1,685 research outputs found
Sensing opportunities in UMTS spectrum
The UMTS radio frequency spectrum is a highly expensive commodity. While the UMTS standards make very efficient use of the allocated bands there is however opportunity for further advancements. This paper focuses on opportunistic use of the UMTS spectrum as a means of ensuring that the maximum possible use of this valuable resource is made. In particular we focus on the local detection of UMTS TDD signals through the use of a cyclostationary feature detector. Simulation results for the use of this detector in the presence of multipath propagation and shadowing effects are presented
Sensing UMTS bands using cyclostationary features and cooperation between opportunistic terminals
The Opportunistic Radio (OR) concept relies on the cognitive features of the OR terminals, namely the ability to adapt its transmitter parameters, based upon interaction with the RF environment in which it operates. An OR system operates in
licensed frequency bands, exploiting opportunities and operating with a lower priority regarding the licensed system,
implementing a spectrum pool mechanism. The most important constraint is that the OR network should always avoid harmful
interference with the licensed system, therefore it should reliably detect licensed signals in the used band in order to avoid
interfering with the licensed owner of that band. Given the importance of UMTS systems in current wireless communications, this paper is focused on 3G bands and addresses the problem of sensing weak UMTS signals. The
proposed sensing algorithm exploits the cyclostationary features of UMTS signals and the cooperation between multiple OR terminals clustered in the OR network
Broadband Spectrum Survey Measurements for Cognitive Radio Applications
It is well known that the existing spectrum licensing system results in a gross under-utilization of the frequency spectrum. Spectrum background measurements – spectrum surveys – provide useful data for spectrum regulation, planning or finding frequency niches for spectrum sharing. Dynamic spectrum sharing as a main goal of cognitive radio (CR) is the modern option on how to optimize usage of the frequency spectrum. A spectrum survey measurement system is introduced with results obtained from a variety of markedly different scenarios allowing us, unlike other studies, to focus on wideband and fast spectrum scans. The sensitivity of the receiver is no worse than -113 dBm in the whole band. The utilization of the frequency spectrum is analyzed to prove its under-utilization and to show spectrum sharing opportunities. This was shown to be true in the frequency band higher than 2.5 GHz. A comparison with other spectrum survey campaigns is provided
Cognitive Radio Networks: Realistic or Not?
A large volume of research has been conducted in the cognitive radio (CR)
area the last decade. However, the deployment of a commercial CR network is yet
to emerge. A large portion of the existing literature does not build on real
world scenarios, hence, neglecting various important interactions of the
research with commercial telecommunication networks. For instance, a lot of
attention has been paid to spectrum sensing as the front line functionality
that needs to be completed in an efficient and accurate manner to enable an
opportunistic CR network architecture. This is necessary to detect the
existence of spectrum holes without which no other procedure can be fulfilled.
However, simply sensing (cooperatively or not) the energy received from a
primary transmitter cannot enable correct dynamic spectrum access. For example,
the low strength of a primary transmitter's signal does not assure that there
will be no interference to a nearby primary receiver. In addition, the presence
of a primary transmitter's signal does not mean that CR network users cannot
access the spectrum since there might not be any primary receiver in the
vicinity. Despite the existing elegant and clever solutions to the DSA problem
no robust, implementable scheme has emerged. In this paper, we challenge the
basic premises of the proposed schemes. We further argue that addressing the
technical challenges we face in deploying robust CR networks can only be
achieved if we radically change the way we design their basic functionalities.
In support of our argument, we present a set of real-world scenarios, inspired
by realistic settings in commercial telecommunications networks, focusing on
spectrum sensing as a basic and critical functionality in the deployment of
CRs. We use these scenarios to show why existing DSA paradigms are not amenable
to realistic deployment in complex wireless environments.Comment: Work in progres
Wireless communication, identification and sensing technologies enabling integrated logistics: a study in the harbor environment
In the last decade, integrated logistics has become an important challenge in
the development of wireless communication, identification and sensing
technology, due to the growing complexity of logistics processes and the
increasing demand for adapting systems to new requirements. The advancement of
wireless technology provides a wide range of options for the maritime container
terminals. Electronic devices employed in container terminals reduce the manual
effort, facilitating timely information flow and enhancing control and quality
of service and decision made. In this paper, we examine the technology that can
be used to support integration in harbor's logistics. In the literature, most
systems have been developed to address specific needs of particular harbors,
but a systematic study is missing. The purpose is to provide an overview to the
reader about which technology of integrated logistics can be implemented and
what remains to be addressed in the future
Analysis of communication opportunities in UMTS cellular networks
A scenario based on an UMTS TDD opportunistic
cellular system that operates over UMTS FDD licensed cellular
networks is considered. Therefore a simulation tool was
developed for the analysis and assessment of UMTS TDD
opportunistic radio system in a coexistence environment with
UMTS FDD primary cellular networks. The communication
presents the scenario considered, the main features of the
simulation tool, discusses and proposes metrics to evaluate the
communication opportunities in UMTS FDD primary cellular
networks, and presents numerical simulation results. These show
that a moderate number of UMTS FDD available frequencies
and a reasonable UMTS TDD opportunistic radio transmission
power will allow the deployment of UMTS TDD opportunistic
radio networks in a coexistence environment with existing
licensed systems
Application of game theory in ad- hoc opportunistic radios
The application of mathematical analysis to the study
of wireless ad hoc networks has met with limited success due
to the complexity of mobility, traffic models and the dynamic
topology. A scenario based UMTS TDD opportunistic cellular
system with an ad hoc behaviour that operates over UMTS
FDD licensed cellular network is considered. In this paper, we
describe how ad hoc opportunistic radio can be modeled as a
game and how we apply game theory based Power Control in
ad-hoc opportunistic radio
Simulation-based evaluation of spectrum opportunities in UMTS cellular networks
A scenario based on an UMTS TDD opportunistic cellular system that operates over UMTS FDD licensed cellular
networks is considered. Therefore we develop a simulation tool that addresses the goal of analysis and assessment of UMTS TDD opportunistic radio system in a coexistence environment with UMTS FDD primary cellular networks. The communication
presents the scenario considered, the main features of the tool, discusses and proposes metrics to evaluate the communication opportunities in UMTS FDD primary cellular networks, and presents numerical simulation results. These show that a moderate number of UMTS TDD available frequencies and a reasonable UMTS TDD opportunistic radio transmission power
will allow the deployment of UMTS TDD opportunistic radio networks in a coexistence environment with existing licensed
systems
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