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Wireless Local Area Networks (WLANs)

Wireless Local Area Networks (WLANs). What is a wireless LAN?. Is the linking of two or more computer without using wires Wireless LAN (WLAN) - provides all the features and benefits of traditional LAN technologies such as Ethernet, but without the limitations of wires or cables.

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Wireless Local Area Networks (WLANs)

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  1. Wireless Local Area Networks(WLANs)

  2. What is a wireless LAN? • Is the linking of two or more computer without using wires • Wireless LAN (WLAN) - provides all the features and benefits of traditional LAN technologies such as Ethernet, but without the limitations of wires or cables. • WLAN, like a LAN, requires a physical medium to transmit signals. • In wired network we use physical medium such as: • 1- Coaxial cables • 2- Twisted pair • 3- Fiber optics

  3. What is a wireless LAN? • Instead of using cables, WLANs use: • Infrared light (IR) • 802.11 does include an IR specification • limitations, easily blocked. • Radio frequencies (RFs) • Can penetrate most office obstructions 802.11b Access Point Telephone PDA Bar code scanner

  4. Why are the using of Radio Frequencies (RFs) more than Infrared Light (IR)? • the using of Radio Frequencies (RFs) more than Infrared Light (IR) because of: • 1- Higher Bandwidth • 2- Wider coverage WLAN use 2.4 and 5 GHZ frequency band • 3- Provide freedom and flexibility within building and between buildings

  5. Wireless Network components • The wireless network is less complex than wired networks • There are two basic components in wireless network • 1- Wireless Access Point (WAP) • 2- a wireless NIC

  6. Wireless Network components • First : Wireless Access Point • 1- Is a central component (like a hub or switch) • 2- Its function is to operate as a hub for wireless devices • 3- It has at least one antenna • 4- It has a port to connectthe wireless AP to a wired network

  7. Wireless Network components Second : Wireless NIC Wireless 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 antenna. Wireless antenna act as transmitter and receiver. There are two classes of antennas: 1- OMNI directional antennas (point-to-multipoint): EX: FM antenna 2- Directional (Yagi (or) point-to- point): Yagi is limited in coverage area Most of WAP use OMNI antenna

  8. Why Wireless?

  9. Wireless LAN standards • Infrared networking • Is a type of wireless networking • Point-to-point communication , short distance • Infrared wireless use IrDA standard ( standard for point-to-point) • Data transmission rate (16mbps)updated to (100 mbps) • Max range = 1 meter • Bluetooth networking • Wireless standard • Max throughput = 1 mbps

  10. Wireless LAN standards • 802.11 • Is a set of standards that govern wireless network transmission methods. • Provide authentication and authorization of LAN nodes. • Developed by IEEE LAN/MAN standard in 1997. • Frequency range = 2.4 GHZ • Support Max network bandwidth (Data rate)= 2 Mbps • In noisy environments fall back to 1 Mbps

  11. 802.11a 802.11 is too slow for most application Max data rate (B.W)= 54 Mbps Radio frequency range= 5 GHZ Max range (indoor) = 76 m Max range (outdoor) = 305 m Advantages 1- Fast Max speed 2- Regulated frequency prevent interference from other devices Disadvantages 1- Highest cost 2- shorter range signal that more easily obstructed

  12. 802.11b Data rate (B.W)= 11 Mbps Radio frequency range= 2.4 GHZ Max range (indoor) = 91 m Max range (outdoor) = 457 m Advantages 1- Lowest cost 2- Signal range is good and not easily obstructed 3- It is easy to install Disadvantages 1- Slowest Max speed 2- Home application may interfere on the unregulated frequency band

  13. 802.11g Data rate (B.W)= 54 Mbps Radio frequency range= 2.4 GHZ Max range (indoor) = 91 m Max range (outdoor) = 457 m Advantages 1- Fast Max speed 2- Signal range is good and not easily obstructed Disadvantages 1- cost more than 802.11b 2- application may interfere on the unregulated frequency band

  14. More about WLAN • Modes of Operation • 􀂋 Ad-Hoc mode (Independent Basic Service Set - IBSS) • 􀂋 Infrastructure mode (Basic Service Set - BSS)

  15. Installation type Ad-Hoc mode In this mode , the wireless NICs or other devices can communicate directly without the need for a WAP To 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

  16. Installation type • Infrasructure mode • In this mode , NICs will only communicate with an access point (instead of each other as in ad-hoc mode). • 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

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