المؤلفون: Nenad M. Stojanović, Branislav M. Todorović, Vladimir B. Ristić, Ivana V. Stojanović

المصدر: Vojnotehnički Glasnik, Vol 72, Iss 2, Pp 790-813 (2024)

مصطلحات موضوعية: radiocommunications, military communications, cellular mobile systems, spread spectrum, direct sequence, global positioning system, underwater acoustic communications, unmanned aerial vehicles, wireless fidelity, zigbee, Military Science, Engineering (General). Civil engineering (General), TA1-2040

الوصف: Introduction/purpose: Direct sequence spread spectrum modulation is widely used in many radiocommunications systems. At the first time, this modulation technique was used in military communications and navigation systems. Later, applications became diverse in civil communication systems as well. Today, there are many systems where direct sequence spread spectrum modulation is implemented as a part of the system. This article aims to sublimate knowledge about the direct sequence spread spectrum modulation technique and its applications. Methods: The article presents a review of the historical development of the direct sequence spread spectrum modulation technique, its principles and the most important current applications. Results: Based on a large number of references, this article summarizes the historical development, basic principles and modern applications of the direct sequence spread spectrum modulation in military and commercial communication systems. Conclusion: Direct sequence spread spectrum modulation is widely used in modern wireless and satellite radiocommunications. It is expected to be part of future global communication systems.

وصف الملف: electronic resource

العلاقة: https://scindeks.ceon.rs/article.aspx?artid=0042-84692402790STest; https://doaj.org/toc/0042-8469Test; https://doaj.org/toc/2217-4753Test

الوصول الحر: https://doaj.org/article/d1b5cd600c0943bfb3e8fbd48eb15707Test

المؤلفون: Satea H. Alnajjar, Haneen M. Mahmoud

المصدر: Al-Iraqia Journal for Scientific Engineering Research, Vol 2, Iss 4, Pp 1-8 (2023)

مصطلحات موضوعية: internet of things (iot), light fidelity (li-fi), visible light communication (vlc), wireless fidelity (wi-fi), Science

الوصف: Light Fidelity (Li-Fi) is an optical wireless communication technique that delivers high-speed data transmission rates by utilizing light-emitting diodes (LEDs). It is noteworthy that any light source available has the potential to be transformed into a functional Li-Fi node that can offer the possibility of communicating with the remaining sections of the Li-Fi communication network as well as the entire Internet infrastructure. The Li-Fi node utilizes light to provide efficient and secure communication among internet users, additionally allowing access from any location. Simultaneously, the Internet of Things (IoT) represents a collection of innovative and integrated technologies, offering an array of exciting services and solutions that have the potential to revolutionize our daily lives. The development of IoT results in a significant increase in smart devices and sensors. Such devices demand more efficient, faster, and secure data transmission. Li-Fi technology can satisfy the requirements of the forthcoming 6th generation IoT network. It can enhance data rates while consuming minimal energy. Consequently, it can be effectively integrated with the Internet of Things (IoT) in order to develop innovative and intelligent systems.

وصف الملف: electronic resource

العلاقة: https://ijser.aliraqia.edu.iq/index.php/ijser/article/view/115Test; https://doaj.org/toc/2710-2165Test

الوصول الحر: https://doaj.org/article/9e18e5fbfcba4a94be1f8b96c773ddcfTest

المؤلفون: Bravenec, Tomáš, Torres-Sospedra, Joaquín, Gould, Michael, Fryza, Tomas

مصطلحات موضوعية: Probes, Data privacy, Wireless fidelity, Information integrity, Information filtering, Wireless communication, Privacy, Data models, Signal analysis, Wireless LAN

الوصف: This article centers on the deeper presentation of a new and publicly accessible dataset comprising Wi-Fi probe requests. Probe requests fall within the category of management frames utilized by the 802.11 (Wi-Fi) protocol. Given the ever-evolving technological landscape and the imperative need for up-to-date data, research on probe requests remains essential. In this context, we present a comprehensive dataset encompassing a one-month probe request capture conducted in a university office environment. This dataset accounts for a diverse range of scenarios, including workdays, weekends, and holidays, accumulating over 1 400 000 probe requests. Our contribution encompasses a detailed exposition of the dataset, delving into its critical facets. In addition to the raw packet capture, we furnish a detailed floor plan of the office environment, commonly referred to as a radio map, to equip dataset users with comprehensive environmental information. To safeguard user privacy, all individual user information within the dataset has been anonymized. This anonymization process rigorously balances the preservation of users' privacy with the dataset's analytical utility, rendering it nearly as informative as raw data for research purposes. Furthermore, we demonstrate a range of potential applications for this dataset, including but not limited to presence detection, expanded assessment of temporal received signal strength indicator stability, and evaluation of privacy protection measures. Apart from these, we also include temporal analysis of probe request transmission frequency and period between Wi-Fi scans as well as a peak into possibilities with pattern analysis.

وصف الملف: application/pdf

العلاقة: IEEE Journal of Indoor and Seamless Positioning and Navigation, vol. 1 (2023); https://ieeexplore.ieee.org/abstract/document/10325607Test; T. Bravenec, J. Torres-Sospedra, M. Gould and T. Fryza, "UJI Probes Revisited: Deeper Dive Into the Dataset of Wi-Fi Probe Requests," in IEEE Journal of Indoor and Seamless Positioning and Navigation, vol. 1, pp. 221-230, 2023, doi:10.1109/JISPIN.2023.3335882; http://hdl.handle.net/10234/206068Test

الإتاحة: https://doi.org/10.1109/JISPIN.2023.3335882Test
http://hdl.handle.net/10234/206068Test

المؤلفون: Klus, Lucie, Klus, Roman, Torres-Sospedra, Joaquín, Lohan, Elena Simona, Granell, Carlos, Nurmi, Jari

مصطلحات موضوعية: Databases, Fingerprint recognition, Location awareness, Performance evaluation, Prediction algorithms, Training, Wireless fidelity

الوصف: Indoor positioning performed directly at the end-user device ensures reliability in case the network connection fails but is limited by the size of the RSS radio map necessary to match the measured array to the device’s location. Reducing the size of the RSS database enables faster processing, and saves storage space and radio resources necessary for the database transfer, thus cutting implementation and operation costs, and increasing the quality of service. In this work, we propose EWOk, an Element-Wise cOmpression using k-means, which reduces the size of the individual radio measurements within the fingerprinting radio map while sustaining or boosting the dataset’s positioning capabilities. We show that the 7-bit representation of measurements is sufficient in positioning scenarios, and reducing the data size further using EWOk results in higher compression and faster data transfer and processing. To eliminate the inherent uncertainty of k-means we propose a data-dependent, non-random initiation scheme to ensure stability and limit variance. We further combine EWOk with principal component analysis to show its applicability in combination with other methods, and to demonstrate the efficiency of the resulting multidimensional compression. We evaluate EWOk on 25 RSS fingerprinting datasets and show that it positively impacts compression efficiency, and positioning performance.

وصف الملف: application/pdf

العلاقة: IEEE Transactions on Mobile Computing, 2023.; https://ieeexplore.ieee.org/document/10128720Test; Klus, L., Klus, R., Torres-Sospedra, J., Lohan, E. S., Granell, C., & Nurmi, J. (2023). EWOk: Towards Efficient Multidimensional Compression of Indoor Positioning Datasets. IEEE Transactions on Mobile Computing.; http://hdl.handle.net/10234/206064Test

الإتاحة: https://doi.org/10.1109/TMC.2023.3277333Test
http://hdl.handle.net/10234/206064Test

المؤلفون: Aira , Javier, Olivares Montes, Teresa, Delicado Martínez, Francisco Manuel

مصطلحات موضوعية: Agrochemicals, Contamination, Internet of Things, Monitoring, Pollution measurement, Technological innovation, Wireless fidelity

الوصف: Agrochemicals are to be blamed for the poisoning of millions of human beings worldwide, with acute and chronic exposure to such substances causing thousands of deaths. The presence of agrochemicals in the air is caused by drift—a phenomenon that originates from ground and aerial spraying applied in lands used for agribusiness. Drift refers to the spread and wind-driven transport of agrochemicals that have been volatilized during spraying, and which can easily reach towns and cities. Actively monitoring agrochemical drift is essential to protect the health of citizens and the environment. Many of the systems used for monitoring agrochemicals are currently analog, while those with some degree of digitalization are expensive, complex, and not easily scalable. Therefore, new cost-effective, stand-alone, reliable, easy-to-implement, and citizen-oriented technological tools need to be designed and developed. This article introduces “DriftGLY,” an innovative, low-cost Internet of Things (IoT) early warning system that utilizes a digital traffic light to continuously and automatically monitor the presence of agrochemicals in the air, both individually and in cocktail form. The key innovation of DriftGLY lies in the close relationship between the configuration of its digital traffic light and the precise calculation of the quantity of agrochemicals deposited in spray tanks. This configuration is specifically based on the parameter of the dose rate expressed in liters per hectare of these contaminants. DriftGLY incorporates an original collection system that allows for the indirect detection of agrochemicals in their particulate, gaseous, and, unlike traditional systems, liquid forms. In this manner, DriftGLY displays pollution risk levels through its digital traffic light, transmitting them to an IoT platform via various connectivity options, such as WiFi, LoRaWAN, and GSM/GPRS, and posts them on the social network X (formerly known as Twitter). The aim of this action is to democratize information and promote the ...

وصف الملف: application/pdf

العلاقة: J. Aira, T. Olivares and F. M. Delicado, "DriftGLY: A Low-Cost IoT-Based Ecosystem for Monitoring Agrochemical Spray Drifts," in IEEE Transactions on Instrumentation and Measurement, vol. 73, pp. 1-14, 2024, Art no. 5501414, doi:10.1109/TIM.2024.3350146.; https://ieeexplore.ieee.org/document/10381854Test; https://hdl.handle.net/10578/34256Test

الإتاحة: https://doi.org/10.1109/TIM.2024.3350146Test
https://hdl.handle.net/10578/34256Test
https://ieeexplore.ieee.org/document/10381854Test

المؤلفون: Hameed, Hira, Tahir, Ahsen, Usman, Muhammad, Zhu, Jiang, Lubna, Abbas, Hasan, Ramzan, Naeem, Cui, Tie Jun, Imran, Muhammad Ali, Abbasi, Qammer H.

المصدر: Hameed , H , Tahir , A , Usman , M , Zhu , J , Lubna , Abbas , H , Ramzan , N , Cui , T J , Imran , M A & Abbasi , Q H 2024 , ' Wi-Fi and radar fusion for head movement sensing through walls leveraging deep learning ' , IEEE Sensors Journal , vol. 24 , no. 9 , 10345499 , pp. 14952-14961 . https://doi.org/10.1109/JSEN.2023.3337515Test

مصطلحات موضوعية: Magnetic heads, Sensors, Radar, Wireless fidelity, Deep learning, Radio frequency, Monitoring, micro-Doppler signatures, behavior monitoring, channel state information, features fusion, machine learning, RF sensing, radio frequency (RF) sensing, machine learning (ML), deep learning (DL), /dk/atira/pure/subjectarea/asjc/3100/3105, name=Instrumentation, /dk/atira/pure/subjectarea/asjc/2200/2208, name=Electrical and Electronic Engineering

الوصف: The detection of head movement plays a crucial role in human-computer interaction systems. These systems depend on control signals to operate a range of assistive and augmented technologies, including wheelchairs for Quadriplegics, as well as virtual/augmented reality and assistive driving. Driver drowsiness detection and alert systems aided by head movement detection can prevent major accidents and save lives. Wearable devices, such as MagTrack consist of magnetic tags and magnetic eyeglasses clips and are intrusive. Vision-based systems suffer from ambient lighting, line of sight, and privacy issues. Contactless sensing has become an essential part of next-generation sensing and detection technologies. Wi-Fi and radar provide contactless sensing, however, in assistive driving they need to be inside enclosures or dashboards, which for all practical purposes in this article have been considered as through walls. In this study, we propose a contactless system to detect human head movement with and without walls. We used ultra-wideband (UWB) radar and Wi-Fi signals, leveraging machine and deep learning (DL) techniques. Our study analyzes the six common head gestures: right, left, up, and down movements. Time-frequency multiresolution analysis based on wavelet scalograms is used to obtain features from channel state information values, along with spectrograms from radar signals for head movement detection. Feature fusion of both radar and Wi-Fi signals is performed with state-of-the-art DL models. A high classification accuracy of 83.33% and 91.8% is achieved overall with the fusion of VGG16 and InceptionV3 model features trained on radar and Wi-Fi time-frequency maps with and without the walls, respectively.

وصف الملف: application/pdf

العلاقة: https://researchonline.gcu.ac.uk/en/publications/c9dba7b3-e4d1-41ee-866f-ec0b1e43f2a1Test

الإتاحة: https://doi.org/10.1109/JSEN.2023.3337515Test
https://researchonline.gcu.ac.uk/en/publications/c9dba7b3-e4d1-41ee-866f-ec0b1e43f2a1Test
https://researchonline.gcu.ac.uk/ws/files/82507984/82480190.pdfTest

المؤلفون: Peng Fei Hu, Kwok Wa Leung, Kwai Man Luk, Yong Mei Pan, Shao Yong Zheng

المصدر: Engineering, Vol 23, Iss , Pp 157-169 (2023)

مصطلحات موضوعية: Wireless fidelity, Diversity antennas, Multi-frequency, Glass, Dielectric resonator antennas, Multiple-input multiple-output, Engineering (General). Civil engineering (General), TA1-2040

الوصف: This paper investigates two novel polarization- and pattern-diversity glass dielectric resonator antennas (DRAs), both of which are for tri-band (2.4, 5.2, and 5.8 GHz) wireless fidelity (WiFi) applications. It also investigates what type of diversity antenna is most suitable for WiFi router applications by comparing the two DRAs, along with a new space-diversity glass DRA. These three diversity glass DRAs are also compared with a commercial space-diversity monopole pair to benchmark the performance of the glass DRA in WiFi router applications. In our polarization-diversity antenna, a double-port feeding scheme is developed to excite different DRA modes. The frequencies of the DRA modes are tuned by using a stepped DRA. For the pattern-diversity design, a stacked DRA is introduced to broaden the bandwidth for both the conical and broadside radiation modes. All three of the new diversity antennas were fabricated and measured to verify the simulations. In our experiment, the bit error rate (BER) of the three diversity glass antennas and the reference space-diversity monopole antenna was also measured, and the results are compared and discussed. It is found that the polarization-diversity omnidirectional DRA has the most stable BER among the three.

وصف الملف: electronic resource

العلاقة: http://www.sciencedirect.com/science/article/pii/S2095809922007573Test; https://doaj.org/toc/2095-8099Test

الوصول الحر: https://doaj.org/article/f7969b3592f742a1a42489d6bfa2dcc3Test

المؤلفون: Hansini Vijayaraghavan, Jorg Von Mankowski, Carmen Mas-Machuca, Wolfgang Kellerer

المصدر: IEEE Access, Vol 11, Pp 115415-115429 (2023)

مصطلحات موضوعية: Access point placement, light fidelity (LiFi), multi-objective optimization, wireless fidelity (WiFi), Electrical engineering. Electronics. Nuclear engineering, TK1-9971

الوصف: This paper presents PlaciFi, a comprehensive framework for orchestrating optimal 3D Access Point (AP) placement in LiFi-WiFi heterogeneous networks. Integrating LiFi and WiFi technologies allows leveraging of their strengths in different use cases and environments. This has resulted in new challenges in the effective deployment of APs. To address these challenges, PlaciFi extends traditional network planning approaches by incorporating the three-dimensional positioning of APs. The framework formulates a multi-objective optimization problem to minimize the AP count and maximize the rate coverage while considering illumination uniformity constraints for consistent illumination throughout the coverage area. PlaciFi introduces the consideration of user technology occurrence probability to tailor AP placement based on user requirements, improving network performance and user satisfaction. Various solution methods, including heuristics, meta-heuristics, and off-the-shelf solvers, are explored to offer flexibility to network planners. Through extensive evaluations and simulations, PlaciFi demonstrates its effectiveness in achieving optimal AP placement, balancing infrastructure costs and network performance. The contributions of PlaciFi advance the field of network planning in LiFi-WiFi heterogeneous networks, enabling the deployment of efficient and reliable networks.

وصف الملف: electronic resource

العلاقة: https://ieeexplore.ieee.org/document/10286480Test/; https://doaj.org/toc/2169-3536Test

الوصول الحر: https://doaj.org/article/1735934f835b460b86d652d99f1835ecTest

المؤلفون: Fahimeh Aghaei, Hossien B. Eldeeb, Lina Bariah, Sami Muhaidat, Murat Uysal

المصدر: IEEE Access, Vol 11, Pp 90345-90357 (2023)

مصطلحات موضوعية: Radio frequency (RF), visible light communication (VLC), hybrid RF/VLC, wireless fidelity (Wi-Fi), hybrid networks, hybrid RF/VLC environments, Electrical engineering. Electronics. Nuclear engineering, TK1-9971

الوصف: The demand for ultra-high-speed indoor wireless connectivity is ever-increasing, which poses unique challenges for the next generation wireless communication system design. This has prompted the exploration of higher frequency bands including millimeter wave (MMW) and visible light bands in addition to the conventional sub-6 GHz band. This paper provides a comprehensive comparison of the propagation channels of these frequency bands under the same indoor environment and scenarios. We adopt ray tracing techniques for site-specific channel modeling, which enables the consideration of the three-dimensional models of the indoor environment and objects inside. It allows us to take into account different frequencies, i.e., 2.4 GHz, 6 GHz, 28 GHz, 60 GHz, 100 GHz, and visible light band as well as different transmitter types, i.e., omnidirectional/directional antennas for radio frequency systems and indoor luminaries for visible light communications (VLC). For different frequencies under consideration, we obtain channel impulse responses (CIRs) and present the channel path losses for various user trajectories in indoor environments. Furthermore, we propose closed-form expressions for the cumulative distribution functions (CDFs) of received power levels for all frequency bands under consideration. Our results demonstrate that VLC channels exhibit lower path loss than that in MMW bands but higher than that of 2.4 GHz band. In addition, it is observed that VLC systems exhibit more sensitivity to shadowing and blockage effects. Our findings further indicate that the characteristics of the propagation channel are greatly influenced by the antenna type. For instance, using omnidirectional and rectangular patch antennas results in lower path loss compared to horn antennas, and this difference becomes more significant as the transmission distance decreases.

وصف الملف: electronic resource

العلاقة: https://ieeexplore.ieee.org/document/10225534Test/; https://doaj.org/toc/2169-3536Test

الوصول الحر: https://doaj.org/article/cd90206c81d44a86ac376e6be40954faTest

المؤلفون: Castiglione, Luca Maria, Falcone, Paolo, 1977, Petrillo, Alberto, Romano, Simon Pietro, Santini, S.

المصدر: IEEE/ACM Transactions on Networking. 29(1):303-317

مصطلحات موضوعية: Wireless fidelity, performance measurements, distributed control and coordination, Autonomous vehicles, Real-time systems, 5G networks, Reliability, Junctions, Safety, network-based communication, 5G mobile communication

الوصف: IEEE Autonomous driving is a safety critical application of sensing and decision-making technologies. Communication technologies extend the awareness capabilities of vehicles, beyond what is achievable with the on-board systems only. Nonetheless, issues typically related to wireless networking must be taken into account when designing safe and reliable autonomous systems. The aim of this work is to present a control algorithm and a communication paradigm over 5G networks for negotiating traffic junctions in urban areas. The proposed control framework has been shown to converge in a finite time and the supporting communication software has been designed with the objective of minimizing communication delays. At the same time, the underlying network guarantees reliability of the communication. The proposed framework has been successfully deployed and tested, in partnership with Ericsson AB, at the AstaZero proving ground in Goteborg, Sweden. In our experiments, three heterogeneous autonomous vehicles successfully drove through a 4-way intersection of 235 square meters in an urban scenario.

وصف الملف: electronic

الوصول الحر: https://research.chalmers.se/publication/521353Test
https://research.chalmers.se/publication/521353/file/521353_Fulltext.pdfTest