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Protocolo 802.11

Protocolo 802.11. O IEEE 802.11 define 2 camadas do modelo OSI, as camada e Enlace e Física; Para camada de Enlace o protocolo define duas camadas Logical Link Control (LLC) e Media Access Control (MAC) Para a física (PHY) define três tipos de codificação:

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Protocolo 802.11

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  1. Protocolo 802.11 • O IEEE 802.11 define 2 camadas do modelo OSI, as camada e Enlace e Física; • Para camada de Enlace o protocolo define duas camadas Logical Link Control (LLC) e Media Access Control (MAC) • Para a física (PHY) define três tipos de codificação: • DSSS – DirectSequency Spread Spectrum • FHSS – FrequencyHoupping Spread Spectrum • InfraRed

  2. Protocolo 802.11 802.2 Camada de Enlace 802.11 MAC Camada Física DSSS FHSS IR

  3. Protocolo 802.11 • Quadro da Camada Física (FHSS) • PLPC Preamble • PLPC- physicallayerconvergenceprocedure • Sync –Sincronização, 80 bits usado para identificar a antena correta e sincronização de tempo • SFD (Start Frame Delimiter) – 16 bit para sicronização • PLPC Header • PLW (PLCP_PDU Length Word) – 12 bits de Comprimento do payload, incluindo os 32 bit CRC. PLW < 4096 • PSF (PLCP Signaling Field) – 4 bits indicandovelocidade (1 or 2 Mbit/s) • HEC (Header ErrorCheck) –16 bits de CRC 96 bits 32 bits PLPC Preamble PLPC Header MAC Synch SFD PLW PSF HEC

  4. Protocolo 802.11 • Quadro da Camada Física (DSSS) • PLPC Preamble • PLPC- physicallayerconvergenceprocedure • Sync –Sincronização, 128 bits usado para identificar a antena correta, controlo do ganho, detecção de energia • SFD (Start Frame Delimiter) – 16 bits para sicronização • PLPC Header • PLW (PLCP_PDU Length Word) – 16 bits de Comprimento do payload, incluindo os 32 bit CRC. PLW < 4096 • Service -8 bits com valor 0 para utilização futura • PSF (PLCP Signaling Field) – 8 bits indicandovelocidade (1 or 2 Mbit/s) • HEC (Header ErrorCheck) –16 bits de CRC PLPC Preamble PLPC Header MAC Synch SFD PSF Service PLW HEC

  5. Protocolo 802.11 • Camada de Enlace • Quadro MAC 802.11

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