All over the world, the existing spectrum is already been saturated with ever increasing demand. Every day huge number of users is joined to the existing fixed band frequency but the bandwidth is not increasing. To so...
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All over the world, the existing spectrum is already been saturated with ever increasing demand. Every day huge number of users is joined to the existing fixed band frequency but the bandwidth is not increasing. To solve this issue the cognitive radio is the best choice. Spectrum or white space detection is an essential and very important issue in cognitive radio communication. The aim of channel detection is to find out efficiently the presence or absence of primary or licensed frequency. In this paper, we have developed a Libelium Waspmote sensor based cognitive radio detection scheme which is very easy to use, energy and cost effective. The reason for selecting this type of sensor is it supports IEEE 802.11 b/g and the Tx/Rx antenna transmission and reception sensitivity can be changed by the software. It can scan the available channel resource within its range and can store the data files. Also the security of this type of sensor supports the highest level of wireless security that is Wireless Protected Access V2 or WPA2. It is Windows based which is very common worldwide. The application runs in background without interrupting the PC/Laptop users. It is able to find efficient spectrum hole (Ideal channel) for a secondary or cognitive user to use the primary or licensed band without interrupting the primary user.
In this paper the investigation of the effect using different substrate materials on a textile monopole antenna is discussed. This textile monopole antenna is designed to be used for Body-Centric Wireless Communicatio...
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In this paper the investigation of the effect using different substrate materials on a textile monopole antenna is discussed. This textile monopole antenna is designed to be used for Body-Centric Wireless communications (BCWC) at 2.45 GHz. Three types of non-conductive materials were selected: felt, fleece and foam. The textile monopole was benchmarked against a conventional FR-4 monopole antenna. The results demonstrated a good agreement between simulated return loss of all three substrates used for textile monopole antenna and conventional monopole antenna. The felt-based textile monopole antenna offered higher return loss compared to other substrates and conventional monopole antenna. Moreover, the substrate materials gained bandwidths of up to 1000 MHz in free space where fleece fabric produced broader bandwidth compared to other substrates. The simulated gain characteristics for all three types of substrates agreed reasonably well with conventional monopole antenna.
A design of a 2×3 ceramic microstrip patch array antenna with a 50 Ω microstrip transmission line feed is presented. The antenna was designed to operate at the Worldwide Interoperability for Microwave Access (Wi...
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A design of a 2×3 ceramic microstrip patch array antenna with a 50 Ω microstrip transmission line feed is presented. The antenna was designed to operate at the Worldwide Interoperability for Microwave Access (WiMAX) application. The proposed ceramic which was Bismuth Titanate (BiT) was designed in rectangular form, with high dielectric constant of 21. Simulation using CST Microwave Studio has been carried out in order to verify this design. Due to high dielectric constant values, BiT elements on antenna had been tested as building blocks for miniaturized antenna solutions. The various dimensions of the BiT for both branching strips and radiating patches were investigated and found that different sizes of BiT lead to different resonant frequency. The simulation results were in good agreement with the desired frequency band of 2.3-2.5 GHz.
This paper presents a light-weight, compact and simple textile monopole antenna structure for body-centric wireless communications (BCWC), applications operating in the 2.45 GHz Industrial, Scientific and Medical (ISM...
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This paper presents a light-weight, compact and simple textile monopole antenna structure for body-centric wireless communications (BCWC), applications operating in the 2.45 GHz Industrial, Scientific and Medical (ISM) band. Three different conductive textile materials are chosen: Pure Copper Polyester Taffeta, ShieldIt Super and Nora RS. The result obtained in this investigation showed that all three textile monopoles produced higher reflection coefficient and directivity values compared to the conventional FR-4 monopole antenna. It was found that the simulated gain and radiation pattern characteristics agreed well with the conventional FR4 monopole antenna. The result has also shown that the Nora RS gave better performance in terms of return loss and gain characteristics compared to the other two electrotextiles.
Due to increase computer hardware technologies, software developers are more focusing on to developing embedded operating system. GNU/Linux becomes a common operating system widely use in embedded technologies. In thi...
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Due to increase computer hardware technologies, software developers are more focusing on to developing embedded operating system. GNU/Linux becomes a common operating system widely use in embedded technologies. In this paper, we report performance results on a TS-7800 Single Board computer with different version of kernel that has been released by hardware provider. We compare the performance between operating system with the latest kernel given by hardware provider, Linux kernel (2.6.34) and the previous kernel (2.6.21) Our results indicate that the new kernel has better performance in kernel benchmark, more bandwidth and less latency. In other experiments we found that the results are almost the same and in some cases the kernel (2.6.21) has better performance than the kernel (2.6.34).
In recent years, there have been a number of reported studies on the design of communication protocols using simulation platform. However, most of the reported works were evaluated using simple or idealistic wireless ...
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In recent years, there have been a number of reported studies on the design of communication protocols using simulation platform. However, most of the reported works were evaluated using simple or idealistic wireless ...
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In recent years, there have been a number of reported studies on the design of communication protocols using simulation platform. However, most of the reported works were evaluated using simple or idealistic wireless communication channel modeling. Experimental results have shown that the characterization and modeling of wireless communication channel is important to achieve a successful implementation of wireless sensor network (WSN) systems in agricultural based application. This paper investigates the impact of propagation model towards WSNs system under OMNeT++ simulation environment. Several realistic propagation models for WSNs are also reviewed. Several well known empirical vegetation models, namely MED Weissberger Model and ITU-Recommendation model are implemented in OMNeT++ simulation platform. It is observed that propagation model used gives significant impact towards the network performances. The results show that a combination of plain earth (PE) and vegetation model give more realistic result and can best describe the behavior of actual WSN systems when deployed in a real environment. Antenna heights and vegetation density are important parameters that affect communication network coverage and connectivity.
Power consumption is a subject of serious consideration in embedded systems design because embedded systems are constrained to stringent power and energy requirements. The mission of lowering power consumption and ene...
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