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Access Network Technologies

Access Network Technologies. IS250 Spring 2010 chuang@ischool.berkeley.edu. Access Network Options. Copper: DSL, cable, power line (PLC/BPL) Silicon: FTTH Copper/Silicon Hybrid: HFC, FTTC Wireless: WiFi, WiMax, cellular (2G, 3G), satellite. Local Loop.

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Access Network Technologies

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  1. Access Network Technologies IS250 Spring 2010 chuang@ischool.berkeley.edu

  2. Access Network Options • Copper: DSL, cable, power line (PLC/BPL) • Silicon: FTTH • Copper/Silicon Hybrid: HFC, FTTC • Wireless: WiFi, WiMax, cellular (2G, 3G), satellite

  3. Local Loop • The “last mile” or “first mile”: connection between customer premise and central office (CO) of telephone company

  4. POTS to PANS • Originally for analog POTS (plain old telephone service) • Also used for digital service • Integrated Services Digital Network (ISDN) • Supports voice and data • Digital Subscriber Line (DSL) • Several variants, e.g., ADSL, VDSL, SDSL, … A Central Office Location of CO’s in U.S.

  5. Asymmetric Digital Subscriber Line Modulation technique: DMT (discrete multi-tone)/OFDM (Orthogonal Frequency Division Multiplexing) Data rate as a function of distance ADSL http://www.maxim-ic.com/images/appnotes/3638/3638Fig02.gif

  6. Active Node Home FROM BROADCAST SOURCES Headend Feeder (Fiber) Drop Loop Cable Plant • Cable plant originally designed for one-way delivery of CATV programming; upgraded to support two-way data communication • Groups of subscribers in neighborhood share network • Hybrid Fiber Coax (HFC): • Optical fiber from cable headend to neighborhood concentration points • Coax cable to subscriber premises • Cable modem: uses FDM + TDM

  7. FTTx • Fiber-to-the-node (FTTN) • Fiber-to-the-curb (FTTC) • Fiber-to-the-building (FTTB) • Fiber-to-the-home (FTTH)

  8. WiFi Access Networks • Different scales, different economic models • Wireless ISPs (e.g., Boingo) • Municipal WiFi networks (e.g., Philadelphia, Taipei, Mountain View) • Community mesh networks • Private Access Points • Interference between provider, public and private APs an unresolved issue • WiFi operates in unlicensed spectrum Source: http://www.wigle.net/

  9. Wi-Max (802.16) • WMAN standard supporting point-to-multipoint wireless broadband access (WBA) • Up to 30 miles range • Up to 70 Mbps data rate • 802.16e provides mobility support • Complements 802.11 • Competes against 3G/4G (cellular-based) http://en.wikipedia.org/wiki/Image:30WiMAX.gif

  10. Cellular Communications • 1st generation (1G): analog, circuit switched, voice • 2nd generation (2G): digital, circuit switched, voice • 2½ generation (2.5G): digital, packet switched, voice and narrowband data • 3rd generation (3G): digital, packet switched, voice and broadband data • 4th generation (4G): “beyond 3G” Source: Rappaport, Wireless Communications, Prentice Hall

  11. Cellular Communications Source: Rappaport, Wireless Communications, Prentice Hall Public switched telephone network Mobile switching center

  12. Frequency Reuse • Cells with same letter use the same set of frequencies • Cell cluster (outlined in bold) replicated over coverage area • Example: cell cluster size, N = 7 • Frequency reuse factor = 1/N Source: Rappaport, Wireless Communications, Prentice Hall

  13. Cell Splitting • Cell splitting allows channels to be added with no new spectrum usage • Note: vertices are locations of cell towers Source: Rappaport, Wireless Communications, Prentice Hall

  14. Call Handoff • Calls need to be seamlessly handed off from one base station to another to support mobility

  15. Umbrella Cells • Supporting users with different mobility rates Source: Rappaport, Wireless Communications, Prentice Hall

  16. Local Loop Economics • Cost to deploy new wire: ~$1000 per home • Depends on population density (higher in rural areas) • Example: Verizon FiOS $23B for 18 mil homes • Cost per subscriber is higher • Number of households in U.S.: 100 million • Total cost: at least $100 Billion • Wireless: • AT&T wireless capital investment $20B in 2010 • Number of wireless subscribers 85Mil • Wireless revenue $50B

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