Blekinge Institute of Technology
Electronic Research Archive - Blekinge Tekniska HögskolaNot a member yet
1855 research outputs found
Sort by
Cognitive Radio Spectrum Decision Based on Channel Usage Prediction
No full textThe paper is about a new strategy suggested for spectrum decision in Cognitive
Radio (CR) networks.
By jointly considering sensing error, Secondary Users (SUs) competition and SUs
transmission collision, a new parameter called Channel Usage State (CUS) is
introduced. For a particular channel, we predict the respective probabilities
of occurrence of CUS states by using the LeZi-update scheme. We also adopt a
fuzzy comparison algorithm to combine the prediction results as a joint value.
The largest joint value is associated with the most available channel for
access by SUs in the near future. By comparing with random channel access, the
suggested strategy can improve SUs transmission throughput. This is
demonstrated by the simulation evaluations
Exact Outage Probability of Cognitive Underlay DF Relay Networks with Best Relay Selection
No full textIn this letter, we address the performance analysis of underlay selective
decode-and-forward (DF) relay networks in Rayleigh fading channels with
non-necessarily identical fading parameters. In particular, a novel result on
the outage probability of the considered system is presented. Monte Carlo
simulations are performed to verify the correctness of our exact closed-form
expression. Our proposed analysis can be adopted for various underlay spectrum
sharing applications of cognitive DF relay networks
Procurement as driver of sustainable product-service innovation
No full textCurrent patterns of production and consumption need to change and they need to
do so radically. For this shift sustainability-oriented product-services are
highly potential contributors. Product-services have been described as a market
proposition that extends the functionality of a product beyond the traditional
view by inclusion of additional services into the product-service system. From
a producer perspective this opens up for a differentiation from competitors and
thereby for strategic market opportunities. For the customer this means the
possibility to be released from responsibilities linked to asset ownership,
more differentiated options and increased function availability .For society at
large it means the possibility to gain sustainability achievements.
However, the market adoption of product-services or functional products brings
with it significant challenges. The demand side is still hesitant to ownerless
consumption and the supply side faces economical and company culture-related
challenges. The challenges also include customer-related challenges and the
development of product-services will require joint efforts of a number of
actors along the value chain, actors that traditionally have been outside the
buyer-seller relationship. Product-services need to be developed on a
case-by-case basis and involve the users perspective from initial need phase
until end-of-life in a collaborative process that is not practice today.
This paper explores the strategic position of a procurer in this development.
It aims at providing guidelines for procurement processes on how to
successively and systematically utilize its potential as drivers for
sustainability-oriented product-service solutions. Three procurement cases are
studied for which a movement from a traditional product-oriented process to a
functional-oriented process was the selection criteria. These cases were used
to gain a deepened understanding of drivers and barriers for function-oriented
procurement processes.
A template for sustainable product development is used as a base for the
development. The result from the cases is used to adapt the guidelines to
current procurement processes and to meet the procurers where they are today
Moving Target Relative Speed Estimation and Refocusing in Synthetic Aperture Radar Images
No full textIn this paper, a method for moving target relative speed estimation and
refocusing based on synthetic aperture radar (SAR) images is derived and tested
in simulation and on real data with good results. Furthermore, an approach on
how to combine the estimation method with the refocusing method is introduced.
The estimation is based on a chirp estimator that operates in the SAR image and
the refocusing of the moving target is performed locally using subimages.
Focusing of the moving target is achieved in the frequency domain by phase
compensation, and therefore makes it even possible to handle large range cell
migration in the SAR subimages. The proposed approach is tested in a simulation
and also on real ultrawideband (UWB) SAR data with very good results. The
estimation method works especially well in connection with low frequency (LF)
UWB SAR, where the clutter is well focused and the phase of the smeared moving
target signal becomes less distorted. The main limitation of the approach is
target accelerations where the distortion increases with the integration time
Alignment of business, architecture, process, and organisation in a software development context
No full textIn this paper we investigate the current state of work regarding alignment of
Business, Architecture, Process, and Organisation (BAPO) perspectives in a
software product development context. We planned to do that by conducting a
systematic literature study to capture the state of the art in alignment of
BAPO in software development. But, as it turned out we found that almost no
substantial information is available about the alignment of BAPO in software
development. Thus, based on the available literature and a small qualitative
study, we defined a conceptual model of the alignment of BAPO including five
levels of alignment that can be used as a basis for future empirical studies
An Exploratory Study of Software Evolution and Quality: Before, During and After a Transfer
No full textIn the light of globalization it is not uncommon that different teams from
different locations get involved in the development of a software product
during its evolution. However, empirical evidence that demonstrates the effect
of changing team members on software quality is scarce. In this paper, we
investigate quality of a software product, across subsequent software releases,
that was first developed in one location of Ericsson, a large multinational
corporation, then jointly with an offshore location of the same company, and
finally transferred offshore. To get a better understanding multiple data
sources are used in the analysis: qualitative data, consisting of interviews
and documentation, and quantitative data, consisting of release history and
defect statistics. Our findings confirm an initial decline in efficiency and
quality after a transfer, and highlight the areas of concern for companies that
are considering transferring their product development from experienced teams
to those having limited or no previous engagement with the product
Applications of Lie Group Analysis to Mathematical Modelling in Natural Sciences
No full textToday engineering and science researchers routinely confront problems in
mathematical modeling involving solutions techniques for differential
equations. Sometimes these solutions can be obtained analytically by numerous
traditional ad hoc methods appropriate for integrating particular types of
equations. More often, however, the solutions cannot be obtained by these
methods, in spite of the fact that, e.g. over 400 types of integrable
second-order ordinary differential equations were summarized in voluminous
catalogues. On the other hand, many mathematical models formulated in terms of
nonlinear differential equations can successfully be treated and solved by Lie
group methods. Lie group analysis is especially valuable in investigating
nonlinear differential equations, for its algorithms act here as reliably as
for linear cases. The aim of this article is, from the one hand, to provide the
wide audience of researchers with the comprehensive introduction to Lie's group
analysis and, from the other hand, is to illustrate the advantages of
application of Lie group analysis to group theoretical modeling of internal
gravity waves in stratified fluids
TAPAS: A multi-agent-based model for simulation of transport chains
No full textWe present the Transportation And Production Agent-based Simulator (TAPAS),
which is an agent-based model for simulation of transport chains that can be
used, e.g., for analysis of transport-related policy and infrastructure
measures. TAPAS is more powerful than traditional approaches to freight
transport analysis, as it explicitly models production and customer demand, and
it captures the interaction between individual transport chain actors, their
heterogeneity and decision making processes, as well as time aspects. Whereas
traditional approaches rely on assumed statistical correlation, TAPAS relies on
causality, i.e., the focus is on the decisions and negotiations that lead to
activities. TAPAS is composed of two connected layers, one that simulates the
physical activities, e.g., production and transportation, and one that
simulates the decision making and interaction between actors. We illustrate
TAPAS with a scenario in which the consequences of three transport policy and
infrastructure measures are studied
On the ambiguity of Quality of Service and Quality of Experience requirements for eHealth services
No full textThe use of end-to-end communication systems as a medium of delivery for
electronic healthcare (eHealth) services is considered to be uncertain, with
respect to its reliability leading to hesitation in acceptance of such
services. There exist different influential dimensions that pose stringent
requirements on end-to-end communication systems, influence user perception and
might hinder user acceptance. The later is referred to as Qualityof Experience
(QoE), which among others depends on the Quality of Service (QoS) of the
end-to-end communication system. QoE is considered as a key component
determining user acceptance. This paper identifies and analyzes characteristics
of a set of eHealth services and the influential dimensions resulting in
different QoS requirements and potential impact of QoS on QoE. It highlights
the role of QoS and QoE for acceptance of these services. The issue of
non-uniform views regarding QoS parameter specifications and related
requirements, clinically acceptable thresholds and their qualitative
representation in eHealth literature is reviewed and presented