|
IEEE 802.11af
IEEE 802.11af, also referred to as White-Fi and Super Wi-Fi, is a wireless computer networking standard in the 802.11 family, that allows wireless local area network (WLAN) operation in TV white space spectrum in the VHF and UHF bands between 54 and 790 MHz. The standard was approved in February 2014. Cognitive radio technology is used to transmit on unused portions of TV channel band allocations, with the standard taking measures to limit interference for primary users, such as analog TV, digital TV, and wireless microphones. Physical layer The physical (PHY) layer in 802.11af is based on the orthogonal frequency-division multiplexing (OFDM) scheme specified in 802.11ac.Broadcast TV&Radio( DVB-T, Digital Radio Mondiale) also uses OFDM in this band. The propagation path loss as well as the attenuation by materials such as brick and concrete is lower in the UHF and VHF bands than in the 2.4 and 5 GHz bands, which increases the possible range compared to 802.11 a/b/g/n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super Wi-Fi
Super Wi-Fi refers to IEEE 802.11g/ n/ ac/ ax Wi-Fi implementations over unlicensed 2.4 and 5 GHz Wi-Fi bands but with performance enhancements for antenna control, multiple path beam selection, advance control for best path, and applied intelligence for load balancing giving it bi-directional connectivity range for standard wifi enabled devices over distances of up to 1,700 meters. Hong Kong-based Altai Technologies (http://www.altaitechnologies.com) developed and patented Super Wi-Fi technology and manufacturers a product line of base stations and access points deployed extensively around the world beginning in 2007. Due to its extended range and advanced interference mitigation, Super Wi-Fi is primarily used for expansive outdoor and heavy industrial use cases. (https://www.altaitechnologies.com/case-studies-logistics/) Krysp Wireless, LLC (https://kryspwireless.com) is Altai Technologies' Master Distributor for North America focused on the sale and distribution of Super Wi-Fi p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TV White Space Database
TV White Space database, also commonly referred to as (TV) geolocation database, is an entity that controls the TV spectrum utilization by unlicensed white spaces devices within a determined geographical area. Its sole objective is to enable unlicensed access to white space spectrum while protecting incumbent broadcasting services. TV White Space database was first brought as a way to overcome the technical hurdles faced by spectrum sensing techniques to precisely detect very weak primary signals. Spectrum is deemed available, or unavailable, to unlicensed usage depending on criteria that are regulator specific and thus the database operation can significantly vary between countries. Regulations on white space spectrum utilization are of extreme importance since they pose limits to the amount of white space spectrum that can be reclaimed by White Space technology for wireless broadband access. Having a certain degree of spectrum accessibility is crucial to the relevance and the su ... [...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] |
Ofcom
The Office of Communications, commonly known as Ofcom, is the government-approved regulatory and competition authority for the broadcasting, telecommunications and postal industries of the United Kingdom. Ofcom has wide-ranging powers across the television, radio, telecoms and postal sectors. It has a statutory duty to represent the interests of citizens and consumers by promoting competition and protecting the public from harmful or offensive material. Some of the main areas Ofcom presides over are licensing, research, codes and policies, complaints, competition and protecting the radio spectrum from abuse (e.g., pirate radio stations). The regulator was initially established by the Office of Communications Act 2002 and received its full authority from the Communications Act 2003. History On , the Queen's Speech to the UK Parliament announced the creation of Ofcom. The new body, which was to replace several existing authorities, was conceived as a "super-regulator" to ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Telecommunications Standards Institute
The European Telecommunications Standards Institute (ETSI) is an independent, not-for-profit, standardization organization in the field of Information and communications technology, information and communications. ETSI supports the development and testing of global technical standards for ICT-enabled systems, applications and services. Overview ETSI was set up in 1988 by the European Conference of Postal and Telecommunications Administrations (European Conference of Postal and Telecommunications Administrations, CEPT) following a proposal from the European Commission. ETSI is the officially recognized body with a responsibility for the standardization of Information and Communication Technologies (ICT). It is one of the three bodies, the others being European Committee for Standardization, CEN and CENELEC, officially recognized by the European Union as a European Standards Organization (ESO). The role of the European Standards Organizations is to support EU regulation and poli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TV White Space Database
TV White Space database, also commonly referred to as (TV) geolocation database, is an entity that controls the TV spectrum utilization by unlicensed white spaces devices within a determined geographical area. Its sole objective is to enable unlicensed access to white space spectrum while protecting incumbent broadcasting services. TV White Space database was first brought as a way to overcome the technical hurdles faced by spectrum sensing techniques to precisely detect very weak primary signals. Spectrum is deemed available, or unavailable, to unlicensed usage depending on criteria that are regulator specific and thus the database operation can significantly vary between countries. Regulations on white space spectrum utilization are of extreme importance since they pose limits to the amount of white space spectrum that can be reclaimed by White Space technology for wireless broadband access. Having a certain degree of spectrum accessibility is crucial to the relevance and the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
North American Broadcast Television Frequencies
The Pan-American television frequencies are different for terrestrial and cable television systems. Terrestrial television channels are divided into two bands: the VHF band which comprises channels 2 through 13 and occupies frequencies between 54 and 216 MHz, and the UHF band, which comprises channels 14 through 36 and occupies frequencies between 470 and 700 MHz. These bands are different enough in frequency that they often require separate antennas to receive (although many antennas cover both VHF and UHF), and separate tuning controls on the television set. The VHF band is further divided into two frequency ranges: VHF low band (Band I) between 54 and 88 MHz, containing channels 2 through 6, and VHF high band (Band III) between 174 and 216 MHz, containing channels 7 through 13. The wide spacing between these frequency bands is responsible for the complicated design of rooftop TV antennas. The UHF band has higher noise and greater attenuation, so higher gain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Communications Commission
The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdiction over the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security. The FCC was formed by the Communications Act of 1934 to replace the radio regulation functions of the Federal Radio Commission. The FCC took over wire communication regulation from the Interstate Commerce Commission. The FCC's mandated jurisdiction covers the 50 states, the District of Columbia, and the territories of the United States. The FCC also provides varied degrees of cooperation, oversight, and leadership for similar communications bodies in other countries of North America. The FCC is funded entirely by regulatory fees. It has an estimated fiscal-2022 budget of US $388 million. It has 1,482 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies. The nodes of a computer network can include personal computers, servers, networking hardware, or other specialised or general-purpose hosts. They are identified by network addresses, and may have hostnames. Hostnames serve as memorable labels for the nodes, rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the transmission medium used to carry signals, bandwidth, communications pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Local Area Network
A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. This gives users the ability to move around within the area and remain connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet. Wireless LANs based on the IEEE 802.11 standards are the most widely used computer networks in the world. These are commonly called Wi-Fi, which is a trademark belonging to the Wi-Fi Alliance. They are used for home and small office networks that link together laptop computers, printers, smartphones, Web TVs and gaming devices with a wireless router, which links them to the internet. Hotspots provided by routers at restaurants, coffee shops, hotels, libraries, and airports allow consumers to access the internet with portable wireless devices. History Norman ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space–time Block Code
In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why different observers perceive differently where and when events occur. Until the 20th century, it was assumed that the three-dimensional geometry of the universe (its spatial expression in terms of coordinates, distances, and directions) was independent of one-dimensional time. The physicist Albert Einstein helped develop the idea of spacetime as part of his theory of relativity. Prior to his pioneering work, scientists had two separate theories to explain physical phenomena: Isaac Newton's laws of physics described the motion of massive objects, while James Clerk Maxwell's electromagnetic models explained the properties of light. However, in 1905, Einstein based a work on special relativity on two postulates: * The laws of physics are invariant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Radio Mondiale
Digital Radio Mondiale (DRM; ''mondiale'' being Italian and French for "worldwide") is a set of digital audio broadcasting technologies designed to work over the bands currently used for analogue radio broadcasting including AM broadcasting—particularly shortwave—and FM broadcasting. DRM is more spectrally efficient than AM and FM, allowing more stations, at higher quality, into a given amount of bandwidth, using xHE-AAC audio coding format. Various other MPEG-4 and Opus codecs are also compatible, but the standard now specifies xHE-AAC. Digital Radio Mondiale is also the name of the international non-profit consortium that has designed the platform and is now promoting its introduction. Radio France Internationale, TéléDiffusion de France, BBC World Service, Deutsche Welle, Voice of America, Telefunken (now Transradio) and Thomcast (now Ampegon) took part at the formation of the DRM consortium. The principle of DRM is that bandwidth is the limiting factor, and comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
