3,564 research outputs found
Full-Duplex Cognitive Radio: A New Design Paradigm for Enhancing Spectrum Usage
With the rapid growth of demand for ever-increasing data rate, spectrum
resources have become more and more scarce. As a promising technique to
increase the efficiency of the spectrum utilization, cognitive radio (CR)
technique has the great potential to meet such a requirement by allowing
un-licensed users to coexist in licensed bands. In conventional CR systems, the
spectrum sensing is performed at the beginning of each time slot before the
data transmission. This unfortunately results in two major problems: 1)
transmission time reduction due to sensing, and 2) sensing accuracy impairment
due to data transmission. To tackle these problems, in this paper we present a
new design paradigm for future CR by exploring the full-duplex (FD) techniques
to achieve the simultaneous spectrum sensing and data transmission. With FD
radios equipped at the secondary users (SUs), SUs can simultaneously sense and
access the vacant spectrum, and thus, significantly improve sensing
performances and meanwhile increase data transmission efficiency. The aim of
this article is to transform the promising conceptual framework into the
practical wireless network design by addressing a diverse set of challenges
such as protocol design and theoretical analysis. Several application scenarios
with FD enabled CR are elaborated, and key open research directions and novel
algorithms in these systems are discussed
Optimal Scanning Bandwidth Strategy Incorporating Uncertainty about Adversary's Characteristics
In this paper we investigate the problem of designing a spectrum scanning
strategy to detect an intelligent Invader who wants to utilize spectrum
undetected for his/her unapproved purposes. To deal with this problem we model
the situation as two games, between a Scanner and an Invader, and solve them
sequentially. The first game is formulated to design the optimal (in maxmin
sense) scanning algorithm, while the second one allows one to find the optimal
values of the parameters for the algorithm depending on parameters of the
network. These games provide solutions for two dilemmas that the rivals face.
The Invader's dilemma consists of the following: the more bandwidth the Invader
attempts to use leads to a larger payoff if he is not detected, but at the same
time also increases the probability of being detected and thus fined.
Similarly, the Scanner faces a dilemma: the wider the bandwidth scanned, the
higher the probability of detecting the Invader, but at the expense of
increasing the cost of building the scanning system. The equilibrium strategies
are found explicitly and reveal interesting properties. In particular, we have
found a discontinuous dependence of the equilibrium strategies on the network
parameters, fine and the type of the Invader's award. This discontinuity of the
fine means that the network provider has to take into account a human/social
factor since some threshold values of fine could be very sensible for the
Invader, while in other situations simply increasing the fine has minimal
deterrence impact. Also we show how incomplete information about the Invader's
technical characteristics and reward (e.g. motivated by using different type of
application, say, video-streaming or downloading files) can be incorporated
into scanning strategy to increase its efficiency.Comment: This is the last draft version of the paper. Revised version of the
paper was published in EAI Endorsed Transactions on Mobile Communications and
Applications, Vol. 14, Issue 5, 2014, doi=10.4108/mca.2.5.e6. arXiv admin
note: substantial text overlap with arXiv:1310.724
Green Cellular Networks: A Survey, Some Research Issues and Challenges
Energy efficiency in cellular networks is a growing concern for cellular
operators to not only maintain profitability, but also to reduce the overall
environment effects. This emerging trend of achieving energy efficiency in
cellular networks is motivating the standardization authorities and network
operators to continuously explore future technologies in order to bring
improvements in the entire network infrastructure. In this article, we present
a brief survey of methods to improve the power efficiency of cellular networks,
explore some research issues and challenges and suggest some techniques to
enable an energy efficient or "green" cellular network. Since base stations
consume a maximum portion of the total energy used in a cellular system, we
will first provide a comprehensive survey on techniques to obtain energy
savings in base stations. Next, we discuss how heterogeneous network deployment
based on micro, pico and femto-cells can be used to achieve this goal. Since
cognitive radio and cooperative relaying are undisputed future technologies in
this regard, we propose a research vision to make these technologies more
energy efficient. Lastly, we explore some broader perspectives in realizing a
"green" cellular network technologyComment: 16 pages, 5 figures, 2 table
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