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Broadband and Personal Area Network

This overview provides information on broadband technologies including DSL and cable modems, as well as personal area network technologies such as Wi-Fi and Bluetooth.

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Broadband and Personal Area Network

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  1. Broadband and Personal Area Network 2110472 Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University

  2. Outline • Overview. • Broadband. • Personal Area Network • Wi-Fi. • Bluetooth.

  3. Overview

  4. Broadband Speed 56k modem: 96sec - 1.5min ISDN-data : 43 seconds DSL: 2.5 -8.5 sec Cable 2-way ( faster than or = to DSL )

  5. DSL • Modem over PSTN • Carry data over voice networks. • Slow and difficult to handle. • Digital Subscriber Line (DSL) • Dedicate line using special modems to transmit digital information. • Use the existing PSTN. • ADSL: Asynchronous Digital Subscriber Line.

  6. ADSL Speed • Unbalanced upstream/downstream bandwidth • Allocate more for downstream traffic. • Up to 10 to 1 ratio. • Max downstream bandwidth is varied based on the length from access point • 6 Mbps – within 3 Kms. • 1.5Mbps – more than 3 Kms.

  7. Cable Modem • Broadband alternative. • Comes with cable TV over • Coaxial cable: 2-way. • Satellite dish (DSS): 1-way. • Coaxial cable • Shared medium among neighbors. • Send both downstream and upstream via the cable.

  8. Cable Modem • Satellite Dish – 1-way • Can receive only the downstream. • Use normal modem over PSTN for upstream.

  9. Personal Area Network • Network within small spaces. • Most of them are wireless • Wi-Fi (802.11b). • HomeRF. • Bluetooth. • Requirements • Small. • Low-power consumption.

  10. Wireless LAN • Based on Ethernet Standard. • 802.11a – up to 54 Mbps. • 802.11b : WiFi – up to 11 Mbps. • Use CSMA/CA • Similar to TDMA concept. • Characteristics • 5 GHz (802.11a) and 2.4 GHz (802.11b). • Frequency hopping scheme. • Wired Equivalent Privacy (WEP) • Similar to SSL.

  11. Frequency Hopping Scheme

  12. Adhoc Configuration Basic Service Set

  13. Interconnection Extended Service Set Basic Service Set

  14. Typical WLAN Configuration

  15. 802.11 Comparison • 802.11a • Provide more bandwidth. • Can cover shorter distance. • 802.11b (WiFi) • Low power consumption. • Cheaper to produce. • In market now.

  16. Bluetooth • Wireless technology specifically for: • Short range – up to 10 meters typically. • 2.4 GHz, Frequency Hoping. • Modest performance (721Kbps). • Dynamic configurability • i.e. ad hoc networking/roaming. • Low power, low cost, and small. • Well suited to handheld applications. • Support for both voice and data.

  17. History of Bluetooth • Ericsson, the principal inventor, borrowed the name from Harald Bluetooth (son of Gorm) • The King of Denmark circa 900AD • United Denmark and Norway • Seemed like a good name for uniting many dissimilar devices from different manufacturers

  18. Short-range wireless connectivity within three areas: Data and voice access points Cable replacement Ad-hoc networking What is Bluetooth Good For?

  19. Digital Camera Computer Scanner Inkjet Printer MP3 Player PDA Cell Phone Home Audio System Cordless Phone Base Station xDSL Access Point Bluetooth in the Home

  20. Car Audio System PDA Cell Phone Headset MP3 Player Pay Phone & Access Point Laptop Hotel Phone & Access Point And On the Road

  21. How Does Bluetooth Work? Operational States Master Active Slave Parked Slave* Standby* D F N M P O * Low power state J Q I C

  22. In the Beginning • Initially Bluetooth devices only know about themselves • Everyone passively monitors in Standby mode • No devices are synchronized D F N H G M A P B O E K J L Q I C

  23. Note that a device can be “Undiscoverable” H InquiryDiscovering Who’s Out There • Inquiry discovers what other devices are within range D F N H G M A P B O E K J L Q I C 10 meters

  24. B PagingCreating a Piconet • Paging creates a Master/Slave link called a Piconet D F N H G M A A P B O E K J L Q I C 10 meters

  25. F G B E K J I Expanding a Piconet (1) • Successive Pages can attach up to 7 Active Slaves to a Piconet at one time D F N H M G A P O E K J L Q I C 10 meters

  26. B B J J Parking • To save power and/or to connect to even more devices Active Slaves can be Parked (up to 256 total!) D F N H G M A P O E K L I Q C 10 meters

  27. H C Expanding a Piconet (2) • Masters can then attach additional Active Slaves using Active Member Addresses freed up through Parking D F N H G M A P B O E K J L I Q C 10 meters

  28. Scatternets • Bluetooth devices can participate in multiple Piconets simultaneously creating a topologies called Scatternets D F H N G M A B P O E K J L I Q C

  29. Advanced Scatternets • Scatternets can evolve into extremely complex structures creating a rich fabric of many, many, devices D F N H G M A P B O E K L J Q I C

  30. Summary • Broadband • ASDL. • Cable Modem. • Personal Area Network • Wi-Fi. • Bluetooth.

  31. References • J. Kurose and K. Ross, Computer Networking: A Top-Down Approach Featuring the Internet, Addison Wesley, 2001. • And many more.

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