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Características dos Padrões e Produtos

Características dos Padrões e Produtos. IEEE 802.11. Principais Aplicações. Padrões IEEE 802.11. 802.11a 5GHz, 54Mbps 802.11b 2.4GHz, 11Mbps 802.11c Protocolo para bridges 802.11d World Mode (Europa 20 dB, EUA-BR 36dB 802.11e Qualidade de Serviço

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Características dos Padrões e Produtos

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  1. Características dos Padrões e Produtos IEEE 802.11

  2. Principais Aplicações

  3. Padrões IEEE 802.11 • 802.11a 5GHz, 54Mbps • 802.11b 2.4GHz, 11Mbps • 802.11c Protocolo para bridges • 802.11d World Mode (Europa 20 dB, EUA-BR 36dB • 802.11e Qualidade de Serviço • 802.11f Inter-Access Point Protocol • 802.11g 2.4GHz, 54Mbps, modulação digital OFDM • 802.11h Seleção dinâmica de frequência • 802.11i Autenticação e Segurança • 802.11n

  4. Access Point • Short for Access Point, a hardwaredevice 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.

  5. Infrastructure Mode • An 802.11networking 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).

  6. 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.

  7. Ad-hoc Mode • An 802.11networking 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 802.11a X 802.11b

  15. 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)

  16. 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.

  17. 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.

  18. A Pilha de Protocolos 802.11 Camadas Superiores Subcamada LLC Camada de Enlace Subcamada MAC IEEE 802 Infra- vermelho 802.11 FHSS 802.11 DSSS 802.11a OFDM 802.11b HR-DSSS 802.11gOFDM IEE Camada Física

  19. MAC - CSMA/CA • Short for Carrier Sense Multiple Access/Collision Avoidance, a networkcontentionprotocol that listens to a network in order to avoid collisions. • Unlike CSMA/CD that deals with network transmissions once collisions have been detected.

  20. 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.

  21. Camada Física - OFDM • Short for Orthogonal Frequency Division Multiplexing, an FDMmodulation technique for transmitting large amounts of digital data over a radio wave.

  22. OFDM • OFDM works by splitting the radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies to the receiver.

  23. OFDM • OFDM reduces the amount of crosstalk in signal transmissions. • 802.11aWLAN, 802.16 and WiMAX technologies use OFDM.

  24. Camada Física - FHSS • Acronym for Frequency-Hopping Spread Spectrum. FHSS is one of two types of spread spectrum radio, the other being direct-sequence spread spectrum.

  25. 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.

  26. Camada Física - 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.

  27. Camada Física - 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.

  28. 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.

  29. Camada Física - DSSS • Acronym for Direct-Sequence Spread Spectrum. • DSSS is one of two types of spread spectrum radio, the other being frequency-Hopping spread spectrum.

  30. 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.

  31. 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.

  32. 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.

  33. 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.

  34. 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.

  35. CCK • CCK applies sophisticated mathematical formulas to the DSSS codes, permitting the codes to represent a greater volume of information per clock cycle.

  36. 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.

  37. Wireless Products IEEE 802.11

  38. L-G700AP  >  High Speed 2.4GHz (802.11g) Wireless Access Point

  39. 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

  40. 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-to-Multipoint Bridge, Repeater, Wireless Client.

  41. Wireless G USB Adapter

  42. 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

  43. DWL-G122  >  High Speed 2.4GHz (802.11g) Wireless USB Adapter

  44. 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

  45. WIMAX IEEE 802.16

  46. IEEE802.16 (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).

  47. 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).

  48. Redes sem Fio de Banda Larga • Empresas de telefonia têm permissão para oferecer serviços locais de voz e Internet de alta velocidade. • Há uma grande demanda por estes serviços. • Problema: estender par trançado categoria 5 ou cabos coaxial ou de fibra até milhares de residências é algo dispendioso.

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