IEEE is basically used for WLAN i.e wireless local area network. It provides time bounded and asynchronous services for different downloading and uploading speed with time limitation. This is the standard protocol used all over the world. 802.11 comes under the most popular IEEE specification for wireless LAN. It covers the physical and data link layers. This post includes Wireless Communication Notes on IEEE 802.11 Standards for WLAN for the students to provide a help for Communication students to perform well in their exams and interviews.
802.x belongs to different families of IEEE protocol where x denotes types of services. Different protocols used for different services are:
- 802.11 is used for Wi-Fi.
- 802.15 is used for bluetooth.
- 802.16 is used for Wi-Max.
IEEE 802.11 Architecture
IEEE 802.11 defines two types of services which are
1) Basic Service Set (BSS)
2) Extended Service Set (ESS)
Basic Service Set (BSS): IEEE 802.11 has defined the BSS as the basic building block of wireless LAN. A BSS is made of stationary or moving wireless stations and a central base station called as the access point (AP).
BSS can exist with and without AP. BSS without access point cannot send data to another BSS. So, it is known as a stand alone network or ad hoc architecture. In this type of architecture stations can form a network without using AP.
Extended Service Set (ESS): An extended service set consists of two or more BSSs with access points. The BSS in this system are connected to each other via a distribution system which is generally a wired LAN. The distribution system connects the access points to each other. The distribution system can be any type LAN such as Ethernet. thus ESS contains two types of station:
- Mobile Stations
- Stationary of non-moving stations
Out of these, the non-moving stations are the access points which are a part of the wired LAN whereas the mobile stations are those contained in the BSS. The BSSs are connected to each other to form a network called infrastructure network. In such networks the station close to each other can communicate taking help of access points.
But if two stations are located in two different BSS wish to communicate with each other, than they have to do do through access points. This type of communication is very similar to that in the cellular communication. The BSS acts as a cell and AP as base station.
Types of Stations in ESS are as follow:
There are three types of stations are defined by IEEE 802.11 depending on their mobility in the wireless LAN as
1) No transition Mobility : It is defined as a station which is non-moving (stationary) or moving only inside a BSS.
2) BSS Transition Mobility : A station having BSS transition mobility is the one which can move from BSS to another but does not move outside one ESS.
3) ESS transition Mobility : A station having ESS transition mobility is the one which can move from one ESS to another. But IEEE 802.11 does not guarantee communication when the station is moving.
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