Wireless Local Area Networks (WLANs)

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Wireless Local Area Networks(WLANs)

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What is a wireless LAN

bull In wired network we use physical medium such as bull 1- Coaxial cablesbull 2- Twisted pairbull 3- Fiber optics

bull Is the linking of two or more computer without using wires

bull Wireless LAN (WLAN) - provides all the features and benefits of traditional LAN technologies such as Ethernet but without the limitations of wires or cables

bull WLAN like a LAN requires a physical medium to transmit signals

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What is a wireless LAN

bull Instead of using cables WLANs usendash Infrared light (IR)

bull 80211 does include an IR specificationbull limitations easily blocked

ndash Radio frequencies (RFs)bull Can penetrate most office obstructions

80211b Access Point

Bar code scannerPDATelephone

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Why are the using of Radio Frequencies (RFs) more than Infrared Light (IR)

bull the using of Radio Frequencies (RFs) more than Infrared Light (IR) because of

bull 1- Higher Bandwidthbull 2- Wider coverage WLAN use 24 and 5

GHZ frequency bandbull 3- Provide freedom and flexibility within

building and between buildings

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Wireless Network components bull The wireless network is less complex than wired networksbull There are two basic components in wireless network1- Wireless Access Point (WAP) 2- a wireless NIC

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Wireless Network components

bull First Wireless Access Point bull 1- Is a central component (like a hub or switch)bull 2- Its function is to operate as a hub for wireless devicesbull 3- It has at least one antennabull 4- It has a port to connect the wireless AP to a wired

network

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Wireless Network components

Second Wireless NICWireless NIC does the same job as traditional NIC but instead of having a socket to plug some cable into the wireless NIC will have a radio antennaWireless antenna act as transmitter and receiver

There are two classes of antennas1- OMNI directional antennas (point-to-multipoint)EX FM antenna2- Directional (Yagi (or) point-to- point)Yagi is limited in coverage areaMost of WAP use OMNI antenna

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Why Wireless

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Wireless LAN standards

Infrared networking bull Is a type of wireless networkingbull Point-to-point communication short distance bull Infrared wireless use IrDA standard ( standard for point-to-point)bull Data transmission rate (16mbps)updated to (100 mbps)bull Max range = 1 meter

Bluetooth networkingbull Wireless standard bull Max throughput = 1 mbps

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Wireless LAN standards

80211 bull Is a set of standards that govern wireless network transmission

methodsbull Provide authentication and authorization of LAN nodesbull Developed by IEEE LANMAN standard in 1997bull Frequency range = 24 GHZbull Support Max network bandwidth (Data rate)= 2 Mbpsbull In noisy environments fall back to 1 Mbps

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80211a80211 is too slow for most applicationMax data rate (BW)= 54 MbpsRadio frequency range= 5 GHZMax range (indoor) = 76 mMax range (outdoor) = 305 mAdvantages1- Fast Max speed2- Regulated frequency prevent interference from other devicesDisadvantages1- Highest cost2- shorter range signal that more easily obstructed

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80211bData rate (BW)= 11 MbpsRadio frequency range= 24 GHZ Max range (indoor) = 91 mMax range (outdoor) = 457 mAdvantages1- Lowest cost2- Signal range is good and not easily obstructed3- It is easy to installDisadvantages1- Slowest Max speed2- Home application may interfere on the unregulated frequency band

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80211g

Data rate (BW)= 54 MbpsRadio frequency range= 24 GHZMax range (indoor) = 91 mMax range (outdoor) = 457 mAdvantages1- Fast Max speed2- Signal range is good and not easily obstructedDisadvantages1- cost more than 80211b2- application may interfere on the unregulated frequency band

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More about WLAN

bull Modes of Operation

bull 1048715 Ad-Hoc mode (Independent Basic

Service Set - IBSS)

bull 1048715 Infrastructure mode (Basic Service

Set - BSS)

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Installation type Ad-Hoc modeIn this mode the wireless NICs or other devices can communicate directly without the need for a WAPTo setup a basic ad-hoc wireless network all you need are two wireless NIC and two computers during the installation of the software you will be asked at some point if you want to setup the NIC in ad-hoc mode or infrastructure mode choose ad-hoc mode the bring the computers within range (90-100) meter then you will be able to connect to each other

Client A Client B

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Installation type Infrasructure modebull In this mode NICs will only communicate with an access point

(instead of each other as in ad-hoc mode)bull The access point will facilitate communication between the wireless

nodes as well as communication with a wired network (if present)

Client A

Access point

Client B