International Journal of Wireless and Microwave Technologies @ijwmt
Статьи журнала - International Journal of Wireless and Microwave Technologies
Все статьи: 574
Numerical Analysis of Slot Position of Rectangular U Slot Microstrip Patch Antenna
Статья научная
The main focus of this paper is to study and analyze how the performance of rectangular U slot antenna is affected by the variation of U slot position. The work presented herein is a simulation based study. Experimentally, it has been revealed that variations in parameters such as the width and length of the U-slot, height and size of the patch, probe size and location as well as substrate permittivity can dramatically change the antenna's behavior. Till date, no analytical methods have been developed that accurately relate the complex relationships between the antenna dimensions and individuality. This paper describes the behavior of antenna with change of U slot position. A numerical solution is obtained by varying the various positions of U slot along all the axis and the effect of U slot position on various antenna output parameters is analyzed.
Бесплатно
Numerical Investigation of a Polarization-insensitive Energy Harvesting Metasurface
Статья научная
This paper presents the numerical study of a polarization-insensitive energy harvesting metasurface. The proposed metasurface is designed to harvest ambient electromagnetic (EM) energy at 2.45 GHz. The basic constituent element of the metasurface is an electric-field-coupled (ELC) resonator, which is used to synthesize a 2 x 2 super-cell with polarization-insensitive features. Finally, the metasurface is realized as a 3 x 3 array of ELC super-cells, and presents an energy harvesting efficiency of 95.4% at 2.45 GHz. The achieved energy harvesting efficiency is maintained irrespective of the polarization of the incident excitation. The proposed metasurface configuration holds promise for the implementation of ambient EM harvesters, able to scavenge energy from wireless technologies operating in the 2.45 GHz band.
Бесплатно
OFDM synchronization techniques for 802.11ac WLAN
Статья научная
It would be dire need of accurate and fast wireless communication in the present as well as future era. Few years ago, error free wireless link design was only challenge and it had opened a way of digital communication. Now speed of communication becomes vital and essential part of research in the field of wireless communication. In wired communication category, optical communication is a solution to achieve targeted data speed but wireless channel for serial communication is highly disturbed with the phenomena of multipath and frequency selective fading for a data rate over a specific limit. A new technology named Orthogonal Frequency Division Multiplexing (OFDM) is a perfect key to open this locking situation of limited data rate with optimum use of bandwidth in the multipath fading channel. Supporting high data rates and robust response against narrowband interferences, OFDM had penetrated itself in many broadband wireless services. There are many issues with OFDM too and one of them is synchronization between orthogonal frequency channels at receiver. It is mandatory condition in the use of OFDM technology to maintain orthogonality among subcarriers for error free communication. Timing and frequency synchronization errors are quite detrimental to this condition because these errors ultimately disturb the orthogonality which is perfectly set at transmitter. Synchronization errors need to be handled properly otherwise they create Inter-Symbol Interference (ISI) and Inter-Channel Interference (ICI) which after all resulted into the deterioration of Bit Error Rate (BER). This paper covers types of synchronization and its effects, algorithms to decrease it and analysis of the same.
Бесплатно
On Design of Modified Hexagonal Slot UWB Antenna with Band Notched Characteristics
Статья научная
A micro strip-fed printed, modified hexagonal slot ultra wideband antenna with a band notch function is presented as well as investigated in this paper. The basic antenna comprises a U-shape radiating patch on one side of the substrate and ground plane with modified hexagonal slot on the other side of the substrate. Proper alignment and use of a modified hexagonal slot gives additional resonances and much wider impedance bandwidth is obtained. To create a notched band for WiMAX, symmetrical L- shape parasitic stubs are embedded in the upper edge of the modified hexagonal slot of the ground plane. The proposed antenna operates over the frequency band from 2.71 GHz to 11.73 GHz with a band rejection from 3.27-4 GHz (for WiMAX).The proposed antenna is fabricated on a FR-4 substrate having a dielectric constant of 4.4 with an overall size of 28 x 28 x 1.6mm3. Parametric studies have been conducted by changing length, width and thickness of symmetrical L- shape parasitic stubs. Simulated results are in good agreement with measured results. Designed antenna exhibits good radiation, efficiency greater than 80% within the entire ultra wideband except for WiMAX frequency.
Бесплатно
Статья научная
5G Heterogeneous network is characterized with small cells in close proximity with one another which in most cases are active even at low traffic load periods. Such scenarios lead to unnecessary large energy consumption and co-frequency interference. This large energy consumption and interference in 5G heterogeneous networks have been an issue widely discussed in several technical literature. Different and attractive techniques on energy management have been investigated and proposed. All these have been in seeking ways of minimizing or reducing energy consumption in mobile networks. In this study the on/off and sleep-mode schemes as energy management techniques have been reviewed with the major aim of identifying weak areas of both techniques and suggesting ways which will be useful for further research works in the future. In doing so recent literature on the subject matter were consulted. The on/off and sleep-mode schemes involve switching processes which result to loss of data and information during change of state. Quality of service issues arising from incomplete or proper switching process and unnecessary delay perceived by the users were observed as major concern for both schemes. For further work, amongst other suggestions, it is suggested that the time needed between system switching command and switching operations be considered as an important factor in eliminating switching problems which will positively affect the overall quality of service.
Бесплатно
Optimal Cluster Size for Wireless Sensor Networks
Статья научная
Since energy consumption is one of the main challenges in wireless sensors networks performance and efficiency, this paper discusses and proposes a mathematical model that compromises these two crucial parameters. In addition, number of clusters, cluster size, and number of cluster heads all contribute in network robustness; they have been studied and manipulated in details. This paper suggests a mathematical model that calculates and finds the optimal cluster size and number of sensors for Low Energy Adaptive Cluster Hierarchy (LEACH) protocol. Wireless Sensor Network (WSN) is a network includes devices (sensors) for collecting data by sensing the field. Clustering is one of the simplest strategies used to minimize the power lost in WSNs. Its performance is affected by network area and number of sensors. The cluster head is elected based on traditional Low Energy Adaptive Cluster Hierarchy protocol. The optimal cluster number is detected based on the condition of the LEACH delivery ratio. NS2.35 and MannaSim framework are applied for validating the proposed model. The results show that the proposed model is approved at different areas and nodes density. The optimal cluster size obtained by the proposed model is equivalent to optimal clusters number for 100 % delivery ratio of LEACH.
Бесплатно
Optimal Spectrum Access for Users in Multi-Channel Cognitive Radio Networks
Статья научная
Cognitive Radio, a software defined radio, is an emerging technology which uses opportunistic spectrum access (OSA) for the efficient utilization of the spectrum. Its main aim is to utilize the unused portions of the spectrum by allowing unlicensed users (secondary users) to transmit data in absence of primary users. In this paper the assignment of multiple primary and secondary users in a multiple channel system is addressed with the sole aim of optimizing the total throughput. We have considered an optimal spectrum access (OSA) algorithm for the allotment of both the primary and secondary users in a multiple channel system and compared the results with the well-known meta-heuristic techniques such as Simulated Annealing (SA) and Tabu Search (TS). The results reveal that OSA algorithm is more efficient as compared to SA and TS as far as throughput optimization is considered.
Бесплатно
Статья научная
This paper explores the potential of Ultra-Massive Multiple Input Multiple Output (UM MIMO) systems as a key technology for 6G wireless communications within the Terahertz (THz) frequency band (0.1 – 10 THz). The THz spectrum offers immense capacity and speed advantages but presents significant challenges, such as higher propagation losses and limited coverage range due to atmospheric absorption and signals spreading. The study provides a comprehensive analysis of UM MIMO’s technical performance in overcoming these challenges, focusing on key metrics such as signal propagation, system capacity, and coverage range. Additionally, the research examines the optimization of beam dynamics and spectral efficiency in UM MIMO systems under various wireless channel conditions and precoding techniques. The findings highlight the importance of advanced antenna techniques and adaptive beam management in maximizing the efficiency and viability of 6G THz networks, positioning UM MIMO as a fundamental solution for next-generation wireless communication.
Бесплатно
Статья научная
OFDM is a technique that is chosen for high data rate communication and is important for 4th generation communication systems. To provide best possible quality of service, intelligent allocation of resources such as power, bandwidths are necessary. Various algorithms have been proposed for allocation of resources. Fuzzy Rule Based System (FRBS) and Particle Swarm Optimization (PSO) algorithm are used for optimization of code rate, modulation and power. FRBS is used to choose the best possible modulation and code rate and PSO is used for better power allocation.
Бесплатно
Статья научная
Researches in the reduction of peak-to-average power ratio (PAPR) from orthogonal frequency division multiplexing (OFDM) output signals are being done using many techniques. Selected mapping (SLM) technique is a distortion-less technique and is a well known method to reduce high PAPR of OFDM signal. One drawback of SLM is its requirement of side information bits to recover original data block at the receiver side which lead rate of data loss. In this paper, we have proposed a sequential phase sequence SLM (SPS-SLM) based OFDM transceiver without side information and studied its performance. For the proposed method, a specific set of phase sequences is designed. MATLAB simulation shows that the proposed scheme performs well in terms of PAPR. Proposed method provides almost the same PAPR reduction performance compared to the conventional SLM method requiring side information.
Бесплатно
PPLS: personnel presence locator system – an amalgam of RF ranging & Zigbee in WSN
Статья научная
In this day and age of occupied time plans, individuals are confronting numerous issues in following the employees and specialists in colleges, schools, universities, doctor's facilities and so forth, hence it ends up vital that each assignment is expert intelligently, productively and in an auspicious way. To achieve this, easy accessibility of people of interest is a must. To alleviate this problem, we propose a solution called “Personnel Presence Locator System (PPLS)” that is an internetworked amalgam of small systems working independently. Moreover, in this article, we give an overview of the naturally multidisciplinary writing of human-detection, concentrating essentially on the extraction of five regularly required properties: in particular Location, Count, Presence, Track, and Identity. The objective of this work is to uncover the abilities and constraints of existing solutions from different disciplines, to manage the production of new frameworks like PPLS and point toward future research bearings.
Бесплатно
PRDSA: Effective Parallel Digital Signature Algorithm for GPUs
Статья научная
RSA based Digital Signature algorithm is an electronic scheme to ensure the security, authenticity and integrity of an electronic document intended to be used on Internet. Due to the involvement of RSA in signing and signature verification which is based on the series of modular multiplications and modular reductions on very large integers, the RSA based digital signature algorithm become compute-intensive and takes lot of time and energy to execute. A potential solution to this problem is to use the massive parallel powers of the multiprocessors of GPU that can simplify its complex computational part via CUDA programming. This paper presents a faster GPU based pRDSA algorithm which serves the same purpose as the RSA Digital Signature Algorithm but with less computational complexity. Proposed algorithm is an energy efficient parallel version of Digital Signature Algorithm to achieve high performance in the area of network security. It is based on SIMD model of parallel programming and implements repeated square-and-multiply method to compute the digital signature. The conceptual model of pRDSA and its performance have been discussed in this paper.
Бесплатно
PRoPHET Using Optimal Path Hops
Статья научная
The opportunistic network paradigm has no stable path and synchronous end-to-end communication. In such an environment, the bundle originator or the infected node stores a redundant copy in its buffer. This copy is replicated to other encountered susceptible nodes based on routing decision. The performance of the employed routing is based on delivering the bundle through optimal paths. This paper improves the decision criteria of the PRoPHET routing. This enhancement is achieved by employing the bundle probability and the optimal path hops. We have called our proposed improved PRoPHET utilizing Optimal Path Hops (PRoPHET-OPH). The evaluating of its performance is conducted by delivery probability, mean delay and percentage of overhead. Numerical findings exhibit that the PRoPHET-OPH performance is superior compared with the traditional PRoPHET.
Бесплатно
Pattern-based and Time-Synchronised Passwords
Статья научная
World has been changed; every person is using a number of software, websites, and other systems that are using text-based passwords as a method of authentication. These passwords need to be strong, hard to guess, and need to be stored in a secure environment. Major problems with passwords are caused by human limitations to remember passwords for different accounts. A trade-off between password security and human-memorability made it difficult to create passwords that are strong enough and easy to remember. No satisfactory solutions have been offered to problems associated with a password such as shoulder surfing, eavesdropping, keylogging programs, Trojan horse, brute force attacks, etc. This study suggests a new easy to use approach for creating a password that is easy to remember even for a large number of accounts. Here in this paper, we proposed two methods one is pattern-based passwords, a simple method that is solving the problem of memorability, another is the idea of Time-Synchronized Passwords (TSP), a novel method for creating passwords that are dynamic in nature and change with the passage of time. The novality of TSP is that instead of storing the passwords in database the patterns are stored, and these patterns are related linked with time. The significance of storing pattern instead of actual password is that at a specific time, the password will have only one instance known to the creator of the password, and this particular instance will be different from instances at other times and thus avoids shoulder surfing, eavesdropping, keylogging, and other problems associated with passwords. These methods are easy to implement and can be used in any system.
Бесплатно
Performance Analysis between Analog OFDM & Digital OFDM System
Статья научная
Orthogonal Frequency Division Multiplexing (OFDM) signaling has been widely used for high data rate transmission applications due to its high spectral efficiency and robustness to the frequency selective fading channels. One of the major drawbacks of the analog OFDM system is frequency shifting in every sub-carrier. That's why bit error rate increased in analog OFDM system. In this research, we want to solve the problem of the analog OFDM system by using IFFT circuit instead of the local oscillator. The IFFT circuit takes an input as frequency domain and provides output as a time domain signal for 4-QAM modulation. Basically IFFT circuit acts as a local oscillator in the analog OFDM system. The IFFT circuit only executes operation on a discrete frequency domain signal which is converted into a time domain signal by its. So no frequency shifting occurs in every sub-carrier in the digital OFDM system. As a result BER also decrease in digital OFDM system over the analog OFDM system.
Бесплатно
Performance Analysis of Differential Evolution Algorithm based Beamforming for Smart Antenna Systems
Статья научная
This paper presents smart antenna array beamforming using differential evolution algorithm. The excitation values of the elements in the array are smartly adjusted to control side lobe levels and placing nulls in the interference signal direction while maintaining the beam in the desired signal direction. Different cases are considered to illustrate the performance of this technique. Simulation results show that this evolution algorithm is better than the traditional beamforming algorithms for Smart antenna systems.
Бесплатно
Performance Analysis of FBMC over OFDM for High Data Rate MIMO Configurations
Статья научная
The burgeoning demand of high data rate in next generation wireless communication, the antecedent of the evolution of new multicarrier modulation technique FBMC (Filter Bank Multicarrier) system is OFDM (Orthogonal Frequency Division Multiplexing). Although OFDM has numerous merits but it consumes higher bandwidth due to its cyclic prefix to eliminate ISI (Inter Symbol Interference) in fading channel and shows large PAPR (Peak to Average Power Ratio) in transmission system. To mitigate these problems, FBMC is more suitable candidate in high speed MIMO (multiple input multiple output) system. At first, in this paper, the responses of OFDM and FBMC system have been analyzed with AWGN and Rayleigh fading channel under theoretical and simulation environment. Besides this, Peak to Average Power Ratio (PAPR) with reduction technique, clipping is applied to know the behavior of these systems. Finally, in the area of MIMO scheme, each system is concatenated with MRC, Alamouti STBC and Generalized STBC to find FBMC as superior contender for 5G. Results show that using 16 QAM modulation, BER performance of FBMC significantly achieves 2dB compared to error rate of OFDM in theoretical and empirical analyses under AWGN and Rayleigh channel. Moreover, the clipping technique enhances the response of FBMC in terms of PAPR compared to OFDM approximately 0.5 dB. In MIMO configurations, MRC-FBMC exhibits the improved performance with 2 dB approximately over MRC-OFDM system. Results also show that in the case of Alamouti STBC, at 30dB and 35dB, FBMC (2×1) and (2×2) configurations achieve BER improvement 5×10-4, 3×10-4 respectively than OFDM (2×1) and (2×2) configurations. Generalized STBC investigation reveals that to reach FBMC BER performance, OFDM needs at least 2dB increment at specific error rate. In a nutshell, this paper brings up three distinct types of appealing features of FBMC such as good BER response, reduced PAPR, and suitability in MIMO configuration compared to OFDM. These distinct features make FBMC an ultimate choice in the emerging areas of MIMO networks.
Бесплатно
Performance Analysis of HWMP Protocol in Wireless Mesh Network
Статья научная
Wireless Mesh Networks (WMNs) play a vital role in next-generation wireless networking, with applications ranging from last-mile wireless internet, transportation systems enterprise, enterprise networks, home networking, and wireless community networks are all examples of wireless community networks.Individual vendors created several proprietary mesh systems, but IEEE organized the IEEE 802.11s task force to design a meshed networking exposition to assure interoperability.In this paper, we evaluate the Quality of service parameters such as throughput, delay, PDR and jitter of mesh protocol.We simulated the HWMP protocol's performance,the present work is an attempt to address the problem related to wireless mesh networks by minimizing the delay and maximizing the throughput of the network.
Бесплатно
Performance Analysis of IoT Cloud-based Platforms using Quality of Service Metrics
Статья научная
There are several IoT platforms providing a variety of services for different applications. Finding the optimal fit between application and platform is challenging since it is hard to evaluate the effects of minor platform changes. Several websites offer reviews based on user ratings to guide potential users in their selection. Unfortunately, review data are subjective and sometimes conflicting – indicating that they are not objective enough for a fair judgment. Scientific papers are known to be the reliable sources of authentic information based on evidence-based research. However, literature revealed that though a lot of work has been done on theoretical comparative analysis of IoT platforms based on their features, functions, architectures, security, communication protocols, analytics, scalability, etc., empirical studies based on measurable metrics such as response time, throughput, and technical efficiency, that objectively characterize user experience seem to be lacking. In an attempt to fill this gap, this study used web analytic tools to gather data on the performance of some selected IoT cloud platforms. Descriptive and inferential statistical models were used to analyze the gathered data to provide a technical ground for the performance evaluation of the selected IoT platforms. Results showed that the platforms performed differently in the key performance metrics (KPM) used. No platform emerged best in all the KPMs. Users' choice will therefore be based on metrics that are most relevant to their applications. It is believed that this work will provide companies and other users with quantitative evidence to corroborate social media data and thereby give a better insight into the performance of IoT platforms. It will also help vendors to improve on their quality of service (QoS).
Бесплатно
Статья научная
Millimeter-wave (mm-wave) communication stands as a vital technology for future wireless networks, necessitating efficient beamforming techniques to mitigate significant path loss and harness the extensive mm-wave spectrum. Traditional fully digital beamforming methods are often deemed unfeasible due to the substantial costs and energy requirements, which stem from the need for individual radio frequency (RF) chains for each antenna element particularly in Massive MIMO systems. Hybrid beamforming emerges as a more economical solution, reducing both hardware expenses and energy consumption by utilizing a limited number of RF chains. This paper offers an in-depth evaluation of hybrid beamforming in 5G and beyond mm-wave systems, proposing a new classification framework for various hardware configurations. The research employs a practical approach to compare different strategies, focusing on two main factors: the beam patterns produced with optimal and hybrid weights, and the resulting spectral efficiency, which is a key performance metric. The findings indicate that the beam patterns generated with both optimal and hybrid weights display comparable characteristics, especially for dominant beams. Additionally, the study shows that increasing the number of data streams leads to a significant boost in spectral efficiency, an essential element for enhancing 5G network performance. The systematic comparisons delve into the interactions and trade-offs between these design aspects, highlighting promising candidates for hybrid beamforming in the wireless communication systems of the future.
Бесплатно
