23,099 research outputs found
A Sensing Error Aware MAC Protocol for Cognitive Radio Networks
Cognitive radios (CR) are intelligent radio devices that can sense the radio
environment and adapt to changes in the radio environment. Spectrum sensing and
spectrum access are the two key CR functions. In this paper, we present a
spectrum sensing error aware MAC protocol for a CR network collocated with
multiple primary networks. We explicitly consider both types of sensing errors
in the CR MAC design, since such errors are inevitable for practical spectrum
sensors and more important, such errors could have significant impact on the
performance of the CR MAC protocol. Two spectrum sensing polices are presented,
with which secondary users collaboratively sense the licensed channels. The
sensing policies are then incorporated into p-Persistent CSMA to coordinate
opportunistic spectrum access for CR network users. We present an analysis of
the interference and throughput performance of the proposed CR MAC, and find
the analysis highly accurate in our simulation studies. The proposed sensing
error aware CR MAC protocol outperforms two existing approaches with
considerable margins in our simulations, which justify the importance of
considering spectrum sensing errors in CR MAC design.Comment: 21 page, technical repor
Almost sure exponential stabilisation of stochastic systems by state-feedback control
So far, a major part of the literature on the stabilisation issues of stochastic systems has been dedicated to mean square stability. This paper develops a new class of criteria for designing a controller to stabilise a stochastic system almost surely which is unable to be stabilised in mean-square sense. The results are expressed in terms of linear matrix inequalities (LMIs) which are easy to be checked in practice by using MATLAB Toolbox. Moreover, the control structure in this paper appears not only in the drift part but also in the diusion part of the underlying stochastic system
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