Wi Fi

Last week ,[object Object],[object Object],[object Object]

Wifi, Bluetooth, Ethernet Couche 5 Couche 4 Couche 3 Couche 2: Lien Couche 1: Physique ,[object Object],[object Object],[object Object],[object Object]

= la norme IEEE 802.11 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

IEEE 802.11 standard ,[object Object],[object Object]

Infrastructure mode in urban situation

[object Object],[object Object],[object Object],[object Object],IEEE 802.11 basic

Frequencies ,[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],coding IEEE 802.11b ,[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],IEEE 802.11b,a,g,n

Basic CSMA: listen before talk ,[object Object],forbidden zone emitter destination packet ack forbidden period DIFS

Hidden nodes collisions avoidance ,[object Object],emitter destination packet ack forbidden period RTS CTS

Collision management ,[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Forbidden period slot slot slot Forbid. period Example: time for a backoff of 3 slots Retransmissions packet ack Forbidden Period RTS CTS packet ack forbidden period DIFS

[object Object],AP terminal Distribution system BSS ESS AP: Access Point BSS: Basic Set Service ESS: Extended Set Service IBSS: Independent Basic Set Service Terminology IBSS ,[object Object]

[object Object],[object Object],preamble MAC header Data part (IP packet) Check sum packet ACK SISF Emitter node Intended Receiver node Formats (packets)

[object Object],[object Object],[object Object],[object Object],Address 1 Address 2 Address 3 Address 4 control sequence Formats (MAC header)

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],WEP security ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],IEEE 802.11 IEEE 802.1x Authentification agent improved security

= IEEE 802.15.1 ,[object Object],[object Object],[object Object],[object Object],[object Object],master slaves piconet

[object Object],[object Object],[object Object],[object Object],IEEE 802.15.1 esclaves

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],IEEE 802.15.1

[object Object],[object Object],[object Object],[object Object],[object Object],IEEE 802.15.1 From master From slave

[object Object],[object Object],[object Object],Formats

frequency hoping Periodic change of frequencies. Predetermined sequence fixed in standard. Goal: use uncongested frequencies.

[object Object],[object Object],[object Object],[object Object],[object Object],Connection

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Sécurity ,[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],Authentification

[object Object],[object Object],[object Object],[object Object],Encryption ,[object Object],[object Object],[object Object],[object Object],[object Object]

Wi Fi

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Wi Fi