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Wireless in Schools

Wireless in Schools. Term 4 2010. What is a Wireless LAN. “ Wireless network refers to any type of computer network that is wireless”

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Wireless in Schools

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  1. Wireless in Schools Term 4 2010

  2. What is a Wireless LAN • “Wireless network refers to any type of computer network that is wireless” • “A wireless local area network (WLAN) links two or more devices using a wireless distribution method, and usually providing a connection through an access point to the wider internet. This gives users the mobility to move around within a local coverage area and still be connected to the network”. • Wikipedia

  3. Parts of WLAN Wireless Adapter • Enables to computer to connect to a wireless network. • Can be built in or external. Wireless Access Point • Provides the (bridge) connectivity between the Wireless Network and the Wired (cabled) network.

  4. What is 802.11<?> • 802.11 is the IEEE standards covering Wireless networking: • a – 54 Mb/s, 5 GHz Band • b – 11 Mbs, 2.4 GHz Band • g – 54 Mbs, 2.4 GHz Band • n – 2.4 or 5 GHz Bands • Users Multiple Antenna (MIMO) + wider channels • 20 MHz Channels – 2 Streams - 300 Mbs • 40 MHz Channels – 4 Streams - 600 Mbs,

  5. 2.5 GHz vs 5 GHz 2.4 MHz 5 GHz Newer Standards (a, n) Older devices may not operate in this band Less other devices in this band Poorer range top signal strength ratio especially through walls etc • Older Standard (b, g, n) • Legacy Devices may only operate in this band • Interference from other devices such as Microwave ovens, cordless phones, Bluetooth. • Better range to signal strength especially through walls etc

  6. Wireless Channels 2.4 GHz • 11 (13) Channels are available. • APs can not sit on overlapping channels • For a, b, g: • Only 3 available non-overlapping channels • For n (2.4 GHz) – 40 MHz (Bonded channels) • 1 non-overlapping Channel available • For n (5 Ghz) - 40 MHz (Bonded channels) • 22 non-overlapping Channels available

  7. Wireless Channels 5 GHz • For n - 20 MHz – Single Channels • 23 non-overlapping Channels are available. • Not all at full strength • For n - 40 MHz (Bonded channels) • 12 non-overlapping Channels available

  8. Advantages of Wireless • Provides network connectivity without the need for cables. • Provides a mobile solution • Establishment Costs – (unmanged solutions)

  9. Wireless Myths • Wireless Access points can support 255 clients. • Wireless range can be increased to cover the school from a single access point. • Wireless networks mean we do not need cable

  10. Limitations of Wireless • Shared Media • Half Duplex + overheads • Security • Speed – always slower than cable • Distance – speed drops as distance is increased • Signal Barriers • No Seamless Roaming (unmanaged)

  11. Shared Medium • All wireless clients share the same wireless space. • Speed shared among all clients • Effective speed is determined by slowest client and number of clients.

  12. Signal Barriers • Any solid object can block or interfere with Wireless signal reducing range and strength: • Concrete and Brick Walls/floors • Trees • Metal Walls (Demountables) • Water (Rain) • People • Reflective Film

  13. Wireless Speed • Speed is determined by factors such as distance, interference, client used etc • True Theoretical throughput (1 Client)

  14. Wireless Speed (cont) • Starting Point – Assuming all devices are within Max range • Effective two way speed after overhead 802.11g 1 Client – 20 Mbs 2 Clients – 10 Mbs 5 Clients – 4 Mbs 10 Clients – 2 Mbs 20 Clients – 1 Mbs 802.11n 1 Client – 50 Mbs 2 Clients – 25 Mbs 5 Clients – 10 Mbs 10 Clients – 5 Mbs 20 Clients – 2.5 Mbs

  15. Wireless Speed (cont) • As distance (and obstacles) increase speed decreases. • Any impact on wireless signal/speed achieved by any client AFFECTS ALL clients connected to same access point. • i.e. Speed is determined by slowest client

  16. The Non-Managed solution • Use of Standard Access points • Each WAP is configured separately and operates independently • No Seamless roaming • No load balancing • Channel management is important • Wireless Security is manually configured • Affected by Interfering/Rogue WAPs

  17. Unmanaged Solution • Up to 3 Access points • Fixed location or attached to Laptop trolley • HP ProCurve M410 WW Access Point • A, b, g and n Indoor • HpProcurve 1 Port Power Injector • $ 458

  18. The Managed Solution • Uses “thin” WAPs • Requires a controller • Seamless Roaming • Automatic load balancing • Channel management is carried out by Controller. • Wireless Management can be controlled by controller • Affected by Interfering/Rogue WAPs

  19. Full School Coverage • 20 Access Points Required (Minimum)

  20. The DER Model

  21. Any Final Questions?

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