Статьи журнала - International Journal of Wireless and Microwave Technologies
Все статьи: 454
Performance Comparison Of Beamforming And Multiplexing Techniques Using Smart Antenna Array
Статья научная
Meeting the demands that are expected from future wireless generation networks poses intriguing challenges for today's wireless system designers. The demand for higher data rate and better quality of service (QoS) in wireless communications continue to grow rapidly in current world global community. Obtaining these requirements becomes challenging for wireless communication systems due to the problems of channel fading, higher power and bandwidth limitations. One of the most promising solutions to this problem is the Multiple Input Multiple Output (MIMO) system. This paper compared the performance of spatial multiplexing MIMO scheme with beamforming at a data rate of 100Mb/s. The proposed wireless system was developed with smart antenna arrays at both the transmitter and receiver. The results obtained show that spatial multiplexing technique produced better spectral efficiency than beamforming. The BER performance of beamforming technique outperforms that of spatial multiplexing technique even when enhanced by V-BLAST algorithm under the same simulation environment. The proposed system outperforms the conventional MIMO.
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Статья научная
In this paper, we have investigated the performance of IEEE 802.15.3a channel model with different modulation scheme. The performance parameter Average Bit Error Rate (ABER) is selected. We find out the BER performance of UWB system over the 802.15.3a indoor channel model for all channels profile CM1, CM2, CM3 and CM4 with different modulation scheme. In this paper, all modulation scheme used in UWB are included in different main categories. The major categories are synchronous and asynchronous. In synchronous mode, we again divided different modulation scheme e.g. BPSK, PPM, PAM etc into antipodal and orthogonal schemes. In the asynchronous category, we have studied about DPSK. All these modulation categories are comparing on the common platform and finally we got antipodal modulation scheme category is good for UWB in term of ABER.
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Performance Evaluation of Channel Codes for High Data Rate Mobile Wireless System
Статья научная
Mobile wireless system incorporates dual sphere in terms of mobility as well as computing. Such systems have revamped momentously resulting in expedient wireless devices. Current wireless communication requires enormous data rates, streaming audio/video, asymmetric access/multiple access, fully-integrated, low cost, reliable seamless systems with the capability of providing voice, high speed data, and video with minimum latency and long battery life to enhance error free communication. However, there are many obstacles and bottlenecks to achieving this in practice. These bottlenecks include limited spectrum, limited energy, multipath fading and propagation loss, cost, standardization processes. This paper focuses on coding and modulation techniques for wireless communications so as to reduce/overcome many of these obstacles. To put the discussion in perspective, a short background on the coding and modulation approaches of wireless communication systems is provided. The turbo coding is mainly chosen to facilitate the wireless communication. The paper enlightens the impetus behind using turbo codes for high data rate mobile wireless systems. Paper explains how better out-turns can be yielded when approaches like cyclic redundancy check and scrambling are embedded with coding. The BER performance and SNR ratio are observed for illustrating variance between convolution and turbo coding for different rates and modulations. Simulation results are plotted using Matlab software.
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Статья научная
Convergecast communication is used in many sensor applications .The flow of data in convergecast routing is from many to one i.e. many sensory nodes sense the data and send through parent child relation to the root node or sink node. Convergecast routing is always followed by broadcasting. In broadcast communication is from one to many and in convergecast it is from many to one. As sensor nodes have limited battery capacity main focus is to save energy. As compare to wired network wireless network is prone to attacks and it is less reliable than the wired network. This paper investigates the affect of header length of network layer on the BER, SNIR, backoff duration, SNR and latency of convergecast routing with the help of omnet++ simulator.
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Статья научная
This paper presents a microstrip patch antenna incorporated with electromagnetic band gap (EBG) structure on substrate and defected ground structure (DGS) in the ground plane. Electromagnetic Band Gap materials are artificially engineered structures that improve the performance of the patch antennas. It is manifested that applications of both EBG and DGS outcomes in the remarkable improvement of return loss level from -20.2dB to -31.5dB and bandwidth from 155MHz to 202 MHz respectively. The most fascinating characteristic of the proposal is the capability of increasing the gain, directivity and the total efficiency of the antenna without affecting the other essential parameter like bandwidth which makes the designed antenna applicable for Radio Frequency portable devices operating at 6.1 GHz.
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Performance analysis of NLM interleaving scheme for CPM OFDM system
Статья научная
A New Logistic Map interleaving is the most common method for continuous phase modulation based orthogonal frequency division multiplexing (CPM-OFDM) system over a fading channel. The selection of a "good" interleaver having to express in order that the interleavers are weakly correlated. Interleaver doesn’t involve massive memory to reserve it and a massive bandwidth to communicate in the midst of the transmitter and the receiver, and need to be simple to produce. An efficient chaotic maps randomization (CMR) generates scrambled uncorrelated randomized data can greatly improved the performance of CPM-OFDM system and improved symbol error rate (SER) could be attained. In this study, advise a new one-dimensional chaotic map, the "New Logistic Map (NLM)". Encryption is carried out with logistic map even as a chaotic logistic map interleaving process is used to boost the immunity to noise and fading in communication channel. Furthermore, a evaluation between NLM interleaving and random interleaving is performed in terms of bit error rate(BER).Simulation results shows that the data transmission over wireless channel using propose NLM interleaving is more immune to fading and noise and get better the performance of CPM-OFDM system.
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Performance optimization of ad hoc on demand vector routing protocol in cognitive radio network
Статья научная
Mobile Ad Hoc Network has given importance in last few years by researchers. Implementations of Ad Hoc network in cognitive radio environment are emerging kind of wireless network [1, 5]. The communication is done by the secondary user in the free frequency band available in the spectrum of the primary user. In this paper, we have projected proficient routing solution by the maintenance of the link for AOMDV protocol for cognitive radio ad hoc Network. We have used ns2 Simulator for simulations. The link maintenance makes the system more efficient that is evaluated by simulation and comparing it with a classical routing protocol.
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Polynomial Algorithm for Node Deployment in Hybrid Wireless Sensor Networks
Статья научная
When detecting a target or monitoring a physical phenomenon in a region, the deployment problem is fundamental in these applications. Traditionally, stationary sensor networks are deployed to carry out the sensing operations. It is well known that the mobility of sensor nodes can improve the coverage and the probability of the detecting, so we deal with the problem of detecting a target using hybrid sensor networks which contain both stationary sensors and mobile sensors. In this paper, to begin with, we prove that the node deployment problem is NP-complete. Then, one polynomial algorithm for node deployment in hybrid wireless sensor networks is proposed, which aims at minimizing the number of all sensors to reduce the cost. The simulations verify the efficiency of our algorithm.
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Positioning Algorithm for Wireless Sensor Network Based on Adaptive Genetic Algorithm
Статья научная
It is very important for wireless sensor network to position the nodes’ location because location information is favorable for providing network service such as geographic routing, people tracking and so on. After researching the range-based atomic multilateration algorithm carefully, this paper presents a novel positioning algorithm based on adaptive genetic algorithm (AGA). The new positioning algorithm uses adaptive genetic algorithm to search the optimal solution of nonlinear multivariate positioning equations set. Furthermore, the proposed algorithm uses a new model to estimate range error in order to improve the localization accuracy. Simulation results show that the proposed scheme has better robust performance. Compare with general genetic algorithm, adaptive genetic algorithm has better localization accuracy and higher speed of convergence.
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Power Allocation for Balancing Spectrum Efficiency and Power Consumption in Cognitive Relay Networks
Статья научная
In order to guarantee the QoS requirement of secondary users and not to affect the outage probability of primary user in cognitive relay networks, we propose two optimal power allocation models: (1) maximizing the transmission rate of secondary users; (2) minimizing the total power consumption. Theory analysis shows that two optimal power allocation models conflict between spectrum efficiency and power consumption. Furthermore, an optimal power allocation model which joints the transmission rate and the total power consumption in cognitive relay networks is proposed. By using the Lagrangian method, the optimization algorithm for this model is designed. The proposed algorithm can achieve the trade-off between the transmission rate and the total power consumption by varying the weight. Simulation results show that the proposed algorithm can effectively adjust the transmission rate and the total power consumption of secondary users.
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Power Factor Analysis of the Linear Motor in Mines
Статья научная
This paper introduces the structure of linear motor in mines. Analyze the power relation of power-AC -linear motor – vibrant machine, based on this, count the power factor; and make mechanical analysis to the vibrancy, get the power factor, which should be: in the precondition of without collision for the top and bottom magnet, do best to decrease the δ_0 to close to ΔΧ_m (ΔΧ_m depends on the technique of the vibrant load), make Κ_δ close to 1 and λ_e close to critical maximum λ_(em) . It is significantly useful to design linear motor.
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Статья научная
Prediction of location has gained lot of attention in different applications areas like predicting the path or any deviation like taxi-route, bus route, human trajectory, robot navigation. Prediction of the next location or any path deviation in RFID enabled supply chain path followed in the process is quite a novel area for the related techniques. The paper defines the architecture for the outlier detection in RFID enabled Supply Chain Path based on historical datasets .Given the training datasets, different classification models are compared for the accurate prediction of the outlierness of the path followed by the tagged objects read by RFID readers during the supply chain process. Comparison of Hidden Markov Model(HMM), XGBoost(decision tree based boosting),Recurrent Neural Network(RNN) and state of art technique in RNN known as Long Short Term Memory (LSTM) is done .To our knowledge LSTM has never been used for this application area for outlier prediction. For the longer path sequences, LSTM has outperformed over other techniques. The training datasets used here are in the form of the record of the outlier positions in particular path and at particular time and location.
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Preserving privacy in cloud identity management systems using DCM (Dual Certificate Management)
Статья научная
In these days all businesses trying to use global applications on cloud computing infrastructure to reduce their costs and also decentralize their application. This movement also causes more security risks over the unbounded cloud environment. Therefore, accessing enterprise information for an unwanted user will be more than other environments. Thus, the proposed Identity Management System (IDMS) tries to preserve security in communication between clients and server over cloud computing. The proposed method suggested token based Identity Management and also enhanced privacy by adding one. Dual Certificate Manager (DCM) block is a replacement for a combination of symmetric and asymmetric cryptography, which is commonly used for SSL/TLS protocol to immune data transmission, uses asymmetric cryptography in both participants. Furthermore, for more privacy and invulnerability DCM uses Elliptic Curve Cryptography (ECC) as asymmetric cryptography algorithm.
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Prevention of session hijacking attack in VANETs using intrusion detection system
Статья научная
Vehicular Adhoc Networks (VANET) is a type of road network that provides road safety and other infotainment applications to drivers and passengers for an effective and uninterrupted communication. In this network, the communication between the vehicles are equipped with the Road Side Units (RSU). VANET is the major component of Intelligent Transportation System (ITS). Research on Vehicular Adhoc network security presents many challenging issues to the researchers. The security mechanism available for VANETs are not highly effective. Hence it is as on time requirement of new and sophisticated security solutions. This paper mainly focuses on Intrusion Detection System (IDS) for VANETs to prevent Session Hijacking Attack (SHA). The work discusses on the total number of packet generated, sent, received and dropped with varying number of nodes with the help of Network Simulator-2 (NS2) and the inferred results are discussed.
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Статья научная
Pertaining to the rapid usage of cloud computing, cloud based approaches are growing as an fascinating domain for numerous malignant tasks. Security is one of the vital issues faced by the cloud computing environment while sharing resources over the internet. Consumers are facing distinct security hazards while using cloud computing platform. Previous works mainly attempted to mitigate the side channels attacks by altering the infrastructure and the internal procedures of the cloud stack. However, the deployments of these alterations are not so easy and could not resist the attacks. In this paper, the authors attempted to solve the issues by enhancing the VM Placement policies in such a way that, it is complex for the invaders to collocate their object. A secure Dynamic VM placement approach is presented for the VM allocations into different servers in the cloud. The performance comparison of the suggested methodology is shows that the proposed approach has better efficiency evaluations such as hit rate, loss rate and resource loss when compared to other V M placement policies.
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Privacy Preserving Similarity Measurement
Статья научная
Data similarity measurement is an important direction for data mining research. This paper is concentrated on the issue of protecting the underlying attribute values when sharing data for the similarity of objects measurement and proposes a simple data transformation method: Isometric-Based Transformation (IBT). IBT selects the attribute pairs and then distorts them with Isometric Transformation. In the process of transformation, the goal is to find the proper angle ranges to satisfy the least privacy preserving requirement and then randomly choose one angle in this interval. The experiment demonstrates that the method can distort attribute values, preserve privacy information and guarantee valid similarity measurement.
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Probabilistic Constellation Extension Scheme for PAPR Reduction in OFDM Signals
Статья научная
In this paper, a combinational method is proposed to mitigate the peak-to-average power ratio problem in orthogonal frequency division multiplexing signals. The proposed algorithm is an intelligent combination of the constellation extension and probabilistic techniques. It is shown that proposed technique achieves the significant reduction in peak-to-average power on maintaining sufficient bit error rate with a slight increase in computational complexity compared to conventional schemes.
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Статья научная
Beibuwan Economical Zone of Guangxi Province has the necessary basis and conditions to develop the madicine manufacturing industry.It is significant to select products which ficilitate the development of madicine manufacturing industry from the prospective of promoting the development of the industry smoothly. The feature of selection of essential products of medicine manufacturing can be summarized as multi-objectiveness, multi-layer, fuzziness and the interaction and penetration of different objectives. Due to these characteristics, analysis is made through analytic hierarchy process (AHP) by this thesis. The paper put forward the developmental sequence of madicine manufacturing industry in Beibuwan Economical Zone of Guangxi Province by adopting analytic hierarchy process, and pointed out that, among others, the technical competence is the most influnctial factor of a company. The appropriate developmental sequence of the products selected is biological and biochemical products, medicinal chemicals, chemical medicine and preparations. This research is in favor of speeding up the development of competitive products and creating industry competition.
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Статья научная
One of the important studies in 6G aerial radio access networks is the propagation channel modeling. The high accurate propagation channel model will save cost and time, and is more effective in the design of the air radio access network system. However, existing channel models are limited to 1 THz, while 6G wireless technology is expected to operate up to 3 THz. In this paper, the propagation channel from 275 GHz to 3 THz is modeled by modifying the Friis equation, and each parameter in the model is described and analyzed analytically. The main factors that contribute to wireless signal attenuation at terahertz, such as atmospheric oxygen and water vapor, rainfall, and cloud factors, are also discussed in detail. Furthermore, the propagation channel calculation App for 6G low-altitude platform access networks application has been built using MATLAB GUI.
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Propagation Profile and Signal Strength Variation of VHF Signal in Ekiti State Nigeria
Статья научная
This paper presents the experimental results of a study on radio frequency attenuation path loss conducted in Ekiti State, Nigeria. The objective of the study is to develop a path loss model comparable to the existing path loss models through a real time application of outdoor VHF signal propagation measurements of the Nigeria Television Authority (NTA) Channel 5 and carrier frequency of 175.25 MHz located in Ado-Ekiti, Ekiti State, Nigeria. Experimental measurements were taken in three routes covering the entire state. Analysis of the data collected from the experiments resulted in models which are in agreement with the existing standard models. Root Mean Square Errors were calculated for all the path loss models. Results show that the signal of the station was generally poor along the routes considered as the deviations of the measured path losses from the free space path loss exceed 6 dB in most cases.
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