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IEEE 802.15.4a
IEEE 802.15.4a (formally called IEEE 802.15.4a-2007) was an amendment to IEEE 802.15.4-2006 specifying that additional physical layers (PHYs) be added to the original standard. It has been merged into and is superseded by IEEE 802.15.4-2011. Overview IEEE 802.15.4-2006 specified four different PHYs, three of which utilized direct-sequence spread spectrum (DSSS), and one which used parallel-sequence spread spectrum (PSSS). IEEE 802.15.4a specifies two additional PHYs using ultra-wideband (UWB) and chirp spread spectrum (CSS). The UWB PHY is designated frequencies in three ranges: below 1 GHz, between 3 and 5 GHz, and between 6 and 10 GHz. The CSS PHY is designated to the 2450 MHz ISM band.IEEE Computer Society, (August 31, 2007). IEEE Standard 802.15.4a-2007. New York, NY: IEEE. History The IEEE 802.15 Low Rate Alternative PHY Task Group (TG4a) for wireless personal area networks (WPANs), as its name implies, was tasked with amending the 802.15 standard to provide alternate PHY s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IEEE 802
IEEE 802 is a family of Institute of Electrical and Electronics Engineers (IEEE) standards for local area networks (LAN), personal area network (PAN), and metropolitan area networks (MAN). The IEEE 802 LAN/MAN Standards Committee (LMSC) maintains these standards. The IEEE 802 family of standards has had twenty-four members, numbered 802.1 through 802.24, with a working group of the LMSC devoted to each. However, not all of these working groups are currently active. The IEEE 802 standards are restricted to computer networks carrying variable-size packets, unlike cell relay networks, for example, in which data is transmitted in short, uniformly sized units called cells. Isochronous signal networks, in which data is transmitted as a steady stream of octets, or groups of octets, at regular time intervals, are also outside the scope of the IEEE 802 standards. The number 802 has no significance: it was simply the next number in the sequence that the IEEE used for standards projects. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct-sequence Spread Spectrum
In telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. After the despreading or removal of the direct-sequence modulation in the receiver, the information bandwidth is restored, while the unintentional and intentional interference is substantially reduced. The first known scheme for this technique was introduced by a Swiss inventor, Gustav Guanella. With DSSS, the message bits are modulated by a pseudorandom bit sequence known as a spreading sequence. Each spreading-sequence bit, which is known as a chip, has a much shorter duration (larger bandwidth) than the original message bits. The modulation of the message bits scrambles and spreads the pieces of data, and thereby results in a bandwidth size nearly identical to that of the spreading sequence. The smaller the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultra-wideband
Ultra-wideband (UWB, ultra wideband, ultra-wide band and ultraband) is a radio technology that can use a very low energy level for short-range, high-bandwidth communications over a large portion of the radio spectrum. UWB has traditional applications in non-cooperative radar imaging. Most recent applications target sensor data collection, precise locating, and tracking. UWB support started to appear in high-end smartphones 2019. Characteristics Ultra-wideband is a technology for transmitting information across a wide bandwidth (>500 MHz). This allows for the transmission of a large amount of signal energy without interfering with conventional narrowband and carrier wave transmission in the same frequency band. Regulatory limits in many countries allow for this efficient use of radio bandwidth, and enable high-data-rate personal area network (PAN) wireless connectivity, longer-range low-data-rate applications, and the transparent co-existence of radar and imaging systems with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chirp Spread Spectrum
In digital communications, chirp spread spectrum (CSS) is a spread spectrum technique that uses wideband linear frequency modulated chirp pulses to encode information. A chirp is a sinusoidal signal whose frequency increases or decreases over time (often with a polynomial expression for the relationship between time and frequency). Overview As with other spread spectrum methods, chirp spread spectrum uses its entire allocated bandwidth to broadcast a signal, making it robust to channel noise. Further, because the chirps utilize a broad band of the spectrum, chirp spread spectrum is also resistant to multi-path fading even when operating at very low power. However, it is unlike direct-sequence spread spectrum (DSSS) or frequency-hopping spread spectrum (FHSS) in that it does not add any pseudo-random elements to the signal to help distinguish it from noise on the channel, instead relying on the linear nature of the chirp pulse. Additionally, chirp spread spectrum is resistan ... [...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 radio-frequency process 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless
Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most common wireless technologies use radio waves. With radio waves, intended distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio ''wireless technology'' include GPS units, garage door openers, wireless computer mouse, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications involve other electromagnetic phenomena, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Personal Area Network
A personal area network (PAN) is a computer network for interconnecting electronic devices within an individual person's workspace. A PAN provides data transmission among devices such as computers, smartphones, tablets and personal digital assistants. PANs can be used for communication among the personal devices themselves, or for connecting to a higher level network and the Internet where one master device takes up the role as gateway. A PAN may be wireless or carried over wired interfaces such as USB. A wireless personal area network (WPAN) is a PAN carried over a low-powered, short-distance wireless network technology such as IrDA, Wireless USB, Bluetooth or ZigBee. The reach of a WPAN varies from a few centimeters to a few meters. WPANs specifically tailored for low-power operation of the sensors are sometimes also called low-power personal area network (LPPAN) to better distinguish them from low-power wide-area network (LPWAN). Wired Wired personal area networks provide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zigbee Alliance
The Connectivity Standards Alliance (CSA), formerly the Zigbee Alliance, is a group of companies that maintain and publish the Zigbee standard and the soon to be Matter (standard), Matter standard. The name Zigbee is a registered trademark of this group, and is not a single technical standard. The organization publishes application profiles that allow multiple Original equipment manufacturer, OEM vendors to create interoperable products. The relationship between IEEE 802.15.4 and Zigbee is similar to that between IEEE 802.11 and the Wi-Fi Alliance. Over the years, the Alliance's membership has grown to over 500 companies, including the likes of Comcast, Ikea, Legrand, SmartThings, Samsung SmartThings, and Amazon. The Zigbee Alliance has three levels of membership: adopter, participant, and promoter. The adopter members are allowed access to completed Zigbee specifications and standards, and the participant members have voting rights, play a role in Zigbee development, and have earl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WiMedia Alliance
The WiMedia Alliance was a non-profit industry trade group that promoted the adoption, regulation, standardization and multi-vendor interoperability of ultra-wideband (UWB) technologies. It existed from about 2002 through 2009. History The Wireless Multimedia Alliance was founded by 2002. The WiMedia Alliance developed reference technical specifications including: * Physical layers and media access control (MAC) layers * Convergence architecture to provide coexistence and fairness including support for multiple applications * A protocol adaptation layer for the Internet Protocol * IP-based application profiles The WiMedia ultra-wideband (UWB) common radio platform incorporated MAC layer and PHY layer specifications based on multi-band orthogonal frequency-division multiplexing (MB-OFDM). It was intended for short-range multimedia file transfers at data rates of 480 Mbit/s and beyond with low power consumption, and operates in the 3.1 to 10.6 GHz UWB spectrum. WiMedia UWB was p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zigbee
Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and other low-power low-bandwidth needs, designed for small scale projects which need wireless connection. Hence, Zigbee is a low-power, low data rate, and close proximity (i.e., personal area) wireless ad hoc network. The technology defined by the Zigbee specification is intended to be simpler and less expensive than other wireless personal area networks (WPANs), such as Bluetooth or more general wireless networking such as Wi-Fi. Applications include wireless light switches, home energy monitors, traffic management systems, and other consumer and industrial equipment that requires short-range low-rate wireless data transfer. Its low power consumption limits transmission distances to 10–100 meters line-of-sight, depending on power output ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultra-wideband
Ultra-wideband (UWB, ultra wideband, ultra-wide band and ultraband) is a radio technology that can use a very low energy level for short-range, high-bandwidth communications over a large portion of the radio spectrum. UWB has traditional applications in non-cooperative radar imaging. Most recent applications target sensor data collection, precise locating, and tracking. UWB support started to appear in high-end smartphones 2019. Characteristics Ultra-wideband is a technology for transmitting information across a wide bandwidth (>500 MHz). This allows for the transmission of a large amount of signal energy without interfering with conventional narrowband and carrier wave transmission in the same frequency band. Regulatory limits in many countries allow for this efficient use of radio bandwidth, and enable high-data-rate personal area network (PAN) wireless connectivity, longer-range low-data-rate applications, and the transparent co-existence of radar and imaging systems with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DASH7
DASH7 Alliance Protocol (D7A) is an open-source wireless sensor and actuator network protocol, which operates in the 433 MHz, 868 MHz and 915 MHz unlicensed ISM band/SRD band. DASH7 provides multi-year battery life, range of up to 2 km, low latency for connecting with moving things, a very small open-source protocol stack, AES 128-bit shared-key encryption support, and data transfer of up to 167 kbit/s. The DASH7 Alliance Protocol is the name of the technology promoted by the non-profit consortium called the DASH7 Alliance. International standard DASH7 Alliance Protocol originates from the ISO/IEC 18000-7 standard describing a 433 MHz ISM band air interface for active RFID. This standard was mainly used for military logistics. The DASH7 Alliance re-purposed the original 18000-7 technology in 2011 and made it evolve toward a wireless sensor network technology for commercial applications. The DASH7 Alliance Protocol covers all sub-GHz ISM bands, mak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
