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11ah
IEEE 802.11ah is a wireless networking protocol published in 2017 called Wi-Fi HaLow () as an amendment of the IEEE 802.11-2007 wireless networking standard. It uses 900 MHz license-exempt bands to provide extended-range Wi-Fi networks, compared to conventional Wi-Fi networks operating in the 2.4 GHz, 5 GHz and 6 GHz bands. It also benefits from lower energy consumption, allowing the creation of large groups of stations or sensors that cooperate to share signals, supporting the concept of the Internet of things (IoT). The protocol's low power consumption competes with Bluetooth, LoRa, Zigbee, and Z-Wave, and has the added benefit of higher data rates and wider coverage range. Description A benefit of 802.11ah is extended range, making it useful for rural communications and offloading cell phone tower traffic. The other purpose of the protocol is to allow low rate 802.11 wireless stations to be used in the sub-gigahertz spectrum. The protocol is one of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of WLAN Channels
Wireless LAN (WLAN) channels are frequently accessed using IEEE 802.11 protocols. The 802.11 standard provides several radio frequency bands for use in Wi-Fi communications, each divided into a multitude of channels numbered at 5 MHz spacing (except in the 45/60 GHz band, where they are 0.54/1.08/2.16 GHz apart) between the centre frequency of the channel. The standards allow for channels to be bonded together into wider channels for faster throughput. 860/900 MHz (802.11ah) 802.11ah operates in sub-gigahertz unlicensed bands. Each world region supports different sub-bands, and the channels number depends on the starting frequency on the sub-band it belongs to. Therefore there is no global channels numbering plan, and the channels numbers are incompatible between world regions (and even between sub-bands of a same world region). The following sub-bands are defined in the 802.11ah specifications: 2.4 GHz (802.11b/g/n/ax/be) 14 channels are designated in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISM Band
The ISM radio bands are portions of the radio spectrum reserved internationally for ''industrial, scientific, and medical'' (ISM) purposes, excluding applications in telecommunications. Examples of applications for the use of radio frequency (RF) energy in these bands include RF heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so these devices are limited to certain bands of frequencies. In general, communications equipment operating in ISM bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation in these bands. Despite the intent of the original allocations, in recent years the fastest-growing use of these bands has been for short-range, low-power wireless communications systems, since these bands are often approved for such devices, which can be used w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wi-Fi
Wi-Fi () is a family of wireless network protocols based on the IEEE 802.11 family of standards, which are commonly used for Wireless LAN, local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves. These are the most widely used computer networks, used globally in small office/home office, home and small office networks to link devices and to provide Internet access with wireless routers and wireless access points in public places such as coffee shops, restaurants, hotels, libraries, and airports. ''Wi-Fi'' is a trademark of the Wi-Fi Alliance, which restricts the use of the term "''Wi-Fi Certified''" to products that successfully complete Interoperability Solutions for European Public Administrations, interoperability certification testing. Non-compliant hardware is simply referred to as WLAN, and it may or may not work with "''Wi-Fi Certified''" devices. the Wi-Fi Alliance consisted of more than 800 companies from ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internet Of Things
Internet of things (IoT) describes devices with sensors, processing ability, software and other technologies that connect and exchange data with other devices and systems over the Internet or other communication networks. The IoT encompasses Electronic engineering, electronics, Telecommunications engineering, communication, and computer science engineering. "Internet of things" has been considered a misnomer because devices do not need to be connected to the public internet; they only need to be connected to a network and be individually addressable. The field has evolved due to the convergence of multiple technologies, including ubiquitous computing, commodity sensors, and increasingly powerful embedded systems, as well as machine learning.Hu, J.; Niu, H.; Carrasco, J.; Lennox, B.; Arvin, F.,Fault-tolerant cooperative navigation of networked UAV swarms for forest fire monitoring Aerospace Science and Technology, 2022. . Older fields of embedded systems, wireless sensor netw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bluetooth
Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limited to 2.5 milliwatts, giving it a very short range of up to . It employs Ultra high frequency, UHF radio waves in the ISM bands, from 2.402GHz to 2.48GHz. It is mainly used as an alternative to wired connections to exchange files between nearby portable devices and connect cell phones and music players with wireless headphones, wireless speakers, HIFI systems, car audio and wireless transmission between TVs and soundbars. Bluetooth is managed by the Bluetooth Special Interest Group (SIG), which has more than 35,000 member companies in the areas of telecommunication, computing, networking, and consumer electronics. The Institute of Electrical and Electronics Engineers, IEEE standardized Bluetooth as IEEE 802.15.1 but no longer maintains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LoRa
LoRa (from "long range", sometimes abbreviated as "LR") is a physical proprietary radio communication technique. It is based on spread spectrum modulation techniques derived from chirp spread spectrum (CSS) technology. It was developed by Cycleo, a company of Grenoble, Grenoble, France, and patented in 2014. In March 2012, Cycleo was acquired by the US company Semtech. LoRaWAN (long range wide area network) defines the communication protocol and system architecture. LoRaWAN is an official standard of the International Telecommunication Union (ITU), ITU-T Y.4480. The continued development of the LoRaWAN protocol is managed by the open, non-profit LoRa Alliance, of which Semtech is a founding member. Together, LoRa and LoRaWAN define a low-power wide-area network, low-power, wide-area (LPWA) networking protocol designed to wirelessly connect battery operated devices to the Internet in regional, national or global networks, and targets key Internet of things (IoT) requirements, suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OFDM
In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission used in digital modulation for encoding digital (binary) data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, DSL internet access, wireless networks, power line networks, and 4G/ 5G mobile communications. OFDM is a frequency-division multiplexing (FDM) scheme that was introduced by Robert W. Chang of Bell Labs in 1966. In OFDM, the incoming bitstream representing the data to be sent is divided into multiple streams. Multiple closely spaced orthogonal subcarrier signals with overlapping spectra are transmitted, with each carrier modulated with bits from the incoming stream so multiple bits are being transmitted in parallel. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Network
A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking allows homes, telecommunications networks, and business installations to avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Admin telecommunications networks are generally implemented and administered using radio communication. This implementation takes place at the physical level (layer) of the OSI model network structure. Examples of wireless networks include cell phone networks, WLAN, wireless local area networks (WLANs), wireless sensor networks, satellite communication networks, and terrestrial microwave networks. History Wireless networks The first professional wireless network was developed under the brand ALOHAnet in 1969 at the University of Hawaii and became operational in June 1971. The first commercial wireless network was the WaveLAN product family, developed by NCR Corpor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase-shift Keying
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave. The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication. Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of binary digits. Usually, each phase encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular phase. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data. This requires the receiver to be able to compare the phase of the received signal to a reference signal such a system is termed coherent (an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fast Fourier Transform
A fast Fourier transform (FFT) is an algorithm that computes the discrete Fourier transform (DFT) of a sequence, or its inverse (IDFT). A Fourier transform converts a signal from its original domain (often time or space) to a representation in the frequency domain and vice versa. The DFT is obtained by decomposing a sequence of values into components of different frequencies. This operation is useful in many fields, but computing it directly from the definition is often too slow to be practical. An FFT rapidly computes such transformations by Matrix decomposition, factorizing the DFT matrix into a product of Sparse matrix, sparse (mostly zero) factors. As a result, it manages to reduce the Computational complexity theory, complexity of computing the DFT from O(n^2), which arises if one simply applies the definition of DFT, to O(n \log n), where is the data size. The difference in speed can be enormous, especially for long data sets where may be in the thousands or millions. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pilot Signal
In telecommunications, a pilot signal is a signal, usually a single frequency, transmitted over a communications system for supervisory, control, equalization, continuity, synchronization, or reference purposes. Uses in different communication systems FM Radio In FM stereo broadcasting, a pilot tone of 19 kHz indicates that there is stereophonic information at 38 kHz (the second harmonic of the pilot tone). The receiver doubles the frequency of the pilot tone and uses it as a frequency and phase reference to demodulate the stereo information. If no 19 kHz pilot tone is present, then any signals in the 23–53 kHz range are ignored by a stereo receiver. A guard band of ±4 kHz (15–23 kHz) protects the pilot tone from interference from the baseband audio signal (50 Hz–15 kHz) and from the lower sideband of the double sideband stereo information (23–53 kHz). The third harmonic of the pilot (57 kHz) is used for Radio Data System. The fourth harmonic (76 kH ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basic Service Set
In IEEE 802.11 wireless local area networking standards (including Wi‑Fi), a service set is a group of wireless network devices which share a ''service set identifier'' (''SSID'')—typically the natural language label that users see as a network name. (For example, all of the devices that together form and use a Wi‑Fi network called "Foo" are a service set.) A service set forms a logical network of nodes operating with shared link-layer networking parameters; they form one logical network segment. A service set is either a ''basic service set'' (''BSS'') or an ''extended service set'' (''ESS''). A ''basic service set'' is a subgroup, within a service set, of devices that share physical-layer medium access characteristics (e.g. radio frequency, modulation scheme, security settings) such that they are wirelessly networked. The basic service set is defined by a ''basic service set identifier'' (''BSSID'') shared by all devices within it. The BSSID is a 48-bit label that conf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
