HomeworkHomework Final Exam Final Exam

Wednesday, 3 May, 5:30-7:20 pmWednesday, 3 May, 5:30-7:20 pm Readings:Readings:

[26] “Cable It’s not just for TV”[26] “Cable It’s not just for TV”[27] “Battling for Local Phone Customers”[27] “Battling for Local Phone Customers”[28] “IP/ATM Integrated Services over [28] “IP/ATM Integrated Services over Broadband Access Copper Technologies”Broadband Access Copper Technologies”

Video...Video...

Uncompressed NTSC video requires about 90 Mbps

Broadcast Quality compressed videorequires 45 Mbps

‘VHS Quality’ compressed video requires1.5 Mbps

The OSU Teleconferencing system isrunning at 384 Kbps

MPEG 1MPEG 1 Compression of motion video & audio at about 1.5

Mbps Targeted at digital playback & storage Has Random Access capabilities Employs Motion Estimation Algorithms, Discrete

Cosine Transforms, & Huffman Coding Codes frames as Intrapictures, Predicted Pictures,

and Bidirectional Pictures Standard since 1992

MPEG 2MPEG 2

Targets higher quality compression,typically at 3-6 Mbps bit rates

Being used for Direct Broadcast TV Large chunks of MPEG2 used in

U.S. HDTV standard Standard since 1994

MPEG 4MPEG 4

Aimed at Multimedia Coding Bit rates from 8 Kbps - 35 Mbps Codes objects as opposed to 8x8 blocks

Ability to interact & manipulate objects Standard in 1999

MPEG 7MPEG 7 Ability to describe and search for multi-media Ability to describe and search for multi-media

objects (under development)objects (under development) Audio clipsAudio clips video imagesvideo images

MP3 MP3 Web audio clipsWeb audio clips Uses audio compression from MPEG 1Uses audio compression from MPEG 1

12-1 typical compression ratio12-1 typical compression ratio

H.261 (a.k.a. Px64)H.261 (a.k.a. Px64) Subset of MPEG Targets real time videoconferencing Bit rates from 64 Kbps to 2.048 Mbps

64 Kbps - 128 Kbps: Face shot (video phone) 384 Kbps: considered to be minimum speed for

decent full screen videoconferencing H.263 is a modified H.261

Offers better qualityRequires more processing power

Channel Capacity (C)Channel Capacity (C) C = W*LogC = W*Log22(1 + SNR) bps(1 + SNR) bps

W = channel bandwidth (Hz)W = channel bandwidth (Hz) SNR = channel signal-to-noise ratioSNR = channel signal-to-noise ratio

Maximum bit rate that can be reliably shoved down a Maximum bit rate that can be reliably shoved down a connection connection

EX) Analog Modem (30 dB SNR)EX) Analog Modem (30 dB SNR)C = 3500 *LogC = 3500 *Log22(1 + 1000) = 34,885 bps(1 + 1000) = 34,885 bps

EX) 6 MHz TV RF Channel (42 dB SNR)EX) 6 MHz TV RF Channel (42 dB SNR)C = 6,000,000 *LogC = 6,000,000 *Log22(1 + 15,849) = 83.71 Mbps (1 + 15,849) = 83.71 Mbps

Local Loop Capacity about 34.8 Kbpsdue to filter at input of CO A/D converter

Local Loop Capacity about 34.8 Kbpsdue to filter at input of CO A/D converter

Phone Phone

CO CO

Fiber OpticTrunk

CopperLocalLoop

CopperLocalLoop

4 Wire 4 Wire2 Wire 2 Wire‘4 Wire’

Analog Analog Digital TDM64 Kbps

56 Kbps Modem requires Digital Source

56 Kbps Modem requires Digital Source

Server Phone

CO CO

Fiber OpticTrunk

CopperLocalLoop

CopperLocalLoop

4 Wire4 or 2 Wire 2 Wire‘4 Wire’

Analog Digital (ISDN, xDSL, etc.)

Delivery: Over the AirDelivery: Over the Air

300 mAnalogFDM

Digital by 2006(FCC edict)

50-60 miles

Video Delivery SystemsVideo Delivery Systems Satellite

Older systems analog 1 channel per 6 MHZ of RF bandwidth

Newer Systems digital MPEG2 & TDM allow 4-6 channels per 6 MHz of RF

bandwidth Cable TV

Distribution systems originally all coaxFiber deployed from Head End side moving

out

Who will be your one-stop telecom provider?

Who will be your one-stop telecom provider?

Cable TV Companies?Physical Tree with Large BandwidthSimplex & No SwitchingFair/Poor quality cable plant

Solution: Cable ModemsRe-engineer system for 2-way trafficShared AccessInstall data switches at Head EndInstall voice switches at Head End

PC to ISP Connectivity: Cable PC to ISP Connectivity: Cable

HeadendVoice

Switch

Cable TV Network

Home

EthernetNIC

ISP Router

To Internet

Cable Modem will use sharedbandwidth to get to Cable TV Headend.

Voicenetwork

Mux

Voice

Data

PC

Cable Modem

Data

Voice

Video

Who will be your one-stoptelecom provider?

Who will be your one-stoptelecom provider?

Local Telephone Companies?Physical Star with Narrow BandwidthFull Duplex & SwitchedGood quality cable plant

Solution: Digital Subscriber LinesSwitched AccessInstall data switches at COInstall video switches at CO

Home PC to ISP Connectivity Home PC to ISP Connectivity

CO

VoiceSwitch

Local Loop

Home

Modem

ISP Modem Bank

To Internet

This configuration causes call blocking problems at some CO switches due to longer than designed-for call holding times.

Voicenetwork

PC

PC to ISP Connectivity: DSL PC to ISP Connectivity: DSL

COVoiceSwitch

Local Loop(Voice & Data)

Home

ADSLModem

ISP Router

To Internet

ADSL will off load data traffic from CO voice switches, & provide more CO-Home bandwidth.

Voicenetwork

DSLAM

Voice

Data

PC

Splitter

Data

Voice

Who will be your one-stoptelecom provider?

Who will be your one-stoptelecom provider?

The Typical Telco can get xDSL running on existing twisted pair cable plant with less re-engineering than the typical Cable Company requires to get Cable Modems running on existing coax/fiber networks.

But Cable network has more bandwidth Whoever gets to market first, with a cost-effective

solution, will be in the driver’s seat. Advantage ???