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Summary: The rapid growth in wireless communication technology and the proliferation of multimedia applications, specifically Voice over Wireless Fidelity (VoWiFi), necessitate the exploration of innovative techniques for improving network performance and quality‐of‐service (QoS). This research paper presents an innovative approach to enhance VoWiFi cell capacity using aggregate medium access control protocol data unit (A‐MPDU) frame aggregation for variable bit rate (VBR) traffic. In this research article, we investigated the effect that the retransmission of voice packets has on the cell capacity of a wireless local area network (WLAN) standard that provides VoWiFi service while taking into account the A‐MPDU approach. When taking into consideration the constant bit rate (CBR) and VBR traffics, we compared the results obtained using WiFi 6 (i.e., IEEE 802.11ax) with older WLAN standards such as IEEE 802.11b/g/n/ac. [ABSTRACT FROM AUTHOR]

Network traffic and load are only expected to increase. Data is lost while being sent between nodes and devices as a result of traffic congestion at bottlenecks. WLANs are becoming the go-to technology for access in hotspot locations, workplaces, and residences. A station in a wireless local area network may be able to connect to several access points (APs). So, deciding which AP is "optimum" from a selection of potential candidates is a pertinent question. The user merely associates the AP with the strongest received signal strength while using IEEE 802.11. But this could lead to a substantial load imbalance among a number of APs. With only a minor modification to the load distribution mechanism, adopting load balancing can improve efficiency and utilization in addition to reducing processing delays. To increase the effectiveness of the WLAN, we provide a dynamic load balancing strategy in this paper. The network and user overhead will be reduced by the suggested dynamic strategy. The suggested method utilizes network load and throughput as performance criteria for performing load balancing. The method's viability is checked using Riverbed Modeller Simulator. The experimental findings validate the effectiveness of the proposed technique in enhancing network throughput and reducing access point congestion. [ABSTRACT FROM AUTHOR]

This paper presents a dual-band 8-port multiple-input multiple-output (MIMO) antenna specifically designed for fifth-generation (5G) smartphones, featuring two open-slot metal frames. To enhance impedance matching and improve isolation between adjacent antenna elements, each antenna element employed a coupling feed. All simulation results in this paper come from Ansys HFSS. The operational frequency bands of the proposed antenna spanned 3.36–4.2 GHz for the lower band and 4.37–5.95 GHz for the higher band, covering 5G New Radio (NR) bands N78 (3.4–3.6 GHz) and N79 (4.4–4.9 GHz), as well as WiFi 5 (5.15–5.85 GHz). Notably, the antenna demonstrated outstanding isolation exceeding 16.5 dB within the specified operating bands. The exceptional performance positions the proposed antenna as a promising candidate for integration into 5G metal-frame smartphones. [ABSTRACT FROM AUTHOR]

This article proposes a versatile Multiple Input Multiple Output (MIMO) antenna designed for contemporary wireless systems spanning frequencies from 3 to 20 GHz. It serves applications such as 5G mobile, WiFi, WiFi-6E, X-band, partial Ku, and K-band. The original single-element antenna evolves into a 4 × 4 MIMO configuration with optimized ground plane modifications for enhanced performance. A decoupling structure achieves over 20 dB isolation between inter-elements. The feeding structure, featuring a gradually changing design connected to the antenna's radiating structure, achieves wide bandwidth characteristics. This is further improved by a partial ground structure and slots on the radiating element. The lower frequency band of 3 to 7 GHz is attained with a rectangle-shaped radiator, while semi-circular microstrip lines atop the radiator enable the higher frequency bands of 8 to 15.4 and 18.7 to 20 GHz. The slots and ground structure enhance impedance bandwidth, and semicircles improve the radiation pattern. The MIMO antenna demonstrates measured peak gains of 6.23 dBi at 11.5 GHz, maintaining a radiation efficiency exceeding 80%. Validation through metrics like ECC, DG, CCL, and TARC confirms strong agreement between simulated and experimental results, positioning the MIMO antenna as a robust choice for various wireless communication applications. [ABSTRACT FROM AUTHOR]

In a dense IEEE 802.11 WLAN, arranging multiple access points (APs) to achieve suitable area coverage is an urgent problem that needs to be addressed. This paper proposes an elaborate AP selection strategy based on three types of criteria. Furthermore, to effectively implement the selection process, the AP selection decision is modeled as a limited non-cooperative game scheme, and a two-tier approximation game is adopted to determine the final selection decision for a centralized framework. Specifically, a criterion for guaranteeing wireless station (WS) fairness is proposed to realize AP selection. This algorithm takes into account the varying throughput requirements of WSs and maximizes the total throughput Quality of Service (throughput-QoS) of all WSs, thereby enhancing WS satisfaction. Additionally, this paper introduces a load-balancing AP selection algorithm aimed at enhancing network load balancing. In this algorithm, the load balancing index is optimized to distribute the load evenly among APs, thus enhancing resource utilization within the network. Moreover, a joint optimization AP selection algorithm is presented. It employs a joint optimization index to measure the comprehensive performance of the network, striking a balance between average network throughput-QoS and load balancing. Numerical simulations prove the effectiveness of the proposed AP selection strategy incorporating three different criteria. Under larger number of WS, they can improve total throughput-QoS 10%, make load balancing and multi-attribute weighted index reach 0.9770 and 0.6356, respectively. [ABSTRACT FROM AUTHOR]

We introduce the latest trends in the Institute of Electrical and Electronics Engineers (IEEE) 802.11be (11be), which will be the main standard of the next generation of wireless local area networks (LANs), and the IEEE 802.11bn (11bn), the following primary standard of 11be. The IEEE 802.11 standard is the most used unlicensed wireless LAN system globally, recognized as Wi-Fi. Wi-Fi is implemented in laptop computers and smartphones, Internet of Things devices, and home appliances. Its usage models also extend from consumer markets to business solutions such as industrial automation and intelligent agriculture in the 11bn era. [ABSTRACT FROM AUTHOR]

The IEEE 802.11 standard provides multi-rate support for different versions. As there is no specification on the dynamic strategy to adjust the rate, different rate adaptation algorithms are applied according to different manufacturers. Therefore, it is often hard to interpret the performance discrepancy of various devices. Moreover, the ever-changing channels always challenge the rate adaptation, especially in the scenario with scarce spectrum and low SNR. As a result, it is important to sense the radio environment cognitively and reduce the unnecessary oscillation of the transmission rate. In this paper, we propose an environment-aware robust (EAR) algorithm. This algorithm employs an occasional small packet, designs a rate scheme adaptive to the environment, and enhances the robustness. We verify the throughput of EAR using network simulator NS-3 in terms of station number, motion speed and node distance. We also compare the proposed algorithm with three benchmark methods: AARF, RBAR and CHARM. Simulation results demonstrate that EAR outperforms other algorithms in several wireless environments, greatly improving the system robustness and throughput. [ABSTRACT FROM AUTHOR]

The object of research is IEEE 802.11 (Wi-Fi) networks, which are often the targets of a group of attacks called "evil twin". Research into this area is extremely important because Wi-Fi technology is a very common method of connecting to a network and is usually the first target of cybercriminals when they attack businesses. With the help of a systematic analysis of the literature focused on countering attacks of the "evil twin" type, this work identifies the main advantages of using artificial intelligence systems in the analysis of network data and identification of intrusions in Wi-Fi networks. To evaluate the effectiveness of intrusion detection and cybercrime analysis, a number of experiments as close as possible to real attacks on Wi-Fi networks were conducted. As part of the research reported in this paper, a method is proposed for detecting cybercrimes in IEEE 802.11 (Wi-Fi) wireless networks using artificial intelligence, namely a model built on the basis of the k-nearest neighbors method. This method is based on the classification of previously collected data, namely the signal strength from the access point, and then continuous comparison of the newly collected data with the trained model. A compact and energy-efficient prototype of a hardware and software system has been designed for the implementation of monitoring, analysis of ethernet network packets and data storage based on time series. In order to reduce the load on the computer network and taking into account the limited computing power of the system, a method of data aggregation was proposed, which ensures fast transfer of information. The results, namely 100 % of test cases (more than 7 thousand), were classified correctly, which indicates that the chosen method of data analysis will significantly increase the security of information and communication systems at the state and private levels. [ABSTRACT FROM AUTHOR]

Impersonation-based attacks on wireless networks are easy to perform and can significantly impact network security. Their detection is problematic due to the attacks utilizing legitimate functions. This paper proposes a novel algorithm based on Observe-Orientate-Decide-Act (OODA) loop and Cyber Kill Chain (CKC) strategies to detect and neutralize these attacks. To evaluate this approach, we conducted experiments using four attack methods on a wireless router equivalent device, five wireless client devices, and two attack devices. The system employs a Radio Frequency (RF) device identification system and attack state machine implemented using a Software Defined Networking (SDN) architecture and the P4 programming language. The technique remains compliant with the IEEE 802.11 standard and requires no client-side modifications. The results show that the RF section detected 97.5% (average) of impersonated frames, and the overall method neutralized all attacks in the four attack scenarios. This outcome demonstrates that this technique, built on the OODA loops and CKC methodology, using SDN architecture and P4, is suitable for real-time detection and prevention of wireless impersonation attacks. [ABSTRACT FROM AUTHOR]

The objective of this study is developing a new wireless sensor network strategy for analogue measurements to monitor and mitigate natural hazard. The manuscript presents a novel solution for performing analogue measurements during natural hazards through a wireless sensor network that supports mesh topologies. It is based on the Open Link State Routing (OLSR) protocol for routing data through a set of routers supporting every version of the IEEE 802.11 standard (WiFi), from a to ax. In order to overcome every limitation in previous wireless systems, the article presents an overview of existing mesh technologies for microcontroller-based architecture (IEEE 802.15.4) and CPU-based architecture (IEEE 802.11), mainly dedicated to seismic or volcanic hazards. We highlight each of the decisive advantages of the presented technology compared to previous hazard monitoring systems. The new technology purposes multiple topologies, modern network performances and original measurement in real case scenarios, with a same generic solution adaptable to several natural hazards. Topology tests and outdoor experiments were performed in open air; the latter provided analogue measurements in the context of a prescribed vegetation fire and river. These results are discussed in terms of the network latency, user mobility, and measurement uncertainties. Finally, the manuscript concludes with an outlook offered by the novel system for a better understanding of mitigating extreme natural events. [ABSTRACT FROM AUTHOR]

In this paper, an ultra-miniaturized triple-band antenna based on an epsilon negative transmission line (ENG-TL) approach is presented. The proposed antenna has a miniaturized electrical size of 0.247λ0×0.185λ0×0.019λ0 at 3.71 GHz which has been achieved by means of zeroth-order resonance (ZOR). This is recognized as an attractive technique to achieve compactness. It is observed from measured results that the proposed antenna is performing well over 3.63–3.81, 5.21–5.33, and 6.79–7.09 GHz. The novelty of this work lies in the fact that the peak gain has been improved by 1.73 dBi at the lowest order resonant mode. The antenna is able to exhibit measured peak gain of 1.97, 1.09, and 3.42 dBi in the broadside direction at 3.72, 5.27, and 6.92 GHz, respectively. Hence proposed antenna is suitable to work for Wi-MAX 3.5 GHz (3.4–3.8 GHz), WLAN/Wi-Fi 5.2 GHz (5.15–5.35 GHz), mobile/satellite (E-S) (6.875–7.075 GHz) applications. [ABSTRACT FROM AUTHOR]

This paper design and analyses the performance of various hexagonal-shaped metamaterial structures used in the design of band-stop filters (BSFs). This is a comparative study of metamaterial-based BSFs using different resonators like Hexagonal Split Ring Resonator (HSRR), Hexagonal Metamaterial Cell (HMC) or Novel Hexagonal Metamaterial Cell (NHMC). According to IEEE 802.11 standards, the proposed design of the BSF for the 2.4 and 3.6 GHz frequency bands for WLAN and Wi-Fi applications. The proposed NHMCbased BSF shows a reduction in overall size by up to 35%—compared to the HSRR- and HMCbased filters—and a good rejection level of up to 26 dB.The proposed NHMC-based filter design is unique because it is compact and presents sharp rejection and low insertion loss (IL) when compared to previous literature. There is good agreement between the fabricated and the measured results. [ABSTRACT FROM AUTHOR]

The healthcare Internet of Things (H-IoT) is an interconnection of devices capable of sensing and transmitting information that conveys the status of an individual's health. The continuous monitoring of an individual's health for disease diagnosis and early detection is an important application of H-IoT. Ambient assisted living (AAL) entails monitoring a patient's health to ensure their well-being. However, ensuring a limit on transmission delays is an essential requirement of such monitoring systems. The uplink (UL) transmission during the orthogonal frequency division multiple access (OFDMA) in the wireless local area networks (WLANs) can incur a delay which may not be acceptable for delay-sensitive applications such as H-IoT due to their random nature. Therefore, we propose a UL OFDMA scheduler for the next Wireless Fidelity (Wi-Fi) standard, the IEEE 802.11be, that is compliant with the latency requirements for healthcare applications. The scheduler allocates the channel resources for UL transmission taking into consideration the traffic class or access category. The results demonstrate that the proposed scheduler can achieve the required latency for H-IoT applications. Additionally, the performance in terms of fairness and throughput is also superior to state-of-the-art schedulers. [ABSTRACT FROM AUTHOR]

This paper presents the performance comparison of a dual-band conventional antenna with a split-ring resonator (SRR)- and electromagnetic bandgap (EBG)-based dual-band design operating at 2.4 GHz and 5.4 GHz. The compactness and dual-frequency operation in the legacy Wi-Fi range of this design make it highly favorable for wearable sensor network-based Internet of Things (IoT) applications. Considering the current need for wearable antennas, wash cotton (with a relative permittivity of 1.51) is used as a substrate material for both conventional and metamaterial-based antennas. The radiation characteristics of the conventional antenna are compared with the EBG and SRR ground planes-based antennas in terms of return loss, gain, and efficiency. It is found that the SRR-based antenna is more efficient in terms of gain and surface wave suppression as well as more compact in comparison with its two counterparts. The compared results are found to be based on two distinct frequency ranges, namely, 2.4 GHz and 5.4 GHz. The suggested SRR-based antenna exhibits improved performance at 5.4 GHz, with gains of 7.39 dbi, bandwidths of 374 MHz, total efficiencies of 64.7%, and HPBWs of 43.2 degrees. The measurements made in bent condition are 6.22 db, 313 MHz, 52.45%, and 22.3 degrees, respectively. The three considered antennas (conventional, EBG-based, and SRR-based) are designed with a compact size to be well-suited for biomedical sensors, and specific absorption rate (SAR) analysis is performed to ensure user safety. In addition, the performance of the proposed antenna under bending conditions is also considered to present a realistic approach for a practical antenna design. [ABSTRACT FROM AUTHOR]

Currently, several, more or less, suitable means for detecting, identifying and monitoring the position of housed animals exist. However, these means suffer from various limitations, which could be eliminated with regard to the current technical and technological possibilities. One possible solution could be the use of some wireless technologies from the Internet of Things (Wi-Fi, Bluetooth, Zigbee, etc.). The uninterrupted supervision of individual housed animals would bring important information about the daily routine of individuals and then, based on the deviations from this daily routine, the opportunity to derive their physical and mental state from these deviations would be potentially possible. This article presents a proof of concept of a low-cost monitoring system of the movement of housed animals. The proposed system is able to detect the client's (prototype's) position in the space by means of Wi-Fi (IEEE 802.11 standard) and received signal strength indication (RSSI) technologies. A fingerprint method and a triangulation method of analysing the space are used to calculate the position in space with a resulting accuracy within metres of the real position. [ABSTRACT FROM AUTHOR]

Wireless technologies are essential for modern people to maintain uninterrupted connection to the Internet. The most popular standards for wireless technologies are standards of the IEEE 802.11 family. Currently, data transmission rate achievable by IEEE 802.11ac or 802.11ax standards can reach up to 10 Gbit/s. Different IEEE standards have specific data transmission rates. For example, the IEEE 802.11ah standard or Wi-Fi HaLow (code name) operates in the 900 MHz band, which is an unlicensed frequency band below 1 GHz, and is called the "Sub-1-GHz" range. In theory, this standard can provide coverage range of up to 543 meters indoors and data transfer rate of up to 347 Mbit/s (using a maximum of four spatial streams and 16 MHz channel bandwidth). The great benefit of the 802.11ah standard is low energy consumption, which enables communication between devices from the Internet of Things (IoT) over long distances without using a lot of energy. The Wi-Fi HaLow standard is being studied by the authors of the presented article in the ns-3 network simulation program with the 802.11ah module installed and implemented in Docker containers, VirtualBox Virtual Machines (VMs) with a running Linux operating system. During the simulations, results were obtained for the Docker containers simulation with a limited number of stations over different simulation times. These results have been studied in different scenarios. In the scenarios, the results of the Wi-Fi HaLow network simulation were converted into another simulation time, and thus were compared with each other. [ABSTRACT FROM AUTHOR]

Energy-efficient communication technologies are a key enabler for many IoT applications. Many existing communication protocols are based on duty-cycling techniques, that have an inherent tradeoff between delay and energy consumption. In the field of sensor networks, wake-up receivers have been investigated to overcome these problems and to further reduce energy consumption. We now go one step further and investigate the use of wake-up receivers in combination with IEEE 802.11 WLAN. We extend the protocol used to communicate between the access point and the client to introduce a wake-up signal. This can be implemented in a way that is fully compatible with existing wireless LAN (WLAN) standards, thus, it can be deployed gradually with little effort and no need to change existing systems. As a proof of concept and to perform first lab experiments, we developed a hardware prototype using a selective wake-up receiver and off-the-shelf USB-WLAN dongles. All experimental results are verified using an analytical model and a detailed simulation study. We show that our wake-up WLAN can provide connectivity for low-power devices with low delays and low energy consumption at the same time. [ABSTRACT FROM AUTHOR]

The Complementary Split-Ring Resonator (CSRR)-loaded crescent slot circular antenna is presented in this paper. The proposed antenna is resonating at 2.4 GHz with the gain of 2.38 dB. The antenna is designed for a predefined shape, which has a crescent slot, star-shaped small slots and spline split on a circle. The CSRR is carved on the ground surface of the antenna to acquire 2.4 GHz and eliminates the multiple resonances created by various slots. The CSRR provides the miniaturization by shifting the resonance from 2.59 GHz to 2.4 GHz. The measured, − 6 dB impedance bandwidth of the antenna is 11.25%. The antenna is fabricated using an FR4 ( ε r = 4. 4) substrate. The proposed crescent slot circular antenna is simulated using Ansys HFSS 17.0. [ABSTRACT FROM AUTHOR]

In nonsaturated 802.11 distributed coordination function (DCF) networks, existing studies had observed a salient phenomenon: the maximum stable throughput may be far higher than the saturation throughput and last for a long duration (say, months). Such a maximum stable throughput is called the presaturation throughput peak. The long-duration peak suggests that 802.11 DCF networks may provide a far higher stable throughput than what we generally believe, without worrying about a sudden deterioration of quality of service (QoS). This paper is devoted to developing a general theoretical framework to predict the peak. In the framework, we define a backoff entropy to quantify the uncertainty of the inherent random backoff process of 802.11 DCF networks, and then innovatively introduce a BackoffEntropy-Peak linearity property (i.e., the peak is linearly proportional to the backoff entropy) for the peak prediction. This framework is applicable for a general configuration of contention windows (CWs). It enables us to reveal the most essential dependency of the peak on the initial CW size and the number of network nodes. Further, we design peak-based call admission control (CAC) schemes that can be performed quickly and easily, without requiring network performance measurements and complex calculations. We verify our framework and CAC schemes via widely adopted 802.11 DCF ns2 and ns3 simulators (mostly with typical 802.11 standard settings). Extensive simulations show that our framework and CAC schemes trade within 9% peak prediction errors for making 802.11 DCF networks provide high stable throughput with good QoS (such as short delay and low collision probability). This paper is the first to propose applying the information entropy to study the throughput-stability problem. We believe that this study makes a crucial breakthrough in thoroughly investigating nonsaturated performance and network stability of random access wireless networks. [ABSTRACT FROM AUTHOR]

The IEEE 802.11 MAC protocols have been implemented in many wireless ad hoc and infrastructure networks. Most of the IEEE 802.11-based networks adopt a one-hop transmission mechanism (the source and destination communicate using a direct link). While this strategy is simple, it degrades network performance as it limits the number of data transmissions that can concurrently take place. The performance of IEEE 802.11 MAC in terms of delay and overall achieved throughput can be improved when the overall transmission time for each data transmission from the access point (AP) to any node in the network is minimized. Occupying the time-frequency resources for a shorter time period results in more available resources for other potential downlink transmissions to take place. In this work, we present a modified MAC protocol for IEEE 802.11 infrastructure-based networks with device-to-device transmission strategy. The main goal of our proposed protocol is to minimize the transmission time for individual downlink transmissions while maximizing the utilization of network resources by using D2D multi-hop transmissions, thereby improving the overall achieved throughput. In our proposed mechanism, the AP selects the multi-hop path that requires the minimum transmission time to deliver the data packets to destination. This path is selected even though the direct path exists. Compared to the IEEE 802.11 standard, simulation results show significant performance improvements in terms of throughput and fairness. [ABSTRACT FROM AUTHOR]

To determine the optimal network architecture between the Basic Service Set, the Extended Service Set and the Independent Basic Service Set, this study established a new algorithm to assess Voice over Internet Protocol (VoIP) metrics of different IEEE 802.11 technologies. An important coefficient for each VoIP metric parameter has been invented to rank the different IEEE 802.11 standards and to identify the most efficient one for the VoIP application. The best overall network performance that offers good voice quality is ensured by determining the optimum network architecture and technology. Moreover, for the VoIP efficiency parameters, it meets the acceptance threshold values. This algorithm was implemented in different sizes of rooms ranging from 1 × 1 m to 10 × 10 m, and the number of nodes varied from 1 to 65. End to end delay, jitter, throughput and packet loss were the quality of service parameters used. [ABSTRACT FROM AUTHOR]

IEEE 802.11ax as the newest wireless local area networks (WLANs) standard brings enormous improvements in network throughput, coverage and energy efficiency in densely populated areas. Unlike previous IEEE 802.11 WLAN standards where power saving mechanisms have a limited capability and flexibility, 802.11ax comes with a different mechanism called target wake time (TWT) where stations (STAs) wake up only after each TWT interval and different STAs can wake up at different time instance depending on their application requirements. As an example, for a periodic data arrival occurring in IoT applications, STA can wake up by following the data period and go to sleep mode for a much longer time, and STAs with high traffic volume can have shorter TWT interval to wake up more frequently. Moreover, as multiuser transmission capability is added to 802.11ax, multiple STAs can have the same TWT interval and wake up at the same time, and hence there is a great opportunity to have collision-free transmission by scheduling multiple STAs on appreciate TWT intervals to reduce energy consumption and also increase network throughput. In this paper, we investigate the problem of STAs scheduling and TWT interval assignment together to reduce overall energy consumption of the network. We propose an algorithm that dynamically selects STAs to be served and assigns the most suitable TWT interval given STAs’ traffic and channel conditions. We analyze our algorithm through Lyapunov optimization framework and show that our algorithm is arbitrarily close to the optimal performance at the price of increased queue sizes. Simulation results show that our algorithm consumes less power and support higher traffic compared to a benchmark algorithm that operates randomly for TWT assignment [ABSTRACT FROM AUTHOR]

As a complementary technology to existing Radio Frequency (RF)-based solutions such as Cellular V2X (C-V2X) and Dedicated Short Range Communication (DSRC), Vehicular VLC (V-VLC) is gaining more attention in the research community as well as in the industry. This paper introduces a complete IEEE 802.11 compliant V-VLC system. The system relies on Universal Software Radio Peripheral (USRP) software defined radios programmed using the GNU Radio framework, a typical car headlight plus a custom driver electronics for the high-power car LEDs (sender), and a photodiode (receiver). Building upon our earlier work, we, for the first time, experimentally explore the communication performance in outdoor scenarios, even in broad daylight, and show that rather simple optical modifications help to reduce the ambient noise to enable long distance visible light communication. Our system also supports Orthogonal Frequency-Division Multiplexing (OFDM) with a variety of Modulation and Coding Schemes (MCS) up to 64-QAM and is fully compliant with IEEE 802.11. We performed an extensive series of experiments to explore the performance of our system, even using higher order MCS in daylight. Our results demonstrated a high reliability for distances up to 75m with the presented system, regardless of the time of the day. [ABSTRACT FROM AUTHOR]

Agricultural mechanization has become the main mode of agricultural production and represents the development direction of modern agriculture. The amount of data generated in the agricultural production process is extremely huge, so it is necessary to introduce the concept and analysis method of big data. Combining agricultural robots with big data can improve the performance and application effect of robots. This paper combines big data, WLAN technology and robot technology to realize man-machine remote cooperation platform. This gives full play to the advantages that people are good at object recognition and robots are good at execution, and improves the fruit picking efficiency. The target fruit positioning and recognition system aided by machine vision is adopted to realize the accurate positioning of the fruit to be picked. Design of LFM control signal fitting based on big data clustering. In order to verify the feasibility of the scheme, taking the tomato picking robot as an example, the communication error and control accuracy using big data and WIFI (Wireless Fidelity) technology were tested, and the positioning and navigation efficiency with and without remote monitoring system was compared. Test results show that using big data and WIFI remote monitoring technology can effectively improve the efficiency and accuracy of positioning and navigation of remote operating system, which is of great significance for the design of automatic control system of picking robot. [ABSTRACT FROM AUTHOR]

Wireless technologies are continuously evolving, including features such as the extension to mid- and long-range communications and the support of an increasing number of devices. However, longer ranges increase the probability of suffering from hidden terminal issues. In the particular case of Wireless Local Area Networks (WLANs), the use of Quality of Service (QoS) mechanisms introduced in IEEE 802.11e compromises scalability, exacerbates the hidden node problem, and creates congestion as the number of users and the variety of services in the network grow. In this context, this paper presents a configurable Colored Petri Net (CPN) model for the IEEE 802.11e protocol with the aim of analyzing the QoS support in mid- and long-range WLANs The CPN model covers the behavior of the protocol in the presence of hidden nodes to examine the performance of the RTS/CTS exchange in scenarios where the QoS differentiation may involve massive collision chains and high delays. Our CPN model sets the basis for further exploring the performance of the various mechanisms defined by the IEEE 802.11 standard. We then use this CPN model to provide a comprehensive study of the effectiveness of this protocol by using the simulation and monitoring capabilities of CPN Tools. [ABSTRACT FROM AUTHOR]

The IEEE 802.11 standard for wireless local area networking (WLAN), commercially known as Wi-Fi, has become a necessity in our day-to-day life. Over a billion Wi-Fi access points connect close to hundred billion of IoT devices, smart phones, tablets, laptops, desktops, smart TVs, video cameras, monitors, printers, and other consumer devices to the Internet to enable millions of applications to reach everyone, everywhere. The evolution of Wi-Fi technology also resulted in the first commercial piloting of spread spectrum, high speed optical communications, OFDM, MIMO and mmWave pulse transmission technologies, which then became more broadly adopted by cellular phone and wireless sensor networking industries. The popularity and widespread Wi-Fi deployment in indoor areas further motivated innovation in opportunistic cyberspace applications that exploit the ubiquitous Wi-Fi signals. The RF signal radiated from Wi-Fi access points creates an "RF cloud" accessible to any Wi-Fi equipped device hosting or supporting these opportunistic applications. Wi-Fi positioning and location intelligence were the first popular opportunistic applications of Wi-Fi's RF cloud. Today, researchers are investigating opportunistic applications of Wi-Fi signals for gesture and motion detection as well as authentication and security. This paper provides a holistic overview of the evolution of Wi-Fi technology and its applications as the authors experienced it in the last few decades. [ABSTRACT FROM AUTHOR]

A composite right/left handed (CRLH) metamaterial antenna is proposed in this paper. The antenna is designed for WLAN IEEE 802.11 standard; where bands 2.4 GHz usage frequency 2401–2495 MHz and 5 GHz usage frequency 5170–5875 MHz worldwide. A composite right left handed metamaterial has combined effect of right handed and left handed metamaterial and which creates dual band resonance in the antenna. By providing shorting pin loading at edge of the radiating metal, the left handed metamaterial property is created in the antenna. The antenna occupies rectangular area of 38.2 × 29.1 mm 2 and 6 mm air gap from ground plane. The return loss of - 10 dB is achieved over the bandwidth with promising peak gain of 2.3 dBi and 8.6 dBi for 2.4 GHz and 5 GHz band, respectively. The antenna is fabricated, and measured values are closely matching with simulation results. The proposed antenna has orthogonal radiation patterns and maximum efficiency of 84.2% and 90.3% for dual frequencies. [ABSTRACT FROM AUTHOR]

In this article, a simple design of stacked radiating system with enhanced gain, impedance bandwidth, and radiation efficiency for mobile base station application is presented. The proposed antenna consists of a driven patch with a semicircular parasitic patch printed on the bottom layer and five parasitic patches printed on the top layer. The driven patch is feed by a co-axial probe and both the layers are separated in air. The second layer has four truncated circular parasitic patches on one side and one circular patch on the other side to enhance the directive gain acts as a directive reflector. This staked system encompasses some prominent features such as wide bandwidth, good gain, low profile, better radiation efficiency simple design, and integration for the mobile base station. Meanwhile, this configuration exhibits a bandwidth of 2 GHz with the minimized volume is 0.75 λ0 × 0.75 λ0 × 0.08 λ0. Experimentally validated results have an average and peak gain of 10.7 and 12.7 dBi, impedance bandwidth of more than 30.7% for |S11| < −10 dB, and radiation efficiency of above 86%. The proposed stacked radiating system finds its applications in Wi-Fi, WLAN, Wi-Max, Indoor UWB, and Marine Radar applications. [ABSTRACT FROM AUTHOR]

This paper presents a novel, close-packed coplanar waveguide fed Frequency Reconfigurable antenna. The substrate used in the proposed design is Rogers RT/Duroid 5880 with dimensions 15 mm x 8 mm. This has a thickness of 0.508 mm. The dependent variable, resonant frequency, is a function of current distribution which can be organized by integrating two switches on the surface of the antenna. All possible switch positions result in different current distributions which in turn change the resonant frequencies. The antenna design is simulated on Computer Simulation Technology Microwave Studio software (CST MWS). Over desired frequency bands, the presented antenna reveals an exceptional radiation patterns with positive gain. Good agreement between the theoretical and practical results exists with this design. With the proposed portable design, devices can be used for the Aeronautical Radio Navigation (4.3 Ghz), AMT fixed services (4.5 GHz), WLAN (5.2 GHz) Unlicensed WiMAX (5.8 GHz) and C-band Applications. [ABSTRACT FROM AUTHOR]

Metamaterial loaded star-shaped dielectric resonator antenna (SDRA) fed by aperture-coupled mechanism is used for the enhancement of bandwidth and gain. The star-shaped structure is made-up using biodegradable poly-lactic acid having a dielectric constant (εr) of 3.45 and loss tangent (tan δ) of 0.05, which adopt the cost-effective manufacturing i.e. additive manufacturing technique. The alteration in rectangular dielectric resonator antenna to make SDRA is the foundation for broad bandwidth while hybrid exciting-modes are due to feeding of two apertures (slots) of unequal length. Correspondingly, metamaterial i.e. an arrangement of the split-ring resonators have been used for gain enhancement of antenna. The enhanced peak gain of the metamaterial loaded SDRA is more than 12 dBi and the average radiating efficiency is ~ 81%. The proposed antenna attained a broad bandwidth of 41.1% ranging from 4.15 to 6.3 GHz which is suitable for the IEEE 802.11 WLAN standards and C-band wireless communications. The proposed antenna has also offer circularly polarized characteristics at 6 GHz. Thus such an antenna with a trait of circular polarization can be promising for other wireless applications. [ABSTRACT FROM AUTHOR]

Millimeter wave (mmWave) systems have attracted considerable attention as a benefit of their Gbps services. Therefore, wireless-gigabit (WiGig) transmission has been developed based on the IEEE 802.11ad and 802.11ay standards of wireless local area networks (WLANs) in the 60-GHz band. To overcome the high path loss of mmWave, beamforming and beam-sector based training protocols are specified in 802.11ad/ay. With the increase in service demand, more WiGig access points (APs) will be deployed, hence the transmission frame structure of beam control should be adjustable for supporting both multiple APs and multiple users. The conventional exhaustive beam search (EBS) scheme has a potentially excessive complexity for high number of beams. Furthermore, assigning fixed training slots for users will lead to high-latency beam training under EBS. Hence, we design an advanced protocol for multiple APs and multiple users. Based on this protocol, we propose coordinated multiple AP multiuser training (CMMBT) including variable length framing and adjustable beam training. Our simulations demonstrate that CMMBT provides flexible training control and achieves the lowest training latency and highest average throughput performance amongst the state-of-the-art solutions in the open literature. [ABSTRACT FROM AUTHOR]

Wireless video multicast over IEEE 802.11 WLANs is a viable approach to bridging the gap between limited wireless resources and the ever-increasing mobile video traffic demand. However, existing wireless multicast mechanisms have several limitations, such as low spectral efficiency, high feedback overhead, and lack of consideration of the frame aggregation feature of current WLANs. In this paper, we propose FlexVi, a flexible wireless multicast solution for efficient video streaming over WLANs. Considering the frame aggregation of the current WLANs, FlexVi allows an access point to dynamically adjust the data rate on the basis of three factors: available wireless bandwidth, heterogeneity of the channel qualities among the clients, and the priorities among the video frames in terms of video quality. In addition, by harnessing the orthogonality of the subcarriers in the orthogonal frequency division multiplexing, FlexVi enables multiple clients to deliver their feedback to an access point simultaneously without collision, which results in very low feedback overhead. We verified the feasibility of FlexVi through experiments on a software defined radio platform. We also conducted an extensive simulation study and found that FlexVi outperforms the latest wireless multicast mechanisms. [ABSTRACT FROM AUTHOR]

Within realization of the visions of the Internet-of-Things (IoT), Low Power Wide Area Networks (LPWANs) are undoubtedly one of the fields that attract high interest from both academic and industrial fields. To ensure reliable data exchange between low power and low data rate devices across long distances, which are the main aims of LPWAs, it is necessary to utilize advanced wireless communication technologies. Emerging LPWA technologies, for instance Long-Range (LoRa) and SigFox, offer many benefits for IoT. These technologies have been primarily developed for sub-GHz frequency bands, but, in the future, their deployment is also considered in the 2.4 GHz industrial, scientific and medical (ISM) bands. However, these unlicensed ISM bands are also used by other technologies for Wireless Local Area Network (WLAN also denoted as Wi-Fi) connectivity and other services, and therefore, coexistence issues can occur here in the future. The main aim of this paper is to perform a performance analysis of the LoRa radio signals interfered by Wi-Fi, using interferers confirming to different IEEE 802.11 family standards, in the 2.4 GHz ISM band. For this purpose, an automated measurement setup and methodology on Physical (PHY) layer are proposed and used. In general, the evaluated results confirm theoretical assumptions on high robustness of LoRa against interferences. However, our results reveal that this robustness of LoRa is highly depending not only on the used LoRa system parameters, but also on the interferer properties and the assumed coexistence scenarios (co-channel, in-band and adjacent channel interferences). [ABSTRACT FROM AUTHOR]

Current interference management solutions for dense IEEE 802.11 Wireless Local Area Networks (WLANs) rely on locally measuring the cumulative interference at the Acess Point (AP) in charge of adjusting the spectrum resources to its clients. These solutions often result in coarse-grained spectrum allocation that often leaves many wireless users unsatisfied and increases the spectrum congestion problem instead of easing it. In this paper, we present a centralized interference management algorithm that treats the network-wide interference impact of each channel individually and allows the controller to adjust the radio resource of each AP while it is utilised. This coordinated allocation takes into account the Quality of Service (QoS) requirements of downlink flows while minimizing its effect on neighbouring APs. Therefore, this paper proposes a novel approach for quantifying the interference impact of each employed channel and jointly addressing the user-side quality requirements and the network-side interference management. The algorithm is tailored for operator-agnostic Software-Defined Networking (SDN)-based Radio Resource Management (RRM) in dense Wireless Fidelity (Wi-Fi) networks and adopts a fine-grained per-flow approach. Simulation results show that our algorithm outperforms existing solutions in terms of reducing the overall interference, increasing the capacity of the wireless channel, and improving the users’ satisfaction. [ABSTRACT FROM AUTHOR]

Lots of hopes have been placed on machine learning (ML) as a key enabler of future wireless networks. By taking advantage of large volumes of data, ML is expected to deal with the ever-increasing complexity of networking problems. Unfortunately, current networks are not yet prepared to support the ensuing requirements of ML-based applications in terms of data collection, processing, and output distribution. This article points out the architectural requirements that are needed to pervasively include ML as part of future wireless networks operation. Specifically, we look into wireless local area networks (WLANs), which, due to their nature, can be found in multiple forms, ranging from cloud-based to edge-computing-like deployments. In particular, we propose to adopt the International Telecommunication Union (ITU) unified architecture for 5G and beyond. Based on ITU's architecture, we provide insights on the main requirements and the major challenges of introducing ML to the multiple modalities of WLANs. Finally, we showcase the superiority of the architecture through an ML-enabled use case for future networks. [ABSTRACT FROM AUTHOR]

The use of network infrastructures to replace conventional professional audio systems is a rapidly increasing field which is expected to play an important role within the professional audio industry. Currently, the market is dominated by numerous proprietary protocols which do not allow interoperability and do not promote the evolution of this sector. Recent standardization actions are intending to resolve this issue excluding, however, the use of wireless networks. Existing wireless networking technologies are considered unsuitable for supporting real-time audio networks, not because of lack of bandwidth but due to their inefficient congestion control mechanisms in broadcasting. In this paper, we propose an amendment of the IEEE 802.11 MAC that improves the performance of the standard for real-time audio data delivery. The proposed amendment is offering a solution for the balancing of data flow density in wireless ad-hoc networks for a multi-broadcasting environment. It is based on two innovative ideas. First, it provides a protection mechanism for broadcasting and second, it replaces the classic congestion control mechanism, based in random backoff, with an alternative traffic adaptive algorithm, designed to minimize collisions. The proposed MAC is able to operate as an alternative mode allowing regular Wi-Fi networks to coexist and interoperate efficiently with audio networks, with the last ones being able to be deployed over existing wireless network infrastructures. [ABSTRACT FROM AUTHOR]

IEEE 802.11ay defines new PHY and MAC specifications that enable 100 Gb/s communications in the 60 GHz millimeter-wave (mmWave) band. Among the various use cases supported by IEEE 802.11ay, fixed wireless access, a cost-efficient high-performance alternative and/ or complement to conventional fixed access, differentiates itself due to its unique requirements and characteristics. In this article, our goal is to identify and describe key elements incorporated into IEEE 802.11ay, including scheduling, beamforming, and link maintenance, that efficiently support fixed wireless access. IEEE 802.11ay is thus a viable and strong candidate to form the basis of future generations of standards-compliant (i.e., non-proprietary) mmWave fixed wireless access networks. [ABSTRACT FROM AUTHOR]

The asymmetric network model, in which the access point (AP) is full-duplex (FD) capable while the other nodes are only half-duplex (HD) capable, is motivated by early-stage deployments of FD-capable networks. We propose a medium access control (MAC) protocol called asymmetric FD MAC (AFD-MAC) for this model. It leverages features such as random back-off and carrier sensing of the widely-used 802.11 HD MAC protocol, and it introduces two signals to exploit the FD capability of the AP. We also develop a general, network topology-specific renewal-theoretic analysis that characterizes the saturation throughput of AFD-MAC. It captures the differences in the statistical properties of the nodes and the AP due to differences in their duplexing capabilities or the number of hidden nodes. AFD-MAC can increase the throughput by a factor as large as two and can reduce head-of-line delay by a factor more than half compared to the conventional 802.11 HD MAC protocol. The gains depend on the ratio of the uplink to downlink packet lengths, network topology, and the extent of self-interference cancellation. A contrarian insight that emerges is that hidden nodes can enable the network to exploit its asymmetric FD capability. [ABSTRACT FROM AUTHOR]

To meet the rising demand of mobile data, IEEE 802.11ac was recently developed to offer better network performance than previous IEEE 802.11 standards, representing the 5G Wi-Fi technology. One of the new technologies added to IEEE 802.11ac is a dynamic bandwidth channel access scheme that supports channel bonding (CB) with an up to 160 MHz bandwidth. However, the use of CB increases the number of stations sharing the same medium, resulting in an increased collision rate and severe interference caused by overlapping sub-channels. This problem is further aggravated in densely deployed wireless networks where the service ranges of access points (APs) are likely to be highly overlapping. To resolve these issues, we present an analytical throughput model that considers the effect of both collisions and interference. With this analytical model, we formulate the CB problem to optimize the throughput along with the traffic demand and propose a genetic algorithm for solving the problem. Further, a dynamic channel bonding algorithm (named DCB) is proposed to solve the problem with lower complexity. Extensive simulation results demonstrate that our proposed algorithm provides a higher performance than other recent dynamic CB algorithms with respect to the throughput achieved for the traffic demand. [ABSTRACT FROM AUTHOR]