China
Africa
Explore chapters and articles related to this topic
Application
Published in Benny Raphael, Construction and Building Automation, 2023
Connectivity using Wi-Fi is now common. Wi-Fi uses radio signals to connect to the internet through a wireless router. This technology can also be used to track devices by locating the router to which the device is connected. Signal strength has been used to identify the location of devices using this concept. Zigbee is another global standard for wireless communication and is cheaper as well as energy efficient.
Smart Pole System
Published in Prashant Ranjan, Ram Shringar Rao, Krishna Kumar, Pankaj Sharma, Wireless Communication, 2023
Prashant Ranjan, Ram Shringar Rao, Krishna Kumar, Pankaj Sharma
Easy and convenient way to connect a whole city to access the wireless internet service is Wi-Fi Hotspot. As a part of Wi-Fi solution, the concessionaire wants to offer DNS, Internet bandwidth from Internet Service Provider (ISP), Wi-Fi controller. A hotspot is a physical place where the user can access the Internet, using Wi-Fi, via a wireless local area network (WLAN). These places are referred to as “Wi-Fi hotspots”.
IoT Reference Architectures
Published in Stavros Shiaeles, Nicholas Kolokotronis, Internet of Things, Threats, Landscape, and Countermeasures, 2021
V. Kelli, E. G. Sfakianakis, B. Ghita, P. Sarigiannidis
Wi-Fi, short name for wireless fidelity, is the name of a wireless networking technology that uses radio waves to provide wireless high-speed Internet and network connections. Is based on the IEEE 802.11 family of standards which are commonly used for local area networking of devices and Internet access [14]. A way of getting broadband internet to a device using wireless transmitters and radio signals. Once a wireless transmitter receives data from the internet, it converts the data into a radio signal that can be received and read by Wi-Fi-enabled devices. Information is then exchanged between the transmitter and the device
Evaluating the Performance of Wearable Devices for Contact Tracing in Care Home Environments
Published in Journal of Occupational and Environmental Hygiene, 2023
Kishwer Abdul Khaliq, Catherine Noakes, Andrew H. Kemp, Carl Thompson
Accuracy and reliability in digital contact tracing is important and needs to consider the epidemiological sense of sensitivity [probability of recording a contact when there really has been one] and specificity [probability of ruling out no contact when there really has not been one]. Many factors can influence the accuracy of BLE devices. Other devices using the same frequency (Wi-Fi, mobile phones, wireless technology such as speakers or baby monitors) can interfere with signals. Different building materials, furniture, and objects within the environment can affect signal strength, as can humans that block direct line-of-sight propagation (shadowing). Antenna patterns when BLE devices scan can be anisotropic, with large variations in gain from differing angles and polarization (Schulten et al. 2019). Propagation indoors is vulnerable to multi-path (Rayleigh) fading from nearby reflections. These factors make an evaluation of the accuracy and reliability of the CONTACT trial’s BLE wearables necessary.
Orthogonally crossed triangular monopole antenna for octave band frequencies
Published in International Journal of Electronics Letters, 2023
Sureshkumar S, Sakthidasan Sankaran Krishnan, Rubesh Anand P M, Ankur Prajapati, Lalit Chaudhari
The rapid development of wireless communication has attracted researchers to design broadband antennas with good impedance matching and uniform radiation pattern over a wide frequency range. The Wi-Fi networks operated at 2.4 GHz experience higher interferences from neighbouring wireless networks reducing the efficiency of the device (Zhang et al., 2015). Frequency bands above 3 GHz are free from interferences, larger bandwidth and with reduced antenna size when compared to 2.4 GHz band. The WLAN services use 4.9 GHz (802.11y) for public safety WLAN, 5.9 GHz (802.110), for wireless access in vehicular environment (WAVE), intelligent transportation systems (ITS), 3.65 GHz (802.11y) and 5.0/5.8 GHz (802.11 a/h/j/n/ac/axe) for short range communication in shopping centres, residential complexes, institutions etc. The reported planar antenna designs suffer from poor service area coverage due variation in radiation pattern and reduced gain with increase in frequency. The paper presents an octave band planar monopole antenna with a crossed design to obtain a uniform radiation pattern over the entire bandwidth.
Health effects of WiFi radiation: a review based on systematic quality evaluation
Published in Critical Reviews in Environmental Science and Technology, 2022
Stefan Dongus, Hamed Jalilian, David Schürmann, Martin Röösli
WiFi, also called WLAN (Wireless Local Area Network), is commonly used to connect devices and for Internet access. Typical applications are in private homes, schools, workplaces, and WiFi hotspots in cities and public transport. WiFi is based on the IEEE 802.11 family of standards, which uses various transmission protocols mostly in the frequency range of 2.400 to 2.484 GHz and 5.150 to 5.825 GHz (IEEE, 2016). Data packets are transmitted between multiple devices and access points using various types of modulations such as the multiple-input, multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM). Consequently, WLAN devices transmit short pulses (bursts) and the burst lengths and burst repetition rates are highly dependent on the actual data traffic in the network. The duty factor is the ratio of the pulse duration to the total period, which is usually low for WiFi communication (Khalid et al., 2011). In the absence of data traffic, only the access point transmits a short beacon signal, every 100 ms, which corresponds to a pulse rate of 10 Hz. In this situation, the crest factor, defined as the ratio of peak values to the effective value, is highest (about a factor of 100) (Schmid et al., 2020).