Browsing by Subject "Spatial diversity"

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    Cooperative underwater acoustic communications
    (IEEE, 2013) Al-Dharrab, S.; Uysal, M.; Duman, T.
    This article presents a contemporary overview of underwater acoustic communication (UWAC) and investigates physical layer aspects on cooperative transmission techniques for future UWAC systems. Taking advantage of the broadcast nature of wireless transmission, cooperative communication realizes spatial diversity advantages in a distributed manner. The current literature on cooperative communication focuses on terrestrial wireless systems at radio frequencies with sporadic results on cooperative UWAC. In this article, we summarize initial results on cooperative UWAC and investigate the performance of a multicarrier cooperative UWAC considering the inherent unique characteristics of the underwater channel. Our simulation results demonstrate the superiority of cooperative UWAC systems over their point-to-point counterparts. © 1979-2012 IEEE.
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    The effect of modular systems on spatial design and diversity: analysis through constructed modular buildings
    (2022-07) Sunsal, Beliz
    Modular systems are prefabricated building elements as a product of modern architecture. Compared to conventional methods, modular construction systems can find a place in many different projects with their two- and three-dimensional types, however, they have never become quite popular as an architectural design method. Modular systems, which offer various alternatives in terms of materials and construction methods, are produced as prefabricated; therefore, the problems that may arise during the construction phase and the time for on-site operations are minimized. In this sense, it significantly differs from other techniques in terms of time and work control and provides an advantage. However, modular systems could not provide the necessary place for themselves in the market, and their examples were limited to specific functions and locations. This thesis proposes an analysis method to investigate this problem, through examining the effect of modular systems on spatial design and diversity. In line with this target, this study examines the existing modular building examples worldwide through the number and the distribution of spaces generated, such as public-private zones, circulation areas, and bathrooms. When the relations of these areas with each other and the unit they are located in, are analyzed; it has been observed that the spatial design and diversity vary based on the number of utilized modules and the function of the project. When the shapes of the employed modules, indoor circulation, main entrance, private zones, and the relations of these areas with each other are compared with other examined projects, it is observed that the modular systems do not concentrate on a single type. Since a single type of unit does not have the vast majority, it has been concluded that modular systems have a high potential in terms of spatial diversity and design, they can be used in different projects and functions, but the spatial performance of curvilinear- or organic form-based modules and applicable examples in earthquake zones should also be examined in detail.
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    Sabit karasal noktadan-noktaya sistemlerin çok yollu sönümlenmesini azaltmak için uzaysal çeşitleme tekniğini değerlendirme
    (IEEE, 2015-05) Göktaş, Polat; Topcu, Satılmış; Karaşan, Ezhan; Altıntaş, Ayhan
    Çok yollu sönümlenme mekanizması, 10 GHz altındaki frekanslarda çalışan sabit karasal mikrodalga görüş çizgisi radyo linkleri için belirleyici yayılım faktörüdür. Çok yollu yayılımdan dolayı sönümlenme karasal görüş çizgisi linklerdeki alınan sinyalleri zayıflamakta ve dolayısıyla noktadan-noktaya sistemlerin performasını bozmaktadır. Çeşitli metodlar; çeşitleme ile yada çeşitleme tekniği olmadan çok yollu sönümlenmenin etkilerini azaltmak için kullanılır. Uzay çeşitlemede dikey aralık çok yollu sönümlenmeyi azaltmanın en etkili metodlarından biridir. Bu makalede, sabit karasal mikrodalga görüş çizgisi radyo linkleri için iki anten uzay çeşitleme konfigürasyonu konseptinin değerlendirilmesi yapılmıştır. Arazi hat profili boyunca yerden yansıma noktalarından kaynaklanan çok yolluluktan dolayı çok yollu sönümlenme olayları analiz edilmiştir. Örnek sabit karasal mikrodalga görüş çizgisi radyo linklerindeki farklı anten yerden yüksekliklerinde iki anten konfigürasyonu ile uzaysal çeşitleme benzetim çalışması yapılmıştır. Benzetim sonuçları alıcıdaki güç seviyesine göre degerlendirilmiştir.