ECEN4533 Data CommunicationsECEN4533 Data CommunicationsLecture #1 7 January 2013Lecture #1 7 January 2013Dr. George ScheetsDr. George Scheetswww.okstate.edu/elec-eng/scheets/ecen4533www.okstate.edu/elec-eng/scheets/ecen4533

ECEN4533 Data CommunicationsECEN4533 Data CommunicationsLecture #1 7 January 2013Lecture #1 7 January 2013Dr. George ScheetsDr. George Scheetswww.okstate.edu/elec-eng/scheets/ecen4533www.okstate.edu/elec-eng/scheets/ecen4533

Read Chapter 1.1Read Chapter 1.1 Ungraded Homework Ungraded Homework

Problems: NoneProblems: None

ECEN4533 Data CommunicationsDr. George ScheetsLecture #2 9 January 2013www.okstate.edu/elec-engr/scheets/ecen4533/

ECEN4533 Data CommunicationsDr. George ScheetsLecture #2 9 January 2013www.okstate.edu/elec-engr/scheets/ecen4533/

Read Chapter 1.2 - 1.4Read Chapter 1.2 - 1.4 Problems: NoneProblems: None Quiz #1, Lecture 12, 4 FebruaryQuiz #1, Lecture 12, 4 February

ECEN4533 Data CommunicationsDr. George ScheetsLecture #3 11 January 2013www.okstate.edu/elec-engr/scheets/ecen4533/

ECEN4533 Data CommunicationsDr. George ScheetsLecture #3 11 January 2013www.okstate.edu/elec-engr/scheets/ecen4533/ Read 2.1, 2.2Read 2.1, 2.2 Problems 1.1 - 1.3Problems 1.1 - 1.3 Quiz #1, Lecture 12, 4 FebruaryQuiz #1, Lecture 12, 4 February

GradingGrading In Class: Quizzes, Tests, Final ExamIn Class: Quizzes, Tests, Final Exam

Open Book & Open NotesOpen Book & Open NotesWARNING! WARNING! Study for them like they’re closed book!Study for them like they’re closed book!

Graded Homework: Design ProblemsGraded Homework: Design Problems Ungraded Homework: Ungraded Homework:

Assigned most every classAssigned most every classNot collectedNot collectedSolutions ProvidedSolutions ProvidedPayoff: Tests & QuizzesPayoff: Tests & Quizzes

Why work the ungraded Homework problems?Why work the ungraded Homework problems? An Analogy: Data Com vs. FootballAn Analogy: Data Com vs. Football Reading the text = Reading a playbookReading the text = Reading a playbook Looking at the problem solutions = Looking at the problem solutions =

watching a scrimmage watching a scrimmage WorkingWorking the problems = the problems =

practicing or playing in a scrimmage practicing or playing in a scrimmage Quiz = Exhibition GameQuiz = Exhibition Game Test = Big GameTest = Big Game

To succeed in this class...To succeed in this class...

Show some self-discipline!! Important!!Show some self-discipline!! Important!!For every hour of class...For every hour of class...

... put in 1-2 hours of your own effort.... put in 1-2 hours of your own effort.

PROFESSOR'S LAMENTPROFESSOR'S LAMENTIf you put in the timeIf you put in the timeYou should do fine.You should do fine.If you don't,If you don't,You likely won't.You likely won't.

CheatingCheating Don’t do it!Don’t do it!

If caught, expect to get an 'F' for the course.If caught, expect to get an 'F' for the course.

My idol:My idol:Judge Isaac ParkerJudge Isaac ParkerU.S. Court: Western District of ArkansasU.S. Court: Western District of Arkansas1875-18961875-1896

a.k.a. “Hanging Judge Parker”a.k.a. “Hanging Judge Parker”

General CommentsGeneral Comments Pre/Co-requisitesPre/Co-requisites

Knowledge of probability & statisticsKnowledge of probability & statistics Knowledge of Excel, MatLab, MathCad or something Knowledge of Excel, MatLab, MathCad or something

similarsimilar General FormatGeneral Format

LectureLecture Feel free to interrupt at willFeel free to interrupt at will

GoalGoal Understand data networksUnderstand data networks Design data networksDesign data networks

Twisted Pair CablesTwisted Pair Cables

LAN cables are attached to RJ-45 connection.

Coax cableCoax cable

images fromwww.computingsolutions.ca&www.air802.com

Fiber Optic CableFiber Optic Cable

1 1/4 inch

SC

Channel CapacityChannel Capacity

Claude Shannon1916-2001

Bell Labs, MIT

Ralph Hartley1888-1970Bell Labs

images from wikipedia.com

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

Channel Capacity (C)Channel Capacity (C) Channel Capacity defines relationshipChannel Capacity defines relationship

C = Maximum reliable bit rate C = Maximum reliable bit rate C = W*Log C = W*Log22(1 + SNR) bps(1 + SNR) bps

If bandwidth = W Hertz,If bandwidth = W Hertz, In theory, can move 2W symbols/secIn theory, can move 2W symbols/sec In practice, can move closer to W symbols/sec In practice, can move closer to W symbols/sec Bandwidth sets the maximum baud rate

symbols/second = baud

Channel Capacity (C)Channel Capacity (C) Channel Capacity defines relationshipChannel Capacity defines relationship

C = Maximum reliable bit rate C = Maximum reliable bit rate C = W*Log C = W*Log22(1 + SNR) bps(1 + SNR) bps

SNR sets the maximum number of bits/symbol2 bits/symbol (1 or 0) a.k.a. Binary signalingLog2M bits/symbol a.k.a. M-Ary signaling

+1

-1-1.342

+.447

4-AryBinary

Mathematically, 4-Ary symbols are closer together.

M-Ary SignalingM-Ary Signaling Used when bandwidth is tight & SNR is Used when bandwidth is tight & SNR is

decentdecent Baud rates same? Symbol shapes similar? Baud rates same? Symbol shapes similar?

If yes.. If yes.. Bandwidth required is similarBandwidth required is similar M-Ary signaling allows increased bit rateM-Ary signaling allows increased bit rate

Symbols get closer together if Power fixedSymbols get closer together if Power fixedReceiver detection errors more likelyReceiver detection errors more likely

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

Suppose Suppose at/nearat/near C limit & no extra BW available and... C limit & no extra BW available and... Current SNR = 10 Current SNR = 10 (C = W3.459) (C = W3.459) ??

Need to bump SNR up to 120 to double bps Need to bump SNR up to 120 to double bps (C = W6.919) (C = W6.919) Current SNR = 120?Current SNR = 120?

Need to bump SNR up to 14,640 to double bps Need to bump SNR up to 14,640 to double bps (C = W13.84) (C = W13.84) Current SNR = 14,640?Current SNR = 14,640?

Need to bump SNR up to 214.4M to double bps Need to bump SNR up to 214.4M to double bps (C = W27.68) (C = W27.68) To increase C by factor of 8To increase C by factor of 8

Increase SNR by factor of 214,358,881Increase SNR by factor of 214,358,881

Is increasing BW a better idea?Is increasing BW a better idea?

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

C = W*LogC = W*Log22(1 + [Signal Power]/[Noise Power]) bps(1 + [Signal Power]/[Noise Power]) bps

C = W*LogC = W*Log22(1 + [Signal Power]/[(1 + [Signal Power]/[NNooW]) bpsW]) bps NNoo = Noise Power Spectral Density (watts/Hertz) = Noise Power Spectral Density (watts/Hertz)

Suppose Suppose at/nearat/near C limit, want to increase C by factor of 8, current SNR = 10 C limit, want to increase C by factor of 8, current SNR = 10 C = WLogC = WLog22(1+10) = W3.459(1+10) = W3.459

Bumping W to 8W Bumping W to 8W C = 8WLogC = 8WLog22(1+1.125) = 8W1.170 = W9.359(1+1.125) = 8W1.170 = W9.359

Capacity increases by a factor of 9.359/3.459 = 2.706Capacity increases by a factor of 9.359/3.459 = 2.706

Bumping W by 214,358,881Bumping W by 214,358,881 C = 214,358,881W Log2(1.00000004665) = 14.43WC = 214,358,881W Log2(1.00000004665) = 14.43W C increases by a factor of 14.43/3.459 = 4.172 (worse than SNR!)C increases by a factor of 14.43/3.459 = 4.172 (worse than SNR!)

Channel Capacity, Increasing BothChannel Capacity, Increasing Both C = W*LogC = W*Log22(1 + SNR) bps(1 + SNR) bps

C = W*LogC = W*Log22(1 + [Signal Power]/[Noise Power]) bps(1 + [Signal Power]/[Noise Power]) bps

C = W*LogC = W*Log22(1 + [Signal Power]/[(1 + [Signal Power]/[NNooW]) bpsW]) bps NNoo = Noise Power Spectral Density (watts/Hertz) = Noise Power Spectral Density (watts/Hertz)

Suppose Suppose at/nearat/near C limit, want to increase C by factor of 8, current SNR = C limit, want to increase C by factor of 8, current SNR = 1010

C = WLogC = WLog22(1+10) = W3.459(1+10) = W3.459

Bumping both W & Signal Power by factor of 8 yieldsBumping both W & Signal Power by factor of 8 yields C = 8WLogC = 8WLog22(1+10) = 8W3.459 = W27.67(1+10) = 8W3.459 = W27.67

Capacity increases by a factor of 8Capacity increases by a factor of 8

Best to bump W, but also bump Signal PowerBest to bump W, but also bump Signal Power

33.6 Kbps Dial-Up Modem33.6 Kbps Dial-Up Modem

PC

CO CO

ModemProtocol

Digital Bit Stream(1's & 0's) 64 Kbps

CO Input Line Card Low Pass Filter limits BW (3.5 KHz)CO Input Line Card Low Pass Filter limits BW (3.5 KHz) M-Ary Signaling (256 QAM or something even more complex)M-Ary Signaling (256 QAM or something even more complex)

Channel Capacity says max transfer is around 34 - 35 KbpsChannel Capacity says max transfer is around 34 - 35 Kbps 1960's: 300 bps using binary signaling @ 300 symbols/second1960's: 300 bps using binary signaling @ 300 symbols/second 1980's: 14,400 bps using 128-Ary signaling @ 2400 symbols/second1980's: 14,400 bps using 128-Ary signaling @ 2400 symbols/second 1996: 33,600 bps using 1664-Ary signaling @ 3429 symbols/second1996: 33,600 bps using 1664-Ary signaling @ 3429 symbols/second

PC

ModemProtocol

Fine print indicatesFine print indicates Uses Acceleration (compression)Uses Acceleration (compression) Some material won't be compressedSome material won't be compressed Actual data transmission rates = Actual data transmission rates =

standard dial up ratesstandard dial up rates

Bogus Channel Capacity ClaimsBogus Channel Capacity Claims Silk Road (Summer 1999)Silk Road (Summer 1999)

Claim: Gbps in 64 KHzClaim: Gbps in 64 KHz Stock Analyst: 70% successStock Analyst: 70% success

Claim: > Tbps over Power LinesClaim: > Tbps over Power LinesStep Down Transformers = LP FilterStep Down Transformers = LP FilterUntwisted Pair = Antenna Untwisted Pair = Antenna

Exceeding Channel Capacity?Exceeding Channel Capacity?Same impact as exceeding Speed of LightSame impact as exceeding Speed of Light

ISO OSI Seven Layer ModelISO OSI Seven Layer Model

Layer 7 ApplicationLayer 7 Application User ProgramUser Program Layer 6 Presentation Layer 6 Presentation Windows APIWindows API Layer 5 SessionLayer 5 Session TCP, WindowsTCP, Windows Layer 4 TransportLayer 4 Transport TCP, WindowsTCP, Windows Layer 3 NetworkLayer 3 Network IP, WindowsIP, Windows Layer 2 Data LinkLayer 2 Data Link PC NIC/CPUPC NIC/CPU Layer 1 Physical Layer 1 Physical PC NICPC NIC

TCP/IP ModelTCP/IP Model

Layer 5 Layer 5 Application Application ApplicationApplication Layer 5Layer 5 PresentationPresentation Layer 4 Layer 4 SessionSession Transport (TCP)Transport (TCP) Layer 4 Layer 4 TransportTransport Layer 3 Layer 3 Network Network Internet (IP)Internet (IP) Layer 2 Layer 2 Data LinkData Link Data LinkData Link Layer 1 Layer 1 Physical Physical PhysicalPhysical

}

}

Typical Network: Core & AccessTypical Network: Core & Access

TrunksAccess Lines

a

b

c

d

e

1

3

2

4

i

h

f

g

PSTN: Wired Dial-up ModemPSTN: Wired Dial-up Modem

PC

CO CO

ModemProtocol

Digital TDM (1's & 0's)64 Kbps

Access Line (twisted pair) is expecting analog voiceAccess Line (twisted pair) is expecting analog voice Modem maps PC digital signal to a signal with voice spectral characteristics Modem maps PC digital signal to a signal with voice spectral characteristics

Trunks are digitalTrunks are digital

PC

ModemProtocol

PSTN Connectivity via BRI ISDNPSTN Connectivity via BRI ISDN

CO CO

Fiber OpticTrunk

CopperLocalLoop

CopperLocalLoop

Digital 64 or 128 Kbps

PCServer