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In the proposed antenna design dual band operation is achieved by utilizing the square slot cut of 15 mm length at the center of the patch. In the proposed dual frequency antenna design when feed is given at the suitable position on the patch, there is an enhancement of bandwidth and decrement in the operating frequencies as the square slot cut length increases. The proposed antenna gives better radiation characteristics as compared to a rectangular micro strip antenna of same design specification without square slot cut and the square slot cut of 5 mm and 10 mm. In multichannel applications a small instantaneous band width is required over a large frequency range. Accordingly, tunable antennas provide an alternative to a broadband antenna in which an antenna with a small band width is tuned over a large frequency range. In some applications, the system must work within two frequency bands that are far apart. Here dual band antenna rather than broadband antenna is used. If the antenna operates only at two spot frequencies, then it is known as a dual frequency antenna.
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This paper presents a novel technique for enhancement of impedance bandwidth of Microstrip patch antenna using double coaxial feeding on a single patch structure. The effect of double feed is analyzed for both rectangular and equilateral triangular Microstrip patch of same area which shows 5.927% impedance bandwidth for rectangular patch and 23% impedance bandwidth for equilateral triangular Microstrip patch. The difference between single coaxial feed and double coaxial feed is studied using different dielectric substrates. Ansoft Designer V2 is employed to analyze the proposed antenna structures.
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In the last few years, the expansion of the technology in the sector of hardware and software has been notable. The constant evolution of the Information and Communication Technology increases the ability to acquire and utilize new knowledge and technologies. The utilization of mobile in daily life increased because of their small enough to hold in the palm of your hand and use with a single hand, ever more sophisticated and exhibiting good execution time of tasks. The success of their commercial is due the facility of carrying them, and the user can keep the information at hand anywhere, anytime. This paper presents about the usability of mobile and its applications beyond communication.
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The concept of Orthogonal Frequency Division Multiplexing (OFDM) has been known since many years. The OFDM is an attractive modulation technique for transmitting large amounts of digital data over radio waves. However, one major drawback of OFDM is that, the time domain OFDM signal possesses high Peak to Average Power Ratio (PAPR). Numbers of techniques have been put forward in literature for reducing the PAPR in OFDM systems. In this paper, a new technique is proposed to reduce the PAPR in OFDM. The proposed method consists of 2 steps viz. clipping and companding. The simulation results have shown that the proposed technique significantly reduces the hardware complexity of transmitter and improves BER performance as compared to other distortion methods such as rooting, μ-law and exponential companding, while maintaining the PAPR reduction performance unchanged.
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In this paper, we will present concepts that are vital for the demonstration of the vertically integrated Radio over fiber networks. The goal for the third generation (3G) of mobile communications system is to seamlessly integrate a wide variety of communication services. One of the most promising approaches to 3G is to combine a Wideband Code Division Multiple Access (WCDMA) air interface with Radio over fiber. In this paper we investigate the Bit Error Rate (BER) of radio over fiber technology. The evaluation of the performance of WCDMA RoF is linked to the fiber length to a great extent. In this paper, the relation of fiber length with BER is discussed.
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The objectives in designing an efficient routing protocol for Ad-Hoc networks with critical connectivity should be low convergence time, robustness and minimum routing signaling overhead. In this paper a novel self-organizing approach for routing datagrams in ad hoc networks, called Distributed Ant Routing (DAR) is discussed. This approach belongs to the class of routing algorithms inspired by the behavior of the ant colonies in locating and storing food. Current research on routing protocols for Mobile Ad-hoc NETwork (MANET) has converged to several dominating routing protocols, including Ad-Hoc On-demand Distance Vector (AODV) and Dynamic Source Routing (DSR). At the same time, classic routing protocols such as Open Shortest Path First (OSPF) and Destination Sequenced Distance Vector (DSDV) are improved for the MANET context. Research efforts also focus on issues such as Quality of Service (QoS), energy efficiency, and security, which already exist in the wired networks and are worsened in MANET.
A wireless ad hoc network consists of various battery-powered wireless devices such as Personal Digital Assistants (PDAs), laptops, and cellular phones. Battery lifetime has emerged as a key factor that affects the performance of wireless ad hoc networks. Based on the battery constraint, a new Battery-Aware Routing (BAR) scheme is discussed at the end.
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The In the present scenario, wireless technologies require an advanced receiver which supports multi-standard and multimode transmission. In an ideal software radio, the data conversion process occurs immediately after the antenna in the receiver chain. A/D conversion at an early stage plays an important role for achieving such flexibility at the receiver Analog-to-Digital- Converter (ADC) constitutes a necessary component for the implementation of Software Defined- Radio (SDR) receiver. In ADC, sampling performance is limited by a clock. The sampling inserts the jitter noise, which degrades the performance of the receiver. Continuous–Time (CT) Delta–Sigma (ΔΣ) modulators are capable of suppressing this noise but the impact of clock jitter at the output of the Digital– to–Analog Converter (DAC) in the feedback path of the modulator should be taken into account. This paper presents an analytical approach for analyzing jitter in SDR receivers when a CT–ΔΣ modulator is utilized for Analog–to–Digital Conversion (ADC).
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Mobile Ad-Hoc network (MANET) is a temporary network setup for a specific purpose without help of any pre-existing infrastructure. The nodes in MANET are empowered to exchange packet using a radio channel. The nodes not in direct reach of each other uses their intermediate nodes to forward packets. Therefore threats exist to a mobile ad hoc network both from external nodes unauthorized to participate in the mobile ad hoc networks, and from internal nodes, which have the authorization credentials to participate in the mobile ad hoc network. Internal nodes giving rise to threats can be further divided according to their behaviour – failed, badly failed, selfish and malicious nodes. Badly failed nodes may perform operations incorrectly, introducing false and misleading information into the network. Malicious nodes may deliberately disrupt the network using a variety of attacks. In this paper we have shown Adhoc networks present different threats due to their very different properties and how security is provided and maintained.
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Wireless communication systems require signal processing techniques that improve the link performance in hostile mobile radio environments. The mobile radio channel is particularly dynamic due to multipath propagation and Doppler spread, these effects have a strong negative impact on the bit error rate of any modulation technique. Diversity is technique used to compensate for fading channel impairments and is usually implemented by using two or more receiving antennas. This report provides a brief introduction to the various types of Diversity systems in wireless systems.
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There are several different algorithms, which make the programmable DSP a better choice for systems supporting multiple audio formats. This paper discusses porting two audio compression algorithms, MPEG-1 Layer 3 (MP3) and MPEG-2 Advanced Audio Coding (AAC), to the fixed-point C54X DSP. We also propose speed optimization strategies for the main decoder modules under memory constrains. The modules include Bit streaming, Huffman decoding, inverse quantization, temporal noise shaping and Filter bank.
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Various systems, methods and techniques are in use by patients and medical centers to provide the necessary information and to serve medical profession including hospital information systems. One of the most important services is Personal Health care Record (PHR) portability and management. This problem has become out of history of paper records kept separately by physicians, clinics, hospitals, pharmacies, insurance companies and patients themselves. Many approaches were implemented to improve and manage the PHR including portability solution. These approaches were based on implementing portable memory device such as flash memory and Smart Cards. In this work an embedded PHR system was developed. The developed system allows operating and managing PHR by the help of standalone system.
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The objective of this paper is to create of an algorithm that will separate Moving foreground from a stationary background in a general video sequence. Motion-based segmentation also finds a niche in the realms of video compression and computer vision. Regardless of motion estimator, careful attention must be paid to noise effects when estimating motion. Faulty motion vectors due to image noise can lead to visually unpleasant effects such as isolated background blocks in the resulting segmented image. Noise-reduction filters may be used to alleviate this problem. Another method is to examine the resulting mean-squared error of known zero-motion vector regions. Any error must be due solely to noise and thus this provides information about the noise in a particular image sequence. Accurate knowledge of all the motion vectors in a sequence theoretically provides the means to segment the images into pixels associated with a moving object and pixels associated with a rigid background. The algorithm for tracing motion vectors throughout the sequence is highly recursive and can be computationally expensive, depending on the number of non-zero motion vectors present.
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In this paper, we propose some novel Photonic Crystal Fiber (PCF) structures whose physical dimensions/geometries are derived from Dolph Tschebysheff Polynomials (DTP) based antenna array. The simulations of the proposed structures are carried out using OptiFDTD simulator with full vector mode solver using FDTD method and the results are compared with the PCF structures based on Pascal’s Triangle (PT). It is observed that the proposed structures exhibit almost negligible waveguide dispersion behaviour over avery large wavelength range and the order of dispersion of the PCF structures based on DTP is same as that of the PCF structures based on PT. These structures are therefore suitable candidates for applications demanding such behaviour such as long distance optical communications or high data rate data transfer applications. The birefringence of the structures based on DTP is, however,more than the structures based on PT.
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Optical Code Division Multiple Access (OCDMA) is a multiple access technique in which many users can access the channel simultaneously and arbitrarily. Many codes have been proposed for spectrally amplitude coded-optical code division multiple access (SAC-OCDMA) in order to sort out the problem of Multiple Access Interference (MAI) which is the main cause of degradation for the performance of OCDMA. In our work, code with cross-correlation λc value zero has been carried out in order to overcome the problem of both Multiple Access Interference (MAI) and Phase Induced Intensity Noise (PIIN). As the value of cross-correlation λc is zero, the effect of PIIN has been ignored and finds out that the performance has been degraded only because of the effect of MAI. Direct detection scheme has been used in the proposed setup and with this scheme we find out that 20 users can achieve the Bit Error Rate (BER) upto 4.21E-19, as performance is degraded by increasing the number of users. Comparison is made between different codes such as Walash Hadmard, Modified Double Weight (MDW), Dynamic Cyclic Shift (DCS) and zero cross correlation (ZCC). Although DCS has cross correlation (λc) value very small, simple code construction and less weight, but still ZCC performs better.
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The Universal Serial Bus (USB) has become the most well-liked interface standard for hardware connection, and there has been an outburst in the number of USB Peripheral devices. External USB storage devices, in Particular, are finding widespread application. Unfortunately, because USB affords high transmission speeds and is extremely convenient, many workplaces and businesses have prohibited the use of USB devices to prevent confidential data from being extracted from computer systems via USB ports. However, this compromises the convenience of the USB connection and demonstrates a lack of flexibility in management. Therefore, finding a way to take the considerations of both convenience and management into account has become a significant issue. This study proposes a secure control protocol which provides mutual authentication and key agreement between client and server to solve this problem.
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The Partial Transmit Sequences (PTS) is one of the most attractive schemes to reduce the Peak-to-Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) systems. However, the conventional PTS scheme requires an factors. Consequently, the computational complexity increases exponentially with the number of the sub blocks. By utilizing the correlation among the candidate signals generated in PTS , a novel scheme is proposed to decrease the computational complexity. The performance analysis shows that the proposed scheme can reduce the computational complexity dramatically white achieving the same PAPR reduction compared to the conventional PTS scheme.
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The combination of multiple-input multiple-output (MIMO) system with OFDM techniques is regarded as a promising solution for enhancing the data rates of next-generation wireless communication systems. Multiple-input multiple-output (MIMO) communication refers to wireless communication systems using an array of antennas (i.e. multiple antennas) at either the transmitter or the receiver. Multiplexing would cause interference, but MIMO systems use smart selection and/or combining techniques at the receiving end to transmit more information and to improve signal quality. MIMO systems provide a significant capacity gain over conventional single antenna systems, along with more reliable communication. A crucial parameter required for adaptive transmission is the signal-to-noise ratio (SNR). In this paper, we propose a novel SNR estimation algorithm for wireless MIMO OFDM systems based on the reuse of the synchronization preamble. The periodic structure of the preamble is utilized for the computationally efficient SNR estimation algorithm, based on the second-order moments of received preamble samples.
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A fuzzy logic speed control system based on fuzzy logic approach for an indirect vector controlled induction motor drive for high performance. Their analysis, design and simulation of the fuzzy logic controller for indirect vector control induction motor are carried out based on fuzzy set theory. The proposed fuzzy controller is compared with PI controller with no load and various load condition. The result demonstrates the robustness and effectiveness of the proposed fuzzy controller for high performance of induction motor drive system.
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Recent advances in multimedia mobile communications have sparked much research in techniques that can deliver very high data rates. High data rate is really what broadband is all about. Traditional single carrier modulation techniques can achieve only limited data rates due to the restrictions imposed by the multipath channel and the receiver complexity. Multi-carrier techniques can provide high data rates at reasonable receiver complexities. The idea of OFDM comes from Multi Carrier Modulation (MCM) transmission technique. OFDM is a special form of spectrally efficient MCM technique, which employs densely spaced orthogonal subcarriers and overlapping spectrums. The use of band pass filters is not required in OFDM because of the orthogonality nature of the subcarriers. Hence, the available bandwidth is used very efficiently without causing the Inter-Carrier Interference (ICI). Multicarrier code-division multiple access (MC-CDMA) combines conventional code-division multiple access (CDMA) and orthogonal frequency-division multiplexing (OFDM), This paper gives a comprehensive Comparison of OFDM & MCCDMA. It also discusses the relative merits of MC-CDMA over OFDM.
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The impairments caused by timing jitter are a significant limiting factor in the performance of very high data rate OFDM systems. In this letter oversampling can reduce the noise caused by timing jitter. Both fractional oversampling achieved by hleaving some band edge OFDM subcarriers unused and integral oversampling are considered. The theoretical results are compared with simulation results for the case of white timing jitter showing very close agreement.
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Most of the contemporary applications needs a single message to be securely forwarded to multiple receivers emphasizing on the need to develop a secure framework for Multicast communication. Unicast communication maps messages in one-to-one order. In contrast , multicast communication needs to send data or messages from single or multiple authorized senders to one or more receivers who are authorized. In this paper, we propose a secured framework for Multicast communication , that includes providing better scalability and protocols for secured communication among the members with in a group .We provide a solution to Group scalability by defining protocols for generating a new key and distributing it securely when members joins / leaves. We show that our approach is scalable and adaptable, where member joins / leaves are very frequent.
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The Finite Impulse Response (FIR) filter is a digital filter widely used in Digital Signal Processing applications in various fields like imaging, instrumentation, communications, etc. Programmable Digital Processors Signal (PDSPs) can be used in implementing the FIR filter. However, in realizing a large-order filter many complex computations are needed which affects the performance of the common digital signal processors in terms of speed, cost, flexibility, area etc. Optimizing the speed and area of the multiplier is a major design issue. However, area and speed are usually conflicting constraints so that improving speed results mostly in larger areas. Direct form fixed point FIR filter realization consists of different modules such as multiplier, adder, ram. The low power consumption quality of booth multiplier makes it a preferred choice in designing different circuits . So a power efficient Booth multiplier is used. A multiplier has two stage. In the first stage, the partial products are generated by the booth encoder and the Partial Product Generator (PPG), and are summed by compressors. In the second stage, the two final products are added to form the final product through a final adder.Currently most circuits adopts Static Random Access Memory (SRAM) plus some control/addressing logic to implement delay buffers. Previously, a simplified and thus lower power sequential addressing scheme for SRAM application in delay buffer is used. In this a ring counter is used to point to the target words to be written in and read out. Here, a double edge triggered flip flop is used instead of traditional DFFs in ring counter to halve the operating frequency.The delay buffer using double edge triggered flip flops and modified booth multiplier is used for realization of FIR filter for power optimization and is implemented using VHDL.
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This paper investigates the applications and suitability of WiMAX/IEEE-802.16 – based Broadband Wireless Access (BWA) technologies for mobile teletrauma system. A brief overview of emerging wireless communication technologies for health has been presented. The paper compares the basic features of WiMAX and Wi-Fi broadband access technologies. Finally, performance of WiMAX physical layer has been evaluated for médical image transmission in terms of Bit-Error-Rate (BER), Peak-Signal-To- Noise (PSNR) ratio in MATLAB simulation environment.
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