Статьи журнала - International Journal of Wireless and Microwave Technologies
Все статьи: 454
A Linear Polarized Coaxial Feeding Dual Band Circular Microstrip Patch Antenna for WLAN Applications
Статья научная
A dual band linear polarized micro-strip antenna is designed and simulated to obtain electronic circuit miniaturization of an antenna in high speed wireless local area networks (IEEE 802.11a standard). The proposed antenna contains a substrate layer (FR-4 lossy) with a dielectric constant of 4.4 and there is a circular patch on the upper layer of the substrate. The coaxial probe feed is used to excite the desired antenna which reduces the spurious radiation and hence obtained good efficiency. It is shown that using cavity model 20% excess bandwidth can be achieved while maintaining the lower size of the antenna. An 'E' shaped slot is introduced in the radiating patch to obtain dual band resonance frequency with maximum current distribution on the surface. Finally the simulated results using Computer Simulation Technology (CST) microwave studio 2009 in this design is compared with manual computation results which are found to be suitable for WLAN applications.
Бесплатно
A Low-Cost Noise Wave Correlator for Noise Parameters Extraction by Cold Noise Power Measurement
Статья научная
Conventionally, the noise parameters of a Device under Test (DUT) which generally characterize the noise performance of the DUT, are obtained via the impedance tuner technique. The authors have previously presented a technique which eliminates the need for impedance tuner, and rather employs an 8-port network that enables the extraction of the noise correlation matrix of a given DUT and thus its noise parameters. In this paper, we present a further simplification of the 8-port network technique, which also eliminates the need for a conventional external noise source. Cold noise powers emanating from a DUT are measured via a 6-port network with the aid of matched termination. The measured noise powers provide sufficient information for determining the noise wave correlation matrix of a DUT, which are then converted into the conventional 2-port noise parameters. The proposed technique is simple, fast and is verified to give a good estimation of the noise parameters of selected DUTs.
Бесплатно
A Method of Target Detection in Remote Sensing Image Captured based for Sensor Network
Статья научная
A refined energy constrained minimization method is developed for target detection in hyperspectral remote sensing images captured by unmanned aerial vehicles (UAVs) during their surveillance missions, which has been tested in the experiment under this paper. The experiment result proves, in the detection process, this method can effectively restrain noises so far as the spectral characteristics of any potential target are known, and find sub-pixel targets out effectively from the hyperspectral remote sensing image in unknown background spectrum.
Бесплатно
A Metric for Evaluating Security Models based on Implementation of Public Key Infrastructure
Статья научная
International security evaluation metrics are too general and not focused on evaluating security models implemented using Public Key Infrastructure (PKI). This study was conducted to develop the metric for evaluating security models based on implementation of PKI by using insights from literature. Literature review was done based on inclusion and exclusion criteria. The developed metric was tested using ranking attributes and ranking scales. The results reveal that the developed metric is applicable for evaluating security models based on implementation of PKI. This is verified by the tabular results indicating evaluation of selected security models based on implementation of PKI by using ranking attributes and ranking scales. This study contributes to the body of knowledge a metric for evaluating security models based on implementation of PKI.
Бесплатно
A Multi-objective Fuzzy Logic based Multi-path Routing Algorithm for WSNs
Статья научная
Wireless Sensor Networks (WSNs) have included one of the major challenges as energy efficiency. The optimal routing is the better solution for tackling the energy-efficiency problem as the energy is consumed with massive amount by the communication of a network. The clustering technique is the reliable data gathering algorithm for achieving energy-efficiency. The data transmit to the cluster head (CH) by each node that belonging to the cluster for clustered networks. The data transmission towards the BS or SINK is occurred once all data is received by CH from all member nodes. In multi-hop environments, the data transmission happens via other cluster-heads. It leads to the earlier death of CHs that are nearer to the SINK because of the heavy inter-cluster relay, i.e. called as hot-spot problem. The existing methods of unequal clustering approaches have been used to resolve this issue. The algorithms generate the clusters with smaller sizes while approaching towards the sink for reducing the intra-cluster relay. These algorithms didn’t consider the hotspot problem very effectively. Therefore, in this work, we introduce a multi-objective fuzzy logic based multi-path routing solution (MOFL-MPR) to address the above said problem. The popular clustering algorithms have been evaluated the performance results and the MOFL-MPR is outperformed the existing algorithms based on the obtained experimental results in terms of stable CH selection, energy efficiency and better data delivery.
Бесплатно
A Multi-step Attack Recognition and Prediction Method Via Mining Attacks Conversion Frequencies
Статья научная
Massive security alerts produced by safety equipments make it necessary to recognize and predict multi-step attacks. In this paper, a novel method of recognizing and predicting multi-step attacks is proposed. It calculates attack conversion frequencies, and then mines the multi-step attack sequences. On this basis, it matches the new alert sequences dynamically, recognizes the multi-step attacks and predicts the next attack step. The result of experiment shows that the proposed method is effective and accurate.
Бесплатно
A Multicast Routing Mechanism in Mobile Ad Hoc Network Through Label Switching
Статья научная
Merging MPLS into multicast routing protocol in Mobile Ad hoc network is an elegant method to enhance the network performance and an efficient solution for multicast scalability and control overhead problems. Based on the Wireless MPLS technology, the mechanism and evaluation of a new multicast protocol, the Label Switching Multicast Routing Protocol (LSMRP) is presented in this paper.
Бесплатно
A New Half-blind Algorithm of Smart Antenna for Mobile Terminal
Статья научная
The core of smart antenna is its adaptive algorithm. For the characteristics of TD-SCDMA mobile terminal, we analyze the advantages and disadvantages of various algorithms and propose a semi-blind algorithm combining the NLMS algorithm and the CMA algorithm in this paper. The new semi-blind algorithm has strong robustness and low complexity. It is suitable for smart antenna of TD-SCDMA mobile terminals.
Бесплатно
A New Joint Antenna Selection Algorithm Based on Capacity
Статья научная
Antenna Selection in MIMO systems can increase the system capacity, reduce the MIMO system complexity and cost of radio links effectively. In this paper, a new joint antenna selection algorithm was presented which can adaptively change the number of the selected transmitting and receiving antenna number according to the channel station. It can obtain the similar system capacity with the optimal joint antenna selection algorithm in any correlation coefficient, but the calculated amount is far less than the optimal joint algorithm.
Бесплатно
A New MATLAB based Microstrip Filter Design Tool
Статья научная
This paper presents a new MATLAB-based microstrip filter design tool. Stepped-impedance resonator lowpass filter, parallel-coupled bandpass filter, and end-coupled bandpass filter are included. Circuit-theory based closed-form mathematical expressions are used, instead of rigorous electromagnetic analyses. This results in significant reduction in analytical effort, without substantially affecting the accuracy. The results are verified against results obtained using commercially available Ansoft simulation tool. The agreement between the two sets of results is good enough for all practical purposes.
Бесплатно
A New R*Q-tree Spatial Index based on the Delaying Selection and Clustering Splitting
Статья научная
The original R*Q-tree is an important class of query index in the spatial database, but when carry on frequent insertion and deletion, the efficiency is very low, because its construction cost is much more than that of the other query methods. So the new R*Q-tree using the delaying and Clustering splitting technology has been proposed for improving the shortcomings of the original R*Q-tree. When the data objects are inserted into the new R*Q-tree, the nodes may overflow. During the process of insertion, rather than split the node immediately, it attempts to insert the nodes into the adjacent neighboring nodes by using of the delaying selection splitting technology until they are full. If the adjacent neighboring nodes are full, it will use the clustering technology to split the nodes, data items will be reorganized between the neighboring nodes and the splitted nodes. The new R*Q-tree can ensure the premise of the query performance and the cost of structure greatly reduced, at the same time, significantly the space utilization of the index structure is improved. Finally, the experimental analysis and appraisals show that the operation efficiency of the new R*Q-tree is enhanced. And in the new R*Q-tree and the promoter region, there are no duplicated elements, so the structure of the new R*Q-tree can be simplified.
Бесплатно
A New Ranging Technique for IEEE 802.16e Uplink
Статья научная
Aiming at the shortcomings of the traditional ranging algorithm, this paper proposes a new ranging technique for 802.16e uplink in the frequency domain. The ranging technique eliminates the effect of the timing offset by computing the frequency difference of adjacent sub-carriers in the ranging channel, which reduces the search space from two dimensions to one dimension. When there is slot, the ranging code can be detected by adopting a threshold. The ranging technique is implemented through one-dimension search in the frequency domain, and consequently the complexity can be reduced and without losing the performance of timing estimation. The simulation results show the good ranging performance of this technique.
Бесплатно
A New Secure Strategy for Small-Scale IEEE 802.11 Wireless Local Area Network
Статья научная
As the main secret-key encryption techniques of the wireless local area network (WLAN) have been proven to be unsafe, wireless network security is faced with serious challenges. It is unpractical for home users and small companies to buy expansive network equipments to improve the network security. Therefore, the secure strategy of wireless network needs to be changed. In this paper, we first introduce secure issues of the main secret-key encryption techniques currently adopted by the most popular commercial wireless routers. Then we propose a new strategy for small-scale IEEE 802.11 wireless local area network which can strengthen the network security. The new secure strategy is based on web authentication with unshared key and virtual local area network (VLAN) in wireless network. It can provide protection against practical attacks which are popular nowadays. Moreover, it is simple, wieldy and low-cost.
Бесплатно
A New Solution of Multicast Packets Management for Managed Ethernet Switch
Статья научная
This paper has a discussion on the new solution of IGMP management for multicast message in industrial Ethernet. It proposed a new mechanism to minimize the congestion which is based on the taking an adaptive decision during transferring multicast messages. Proposed approach is that a device requesting to start and stop the reception of the multicast streams is accomplished through IGMP join and Leave message requests. Quality of Service (QOS) as a component is supported by the Switch Manager as well as features built into the micro chip. The IGMP Snooping component monitors (snoops) these join and leave messages to allow it to know which streams to prune from which ports. it is a service provided by most managed Ethernet switches. However, the ICIE (Intelligent Controller for Industrial Ethernet) does not provide this capability and requires that another device in the network supports the querier functionality. It is through the external devices solicitation of join messages that allow the IGMP Snooping component to correctly decipher on which ports the downstream listeners are connected.
Бесплатно
A New Technique for Detection and Prevention of Passive Attacks in Web Usage Mining
Статья научная
Data theft and data attack is very common with internet users and web log files. Web log file is the proof of authentication of any user over any website. Many unauthorized users change them according to their requirement. Attacks like sql injection, brute force attack, IP spoofing might cause severe damage to the database system In this encryption techniques and optimization technique have been applied in order to check the unexpected arrival of messages or queries and the system parameter.
Бесплатно
A New Three-party Key Exchange Protocol Based on Diffie-Hellman
Статья научная
The goal of key exchange protocol is to establish a common and secure session key using the interactive communications. The existing schemes are usually in the pattern of ‘user-server-user’, so are weak in reality. In this paper, a new three-party key exchange protocol based on Diffie-Hellman was proposed which contains the following characteristics: without server; providing key secrecy and forward secrecy; ensuring no key control; ensuring known-key secrecy.
Бесплатно
A Node Localization Algorithm based on Woa-Bp Optimization
Статья научная
With the rapid development of 5G technology, the era of interconnection of all things has arrived. At the same time, a variety of hardware and software are getting more and more location information through sensors, and the accuracy of location information is increasingly important. Because traditional positioning relies on satellite signals, it achieves good results outdoors without obstruction, but indoors, due to the obstruction of various walls, such as Beidou satellite navigation system and U.S. Global Positioning System, it is difficult to meet the accuracy requirements for indoor positioning. Therefore, how to improve the positioning accuracy of indoor nodes has become a research hotspot in the field of wireless sensor. In order to improve the indoor positioning accuracy, this paper combines artificial neural network, intelligent optimization algorithm and node positioning to improve the accuracy of indoor positioning. One of the essences of the neural network is to solve the regression problem. Through the analysis of indoor node positioning, it can be concluded that the accuracy of distance-based positioning method lies in finding the relationship between signal strength and distance value. Therefore, the neural network can be used to regression analysis of signal strength and distance value and generate related models. In order to further improve the accuracy and stability of indoor node positioning, a method combining whale optimization algorithm with neural network is proposed. By using the whale optimization algorithm to find the optimal parameters of the neural network model, the training accuracy and speed of the neural network are improved. Then, using the excellent fitting ability of the neural network, the mapping relationship between RSSI value and distance value of indoor nodes is fitted, and the corresponding regression analysis model is generated, which can minimize the noise problem caused by abnormal signal attenuation and reduce the indoor positioning error. Finally, the data is processed by the neural network to get the parameters needed in the positioning algorithm. The experimental results show that the node positioning model based on the optimized neural network and the single optimization algorithm has significantly improved the positioning accuracy and stability.
Бесплатно
A Novel Approach to Simulate DDoS Attack
Статья научная
Due to the rapid spread of botnets, distributed denial of service attacks have become more and more frequent and fatal. In order to detect and defend DDoS attack, many researches have been done, such as using NS2 to simulate such attacks. However, the major bottlenecks in large-scale network simulation are the memory usage and simulation time. In this paper, we present a novel approach to simulate DDoS attack, called Analytical Packet Forwarding Model (APFM), which simplifies the procedure of packet forwarding based on computation. The experimental results show that our model ensures the authenticity of the overall simulation procedure and simulation results, compared to NS2. The most significant contribution of APFM is that it significantly reduced the memory usage and simulation time.
Бесплатно
Статья научная
In this paper, a novel compact dual-band complementary split ring resonator (CSRR)-loaded microstrip patch antenna placed on ground plane loaded with L-shape slot is proposed for satisfying WLAN and WiMAX applications simultaneously. The proposed antenna consists of a complementary split ring resonator (CSRR) embedded on the patch structure and an L-shape slot on the ground plane. The resonant frequency and effective parameters of the CSRR are also determined. In addition, a design evolution and various parametric analysis of the antenna are carried out in order to study the effects of various parameters and to provide information for designing, modifying, and optimizing such an antenna. The CSRR is exploited to create resonance at 5.775 GHz while the L-shape slot resonates at 3.550GHz for dual-band operation. The -10dB return loss bandwidths of the antenna are 290 MHz (3.40-3.69) GHz and 210MHz (5.65-5.86) GHz, which cover both the WiMAX frequency band (3.4-3.69) GHz and the WLAN frequency band (5.725-5.825) GHz. The overall size of the antenna is 37mm×25mm×1.6mm. Gains of 0.5dB and 2 dB are obtained at 3.550 GHz and 5.775 GHz, respectively.
Бесплатно
A Novel Dual Polarized Dual Feed Multi-Band Meander-Line Antenna for Mobile Applications
Статья научная
A multi-band dual polarized log periodic meander-line antenna is presented in this paper. The Ansoft HFSS 3-D EM simulator is employed for design simulation. The proposed antenna is realized on a FR-4 Epoxy substrate with εr = 4.4 and tan ξ = 0.02. The size of the antenna is 14.5 x 20 x 1.59 mm3. The proposed antenna is fabricated and comparison between simulated and measured result for return loss has been observed and is found in good agreement. In addition to micro-strip transmission line feed, a capacitive probe feed has been introduced and enhancement in impedance bandwidth has been observed as compared to only transmission line feeding method. Small size of the antenna enables itself to be introduced in complex systems and can be used for various applications including GSM1800/1900, WCDMA2100 and LTE1800/2300/3700 TDD for mobile handsets and mobile assisted health applications.
Бесплатно
