Connects PDA’s, Phones, Laptops, Ear pieces and etc.
Uses Bluetooth 802.15
Uses ZigBee
Low Bandwidth and Throughput are Normal with
WPAN use
Wireless Local Area Network (WLAN)
Defined in 802.11-2007
Refined in 802.11 Amendments
May include several AP’s
Common in SOHO Networking
Increasingly Common in Enterprise Networking
Basic Service Set (BSS)
An Access Point (AP) and any associated Stations
Extended Service Set (ESS)
The communication between multiple access points that share a network infrastructure
Is one or more basic service sets that share a distribution system medium.
Independent basic service set(IBSS)
Involves direct communication between 802.11 client stations without the use of an access point
Known as peer to peer network or an ad hoc network
802.11 Configuration Modes
Access Point Modes
–Bridge Mode
–Workgroup Bridge Mode
–Repeater Mode
–Root Mode
–Scanner Mode
•Station Modes
–Infrastructure Mode
–Ad Hoc Mode
Distribution System (DS)
•Interconnects a set of basic service sets
(BBS) via integrated LAN’s creating an Extended Service Set (ESS)
Used for transport of traffic as well as services used for transport of traffic
Distribution System Medium (DSM)
logical physical medium used to connect access points 802.3 backbone
Distribution System Services
(DSS)
used to manage client associations, reassociations, and diassociations
A system service built inside an autonomous access point or WAN controller usually in the form of software
Wireless Distribution System (WDS)
A DS that uses the Wireless Medium
connects accesspoints together
Examples include:
–Bridges
–Repeaters
–Wireless Mesh Networks
Service Set Identifier
(SSID)
The logical name used to identify a wireless
network
Made up of 32 characters and is lower case
Basic Service Set Identifier (BSSID)
The 48 bit MAC address used by
the AP in a Basic Service Set (BSS
Integration Service (IS)
Enables (Mac Service Data Unit) MSDU’s to be
Delivered between the non-802.11 LAN and the Distribution System
A Frame Format Transfer Method
CSMA/CA vs. CSMA/CD
-Collision Detection
More Efficient
Less Overhead
Transmits and listens for collisions
-Collision Avoidance
Less Efficient
More Overhead
Listens to medium prior to transmission
Physical Carrier Sense
Performed by stations not Transmitting or Receiving
Listening for any 802.11 traffic
Virtual Carrier Sense
Uses a logical timer called the Network Allocation Vector (NAV)
Stations can not transmit unless the NAV value is 0
interframe spacing (IFS)
a peroid of tie that exists between transmissions of wireless frames.
Random Back-off Timer
Final Timer used prior to Transmission
Reduces the Chance the two or more Wireless
Stations Transmit Simultaneously
Distributed Coordination Function (DCF)
Mandatory access mode of 802.11 standard
Provides CSMA/CA
Main Components Include:
–Interframe Space
–Virtual Carrier Sense
–Physical Carrier Sense
–Random Back-off Timer
Point Coordination Function (PCF)
Is a form of Polling
The AP acts as a Point Coordinator
Only works within a BSS
Optional Contention Method
Has a great deal of Overhead
Not currently Implemented
Hybrid Coordination Function (HCF)
Introduced in 802.11e
Uses Transmit Opportunities
–Period of time to transmit
–Assigns Priority to traffic
•Creates two Access Methods
–Enhanced Distributed Channel Access (EDCA)
–HCF Controlled Channel Access
the use of TXOPs and access categories in EDCA as well as the use of TXOPs and polling during HCCA
Network Allocation Vector (NAV)
a timer mechanism that maintains a prediction of future traffic on the medium based on duration value information seen in a previous frame transmission