Kosunalp, Selahattin; Tabakcioglu, Mehmet Baris

Wireless sensor networks (WSNs) have recently been a popular research area with a broad range of applications. One of the most significant constraints of WSNs is energy limitation of sensor nodes. Therefore, energy-efficiency has been considered as primarily design criterion in many medium access control (MAC) protocols developed. In order to solve the issue of limited-energy sources, various recent protocols have focused on energy harvesting from surrounding environment, such as solar, wind and vibration energy, resulting in providing unlimited energy source. Ambient energy exhibits a characteristic of unlimited energy source but not available always due to environmental changes. The focus is now being placed on effective utilization of the time-varying ambient energy. This study aims to provide a review of recently proposed MAC protocols for energy-harvesting WSNs describing their operating principles and underlying features.

İncele

Tabakcioglu, Mehmet Baris; Ayberkin, Doruk

To make higher accuracy predictions having less computation complexity, lower computation time, a lot of electromagnetic wave propagation models are developed. These models are classified into two classes, ray tracing based and numerical models. Computation complexity, computation time and accuracy of prediction of numerical model are high. On the contrary, computation complexity and computation time of ray tracing based model is lower. There is a tradeoff between computation time and accuracy. To predict the relative path loss at the receiver accurately, all ray paths have to be determined. In this study, after giving some brief information about some ray tracing based propagation models ray tracing software will be explained.

AtıfWoS1

İncele

Tabakcioglu, Mehmet Baris; Ayberkin, Doruk

Electromagnetic wave propagation models are used in radio planning tool and coverage prediction. These models are based on ray tracing technique or numerical. Slope UTD with convex hull model is a model which has less computation time, higher accuracy of prediction and based on ray tracing technique. S-UTD-CH model is used in multiple diffraction due to that this model gives more accurate results in less computation time. Obstacles can be modelled as knife edge, wedge or cylinder in ultra-high frequencies. inner angle, structure type and relative permittivity constant and conductivity of obstacle and polarization type of electromagnetic wave change the relative path loss at the receiver. In the study, how building parameter changes the relative path loss is discussed.

İncele

Tabakcioglu, Mehmet Baris; Ayberkin, Doruk

In this study, propagation prediction models based on ray tracing in coverage estimation for broadcasting systems are compared with respect to computation time and accuracy. Uniform Theory of Diffraction (UTD), Slope Diffraction (S-UTD) and Slope UTD with Convex Hull (S-UTD-CH) models are compared for computation time and propagation path loss. Moreover in this study, effects of transmitter height to relative path loss at the receiver are analyzed. S-UTD-CH model is optimum model with respect to computation time and relative path loss.

İncele

Tabakcioglu, Mehmet Baris; Cansiz, Ahmet

Propagation prediction models based on ray tracing in coverage estimation for digital broadcasting systems are compared. Geometrical Theory of Diffraction (GTD), Slope Uniform Theory of Diffraction (S-UTD), and Slope UTD with Convex Hull (S-UTD-CH) models are compared for computation time and propagation path loss. S-UTD-CH model is optimum model with respect to computation time and relative path loss.

AtıfScopus8·WoS7·OpenAlex11

İncele

Tabakcioglu, Mehmet Baris; Ayberkin, Doruk; Cansiz, Ahmet

This paper presents a study on a class of algorithms based on Uniform Theory of Diffraction (UTD) for multiple diffractions. S-UTD-CH model can be used for fast and more accurate field prediction for multiple diffractions in transition zone. An extensive simulation results for comparison of UTD based algorithms with respect to the computation time and accuracy was provided.

AtıfWoS2

İncele

Tabakcioglu, Mehmet Baris; Kara, Ali

This article proposes an improved slope uniform theory of diffraction model for fast and more accurate field prediction for multiple wedge diffractions in the transition zone. The proposed method is based on the slope uniform theory of diffraction and the Fresnel zone concept, called the slope uniform theory of diffraction with convex hull. The article also provides simulation results for the comparison of the uniform theory of diffraction based algorithms with respect to the computation time and accuracy.

AtıfScopus23·WoS19·OpenAlex23

İncele