sirbu11 10 03

Broadband Technology and Trends: 

Broadband Technology and Trends Marvin A. Sirbu Engineering and Public Policy Carnegie Mellon University Pittsburgh, Pennsylvania sirbu@cmu.edu

Outline: 

Outline What is “broadband” Broadband technologies Current state of deployment Trends

What is Broadband?: 

What is Broadband? Modems have a top speed of 56 Kilobits per second (Kbps) FCC definitions: High Speed > 200 Kbps in at least one direction Advanced Services > 200 Kbps in both directions Broadband services are often asymmetric Faster downstream than upstream e.g. ADSL at 1.5 Mbps down, 128 Kbps up Peer-to-Peer service growth means actual traffic is becoming more symmetric Current services offer top speeds of 0.5 – 3 Mbps downstream Emerging technologies offer speeds to 100 Mbps Comparable to enterprise LAN

Broadband Technologies: 

Broadband Technologies Digital Subscriber Line Cable Modem Broadband Fixed Wireless Access (BFWA)

Raising the Speed Limit on the Copper Loop: 

Raising the Speed Limit on the Copper Loop Modem speeds limited by the 4 KHz design bandwidth of the PSTN network Bandwidth limit imposed by the line card at the switch or remote terminal Faster speeds on the copper are possible by putting a modem at the CO end of the loop before the switch use frequencies on the copper above 4 KHz—up to 1 MHz or more e.g. T1 runs over copper pairs at 1.5 Mbps Maximum speed depends on distance, wire gauge, and condition of loop (e.g. bridge taps) DSL can be symmetric (SDSL) or asymmetric (ADSL) ILECs focused on ADSL to avoid cannibalizing T1 revenues

Simplex Bit Rate vs Distance for 24 Gauge Copper Loops: 

Simplex Bit Rate vs Distance for 24 Gauge Copper Loops DS1 (T1) 1.544 Mbps 18,000 feet E1 2.048 Mbps 16,000 feet DS2 6.312 Mbps 12,000 feet E2 8.448 Mbps 9,000 feet 1/4 STS-1 12.960 Mbps 4,500 feet 1/2 STS-1 25.920 Mbps 3,000 feet STS-1 51.840 Mbps 1,000 feet Source: ADSL Forum

Simplex Bit Rate vs Distance: 

Simplex Bit Rate vs Distance

DSL from Central Office: 

DSL from Central Office ADSL Modem Splitter Telephone PC DSLAM Voice Switch Data Switch Subscriber Premises Central Office Data carried above 4KHz voice frequencies

Distance Limitations: 

Distance Limitations DSL limited to ~18,000 feet from Central Office Longer loops typically have loading coils which improve voice service but block DSL Increasingly carriers use fiber fed Remote Terminals to serve areas distant from Central Office Also know as Digital Loop Carrier or DLC Fiber Optic Feeder Plant Distribution Plant: Local Access Network Drop Plant Manhole Central Office

DLC Use in the US (1998): 

DLC Use in the US (1998) Percentage of Loops with some form of Pair Gain

DSL Served from Remote Terminal: 

DSL Served from Remote Terminal 100,000 DLC remote terminals must be upgraded to IDLC to support DSL DSL modem Add Drop Mux DSL-ready DLC Or Integrated DLC - IDLC SONET L G X D S X 3 DSLAM line cards ATM Network Copper loop voice Voice Switch NID S p l i t t e r

Colocating DSLAM in Older DLC Cabinet: 

Colocating DSLAM in Older DLC Cabinet DSL Remote Access Mux (RAM)

DSL Summary: 

DSL Summary Central Offices serving most subscribers have been upgraded to support DSL Not all subscribers reachable because of distance limits or loop quality Remote Terminals slowly being upgraded to IDLC Using remote terminals to shorten copper loop length allows higher speeds to be realized DSL competition Competitors can lease copper loops and collocate their own DSLAMs at Central Office Collocation at RT not feasible and incumbents not obliged to make DSL over IDLC available to CLECs

Hybrid Fiber/Coax CATV Plant Architecture: 

Hybrid Fiber/Coax CATV Plant Architecture Source: Dutta-Roy, “Cable: It’s Not Just for TV,” IEEE Spectrum, May, 1999

CABLE MODEMS: 

CABLE MODEMS O/E Video Head End O/E fiber node optoelectronics O/E Internet Backbone IAP Cable Modem CMTS 10 BaseT set top T Source: Stagg Newman Frequency Spectral Use 0 50M U P T V 900M T V T V T V 750M D O W N

Cable Modems: 

Cable Modems Cable plant must be upgraded with fiber trunks and 2-way amplifiers before cable modem service can be deployed 80% of cable plant nationwide upgraded CableLabs has developed standards Cable modems available at retail stores for self install Prices have dropped to <$50 USB or Ethernet interface to PC or home network Multiple households share capacity on the cable 30 Mbps downstream 5 (DOCSIS 1.0) to 20 (DOCSIS 2.0) Mbps upstream

Cable Modem Summary: 

Cable Modem Summary Early standardization of cable modems by CableLabs has enabled faster, cheaper deployment Once upgraded to HFC, distance is not an issue Cable not always deployed/available in business district Focus on residential customers Network inherently asymmetric Straightforward evolutionary path to higher speeds

Wireless Market View: 

Wireless Market View Fixed Broadband IP Based Services Multiservice Applications MMDS UNII 802.11 LMDS Residential/ Campus Data/Voice/Video Services Bluetooth IEEE 802.11 2G Cellular 3G Cellular Mobile Packet Data/Voice Data Services IMT- 2000 GPRS Mobile IP Satellite

Residential Broadband Fixed Wireless Technologies: 

Residential Broadband Fixed Wireless Technologies Base station transmitting to rooftop antenna Shared up to 70 Mbps downstream 25 Mbps upstream Licensed MMDS band- 2.5 GHz Unlicensed WLAN-2.4 GHz, UNI – 5 GHz Many competing technologies and business models Standardized (802.16a) products beginning to appear

MMDS Fixed Wireless Architecture: Base Station and CPE: 

MMDS Fixed Wireless Architecture: Base Station and CPE Small Business Wireless Modem Unit Ethernet LAN Transceiver/Antenna VoIP Adapter Adapter Transceiver/Antenna Wireless Modem Unit Fiber Backhaul To Distribution Hub Wireless Modem Termination System Router/ ATM switch Other MMDS channels Tower and Antenna (Base Station Outdoor Unit) Base Station Indoor Unit Sprint and Nextel own extensive MMDS licenses.

Customer Fixed Wireless Units: 

Customer Fixed Wireless Units Requires clear Line of Sight (LOS) Requires costly site visit to install antenna, run wiring to computer Source: Sprint (Hybrid Networks) (antenna/transceiver only)

Base Station Equipment: 

Base Station Equipment A single tower can cover up to 20 mile radius Depends on terrain As subscribers increase, may need additional base stations/cells for frequency reuse Source: Sprint (Hybrid Networks- Phoenix)

Motorola Canopy Unlicensed 5 GHz: 

Motorola Canopy Unlicensed 5 GHz Motorola Canopy

Wireless ISPs: 

Wireless ISPs There are more than 3000 ISPs providing wireless access (WISP) in the U.S. Majority are using souped up wireless LAN technology Normal WLAN coverage ~ 300 feet With directional antennas, coverage can reach several miles

Antennas for Long Range WLANs: 

Antennas for Long Range WLANs Source: Cisco

Many Wireless Design Tradeoffs: 

Many Wireless Design Tradeoffs Choice of modulation scheme Bit rate versus maximum reach Simple QAM versus more complex OFDM Higher modem costs Use multiple antennas (MIMO) to overcome multipath reflections and allow Non-LOS Trade lower bit rate for improved SNR Could use an indoor antenna e.g. Next Networks IEEE 802.16 standard for BFWA Low cost equipment coming

Cost Comparison by Density Area: 

Cost Comparison by Density Area Source: http://intel.si.umich.edu/tprc/papers/2002/86/FixedWirelessNetworks.zip

Broadband Deployment Status: 

Broadband Deployment Status Roughly 25% of Internet households (15% of all households) in the U.S. have broadband today. Cost Ave Revenue Per User Cable: $42.87 DSL: $42.24 Availability is uneven Roughly 80% of households can get some form of broadband Cable more widely available than DSL DSL more popular where both are available 12% of Zip Codes nationally have NO broadband subscribers

U.S. Broadband Deployment: 

U.S. Broadband Deployment Source: FCC

U.S. Broadband Deployment Lagging Internationally: 

U.S. Broadband Deployment Lagging Internationally

Deployment in Pennsylvania: 

Deployment in Pennsylvania 532,000 residential and SMB 100,000 large business and institutional Source: FCC

Verizon Pa COs Equipped for DSL: 

Verizon Pa COs Equipped for DSL 79% of Verizon Central Offices are equipped for DSL as of Nov 2003 (407 out of 518 COs) Because of distance limits, not all customers of an equipped CO will be able to get service Verizon just beginning to upgrade ~5000 Remote Terminals to support DSL Typical DSL speed: 1.5 Mpbs down, 128 Kbps up

Emerging Trends: 

Emerging Trends Traffic limiting Higher Speeds Fiber to the Curb Fiber to the Home/Business/User -- FTTx

Traffic Limiting: 

Traffic Limiting Broadband ISPs sell 1.5 Mbps access for ~$40/month They count on the fact that the typical subscriber uses only a fraction of that If users constantly ran at full speed, operators would go broke e.g. downloading MP3s, DVDs or streaming video Operators beginning to limit P2P traffic, or kick high volume users off their networks, or Charge heavy users more e.g. $1/Gigabyte above some threshold

Increasing Speeds: 

Increasing Speeds Cable companies use a high speed shared channel (~30 Mbps). User’s top speed limited by operator choice. Speed limits being raised from 1.5 Mbps to 3.0 Mbps to differentiate from DSL at 1.5 Mbps In Korea and Japan, DSL speeds are being increased to 10 Mbps or 25 Mbps

New DSL Technology: 

New DSL Technology RADSL technology adjusts top speed according to distance from the CO If you live close, you can get 7 Mbps down/1.5 Mbps up By pushing fiber deeper into neighborhoods and shortening copper loops, speeds can be raised 10 Mbps for 5000 feet 50 mbps for 1000 feet (Fiber to the Curb) New technologies under development may allow 100 Mbps up to 2000 feet.

Fiber to the Premise: 

Fiber to the Premise In the limit, run fiber all the way to the side of the house Capacity to provide voice, data, video (“triple play”) 94 communities in the U.S. have FTTP today e.g. Kutztown, Pa.

Passive Star Architecture (PON): 

Passive Star Architecture (PON)

Fiber To The Home: Passive Optical Networks: 

Fiber To The Home: Passive Optical Networks Voice, data and video (bi-directional) for 32 subscribers over a single fiber Wave Division Multiplexing supports three wavelengths — 1490/1310/1550 nm 622/155 Mb/s packet rate via two wavelengths - not shared with video pipe Up to 20 km (12.4 mi.) coverage span Dedicated wavelength for video —typically carried as RF FDM multiplex

Active Star Architecture: 

Active Star Architecture

Active Star Architecture: 

Active Star Architecture Electronics at CO, home and remote terminal Architecture similar to Enterprise LAN Powering of remote terminal an issue Typically 100 Mpbs to each subscriber More flexible than PON Regeneration extends distance Video delivery streamed over Internet

Industry Structure: 

Industry Structure Who will own the fiber network? One of the competitors A Consortium The subscribers The municipality A non-service provider e.g. Electric Utility We are seeing a great deal of activity where municipalities or municipal electric utilities are building FTTP networks and providing wholesale service to competing service retailers. Verizon says it will begin installing up to a million lines of FTTP annually in 2005.

Conclusion: 

Conclusion Cable modem dominates broadband deployment to date Rural areas not always well served by cable or DSL Wireless offers great promise for rural deployment Some rural communities building own broadband networks—not waiting for the private sector Technology continues to advance. Today’s “broadband” will be seen as too slow in 5-10 years.