Abstract

Abstract

This paper presents the compact penta-band printed antenna for the application of wireless communication devices. The antenna consists of a main patch and two sub-patches with a L slot, which is applicable for five operating bands at 1.25, 1.75, 2.45, 3.95, 5.1 GHz for the applications, including WLAN/WiMAX. The radiation pattern and gain is improved by using the concept of Defected Ground Structure (DGS). It is found that the parameters of an antenna are changed by the variation in the substrate height. The simulated result shows better performance in terms of return loss, radiation pattern, and gain as well.

Abstract

Many routing algorithms were proposed in wireless ad hoc networks. The main disadvantage of those algorithms is, we need to have reliable knowledge about the network, and also expected average per packet reward criterion is also high. In this paper, the authors have discussed about d-AdaptOR algorithm which doesn't need reliable knowledge about the network structure and channel statistics. This scheme reduces the average per packet reward criterion. This scheme is also advantageous than the classical routing algorithms when we want to broadcast a packet. In this scheme, the next relay node depending upon Estimated Best Score (EBS) has been selected. This algorithm explores and exploits the opportunities in the network. This scheme jointly tackles the problem of learning and routing in an opportunistic context, where the network model is characterized by the transmission success probabilities.

Abstract

Numerous studies of smart antennas have already been conducted using linear or planar arrays, not as much effort has been devoted to other configurations. The performance of smart antennas with circular array and circular array with central element are examined and simulated in MATLAB. In this paper, the first module presents the design of circular antenna array with central element suitable for the beam forming technique in wireless applications such as smart antennas have been analysed. The main objective of the work is to compute the radiation pattern with minimum Side Lobe Level (SLL) for specified Half Power Beam Width (HPBW). Algorithms are applied to determine the non-uniform excitation applied to each element. The effectiveness of the proposed algorithm involves FFA for optimization of antenna problems. Simulation results obtained in each case using both the algorithms such as RLS and FFA are compared in a statistically significant way. The obtained results using Firefly Algorithm shows better performance than RLS provided that the same number of function evaluations have been considered for both the algorithms.

Abstract

A compact shape and size wideband microstrip feed planner antenna is proposed for Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (Wi-MAX) applications. The designed antenna has a rectangular slot with a pair of inverted L, symmetrical U, and two rectangular shaped slots. The proposed antenna has frequencies for 3 WLAN (5.2/5.8 GHz) and Wi-MAX (3.5/5.5 GHz). The antenna size is reduced to (15 x 15 x 1.6 mm ) for wideband. The designed and simulated antenna covered frequency band of 3.19- 8.0 GHz, while rejecting all frequencies which are not desired. Omni-directional radiation pattern and desired gain are obtained in the operating range of frequency.

Abstract

WiLD (WiFi Long Distance) links are used to extend the internet connectivity to the remote areas and under-served regions by using few numbers of hops from the gateway node. Quality of Service (QoS) in a set of qualitative and quantitative traffic individualities explain traffic flow inside specific applications. Throughput, delay, jitter, and packet loss are some of the generally considered QoS parameters. To mitigate the congestion problem in gateway based multi hop, Wi-Fi based long distance networks are used, and to enhance the QoS guarantees in real time traffic, QoS-aware dynamic bandwidth allocation scheme has been employed. The existing work involves the dynamic slot scheduling algorithm to distribute the TDMA slots among the necessary nodes. The distribution process is carried out in a hierarchical manner using parent-child relationship of tree topology. By using the dynamic benefit weighted scheduling, the performance of traffic over the network can be increased. This dynamic benefit weighted scheduling uses the Weighted Round Robin (WRR) or fair queuing policy for calculating the weights and allocates the bandwidth dynamically. The weight calculation depends on two factors: 1) previous weights assigned at time slot, 2) average increase in weights over the traffic. Using such a dynamic bandwidth allocation scheme achieves reduction in packet loss, variation in delay (jitter), and increase in QoS.