1 / 21

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”

naiara
Télécharger la présentation

Wireless in Schools

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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?

More Related