Word
Wireless comes from English: wire (I entrust, cable); less (without); or be: without fios.Wireless then characterizes
any connection type for transmission of information without the use of threads or cables. The net without thread is nothing else than the compartilhamento of information among two or more devices done through waves of radio. It is similar to a local net with conventional thread (that follows the
pattern IEEE 802.3), except for that the net without thread uses waves of radio, instead of cables. . That technology has been adopted thoroughly by treating of a solution that makes possible high-speed at a cost similar to the of the dialed connection. *Tipos of nets without thread I–WLAN (
Wireless Local Área Network) The local nets without thread (WLAN) they provide the same functionality that the nets LAN with cable, however they eliminate the need to install cables and other net equipments. The nets WLAN use waves of radio or infravermelho to send packages of data for the air. Most of the nets WLAN uses the technology of distributed spectrum, which offers a width of limited band, usually inferior to 11Mbps, shared with others of the spectrum. It was through WLAN that the technology Wireless Fidelity, famous Wi-Fi appeared. II–WMAN (Wireless Metropolitan Área Network) Saint nets without thread of long reach and they are disponibilizadas for operators of cellular and that can be used to transmit voice and data. That technology is divided in 3 types: 1G (first generation)–just voice. AMPS (Mobile Advanced Phone Services) - Analogical 2G (second generation)–circuit shared among voice and it dates, speeds of up to 14,4Kbps. CDPD (Digital Cellular Packet Dates)–Digital, GSM, TDMA I-136, CDMA I-95-TO and PCS 2.5G–HSCSD (High Speed Circuit Switched Dates), he/she brought improvements in the communication of data in the nets 2G, that started to have superior speeds (144 Kbps). GPRS and CDMA2000 (1xRTT) 3G (third generation)–system re-developed to increase the capacity, speed (2Mbps) and efficiency for both, voice and data. EDGE/WCDMA and CDMA 1xEV-DO/1xEV-DV That net type can be used for the creation of WMAN, but those frequencies are not licensed by the responsible organs, it is the case of ANATEL, in Brazil. III–WWAN (Wireless Wide Área Network) In this group, there are the technologies that treat of the band accesses it releases for last mile for nets in metropolitan areas, with reach around 6 km; IV - WPAN (Wireless Personal Área Network) it is usually associated Bluetooth (formerly when GOING). it can be seen with the interaction among the devices pieces of furniture of an utilizador. WPAN is projectada for small distance, low cost and low transfer rates. OPERATION *Através of the use of bearers of radio or infravermelho, WLANs establish the communication of data among the points of the net. The data are modulated in the bearer of radio and transmitted through waves eletromagnéticas. *Múltiplas bearers of radio can coexist in a same middle, without umainterfira in the other. To extract the data, the receiver tunes in in a freqüênciaespecífica and it rejects the other bearers of different frequencies. *Num adapts typical, the device transceptor (transmissor/receptor) or access point (access point) it is connected to a local net conventional Ethernet (with thread) .Os access points don''t just supply also the communication with the net convencional,como intermediam the traffic with the access neighbors'' points, in an outline of personal computer cells with roaming similar to a telefoniacelular system WIMAX Still little known in the Market, the pattern wireless 802.16 is on the way to revolutionizing the industry of access of Broadband Wireless. The pattern 802.16 is also known as the aerial interface of IEEE for WirelMAN, that is, of the metropolitan net without threads. This technology is being specified by the group of IEEE that treats of band accesses it releases for last mile in metropolitan areas, with equivalent acting patterns to the of the traditional such means like DSL, Cable modem or E1/T1. Originally, the pattern 802.16, that was ratified in December of 2001, it was basically focando the strips of located frequencies between 10GHz and 66GHz always considering applications with line of having sought. The version 802.16a, that it was concluded in 2003, it passed the focar the applications without line of having sought, inside of the frequency strips between 2GHZ and 11GHZ, also considering the interoperabilidade aspects.