Channel rendezvous is an initial and important process for establishing communications between secondary users (SUs) in distributed cognitive radio networks. Due to the drawbacks of the common control channel (CCC) based rendezvous approach, channel hopping (CH) has attracted a lot of research interests for achieving blind rendezvous. To ensure rendezvous within a finite time, most of the existing CH-based rendezvous schemes generate their CH sequences based on the whole global channel set in the network. However, due to the spatial and temporal variations in channel availabilities as well as the limitation of SUs sensing capabilities, the local available channel set (ACS) for each SU is usually a small subset of the global set. Therefore, following these global-based generated CH sequences can result in extensively long time-to-rendezvous (TTR) especially when the number of unavailable channels is large. In this paper, we propose two matrix-based CH rendezvous schemes in which the CH sequences are generated based on the ACSs only. We prove the guaranteed and full diversity rendezvous of the proposed schemes by deriving the theoretical upper bounds of their maximum TTRs. Furthermore, extensive simulation comparisons with other existing works are conducted which illustrate the superior performance of our schemes in terms of the TTR metrics.
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http://dx.doi.org/10.3390/s18124360 | DOI Listing |
Sensors (Basel)
December 2024
Department of Computer Engineering, Ulsan College, Ulsan 44022, Republic of Korea.
In this paper, we propose a method for applying the -ary m-sequence as a channel-searching pattern for rendezvous in the asymmetric channel model of cognitive radio. We mathematically analyzed and calculated the ETTR when the m-sequence is applied to the conventional scheme, and our simulation results demonstrated that the ETTR performance is significantly better than that of the JS algorithm. Furthermore, we introduced a new channel-searching scheme that maximizes the benefits of the m-sequence and proposed a method to adapt the generation of the m-sequence for use in the newly proposed scheme.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2024
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico.
The electronic states in flat bands possess zero group velocity and null charge mobility. Recently, flat electronic bands with fully localized states have been predicted in nanowires, when their hopping integrals between first, second, and third neighbors satisfy determined relationships. Experimentally, these relationships can only be closely achieved under external pressures.
View Article and Find Full Text PDFMolecules
December 2024
Faculty of Science and Technology, Jan Dlugosz University, Al. Armii Krajowej 13/15, 42-200 Czestochowa, Poland.
The structural and dynamic properties of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(-vinylpyrrolidone--2-hydroxyethyl methacrylate) [P(VP--HEMA)], dry and as hydrogels, were studied by molecular dynamics simulations. The P(VP--HEMA) chains differed in the number of VP mers, distributed randomly or in blocks. In all considered configurations, HEMA and VP side chains proved relatively rigid and stable.
View Article and Find Full Text PDFPhys Chem Chem Phys
December 2024
Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
Conjugated diene molecules are highly reactive upon photoexcitation and can relax through multiple reaction channels that depend on the position of the double bonds and the degree of molecular rigidity. Understanding the photoinduced dynamics of these molecules is crucial for establishing general rules governing the relaxation and product formation. Here, we investigate the femtosecond time-resolved photoinduced excited-state structural dynamics of ,-1,3-cyclooctadiene, a large-flexible cyclic conjugated diene molecule, upon excitation with 200 nm using mega-electron-volt ultrafast electron diffraction and trajectory surface hopping dynamics simulations.
View Article and Find Full Text PDFBioorg Med Chem Lett
December 2024
Lieber Institute for Brain Development, 855 N. Wolfe Street, Baltimore, MD 21205, USA; Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA. Electronic address:
The voltage-gated sodium channel Na1.8 (SCN10A) has strong genetic and pharmacological validation as a potential target for treating acute and chronic pain. While several different chemotypes have been advanced as selective inhibitors, a quinoxaline carboxamide core structure was identified as a particularly attractive core structure due to very high sodium channel subtype selectivity.
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