeted coupon if its belief that the consumer is in the "Alerted" state is below the threshold. We extend this two-state model to consumers with multiple privacy-sensitivity states as well as coupon-dependent state transition probabilities. Furthermore, we study the case with imperfect (noisy) cost feedback from consumers and uncertain initial belief state.Peer reviewed
Robust privacy-utility tradeoffs under differential privacy and Hamming distortion
No full textPeer reviewe
Incentive Schemes for Privacy-Sensitive Consumers
No full textThe final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-25594-1Peer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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