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Wireless la ns(wlan) ieee 802


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Description about IEEE 802.11 Wireless LANs

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Wireless la ns(wlan) ieee 802

  1. 1. SEMINAR ON : Wireless LANs(WLAN)-IEEE 802.11 PRESENTED BY : ABHISHEK G - 4KV13EC002 CHANDRASHEKAR P R - 4KV14EC402 802.11 LAN Basic Service Set (BSS) Extended Service Set (ESS)
  2. 2. . Wireless LANs-IEEE 802.11  Wireless communication is one of the fastest-growing technologies.  WLAN is a wireless computer network that links two or more devices using a wireless distribution method within a limited area  Wireless LANs can be found on college campuses, in office buildings, and in many public areas.  IEEE 802.11 wireless LANs, sometimes called wireless Ethernet.  There are three specification in the family : 802.11, 802.11a and 802.11b .All three specification Use CSMA/CD as the path sharing protocol
  3. 3. 802.11 LAN • 802.11 LAN is based on a cellular architecture. • The system is divided into cell. Each cell is control by base station. • Cell is called as Basic Service Set (BSS) and base station is Acess Point (AP). • Set of BSS can be interconnected by a distribution system to form an Extended Service Set (ESS). • Each BSS has an access point. • An ESS can also provide gateway access for wireless users into a wired network such as internet. • The standard also defines concept of a Portal. Portal is a interconnects between an 802.11 and another 802LAN.
  4. 4. TYPES OF 802.11x 802.11x : Standard Speed Range Range(meter) Frequency 802.11b 11 Mbps 150 Feet 45.72 M 2.4 GHz 802.11g 54 Mbps 50 Feet 15.24 M 2.4 GHz 802.11a* 54 Mbps 50 Feet 15.24 M 5 GHZ 802.11n 300 Mbps 450 Mbps 175 Feet 51.85 M 2.4/5 GHZ
  5. 5. Topics discussed in this section: - Architecture of IEEE 802.11 - MAC Sublayer of IEEE 802.11 - Physical Layer of IEEE 802.11
  6. 6. Continue… Architecture of IEEE 802.11 - The standard defines two kinds of services a. Basic service set (BSS) b. Extended service set (ESS). 1. Basic Service Set (BSS) • IEEE 802.11 defines the basic service set (BSS) as the building block of a wireless LAN. • A BSS defines as a group of stations that co-ordinates their access to the medium under a given instance of the medium access control. • A basic service set is made of stationary or mobile wireless stations and an optional • Each BSS has an Access Point (AP) • central base station, known as the access point (AP).
  7. 7. Continue… Figure 1.25 Basic service sets (BSSs) NOTE: BSS without an AP is called an ad hoc network BSS with an AP is called an infrastructure network
  8. 8. Continue… 2. Extended Service Set (ESS) • An extended service set (ESS) is made up of two or more BSSs with APs. • In this case, the BSSs are connected through a distribution system, which is usually a • wired LAN. • The distribution system connects the APs in the BSSs. • IEEE 802.11 does not restrict the distribution system; it can be any IEEE LAN such as an Ethernet. • Note that the extended service set uses two types of stations: mobile and stationary. • The mobile stations are normal stations inside a BSS. The stationary stations are AP stations that are part of a wired LAN
  9. 9. Continue… Figure 1.26 Extended service sets (ESSs)
  10. 10. Continue…  Station Types IEEE 802.11 defines three types of stations based on their mobility in a wireless LAN. - No-transition: A station with no-transition mobility is either stationary (not moving) or moving only inside a BSS - BSS transition: Station with BSS-transition mobility can move from one BSS to another, but the movement is confined inside one ESS. - ESS-transition mobility: A station with ESS-transition mobility can move from one ESS to another. However, IEEE 802.11 does not guarantee that communication is continuous during the move.
  11. 11. MY SINCERE THANKS TO PROFESSOR SURESHA V Thank you Sir for sharing your gifts of teaching with us and Thanking you for your Guidance and Friendship.