Access Point - UFSC

Caractersticas dos Padres e Produtos IEEE 802.11 Principais Aplicaes Padres IEEE 802.11

802.11a 802.11b 802.11c 802.11d 802.11e 802.11f 802.11g 802.11h 802.11i

802.11n 5GHz, 54Mbps 2.4GHz, 11Mbps Protocolo para bridges World Mode (Europa 20 dB, EUA-BR 36dB Qualidade de Servio Inter-Access Point Protocol 2.4GHz, 54Mbps, modulao digital OFDM Seleo dinmica de frequncia Autenticao e Segurana Access Point

Short for Access Point, a hardware device or a computer's software that acts as a communication hub for users of a wireless device to connect to a wired LAN. APs are important for providing heightened wireless security and for extending the physical range of service a wireless user has access to. Infrastructure Mode

An 802.11 networking framework in which devices communicate with each other by first going through an Access Point (AP). In infrastructure mode, wireless devices can communicate with each other or can communicate with a wired network.

When one AP is connected to wired network, a set of wireless stations it is referred to as a Basic Service Set (BSS). Infrastructure Mode An Extended Service Set (ESS) is a set of two or more BSSs that form a single subnetwork. Most corporate wireless LANs operate in

infrastructure mode because they require access to the wired LAN in order to use services such as file servers or printers. Ad-hoc Mode An 802.11 networking framework in which devices or stations communicate directly with each other, without the use of an access point (AP). Ad-hoc mode is also referred to as peer-to-peer

mode or an Independent Basic Service Set (IBSS). Ad-hoc mode is useful for establishing a network where wireless infrastructure does not exist or where services are not required. 802.11 802.11 refers to a family of specifications developed by the IEEE for wireless LAN technology.

802.11 specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The IEEE accepted the specification in 1997. Specifications in the 802.11 family

802.11 e 802.11a 802.11 -- applies to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4 GHz band using either frequency hopping spread spectrum (FHSS) or direct sequence spread spectrum (DSSS). 802.11a -- an extension to 802.11 that applies to wireless LANs and provides up to 54 Mbps in the 5GHz band. 802.11a uses an

orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS. 802.11b 802.11b (also referred to as 802.11 High Rate or Wi-Fi) -- an extension to 802.11 that applies to wireless LANS and provides 11 Mbps transmission (with 2 and 1 Mbps) in the 2.4 GHz band. 802.11b

802.11b uses only DSSS. 802.11b was a 1999 ratification to the original 802.11 standard, allowing wireless functionality comparable to Ethernet. 802.11b (Wi-Fi) Data Rate: Up to 11Mbps in the 2.4GHz band

Modulation scheme: DSSS with CCK Security: WEP & WPA Products that adhere to this standard are considered "Wi-Fi Certified." Not interoperable with 802.11a. Requires fewer access points than

802.11a for coverage of large areas. 802.11b (Wi-Fi) Offers high-speed access to data at up to 300 feet from base station. 14 channels available in the 2.4GHz band (only 11 of which can be used in the U.S. due to FCC regulations) with only three non-overlapping channels.

802.11a 802.11b 802.11a X 802.11b X 802.11a 54 Mbps Velocidade mxima (Taxa de Dados)

(54, 48, 36, 24,18, 12, 6 Mbps) Real: 28 Mbps rea 802.11b 11 Mbps (11, 5.5, 2, 1 Mbps) Real: 5.2Mbps 50 Metros

100 Metros ISM (5 GHz) ISM (2.4 GHz) Banda de Frequncia Modulao Segurana em redes sem Fio Tecnologia OFDM

Tecnologia DSSS IEEE 802.11g Data Rate: Up to 54Mbps in the 2.4GHz band Modulation Scheme: OFDM above 20Mbps, DSSS with CCK below 20Mbps

Security: WEP & WPA & WPA2 (IEEE 802.11i) IEEE 802.11g Pros/Cons & More Info:

Products that adhere to this standard are considered "Wi-Fi Certified." May replace 802.11b. Improved security enhancements over 802.11. Compatible with 802.11b. 14 channels available in the 2.4GHz band (only 11 of which can be used in the U.S. due to FCC regulations) with only three non-overlapping channels. Bluetooth

Up to 2Mbps in the 2.45GHz band. FHSS. PPTP, SSL or VPN. No native support for IP, so it does not support TCP/IP and wireless LAN applications well. Not originally created to support wireless LANs. Best suited for connecting PDAs, cell phones and PCs in short intervals.

A Pilha de Protocolos 802.11 Camadas Superiores Subcamada LLC Camada de Enlace Subcamada MAC IEEE 802 Infravermelho IEE

802.11 FHSS 802.11 DSSS 802.11a OFDM 802.11b HR-DSSS 802.11g

OFDM Camada Fsica MAC - CSMA/CA Short for Carrier Sense Multiple Access/Collision Avoidance, a network contention protocol that listens to a network in order to avoid collisions.

Unlike CSMA/CD that deals with network transmissions once collisions have been detected. MAC - CSMA/CA CSMA/CA contributes to network traffic because, before any real data is transmitted, it has to broadcast a signal onto the network in order to listen for collision scenarios and to tell other devices not to broadcast.

Camada Fsica - OFDM Short for Orthogonal Frequency Division Multiplexing, an FDM modulation technique for transmitting large amounts of digital data over a radio wave. OFDM OFDM works by splitting the radio signal into

multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver. OFDM OFDM reduces the amount of crosstalk in signal transmissions. 802.11a WLAN, 802.16 and WiMAX technologies use OFDM.

Camada Fsica - FHSS Acronym for Frequency-Hopping Spread Spectrum. FHSS is one of two types of spread spectrum radio, the other being direct-sequence spread spectrum. FHSS FHSS is a transmission technology used

in WLAN transmissions where the data signal is modulated with a narrowband carrier signal that "hops" in a random but predictable sequence from frequency to frequency as a function of time over a wide band of frequencies. Camada Fsica - FHSS The signal energy is spread in time domain rather than chopping each bit into small pieces in the frequency domain.

This technique reduces interference because a signal from a narrowband system will only affect the spread spectrum signal if both are transmitting at the same frequency at the same time. If synchronized properly, a single logical channel is maintained. Camada Fsica - FHSS

The transmission frequencies are determined by a spreading, or hopping, code. The receiver must be set to the same hopping code and must listen to the incoming signal at the right time and correct frequency in order to properly receive the signal. FHSS

Current FCC regulations require manufacturers to use 75 or more frequencies per transmission channel with a maximum dwell time (the time spent at a particular frequency during any single hop) of 400 ms. Camada Fsica - DSSS Acronym for Direct-Sequence Spread Spectrum.

DSSS is one of two types of spread spectrum radio, the other being frequency-Hopping spread spectrum. DSSS DSSS is a transmission technology used in WLAN transmissions where a data signal at the sending station is combined with a higher data rate bit sequence, or chipping code, that divides the user data according to a spreading ratio.

DSSS The chipping code is a redundant bit pattern for each bit that is transmitted, which increases the signal's resistance to interference. If one or more bits in the pattern are damaged during transmission, the original data can be recovered due to the redundancy of the transmission.

CCK - Complementary Code Keying Short for Complementary Code Keying, a set of 64 eight-bit code words used to encode data for 5.5 and 11Mbps data rates in the 2.4GHz band of 802.11b wireless networking. CCK The code words have unique mathematical

properties that allow them to be correctly distinguished from one another by a receiver even in the presence of substantial noise and interference. CCK - Complementary Code Keying CCK works only in conjunction with the DSSS technology that is specified in the original 802.11 standard.

It does not work with FHSS. CCK CCK applies sophisticated mathematical formulas to the DSSS codes, permitting the codes to represent a greater volume of information per clock cycle. CCK

The transmitter can then send multiple bits of information with each DSSS code, enough to make possible the 11Mbps of data rather than the 2Mbps in the original standard. Wireless Products IEEE 802.11 L-G700AP > High Speed 2.4GHz (802.11g) Wireless Access Point

L-G700AP > High Speed 2.4GHz (802.11g) Wireless Access Point Product Features: Up to 54Mbps* WPA for Enhanced Wireless Security

Quickly Add Wireless Access to Your Network Web-based Configuration and Management Product Features: DWL-2100AP > High Speed 2.4GHz (802.11g) Wireless 108Mbps Access Point

Up to 108Mbps* WPA & 802.1x Authentication SNMP Management Software Included Also Work as Point-To-Point Bridge, Point-toMultipoint Bridge, Repeater, Wireless Client. Wireless G USB Adapter

Wireless G USB Adapter Easily Connect to Your Wireless Network from Your Desktop or Notebook PC Works with 802.11g and 802.11b Wireless Networks Check E-mail, Surf the Web, and Chat with

Friends and Family Online DWL-G122 > High Speed 2.4GHz (802.11g) Wireless USB Adapter DWL-G122 > High Speed 2.4GHz (802.11g) Wireless USB Adapter

Product Features: Up to 54Mbps* 802.11g Standard, 802.11b Compatible Protect Your Network with WPA and 802.1x Security Quick and Easy Setup WIMAX IEEE 802.16 IEEE 802.16 (WiMAX)

Specifies WiMAX in the 10 to 66 GHz range. OFDM DES3 and AES Commonly referred to as WiMAX or less commonly as WirelessMAN or the Air Interface Standard, IEEE 802.16 is a specification for fixed

broadband wireless metropolitan access networks (MANs). IEEE 802.16a (Wi-MAX) Added support for the 2 to 11 GHz range. OFDM 3-DES and AES

Commonly referred to as WiMAX or less commonly as WirelessMAN or the Air Interface Standard, IEEE 802.16 is a specification for fixed broadband wireless metropolitan access networks (MANs). Redes sem Fio de Banda Larga Empresas de telefonia tm permisso para oferecer servios locais de voz e Internet de alta velocidade.

H uma grande demanda por estes servios. Problema: estender par tranado categoria 5 ou cabos coaxial ou de fibra at milhares de residncias algo dispendioso. Redes sem Fio de Banda Larga

O que fazer ? Rede sem Fio de Banda Larga. Como fazer ? Uma grande antena e antenas nos clientes mais fcil e econmico. Redes sem Fio de Banda Larga Empresas de telecomunicaes:

Fornecer um servio de comunicao sem fio de vrios megabits para voz, Internet e filmes por demanda. LMDS foi feito para este fim. Redes sem Fio de Banda Larga Mas, cada concessionria elaborava seu prprio sistema ...

Faltava padres ... Impossibilidade de produzir hardware e software em massa. Preos elevados e aceitao baixa.

Redes sem Fio de Banda Larga Um padro de banda larga sem fio era o elemento-chave que estava faltando. IEEE formou um comit da indstria e acadmico para elaborar um padro.

IEEE 802.16 (julho de 1999) Redes sem Fio de Banda Larga Padro IEEE 802.16 final: abril de 2002. Air Interface for Fixed Broadband Wireless Access Systems (Interface Area para Sistemas Fixos de Acesso sem Fio de Banda Larga)

Redes sem Fio de Banda Larga MAN (Metropolitan Area Network) sem Fio ou Loop Local sem Fio. Redes sem Fio de Banda Larga: (Bolcskey et al., 2001) (Webb, 2001)

IEEE 802.16 (Eklund et al., 2002) Comparando 802.11 com 802.16 802.11 e 802.16 resolvem problemas diferentes. 802.16 fornece servio para edifcios e edifcios no so mveis. No migram de uma clula para outra.

802.11 lida com mobilidade, enquanto 802.16, no. Edifcios podem ter muitos computadores. A estao final no 802.11 um notebook. Para edifcios, sinal de rdio melhor essencial. 802.16

Assim, 802.16 deve usar comunicao full-duplex, algo que o 802.11 evita para manter baixo o custo do sinal de rdio (baixo, o custo dos rdios). 802.16 se estende sobre parte de uma cidade. Assim, as distncias envolvidas podem ser de quilmetros, o que significa que a potncia percebida numa estao-base pode variar de estao para estao.

802.16 Essa variao afeta a relao sinal/rudo, que, por sua vez define vrios esquemas de modulao. A comunicao aberta sobre uma cidade significa que a segurana e a privacidade so essenciais e obrigatrias. 802.16

Cada clula 802.16 deve ter muito mais usurios que uma clula tpica 802.11. Espera-se que usurios 802.16 utilizem maior largura de banda que um usurio tpico 802.11. 802.16

Com o 802.16 necessrio mais espectro do que a banda ISM no 802.11. 802.16 opera na faixa de frequncias de 10 a 66 GHz. 802.16 funciona atravs de ondas milimtricas. Ondas milimtricas tm propriedades fsicas diferentes das ondas de rdio, mais longas das bandas ISM.

802.16 O 802.11 omnidirecional. As ondas milimtricas do 802.16 podem ser concentradas em feixes direcionais. Ondas milimtricas so absorvidas pela intemprie (chuva, neve, granizo, nevoeiro, ... ). 802.16

QoS no 802.16: o padro foi projetado para para Internet, telefonia, televiso e uso pesado de multimdia. O 802.11 foi projetado para ser equivalente Ethernet mvel. O 802.16 pode ser usado para dispositivos

mveis ?

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