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Understanding Access Network Technologies: Copper, Fiber, and Wireless Solutions

This overview covers essential access network technologies, including copper options like DSL and cable, fiber technologies such as FTTH (Fiber to the Home), and hybrid approaches combining both. It explores the last mile connection from customer premises to central offices and discusses different wireless technologies like Wi-Fi, WiMax, and cellular communications (1G to 4G). Key aspects such as local loop economics, frequency reuse in cellular networks, and the impact of population density on deployment costs are also examined, highlighting the evolution of access networks in modern telecommunications.

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Understanding Access Network Technologies: Copper, Fiber, and Wireless Solutions

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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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