6.978/ESD.68 Competition in Access Networks. Sharon E. Gillett, MIT

Transcription

1 6.978/ESD.68 Competition in Access Networks Sharon E. Gillett, MIT

2 From (Clark, 1999) The past: Silos POTS Cable TV TV radio Copper Coax Broadcast Figur e 1: Past industry struc ture of resid ential ac cess.

3 The present: Convergence IAP POTS Internet radio TV CLEC ADSL HFC VDSL Copper Coax Wireless Satelli te Broadc ast Figur e 2: Emerging indus try structure of residen tial acc ess From (Clark, 1999)

4 The Future(?): Internet as Platform Web Phone TV radio Internet IAP POTS ADSL HFC Copper Coax Wireless Satelli te Figur e 4 : Poten tial indus try struc ture surround ing the Internet. From (Clark, 1999)

5 Wireless Telephony Competing With Fixed Lines, ,000, ,000, ,000, ,000,000 Access Lines 160,000, ,000, ,000, ,000,000 80,000,000 60,000,000 40,000, ,000, ,000, ,000, ,000,000 80,000,000 60,000,000 40,000,000 Number of Subscribers 20,000, ,000, mil Fixed Lines(1) Wireless(2) Broadband(3) Cable Telephony(4) (1) data from FCC Trends in Telephone Service May 2002 ; data from FCC, Local Telephone Competition: Status as of Dec ; (2) CTIA Semi-Annual Wireless Industry Survey, published 2003; (3) :FCC.COM: Trends in Telephone Service May 2002 (High Speed Lines with 200Kbps in at least one direction; Legg Mason Wood Walker, Inc. "Coming Down the Pipe - Interim Report 4Q 2002/1Q 2003 Industry Update - March 13, 2003 ; (4) NCTA, "Residential Cable Telephony Subscribers

6 Greece Korea Switzerland Finland Norway Sweden Canada United Kingdom Belgium United States Japan Luxembourg Austria France Australia Germany Spain Italy Portugal New Zealand Czech Republic Ireland Hungary Poland Turkey Slovak Republic Mexico Denmark Netherlands Iceland Source: OECD OECD Broadband subscribers per 100 inhabitants, by technology, June 2006 DSL Cable Other OECD average Courtesy of OECD. Source: OECD Broadband Statistics, OECD, 2006.

7 3. Broadband Technologies 7 Courtesy of CSTB. Used with permission.

8 Network Architecture Generic model of a broadband access network system architecture common across technology alternatives important differences in cost-performance and business models IP packets technology-specific part of the system Web Servers, etc. may be shared or switched Multiplexed broadband pipe w/ aggregated data Access Router/ Headend/Cache INTERNET INTERNET Subscriber Interface Access Medium (copper, coax, fiber, wireless) IP packets Consumer Equipment (wired & wireless) 8 Courtesy of CSTB. Used with permission.

9 Wireline Options Hybrid fiber-coax DOCSIS Role of fiber (toward FTTC) Digital subscriber line (DSL) Distance, crosstalk Role of fiber (toward FTTC) Optical fiber Flavors of fiber to the home (FTTH) Service based on equipment at both ends Depends on what kind of FTTH: not all the same High-performance endpoint highest cost Powerline 9 Courtesy of CSTB. Used with permission.

10 DSL/Fiber Architecture Same architecture evolves naturally from ADSL to VDSL to FTTC/FTTH switching equipment tends to migrate closer to subscribers (..remote DSLAM, gigabit Ethernet switches, etc.) system deployment cost dominated by physical wiring, due to rapid improvements in switching & transport cost/performance Access Switch/ Router w/ caches DSLAM or Fiber Switch/ Concentrator High-capacity fiber link (ATM or IP/SONET, etc.) Subscriber Interface in-home or curbside fiber or copper pair may be placed in remote location or central office to multiple ISP s 10 Courtesy of CSTB. Used with permission.

11 HFC Architecture Broadband access over cable based on shared access (DOCSIS standard) to existing TV coax Medium access control (MAC) protocol for coax sharing Signal converted to analog fiber at remote node System cost dominated by fiber upgrade investments, due to rapidly falling cost of DOCSIS modems & switching gear Also evolves naturally towards FTTC/FTTH Aggregated traffic IP Router & cache DOCSIS protocols Fiber Node HFC Analog Fiber Link data upstream data downstream Cable Modem in-home at remote locations shared coax cable TV DOCSIS head-end to Internet 11 Courtesy of CSTB. Used with permission.

12 One Architecture for BPL Backbone network/ Internet O/E Tr Point-to-point Link IPL LAN IPL-modem Distribution substation Optical fiber networks LV networks Customer

13 Wireless Options Mobile/3G Future: seamless mobile & portable broadband Reality: emerging 3G falling short of hype (capacity, speed..) WLAN , unlicensed 2.4 and 5 Ghz bands Bottom-up deployment is accelerating... (airports, offices, homes..) FWA (Fixed Wireless Access) MMDS, LMDS,... much potential, but uncertain business conditions... Satellite Geo-synchronous (GEOS) & Low-earth orbit (LEOS) Viable for certain markets, but with capacity limitations Courtesy of CSTB. Used with permission.

14 Wireless Architecture Broadband wireless based on shared access of radio medium (MMDS, LMDS, 3G, WLAN,..) MAC protocol for shared use of radio (..similar to cable modems) Switching or routing beyond access point (...similar to DSL) FWA, satellite, WLAN & 3G/mobile as potential options, each with different entry cost and system cost/performance trade-offs Fixed Wireless or satellite Wireless subscriber Interface WLAN shared wireless medium Wireless Access Point at remote location or CO radio cell for spatial reuse High-capacity fiber link (ATM or IP/SONET, etc.) Access Switch/ Router w/ caches to multiple ISP s Mobile Wireless (2.5G, 3G) 14 Courtesy of CSTB. Used with permission.

15 Local Access Techs in Context Total cost and performance depends on more than just local access Local access aggregates traffic from multiple premises at POPs, funnels to higher-capacity links Second mile connects to upstream aggregation Broadband providers pay for Internet transit service or establish peering arrangements Caches, service-supporting servers at POPs 15 Courtesy of CSTB. Used with permission.

16 Unbundling DSL To Interoffice Transport POTS Customer Analog Lines IP Gateway Router Call Server DSLAM DSL Lines... ATM Switch DSLAM IP-based Central Office DSL Customer Access to unbundled loop ( Full unbundling) Access to bitstream Figure by MIT OCW. After Fryxell, Sirbu, and Wanichkorn, 1999.

17 Sub-loop Unbundling Copper wire pairs Laser transmitter and receiver Fiber feeder Remote electronics Central Office Remote electronics

18 ADSL Spectrum Allocation (Line Sharing) Upstream channel Bidirectional POTS Downstream channel 10 KHz 50 KHz 1 MHz

19 Open Access and Layering Layer: Municipality provides 0 Conduit and collocation facilities. 1 (Physical Layer Unbundling) 2 (Data Link Layer Unbundling) 3 (Network Layer Unbundling) Dark fiber leasing, or perhaps, Optical Layer unbundling (CWDM or DWDM in PONs) Dark fiber and link-layer electronics at each end. For example, Ethernetbased VLAN, or ATM-based PVCs. Basic network service provided. For example, IP Layer 3 service over cable using policy-based routing to multiple ISPs

20 Regulatory Dilemma Heisenberg s Uncertainty Principle: Can t observe situation without perturbing it Fundamental Economics Competition is sustainable (competitive equilibrium exists) Competition is not sustainable (no competitive equilibrium) Regulatory Assumption About Competition Sustainable Not sustainable Sustainable Not sustainable Outcome Free market Regulation stifles innovation, competition Government-sanctioned, unregulated monopoly Necessarily regulated monopoly

21 Additional Tech Slides

22 Internet Access via Cable TV channels Headend IP router Data (LAN) channel Data (LAN) channel RF Modem Translator Converter RF Modem Translator Converter Rest of Internet

23 Telephone Network Hierarchy Local Loop LEC switching office "CITY" inter-office transmission LEC switching office Local Loop Twisted-pair copper loops dedicated to individual subscribers Physical aggregation at Central Office (CO) via Main Distribution Frame CO Switching: Access IXC Switching: Tandem Increasing aggregation at each level LEC = Local Exchange Carrier (local telephone company) Local Loop Inter-exchange ("long distance") network IXC switch LEC switching office "CITY" inter-office transmission IXC switch LEC switching office IXC = IntereXchange Carrier (long distance company) Local Loop

24 Multiplexing and Concentration in CO Switch 600 subscriber lines TDM 600 subscribers (DS-3) 8:1 concentration 600 trunks (5000 subscribers) port 20-port switch fabric port

25 Telephone Splices represented by Access Network Distribution cable Distribution cable Feeder Distribution Drop Aggregation is physical: bundles of wire-pairs Drop Drop Junction Box Feeder cables Drop Junction Box Drop toward Central Office Drop Drop Drop Drop Distribution cable Distribution cable

26 Internet over ADSL (with VoIP) To Interoffice Transport POTS Customer Analog Lines IP Gateway Router Call Server DSLAM DSL Lines... ATM Switch DSLAM IP-based Central Office DSL Customer Access to unbundled loop ( Full unbundling) Access to bitstream Figure by MIT OCW. After Fryxell, Sirbu, and Wanichkorn, 1999.

27 Telco migration to Fiber-to-the-Neighborhood Copper wire pairs Laser transmitter and receiver Fiber feeder Remote electronics Central Office Remote electronics