Blekinge Institute of Technology
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Cognitive Radio Networks: Elements and Architectures
No full textAs mobility and computing becomes ever more pervasive in society and business,
the non-optimal use of radio resources has created many new challenges for
telecommunication operators. Usage patterns of modern wireless handheld
devices, such as smartphones and surfboards, have indicated that the signaling
traffic generated is many times larger than at a traditional laptop.
Furthermore, in spite of approaching theoretical limits by, e.g., the spectral
efficiency improvements brought by 4G, this is still not sufficient for many
practical applications demanded by end users. Essentially, users located at the
edge of a cell cannot achieve the high data throughputs promised by 4G
specifications. Worst yet, the Quality of Service bottlenecks in 4G networks
are expected to become a major issue over the next years given the rapid growth
of mobile devices. The main problems are because of rigid mobile systems
architectures with limited possibilities to reconfigure terminals and base
stations depending on spectrum availability. Consequently, new solutions must
be developed that coexist with legacy infrastructures and more importantly
improve upon them to enable flexibility in the modes of operation. To control
the intelligence required for such modes of operation, cognitive radio
technology is a key concept suggested to be part of the so-called beyond 4th
generation mobile networks. The basic idea is to allow unlicensed users access
to licensed spectrum, under the condition that the interference perceived by
the licensed users is minimal. This can be achieved with the help of devices
capable of accurately sensing the spectrum occupancy, learning about
temporarily unused frequency bands and able to reconfigure their transmission
parameters in such a way that the spectral opportunities can be effectively
exploited. Accordingly, this indicates the need for a more flexible and dynamic
allocation of the spectrum resources, which requires a new approach to
cognitive radio network management. Subsequently, a novel architecture designed
at the application layer is suggested to manage communication in cognitive
radio networks. The goal is to improve the performance in a cognitive radio
network by sensing, learning, optimization and adaptation
Towards Understanding How To Build Strategic Flexibility Of An IT Organization
No full textIT organizations need to react to changes in the business, the domain (e.g.,
regulatory issues), and the technological development. While some of these
changes can be handled by adopting agile practices, others might have large,
irreversible effects on the organization as a whole. While flexibility and
agility have found their way into software project methodologies, IT
organizations struggle with their adaptation at organizational level. This
paper presents preliminary results of a grounded-theory study aimed at
understanding how experienced managers handle flexibility. The results are a
rich empirical source for improving flexibility of an IT organization at the
strategic level and also a good starting point for further research towards
generalizing agile ideas beyond software projects
Performance Analysis of Randomized Distributed Space-Time Codes over Composite Gamma/Lognormal Fading Channels
No full textThis work investigates the end-to-end performance of randomized distributed
space-time codes with complex Gaussian distribution, when employed in a
wireless relay network. The relaying nodes are assumed to adopt a
decode-and-forward strategy and transmissions are affected by small and large
scale fading phenomena. Extremely tight, analytical approximations of the
end-to-end symbol error probability and of the end-to-end outage probability
are derived and successfully validated through Monte-Carlo simulation. For the
high signal-to-noise ratio regime, a simple, closed-form expression for the
symbol error probability is further provided
Key-hiding on the ARM platform
No full textTo combat the problem of encryption key recovery from main memory using cold
boot-attacks, various solutions has been suggested, but most of these have been
implemented on the x86 architecture, which is not prevalent in the smartphone
market, where instead ARM dominates.
One existing solution does exist for the ARM architecture but it is limited to
key sizes of 128 bits due to not being able to utilise the full width of the
CPU registers used for key storage. We developed a test-implementation of
CPU-bound key storage with 256-bit capacity, without using more hardware
resources than the previous solution. We also show that access to the key can
be restricted for programs executing outside the kernel space
Advancing from efficiency to sustainability in Swedish medium-sized cities: an approach for recommending powertrains and energy carriers for public bus transport systems
No full textEuropean national, regional, and local authorities have started to take action
to make public bus transport services more effective and less polluting. Some
see the possibility to move beyond a narrow focus on efficiency or carbon
dioxide reductions towards an integrated sustainability perspective. This paper
uses this perspective to build and test a new assessment approach that should
enhance decisions on bus transport powertrains and energy carriers for Swedish
medium-sized cities. The study suggests that a superiority of electric
powertrains is revealed if a traditional economic analysis is integrated with a
strategic sustainability perspective
An IOT Architecture For Home-based Elderly Healthcare
No full textThe problem of providing effective and appropriate healthcare to elderly and
disable people home has been increasingly talked around. Information and
communication technology (ICT) is believed to enable home healthcare management
to mitigate some problems. This paper is to contribute IoT (Internet of things)
architecture to achieve connectivity with the patient, sensors and everything
around it. A four-level model including ‘personal-family-community-hospital’ is
constructed in order to provide complete and intelligent health management
services to elderly home, which provides sustainable healthcare service for
elderly people. This new solution makes both the elderly life easier and the
healthcare process more effective
Effect of content characteristics on quality of experience of adaptive streaming
No full textThe growing popularity of adaptive streaming-based video delivery nowadays has
raised the interest about the user's perception when experiencing quality
adaptation. The impact of the video content characteristics on user's
perceptual quality has already become evident. The aim of this study is to
investigate the influence of this factor on the quality of experience of
adaptive streaming scenarios. Our results show that the perceptual quality of
adaptation strategies applied on videos with high spatial and low temporal
amount of activity is significantly lower compared to the other content types
Challenges and Practices in Aligning Requirements with Verification and Validation: A Case Study of Six Companies
No full textWeak alignment of requirements engineering (RE) with verification and
validation (VV) may lead to problems in delivering the required products in
time with the right quality. For example, weak communication of requirements
changes to testers may result in lack of verification of new requirements and
incorrect verification of old invalid requirements, leading to software quality
problems, wasted effort and delays. However, despite the serious implications
of weak alignment research and practice both tend to focus on one or the other
of RE or VV rather than on the alignment of the two. We have performed a
multi-unit case study to gain insight into issues around aligning RE and VV by
interviewing 30 practitioners from 6 software developing companies, involving
10 researchers in a flexible research process for case studies.
The results describe current industry challenges and practices in aligning RE
with VV, ranging from quality of the individual RE and VV activities, through
tracing and tools, to change control and sharing a common understanding at
strategy, goal and design level. The study identified that human aspects are
central, i.e. cooperation and communication, and that requirements engineering
practices are a critical basis for alignment. Further, the size of an
organisation and its motivation for applying alignment practices, e.g. external
enforcement of traceability, are variation factors that play a key role in
achieving alignment. Our results provide a strategic roadmap for practitioners
improvement work to address alignment challenges. Furthermore, the study
provides a foundation for continued research to improve the alignment of RE
with VV
Optimization of switched-beam arrays for communication systems
No full textThis paper presents the application of optimization methods for the synthesis
of a linear array for communication systems. By means of suitably beam
switching, the array should provide coverage of a given angular area in azimuth
and should allow controlling the sidelobe level simultaneously. For this
purpose, two optimization methods have been used to calculate the excitation
coefficient for each desired beam. The synthesis technique is demonstrated for
arrays composed of isotropic and microstrip elements. By comparing the results
obtained for both arrays, the need of consideration of the array element
pattern during the synthesis process is demonstrated
Teaching International Students How to Avoid Plagiarism: Librarians and Faculty in Collaboration
No full textThis paper presents how a plagiarism component has been integrated in a
Research Methodology course for Engineering Master students at Blekinge
Institute of Technology, Sweden. The plagiarism issue was approached from an
educational perspective, rather than a punitive. The course director and
librarians developed this part of the course in close collaboration. One part
of the course is dedicated to how to cite, paraphrase and reference, while
another part stresses the legal and ethical aspects of research. Currently, the
majority of the students are international, which means there are intercultural
and language aspects to consider. In order to evaluate our approach to teaching
about plagiarism, we conducted a survey. The results of the survey indicate a
need for education on how to cite and reference properly in order to avoid
plagiarism, a result which is also supported by students' assignment results.
Some suggestions are given for future development of the course