notes of CN

1. Presentation title
Wireless LAN IEEE 802.11 Bluetooth
Name: Amna Noor
Roll no:21011556-21

2. Wireless LAN:
A wireless local area network (WLAN) is a wireless distribution method for two or more devices. WLANs use high-
frequency radio waves and often include an access point to the Internet. A WLAN allows users to move around the
coverage area, often a home or small office, while maintaining a network connection.
A WLAN is sometimes called a local area wireless network (LAWN).
Advantages of WLAN:
 They provide clutter free homes, offices and other networked places.
 The LANs are scalable in nature, i.e. devices may be added or removed from the network at a greater ease than
wired LANs.
 The system is portable within the network coverage and access to the network is not bounded by the length of the
cables.
 Installation and setup is much easier than wired counterparts.
 The equipment and setup costs are reduced.
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3. Disadvantages of WLAN :
 Since radio waves are used for communications, the signals are noisier with more interference from
nearby systems.
 Greater care is needed for encrypting information. Also, they are more prone to errors. So, they
require greater bandwidth than the wired LANs.
 WLANs are slower than wired LANs
Key Application Areas:
1. Lan extension
2. Cross-building interconnect
3. Nomadic access
4. Ad hock networking
LAN Extension :
 wireless LAN will be linked into a wired LAN on the same premise
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4. Crossing building interconnect :
 connect LANs in nearby buildings
 point-to-point wireless link
 Devices connected are typically bridges or routers.
 Used where cable connection not possible (e.g. across a street)
Nomadic Access:
 Wireless link between LAN hub and mobile data terminal equipped with antenna
 also useful in extended environment such as campus or cluster of buildings
 users move around with portable computers
Ad Hoc Networking :
 Temporary peer-to-peer network set up to meet immediate need.
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5. Infrared LANS:
 constructed using infrared portion of spectrum
 strengths
 spectrum virtually unlimited hence high rates possible
 unregulated spectrum
 infrared shares some properties of visible light
 reflection covers room, walls isolate networks
 inexpensive and simple• weaknesses
 background radiation, e.g. sunlight, indoor lighting
 power limited by concerns for eye safety and power consumption
Spread Spectrum LAN Configuration:
 usually use multiple-cell arrangement
 adjacent cells use different center frequencies
 configurations:
 hub
 connected to wired LANconnect to stations on wired LAN and in other cells
 may do automatic handoff
 peer-to-peer
 MAC algorithm such as CSMA used to control access for ad hoc LANs
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6. Trasmission Techniques:
 directed-beam IR
 point-to-point links
 range depends on power and focusing
 for indoor use can set up token ring LAN
 omnidirectional
 single base station with line of sight to other stations
 acts as a multiport repeater
 other stations use directional beam to it
 diffused configuration
 stations focused / aimed at diffusely reflecting ceiling
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7. TRANSMISSION ISSUE :
Three microwave bands have been set aside by FCC which doesn't need a license if the equipments operates under
1W power they are:
902-928 MHz (915 MHz band)-Industrial Band
2.4-2.4835 GHz (2.4 GHz band)-Scientific Band
 5.725-5.825 GHz (5.8 GHz band)- Medical Band
 Commonly known as ISM band it is used by Wireless LAN with spread spectrum technology
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8. IEEE 802.11:
 IEEE has defined the specifications for a wireless LAN, called IEEE802.11, which covers the physical and data
link layers. Defines standard for WLANs using the following four technologies
 Frequency Hopping Spread Spectrum (FHSS)
 Direct Sequence Spread Spectrum (DSSS)
 Infrared (IR)
 Orthogonal Frequency Division Multiplexing (OFDM)
 Versions: 802.11a, 802.11b, 802.11g, 802.11e, 802.11f, 802.11i
802.11 - Architecture of an infrastructure network:
 Station (STA)
 terminal with access mechanisms to the wireless medium and radio contact to the access pointBasic Service Set
(BSS)
 group of stations using the same radio frequencyAccess Pointstation integrated into the wirelessLAN and the
distribution systemPortal
 bridge to other (wired) networksDistribution System› interconnection network
to form one logical network
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9. Medium Access Control:
 MAC layer covers three functional areas
 reliable data delivery
 access control
 Security Reliable
 Data Delivery
 Loss of frames due to noise, interference, and propagation effects.
 To ensure reliable data delivery IEEE 802.11 includes a frame exchange protocol.
 Two frame exchange
 Source station transmits data
 Destination responds with acknowledgment (ACK)* If source doesn't receive ACK, it retransmits frame.
Four frame exchange for enhanced reliability:
 • Source issues request to send (RTS)
 • Destination responds with clear to send (CTS) Source transmits data
 • Destination responds with ACK
 The RTS alerts all stations that are within reception range of the source that an exchange is under waySimilarly,
the CTS alerts all stations that are within reception rangeof the destination that an exchange is under way
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10. Distributed Coordination Function(DCF):
The lower sub-layer of the MAC layer.>
 DCF sub laver uses CSMA /CA if a station has the frame to send it listening to medium if medium idle, the
station may transmit else waits until the current transmission is complete To ensure the smooth and fair
functioning of CSMA, the MAC frame transmissions are separated by a time gap called IFS.
BLUE TOOTH:
 IEEE 802.11 is a wireless LAN technology using short-range radio links, intended to replace the cables)
connecting portable and/or fixed electronic devices
 is an ad hoc network where devices can automatically find each other, establish connections, and discover what
they can do for each other
 range 10-100 Mrs.
 features are robustness, low complexity, low power and low cost.
 uses a 2.4-GHz ISM band divided into 79 channels of 1 MHz each
 A Bluetooth device has a built-in short-range radio transmitter.
 It uses Frequency Hop Spread Spectrum (FHSS) to avoid any interference.Applications
 Automatic synchronization between mobile and stationary devices
 Connecting mobile users to the internet using Bluetooth-enabled wire-bound connection portsDynamic creation
of private networks
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11. Types of Bluetooth Wireless Technology:
Depending on the power consumption and range of the device, there are 3 Bluetooth Classes:
1. Class 1: Max Power - 100mW Range - 100 m2.
2. Class 2: Max Power - 2.5mW; Range - 10 m3.
3. Class 3: Max Power - ImW; Range - 1 m
Protocol Architecture
 Bluetooth is a layered protocol architecture
 • Core protocols
 • Cable replacement and telephony control protocols
 • Adopted protocols
 • Core protocols
 • Radio• Baseband
 • Link manager protocol (LMP)
 • Logical link control and adaptation protocol (L2CAP)
 •Service discovery protocol (SDP
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12. Cable replacement protocol
RFCOMM" Telephony control protocol
 • Telephony control specification - binary (TCS BIN)
 • Adopted protocols• TCP/UDP/IP• ОВЕХ• WAE/WAP
Radio Layer:
The bottom layer in protocol stack, equivalent to the physical layer of the Internet model.
 It deals with radio transmission and modulation.
 The Radio layer defines the requirements for a Bluetooth transceiver operating in the 2.4 GHz ISM
band.
 divided into 79 channels of 1 MHz each.
 Support data rate: IMbps (Basic Rate) / 3 Mbps (Enhanced DataRate).
Uses a technique called frequency hopping, for establishing radio links with other Bluetooth devices
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13. Thank you