A mobile ad hoc network (MANET) is a self-organized system comprised by multiple mobile wireless nodes. The node misbehavior due to selfish reasons can significantly diminish the performance of MANET. A selfish node attempts to use the resources only for its own purpose and it hesitates to share the resources with their neighbors. So, it is very important to detect the selfish nodes to improve the performance of MANET. Initially, an architectural model of a MANET is constructed and the communication between the mobile is originated. The packet drop can happen in MANET due to the selfish node or network congestion. In this paper, a Record-and Trust-Based Detection (RTBD) technique is proposed to detect the selfish nodes efficiently in MANET. The main reason for using trust in this analysis is to accelerate the detection of misbehaving nodes. This study has been carried out in order to analyze the detection of selfish nodes on essential network functions such as routing and packet dropping. The results show that the proposed selfish node detection method is very efficient, since the detection time of selfish nodes is diminished and the overall overhead is very low. The simulation study demonstrates that the proposed RTBD method enhances the selfish node detection ratio, packet delivery ratio (PDR), and average packet drop ratio.

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Abstract-Design and analysis of a compact coplanar waveguide (CPW) fed Ultra Wideband (UWB) slot antenna is presented in this paper. The antenna consists of a rectangular slot with cross like structure at the anterior portion of the feed which acts as tuning stub. The CPW feed is designed for 50 Ω impedance. The physical dimension of the proposed antenna is 19 mm (length) × 20 mm (width) × 1.6 mm (thickness), and the electrical size is 0.3λ l (length) × 0.32λ l (width) (f l = 4.8 GHz). The characteristics of the designed structure are investigated by using MoM based electromagnetic solver, IE3D. An extensive analysis of the proposed antenna in the frequency and time domains is presented. The antenna was fabricated with FR4 substrate and characterized by measuring return loss, radiation pattern (5.5 GHz) and gain. The measured results are appreciably in good agreement with the simulated ones. A better impedance bandwidth is obtained from 4.8 GHz to 12.8 GHz that constitutes a fractional bandwidth of 90% with return loss less than or equal to −10 dB (VSWR ≤ 2). Time domain analysis of the antenna is also performed, which witnessed the linear phase and less distortion. The simple configuration and low profile nature of the proposed antenna leads to easy fabrication that may be built for any wireless UWB device applications.

Abstract-Design and analysis of a new coplanar waveguide (CPW) fed ultra wideband (UWB) slot antenna is presented in this paper. The physical dimension of the antenna is around 28mm (length) × 21mm (width) × 1.6mm (thickness) and fed by 50Ω coplanar waveguide. An extensive analysis of the proposed antenna in the frequency and time domains are presented. The antenna was fabricated using FR4 substrate and characterized by measuring return loss, radiation pattern (6 GHz) and gain. The measured results are appreciably in good agreement with the simulation results. A better impedance bandwidth is obtained from 3.1 GHz to 11.4 GHz that constitutes a fractional bandwidth of 114 % with return loss less than or equal to -10 dB (VSWR < 2). Time domain analysis of the antenna is also performed that witnessed the linear phase and less distortion. The simple configuration and low profile nature of the proposed antenna leads to easy fabrication that may be built for any wireless UWB device applications.Index Terms-Coplanar Waveguide, slot antenna, standing wave ratio, time domain analysis, ultra wideband. I. INTRODUCTIONUWB is a short range unlicensed wireless communication system which has a potential to offer a high capacity with low power than the current wireless systems for short range applications. In the year 2002, Federal Communications Commission (FCC) released the unlicensed UWB spectrum 3.1 GHz to 10.6 GHz for the commercial purposes. After the release of Ultra Wideband (UWB) by the FCC, it receives much attention by the industries and academia due to its properties of low power consumption, support of high secured data rate and simple configuration [1]. With the rapid developments of such wireless systems, a lot of attention is being given for designing the UWB antennas, since they are the key elements to radiate and receive the UWB short puilse signals. To design an antenna to operate in the UWB band is quiet challenging one because it has to satisfy the requirements such as ultra wide impedance bandwidth, omni directional radiation pattern, constant gain, high radiation efficiency, constant group delay, low profile, compact and easy manufacturing [2]. Interestingly the planar slot antennas with CPW fed posses the above said features with simple structure, less radiation loss, less dispersion and easy integration of monolithic microwave integrated circuits (MMIC) [3]. Hence, the CPW fed planar slot antennas [4][5][6] are identified as the most promising design for wideband J William is a research Scholar in the

Abstract:A coplanar waveguide (CPW) fed Ultra Wideband (UWB) slot antenna with reconfigurable rejection bands is presented. Specific band of the rejection is achieved by placing switching diodes over the rectangular slot in the ground plane at a position of effective length of λ/2 for the center frequency of the rejection band. The rejection of WiMax, IEEE 802.11a and HYPERLAN/2 bands can be achieved by switching the diodes. The simple configuration and low profile of the proposed antenna leads to easy fabrication that may be used in any wireless UWB device applications where reconfigurable rejection bands are required.