In this paper, we use concepts and results from percolation theory to investigate and characterize the effects of multi-channels on the connectivity of Dynamic Spectrum Access networks. In particular, we focus on the scenario where the secondary nodes have plenty of vacant channels to choose from-a phenomenon which we define as channel abundance. To cope with the existence of multi-channels, we use two types of rendezvous protocols: naive ones which do not guarantee a common channel and advanced ones which do. We show that, with more channel abundance, even with the use of either type of rendezvous protocol, it becomes difficult for two nodes to agree on a common channel, thereby potentially remaining invisible to each other. We model this invisibility as a Poisson thinning process and show that invisibility is even more pronounced with channel abundance. Following the disk graph model, we define and characterize connectivity of the secondary network in terms of the available number of channels, deployment densities, number of transceivers per node, and communication range. When primary users are absent, we derive the critical number of channels which maintains super-criticality of the secondary network. When primary users are present, we characterize and analyze the connectivity for all the regions: channel abundance, optimal, and channel deprivation. Our results can be used to decide on the goodness of any channel rendezvous algorithm by computing the expected resultant connectivity.
The proliferation of electronic games, video games and computers has caused children and teenagers to become attracted to these games and become their favorite entertainment. The widespread of these games has generated widespread debate about positive aspects and negative aspects. It is evident that there are two main trends in the impact of electronic games on the behavior of children and adolescents. The first trend is that e-games have positive effects on children and adolescents, especially in cognitive abilities and skills in learning. While the second view sees that electronic games have negative effects that appear in social isolation and lack of movement and aggression. Through the review of previous literature, the current resea
... Show MoreChannel estimation and synchronization are considered the most challenging issues in Orthogonal Frequency Division Multiplexing (OFDM) system. OFDM is highly affected by synchronization errors that cause reduction in subcarriers orthogonality, leading to significant performance degradation. The synchronization errors cause two issues: Symbol Time Offset (STO), which produces inter symbol interference (ISI) and Carrier Frequency Offset (CFO), which results in inter carrier interference (ICI). The aim of the research is to simulate Comb type pilot based channel estimation for OFDM system showing the effect of pilot numbers on the channel estimation performance and propose a modified estimation method for STO with less numb
... Show MoreOur life is a test and the eternal life in the afterlife. So we must work well in our life even win paradise, must always remember the death and there is a life after this death and we will be responsible for everything we've done in our life. God did not create us vain but for reward, punishment, for this we must have to well prepare for this great day and we have to think about what to do in order to win the paradise.
Keywords: paradise, surat al-rahman, preparation.
The main aim of conducting this research is to identify the applications of Smart libraries in the Arab world. The Researcher relied on the documentary and Survey approach to collect information and data through the Internet, and to get to know these libraries. Then the Research came in three sections dealing with the first topic: The general framework of the study. The second topic deals with: introducing Smart libraries and indicating their types and characteristics. The Third topic dealt with the requirements of Smart libraries'application by identifying the basic components of it (Smart building, Smart Librarian , Smart devices, systems and software, Smart information sources,and Smart beneficiaries), and dealt with Smart libraries appl
... Show MoreAN Salih, LO Hamza, Ann. For. Res, 2022 - Cited by 2
The current research deals with the subject of spatial transformations and visual construction in contemporary theater. How the visual system works to create spatial diversity in the contemporary Iraqi theater performance and how visual construction contributes to a spatial development process capable of building a tourism system that creates an architectural architecture that leaves the topography of the scriptural architecture. And the production of various indications and patterns in the scene of theatrical presentation in order to produce the new foundational meaning by creating a new structure that leads to diversity and diversity in the visual system and the beginning of visual constructions and their applications. Knowledge and te
... Show MoreThe current research dealt with the symbolic significance and its effectiveness in the design of the industrial product, the aesthetic communicative discourse that embodies the imagination and human conscience. Whether according to what has been termed custom or what has been approved by traditions long ago, symbolism may be the main actor in linking the identifying components of the product. In addition, symbolism provides the user with the key to accessing a direct awareness of the product’s shape and function, as an identification of the product by stimulating the symbolic form of the consumer’s imagination and inviting him to To meditate in order to realize the implicit meaning behind these forms and thus achieve the symbolism of
... Show MoreThat the diplomatic work and its importance in foreign policy planning assumes the following points: 1. Choosing the tool in the sense of choosing the most correct tool that reflects the reality of the situation on the one hand and the disposal of strong energy to reach the implementation of the political decision. The declaration of war and entering into a resolution that uses force merely to face insulting ambassadors does not mean Power of the State concerned. But an imbalance in its foreign policy. 2. The coordination of the tools, that the foreign policy scheme must be such a role, and on the external style, diplomatic work, military action and propaganda must complement each other, to the extent that each of them is the first attac
... Show MoreThe overlap between science and knowledge is a feature of the 21st century. This integration, which crosses the traditional boundaries between academic disciplines, has occurred because of the emergence of new needs and new professions. This overlap has overshadowed the arts in general and design in particular. The Design achievements have not been far away from the attempts of integration of more than one type or design application to produce new outputs unique in its functional and aesthetic character, including the terms of internal graphic design.
The researcher raises the question of the functional dimension of graphic design in the internal space, in order to answer it through the methodological framework, which includes th
... Show MorePregnancy at an early age of life is a major challenge. The consequences of this problem have an impact on the quality of life of the young mother and her family, and determines an important risk for her offspring. The son of a teenage mother has, in general, greater risks than that of a mother of more than 20 years. The aim of this study is to determine the prevalence and outcome of teenage pregnancy. A descriptive data base study was conducted at Al-Elwia Maternity Teaching hospital in the period from January 1, 2019 to the end of June 2019 within the age between 12 and 19 years old. The mean age of the mother was 17.4 ±1.5 years. The mean age of the father was 23.9 ± 5.7 years with (69.5%) with Vaginal delivery and most of the
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