Recently, using Wi-Fi devices as sensing technology has garnered significant attention and found numerous applications. This trend has given birth to what is known as Wi-Fi sensing. This innovative ...approach has been made possible by analyzing the Channel State Information (CSI) of the Wi-Fi communication channel, which can be calculated from the frame preamble. CSI captures multipath effects, attenuations, and phase shifts in signal propagation, among other fading effects caused, for example, by reflection with objects or a person. Extensive research in this field has revealed that these effects can be utilized for sensing purposes, supposing that the cause of the effects is a person, leading to the development of Wi-Fi sensing applications such as Activity Recognition, Gesture Recognition, and Vital Signs monitoring. This Survey highlights recent works and advances in Wi-Fi sensing applications, identifying and exposing significant applications. For each paper selected, the following sections have been emphasized: Data Collection, Data Preprocessing, Detection Algorithm, Performance, and Application, as these are part of the methodology followed for the functioning of Wi-Fi sensing systems. Furthermore, the techniques and tools commonly used in Wi-Fi sensing are described. Finally, the current challenges associated with Wi-Fi as a wireless sensing technology and possible ways to address these challenges are discussed.
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A Wi-Fi scatter communication method based on microcontroller unit (MCU) is proposed, and an ultra-low power micro Wi-Fi scatter communication device μWi-Fi is designed and implemented. First, ...according to the characteristics of the microcontroller, the software virtual modulation method and the serial communication port direct memory access (DMA) transmission method is proposed to realise Wi-Fi scattering communication. Then the MCU + exclusive OR (XOR) baseband architecture is proposed to further reduce the main frequency of the microcontroller and the system power consumption. The communication test and power consumption measurement results show that μWi-Fi can generate signals conforming to the IEEE802.11b standard, which can be received and forwarded by universal Wi-Fi routers. Its effective communication distance reaches 15 m, its communication peak current reaches 720 μA, and its standby current reaches 390 nA. Compared with traditional internet of things (IOTs) Wi-Fi devices, μWi-Fi can not only reduce the power consumption of Wi-Fi communication by 2–3 orders but also has a simple composition and low cost, which is very helpful for the rapid development of Wi-Fi IoT products.
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The rapid development of Wi-Fi technologies in recent years has caused a significant increase in the traffic usage. Hence, knowledge obtained from Wi-Fi network measurements can be helpful for a more ...efficient network management. In this paper, we propose a methodology to predict future values of some specific network metrics (e.g. traffic load, transmission failures, etc.). These predictions may be useful for improving the network performance. After data collection and preprocessing, the correlation between each target access point (AP) and its neighbouring APs is estimated. According to these correlations, either an only-temporal or a spatio-temporal based prediction is done. To evaluate the proposed methodology, real measurements are collected from 100 APs deployed in different university buildings for 3 months. Deep Learning (DL) methods (i.e. Convolutional Neural Network (CNN), Simple Recurrent Neural Network (SRNN), Gated Recurrent Unit (GRU), Long Short-Term Memory (LSTM), Transformer) are evaluated and compared for both temporal and spatio-temporal based predictions. Moreover, a hybrid prediction methodology is proposed using a spatial processing based on CNN and a temporal prediction based on RNN. The proposed hybrid methodology provides an improvement in the prediction accuracy at expenses of a slight increase in the Training Computational Time (TCT) and negligible in Prediction Computational Time (PCT).
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14.
Wi-Fi 6 Application in Iot Environment Péter János, Varga; Illési, Zsolt
Interdisciplinary Description of Complex Systems,
6/2022, Volume:
20, Issue:
3
Journal Article, Paper
Peer reviewed
Open access
When thinking of wireless communication solutions for IoT devices, the 5G networking technology is the first thing that comes to mind. Besides this, one cannot overlook the fact that a new wireless ...communication solution is also available, built on the 802.11ax standard. Until now, wireless networking solutions allowed to manage the simultaneous connections of 250 devices via a single router. Meanwhile, the new technology is designed to support 1024 concurrent connections with one router. This enables the management of a large number of Internet of Things devices in smart homes.
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Indoor positioning and navigation have been attracting interest from the research community for quite some time. Nowadays, new fields, such as the Internet of Things, Industry 4.0, and augmented ...reality, are increasing the demand for indoor positioning solutions capable of delivering specific positioning performances not only in simulation but also in the real world; hence, validation in real-world environments is essential. However, collecting real-world data is a time-consuming and costly endeavor, and many research teams lack the resources to perform experiments across different environments, which are required for high-quality validation. Publicly available datasets are a solution that provides the necessary resources to perform this type of validation and to promote research work reproducibility. Unfortunately, for different reasons, and despite some initiatives promoting data sharing, the number and diversity of datasets available are still very limited. In this paper, we introduce and describe a new public dataset which has the unique characteristic of being collected over a long period (2+ years), and it can be used for different Wi-Fi-based positioning studies. In addition, we also describe the solution (Wireless Sensor Network (WSN) + mobile unit) developed to collect this dataset, allowing researchers to replicate the method and collect similar datasets in other spaces.
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In IEEE 802.11-based access networks (Wi-Fi), the client remains connected to a far-poor Access Point (AP) rather than switching to a near-better AP. This scenario is termed a sticky client problem. ...This scenario can severely impact the performance of real-time applications. Several standards, such as 802.11k1v/r, are being developed to enhance Wi-Fi roaming capabilities. However, the sticky client problem is yet to be solved completely. This paper proposes Sticky less, a novel method that leverages machine learning to learn the home Wi-Fi network behavior to address the sticky client problem. Initially, Stickyless divides the deployment area of APs into distinct zones, generates training data, and subsequently trains the machine learning module. The Stickyless employs clustering models to recommend selecting the optimal AP within a specific zone by considering the application performance and quality metrics. To conclude, Stickyless assesses performance using a proposed scoring and cascading module. We also developed a prototype to evaluate the Stickyless performance, outperforming the existing methods. The proposed method improves the Wi-Fi roaming experience by reducing stickiness up to 40 %. Thereby, it improves the link quality of the client by an average of 19 % and decreases the packet error rate by up to 3.5 % compared to the existing approaches. We also experimented with popular gaming apps, and Stickyless reduced the latency by up to 7 -fold.
Repeated Wi-Fi studies show that Wi-Fi causes oxidative stress, sperm/testicular damage, neuropsychiatric effects including EEG changes, apoptosis, cellular DNA damage, endocrine changes, and calcium ...overload. Each of these effects are also caused by exposures to other microwave frequency EMFs, with each such effect being documented in from 10 to 16 reviews. Therefore, each of these seven EMF effects are established effects of Wi-Fi and of other microwave frequency EMFs. Each of these seven is also produced by downstream effects of the main action of such EMFs, voltage-gated calcium channel (VGCC) activation. While VGCC activation via EMF interaction with the VGCC voltage sensor seems to be the predominant mechanism of action of EMFs, other mechanisms appear to have minor roles. Minor roles include activation of other voltage-gated ion channels, calcium cyclotron resonance and the geomagnetic magnetoreception mechanism. Five properties of non-thermal EMF effects are discussed. These are that pulsed EMFs are, in most cases, more active than are non-pulsed EMFs; artificial EMFs are polarized and such polarized EMFs are much more active than non-polarized EMFs; dose-response curves are non-linear and non-monotone; EMF effects are often cumulative; and EMFs may impact young people more than adults. These general findings and data presented earlier on Wi-Fi effects were used to assess the Foster and Moulder (F&M) review of Wi-Fi. The F&M study claimed that there were seven important studies of Wi-Fi that each showed no effect. However, none of these were Wi-Fi studies, with each differing from genuine Wi-Fi in three distinct ways. F&M could, at most conclude that there was no statistically significant evidence of an effect. The tiny numbers studied in each of these seven F&M-linked studies show that each of them lack power to make any substantive conclusions. In conclusion, there are seven repeatedly found Wi-Fi effects which have also been shown to be caused by other similar EMF exposures. Each of the seven should be considered, therefore, as established effects of Wi-Fi.
•7 effects have each been repeatedly reported following Wi-Fi & other EMF exposures.•Established Wi-Fi effects, include apoptosis, oxidat. stress &:•testis/sperm dysfunct; Neuropsych; DNA impact; hormone change; Ca2+ rise.•Wi-Fi is thought to act via voltage-gated calcium channel activation.•One claim of no Wi-Fi effects was found to be deeply flawed.
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The Fine Time Measurement (FTM) protocol introduced by IEEE 802.11 includes a new ranging method, named Wi-Fi Round Trip Time (Wi-Fi RTT), which can be used for indoor localization. Pedestrian Dead ...Reckoning (PDR) can provide accurate pedestrian tracking through inertial sensors in a short time. Information fusion of PDR and existing wireless technology is widely used in indoor localization to ensure the robustness and stability. In this paper, we propose a fusion indoor localization method of Wi-Fi RTT and PDR. Firstly, an adaptive filtering system consisting of multiple Extended Kalman Filter (EKF) and a new outlier detection method is proposed to reduce the localization error of Wi-Fi RTT. Secondly, the fusion algorithm based on the Federated Filter (FF) and observability is designed to combine Wi-Fi RTT with PDR. Finally, to further improve the localization performance of the fusion algorithm, a real-time smoothing method with fixed interval is used. We evaluate the proposed method in four different scenarios. The results show that the proposed indoor localization method has better stability and robustness, and the average localization error decreased by 37.4-67.6% compared with the classic EKF-based method.
Multi-link operation (MLO) is a new and essential mechanism of IEEE 802.11be Extremely High Throughput (Wi-Fi 7) that can increase throughput and decrease latency in Wireless Local Area Networks ...(WLANs). The MLO enables a Multi-Link Device (MLD) to perform Simultaneous Transmission and Reception (STR) in different frequency bands. However, not all MLDs can support STR due to cross-link or in-device coexistence interference, while an STR-unable MLD (NSTR-MLD) can transmit multiple frames simultaneously in more than two links. This study focuses on the problems when NSTR-MLDs share a link with Single-Link Devices (SLDs). We propose a Contention-Less Synchronous Transmission (CLST) mechanism to improve fairness between NSTR-MLDs and SLDs while increasing the total network throughput. The proposed mechanism classifies links as MLD Dominant Links (MDLs) and Heterogeneous Coexistence Links (HCLs). In the proposed mechanism, an NSTR-MLD obtains a Synchronous Transmission Token (STT) through a virtual channel contention in the HCL but does not actually transmit a frame in the HCL, which is compensated for by a synchronous transmission triggered in the MDL. Moreover, the CLST mechanism allows additional subsequent transmissions up to the accumulated STT without further contention. Extensive simulation results confirm the outstanding performance of the CLST mechanism in terms of total throughput and fairness compared to existing synchronous transmission mechanisms.
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