Ce diaporama a bien été signalé.
Nous utilisons votre profil LinkedIn et vos données d’activité pour vous proposer des publicités personnalisées et pertinentes. Vous pouvez changer vos préférences de publicités à tout moment.

IEEE 802.11

Livres associés

Gratuit avec un essai de 30 jours de Scribd

Tout voir
  • Soyez le premier à commenter

IEEE 802.11

  1. 1. IEEE 802.11 Presented By: Abhishek Pachisia B.Tech – IT
  2. 2. Foreword - 1 • Belong to 802.x LAN standards. • Primary goal – Simple and Robust WLAN – Time bound and Asynchronous services • MAC Layer – Should be able to operate with multiple physical layers (different medium sense & transmission characteristic. • Physical layer. – Infra red & Spread spectrum radio transmission techniques.
  3. 3. Foreword - 2 • Additional features of WLAN – Support of power management – Handling of hidden nodes – Ability to operate world wide. • 2.4 GHz ISM band – original standard. – 1 Mbits/s – Mandatory – 2 Mbits/s – Optional.
  4. 4. System Architecture - 1 • Basic System Architecture – Infrastructure based – Ad-hoc. • Components – Station (STA) – Access Points (AP) – Basic Service Set (BSS) – Extended Service Set (ESS) – Portal
  5. 5. Architecture of an Infrastructure based IEEE 802.11
  6. 6. System Architecture - 2 • Stations – Access mechanism to wireless medium – Radio contact to the AP. • BSS – BSSi are connected via Distributed System. • ESS – Form Single network, extends wireless coverage area. – ESSID : Name of network; Separate different network • Portal – Internetworking unit to other LANs.
  7. 7. System Architecture - 3 • AP’s support roaming. • Distributed system – Transfer between AP’s. • Infrastructure based network allow ad-hoc network between stations -> IBSS. • IEEE 802.11 does not specify – Routing – Forwarding of data – Exchange of topology Information
  8. 8. Architecture of IEEE 802.11 ad-hoc wireless LANs
  9. 9. Protocol Architecture - 1 • 802.11 fits seamlessly into 802.x wired networks. • Most common scenario – 802.11 & 802.3 via bridge. • Difference in bandwidth is noticed. • Upper part of logical link layer and data link control layer covers MAC differences.
  10. 10. IEEE 802.11 – Protocol architecture and belonging
  11. 11. Protocol Architecture - 2 • Physical Layer(PHY) – Physical Layer Convergence Protocol (PLCP) – Physical Medium Dependent sublayer (PMD) • Medium Access Control Layer (MAC) – To access medium. – To fragment user data. – To encrypt. • PLCP – Carrier sense signal (CSS) – Common Service Access Point(SAP) • PMD – Encoding/Decoding Signals.
  12. 12. Station ManagementDLC LLC MAC MAC Management PLCPPHY PMD PHY ManagementDetailed IEEE 802.11 protocol architecture and management
  13. 13. Physical Layer • Three Layers – Infra red (1) – Radio transmission (2) • Clear Channel Assessment signal (CCA). – MAC mechanism controlling medium access. – Indicates state of medium. • Service Access Point (SAP) • Versions of PHY layer – FHSS – DSSS – Infra red
  14. 14. FHSS • Allows coexistence of multiple networks. • Original Standard – 79 hopping channel North America. – 23 hopping channel Japan • Pseudo random hoping pattern. • Standard – GFSK as modulation for FHSS PHY. • 1Mbits/s is mandatory & 2Mbit/s is optional. • MAC data is scrambled using s(z)=z7+z4+1
  15. 15. Bits 80 16 12 4 16 Variable Synchronization SFD PLW PSF HEC Payload PLCP Preamble PLCP Header Format of an IEEE 802.11 PHY frames using FHSS
  16. 16. DSSS - 1 • Separated by code. • Achieved using 11-chip Barker sequence. • Key characteristics – Robustness against interference – Insensitivity to multipath propagation. • Implementation - Complex than FHSS. • Uses – Differential Binary Phase Shift Keying (DBPSK) – Differential Quadrature Phase Shift Keying (DQPSK)
  17. 17. DSSS - 2 • Maximum transmit power – US => 1W – Europe => 100mW EIRP – Japan => 10mW/MHz • Bits are scrambled by s(z)=z7+z4+1 • Two basic parts – PLCP part (Preamble and header) – Payload part.
  18. 18. Bits 128 16 8 8 16 16 Variable Synchronization SFD Signal Service Length HEC Payload PLCP Preamble PLCP Header Format of an IEEE 802.11 PHY frame using DSSS
  19. 19. Infra red • Uses visible light => 850-950nm. • No line of sight required. • Maximum range =>10m (no interference). • Today no product offer communication based on infra red. • Proprietary products offer up to 4Mbits/s using diffuse infra red light. • Directed infra red communication based on IrDA can be used (IrDA,2002).

    Soyez le premier à commenter

    Identifiez-vous pour voir les commentaires

  • darshana1995

    Jan. 13, 2014
  • Tinusanthosh

    Feb. 18, 2015
  • PenerbitDeepublish

    Oct. 16, 2015
  • syedtalib46

    Feb. 20, 2016
  • RamSit1

    Dec. 9, 2016
  • VasthavVas

    Dec. 12, 2016
  • KailasapuSaikumar1

    Feb. 22, 2017
  • SherlyRaj1

    Mar. 8, 2017
  • SurendharKanna

    May. 17, 2017
  • MrunmayeeSonna

    May. 23, 2017
  • PoojaDassani

    Oct. 3, 2017
  • PanduRk

    Oct. 12, 2017
  • HARISH76674

    Feb. 28, 2018
  • ThangteaVemai

    Apr. 8, 2018
  • Mathumitha15

    Apr. 22, 2018
  • KhatijatulKubra

    Jan. 8, 2020
  • avarnagovindarajan

    Oct. 22, 2020

Vues

Nombre de vues

29 610

Sur Slideshare

0

À partir des intégrations

0

Nombre d'intégrations

43

Actions

Téléchargements

1 120

Partages

0

Commentaires

0

Mentions J'aime

17

×