A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking is a method by which homes, telecommunications networks and business installations avoid the costly process of introducing cables into a building, or as a connection between various equipment locations. Admin telecommunications networks are implemented and administered using radio communication; this implementation takes place at the physical level of the OSI model network structure. Examples of wireless networks include cell phone networks, wireless local area networks, wireless sensor networks, satellite communication networks, terrestrial microwave 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 in 1986. 1973 – Ethernet 802.3 1991 – 2G cell phone network June 1997 – 802.11 "Wi-Fi" protocol first release 1999 – 803.11 VoIP integration Advances in MOSFET wireless technology enabled the development of digital wireless networks.
The wide adoption of RF CMOS, power MOSFET and LDMOS devices led to the development and proliferation of digital wireless networks by the 1990s, with further advances in MOSFET technology leading to increasing bandwidth in the 2000s. Most of the essential elements of wireless networks are built from MOSFETs, including the mobile transceivers, base station modules, routers, RF power amplifiers, telecommunication circuits, RF circuits, radio transceivers, in networks such as 2G, 3G, 4G. Terrestrial microwave – Terrestrial microwave communication uses Earth-based transmitters and receivers resembling satellite dishes. Terrestrial microwaves are in the low gigahertz range, which limits all communications to line-of-sight. Relay stations are spaced 48 km apart. Communications satellites – Satellites communicate via microwave radio waves, which are not deflected by the Earth's atmosphere; the satellites are stationed in space in geosynchronous orbit 35,400 km above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, TV signals.
Cellular and PCS systems use several radio communications technologies. The systems divide the region covered into multiple geographic areas; each area has a low-power transmitter or radio relay antenna device to relay calls from one area to the next area. Radio and spread spectrum technologies – Wireless local area networks use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. IEEE 802.11 defines a common flavor of open-standards wireless radio-wave technology known as. Free-space optical communication uses invisible light for communications. In most cases, line-of-sight propagation is used, which limits the physical positioning of communicating devices. Wireless personal area networks connect devices within a small area, within a person's reach. For example, both Bluetooth radio and invisible infrared light provides a WPAN for interconnecting a headset to a laptop.
ZigBee supports WPAN applications. Wi-Fi PANs are becoming commonplace as equipment designers start to integrate Wi-Fi into a variety of consumer electronic devices. Intel "My WiFi" and Windows 7 "virtual Wi-Fi" capabilities have made Wi-Fi PANs simpler and easier to set up and configure. A wireless local area network links two or more devices over a short distance using a wireless distribution method providing a connection through an access point for internet access; the use of spread-spectrum or OFDM technologies may allow users to move around within a local coverage area, still remain connected to the network. Products using the IEEE 802.11 WLAN standards are marketed under the Wi-Fi brand name. Fixed wireless technology implements point-to-point links between computers or networks at two distant locations using dedicated microwave or modulated laser light beams over line of sight paths, it is used in cities to connect networks in two or more buildings without installing a wired link. To connect to Wi-Fi, sometimes are used devices like a router or connecting HotSpot using mobile smartphones.
A wireless ad hoc network known as a wireless mesh network or mobile ad hoc network, is a wireless network made up of radio nodes organized in a mesh topology. Each node forwards messages on behalf of the other nodes and each node performs routing. Ad hoc networks can "self-heal", automatically re-routing around a node. Various network layer protocols are needed to realize ad hoc mobile networks, such as Distance Sequenced Distance Vector routing, Associativity-Based Routing, Ad hoc on-demand Distance Vector routing, Dynamic source routing. Wireless metropolitan area networks are a type of wireless network that connects several wireless LANs. WiMAX is described by the IEEE 802.16 standard. Wireless wide area networks are wireless networks that cover large areas, such as between neighbouring towns and cities, or city and suburb; these networks can be used to connect branch offices of business or as a public Internet access system. The wireless connections between access points are point to point microwave links using parabolic dishes on the 2.4 GHz and 5.8Ghz band, rather than omnidirectional antennas used with smaller networks.
A typical system contains access points and wireless bridging relays. Other configurations
Douglas E. Moore was a Methodist minister who organized the 1957 Royal Ice Cream Sit-in in Durham, North Carolina. Moore entered the ministry at a young age. After finding himself dissatisfied with what he perceived as a lack of action among his divinity peers, he decided to take a more activist course. Shortly after becoming a pastor in Durham, Moore decided to challenge the city's power structure via the Royal Ice Cream Sit-in, a protest in which he and several others sat down in the white section of an ice cream parlor and asked to be served; the sit-in failed to challenge segregation in the short run, Moore's actions provoked a myriad of negative reactions from many white and African-American leaders, who considered his efforts far too radical. Moore continued to press forward with his agenda of activism. However, Moore's plan of using the sit-in to challenge Durham's power structure proved successful. A new wave of young African-American students, inspired by the actions of the Royal Ice Cream protestors, adopted Moore's agenda, helping to bring about the desegregation of the city's public facilities.
His actions had effects that stretched far beyond the boundaries of Durham. Working with activist leaders he had once spurned, including Martin Luther King, Jr. and inspired by the actions of students in places such as Greensboro, North Carolina, Moore was able to organize additional sit-ins during the sit-in movement that spread all across the South. His work with the sit-in helped to spur the creation of “local movement centers”, which facilitated the collective actions of African-Americans seeking to bring about an end to segregation throughout North Carolina and the region in years to come. In addition, Moore's idea of a group that used the power of nonviolence, using Christianity as an ideological base became the symbol of a new era of activism and civil rights in the United States. Douglas Elaine Moore was born in 1928 in North Carolina. At an early age, he decided to follow in the footsteps of his grandfather and enter the Methodist ministry. Shortly after earning a Bachelor of Arts from North Carolina College in 1949, Moore enrolled at Boston University as a divinity student in 1951.
His political leanings were evident early on, as he joined a radical leftist group on campus and participated in protests of social ills. Moore temporarily joined a student group called the Dialectical Society, which met every week for dinner and a discussion. However, he found the talks dissatisfying, viewing them as far too passive and abstract. In addition, he was not too fond of the leader of the Dialectical Society, the then-unknown Martin Luther King, Jr. Referring to him as “just another Baptist preacher”, Moore invited King to join his student group. However, King declined to do so put off by its radicalness and activist agenda. Moore soon parted ways with the Dialectical Society, he earned his Bachelor of Sacred Theology in 1953 and his Master of Sacred Theology in 1958. After graduating, Moore moved back to the American South, he served as the minister for two small-town Methodist churches before becoming the pastor of Durham's Asbury Temple Methodist Church in 1956. Soon after arriving in the city, Moore began to look for ways to challenge its power structure.
Despite the fact that Durham was known for having better-than-average race relations for the region, Moore concluded that it was the “same as any other place: They wouldn’t give up nothing”. He made several attempts to desegregate the city's public facilities. After his family was denied admission to the all-white Long Meadow Park swimming pool in 1957, Moore appealed to Durham recreation officers, to no avail. Other efforts included petitions to the city council to end segregation at the Carolina Theatre and the Durham Public Library. While these resulted in little to no changes, Moore would make headlines that year via what came to be known as the Royal Ice Cream Sit-in. On June 23, 1957, the 28-year-old Moore led three African-American men and three African-American women into the segregated Royal Ice Cream Parlor, they all asked to be served. Moore told a reporter, “We just decided we wanted to cool off, to get some ice cream or milk shakes.” The truth, was much more far-reaching than that.
Moore said that the parlor was chosen in advance because of its location in a predominantly-African-American neighborhood. He indicated that he intended the sit-in to serve as a barometer – a way to see how much progress African-American protestors could make, as well as what they needed to achieve more in the future. In the end, after being asked to leave by the owner of the parlor and refusing to do so, all of the protestors, including Moore, were arrested, they fined $10 plus court costs. The sit-in soon turned into a protracted court battle: seeking an ally in his fight for the desegregation of public facilities, Moore hired Floyd McKissick, a prominent African-American attorney, to sue Royal Ice Cream. At the same time, he and the other protestors appealed their convictions; the case made its way to the North Carolina Supreme Court, but the defendants lost. The Royal Ice Cream Sit-in produced much controversy from the start. Moore failed to communicate to the sit-in participants all of the possible consequences of their actions: Virginia Williams and Mary Clyburn, two of the protestors, claimed in interviews that they had not expected to be arrested.
The sit-in was carried out anyway, there was immediate backlash from African-American groups in Durham. The Durham Committee on Negro Affairs and the Durham Ministerial Alliance criticized Moore, calling
The Members of the House of Representatives of the Netherlands for GreenLeft, 1989–present is a list of all members of the House of Representatives who have been members of the GreenLeft faction since the party's inception in 1989. GreenLeft is a Dutch green political party, it was formed in 1989 as a merger of four parties: the left-socialist Pacifist Socialist Party, the communist Communist Party of the Netherlands, the progressive Christian Political Party of Radicals, the progressive Christian Evangelical People's Party Members' pre-GreenLeft political background is listed if applicable. Although the PvdA did not merge into GreenLeft, a number of GreenLeft members of the House of Representatives have been members of the PvdA, therefore this affiliation is mentioned as well