ECEN5553 Telecom SystemsDr. George ScheetsWeek #13[30a] "The Bring Your Own Device Delima"[30b] "Is It Still Possible to do Phone Phreaking? Yes, with Android on LTE"[31a] "Next Generation WiFi: As Fast as We'll Need?"[31b] "What to Expect from 11ac’s Next Big Deal: Multiuser MIMO"[32a] "Is it Safe to Use Public Wi-Fi Networks?"[32b] "Worries Mount over Upcoming LTE-U Deployments Hurting Wi-Fi"[32c] "How to Configure Wi-Fi Channels for Top Network Performance"Term Paper (Late Fee = -1 point per working day)

< 13 November (Distant Learning)Final Exam

Friday, 11 December, 1400 – 1550 (Live)< 18 December (Distance Learning)

Exam #2 (90 points) final resultsHi = 88.1, Low = 50.4, Ave = 78.84, σ = 8.46A > 81, B > 70, C > 61, D > 52

ECEN5553 Telecom SystemsDr. George ScheetsWeek #13[30a] "The Bring Your Own Device Delima"[30b] "Is It Still Possible to do Phone Phreaking? Yes, with Android on LTE"[31a] "Next Generation WiFi: As Fast as We'll Need?"[31b] "What to Expect from 11ac’s Next Big Deal: Multiuser MIMO"[32a] "Is it Safe to Use Public Wi-Fi Networks?"[32b] "Worries Mount over Upcoming LTE-U Deployments Hurting Wi-Fi"[32c] "How to Configure Wi-Fi Channels for Top Network Performance"Term Paper (Late Fee = -1 point per working day)

< 13 November (Distant Learning)Final Exam

Friday, 11 December, 1400 – 1550 (Live)< 18 December (Distance Learning)

Exam #2 (90 points) final resultsHi = 88.1, Low = 50.4, Ave = 78.84, σ = 8.46A > 81, B > 70, C > 61, D > 52

Final ExamFinal Exam Comprehensive, 1 hour & 50 minutesComprehensive, 1 hour & 50 minutes Work 5 of 7 pagesWork 5 of 7 pages 2 - 3 pages will be from the Fall '14 final2 - 3 pages will be from the Fall '14 final 85-90% Notes85-90% Notes

10-15% Readings10-15% Readings Use the space provided!Use the space provided!

# Facts should be # Facts should be >> number of points number of pointsetc.etc.

Start Reviewing Now!

Syllabus Grade Break PointsSyllabus Grade Break Points A A >> 410 points (90%) 410 points (90%) B B >> 364 points (80%) 364 points (80%) C C >> 319 points (70%) 319 points (70%) D D >> 273 points (60%) 273 points (60%)

>> 410 points? Guaranteed an A 410 points? Guaranteed an A >> 364 but < 410? Guaranteed a B, etc. 364 but < 410? Guaranteed a B, etc. Otherwise, at mercy of CourtOtherwise, at mercy of Court

Fall 2014 Break PointsFall 2014 Break Points A A >> 391 points (86%) 391 points (86%) B B >> 346 points (76%) 346 points (76%) C C >> 300 points (66%) 300 points (66%) D D >> 255 points (56%) 255 points (56%)

Fall 2015 points likely not the same.Fall 2015 points likely not the same. Probably in same vicinityProbably in same vicinity Won't know for sure until everything's gradedWon't know for sure until everything's graded

Techniques to Improve BERTechniques to Improve BER Use FECUse FEC Increase Received Signal PowerIncrease Received Signal Power

Increase transmitter power outIncrease transmitter power out Use directional antennasUse directional antennas

Change Modulation TechniqueChange Modulation Technique Go to lower "M" in M-aryGo to lower "M" in M-ary

Build a Quieter ReceiverBuild a Quieter Receiver Slow Down Transmitted Bit RateSlow Down Transmitted Bit Rate

Techniques to Increase Bit Rate(Per Channel Basis)

Techniques to Increase Bit Rate(Per Channel Basis)

Use FECUse FEC Increase Received Signal PowerIncrease Received Signal Power

Increase transmitter power outIncrease transmitter power out Use directional antennasUse directional antennas

Change Modulation TechniqueChange Modulation Technique Go to higher "M" in M-aryGo to higher "M" in M-ary

Build a Quieter ReceiverBuild a Quieter Receiver Slow Down Transmitted Bit RateSlow Down Transmitted Bit Rate Increase Available BandwidthIncrease Available Bandwidth Compress the Application SignalCompress the Application Signal

Increases Increases apparentapparent bit rate bit rate

Cellular Telephony Advantages:Cellular Telephony Advantages: Frequency Reuse Reduced Transmitter Power Out Reduced brain damage? Reduced Multipath Problems Subdividing Cells increases System

Capacity More Reliable due to cell overlap

Cellular Telephony - OperationPower Up & Intermittently ThereafterCellular Telephony - OperationPower Up & Intermittently Thereafter

Mobile tunes to strongest control channelMobile tunes to strongest control channel Mobile communicates with BS/MTSOMobile communicates with BS/MTSO Local MTSO notes in database Local MTSO notes in database

mobile is active & which cell it's inmobile is active & which cell it's in If mobile is roaming, Home MTSO isIf mobile is roaming, Home MTSO is

notified, typically via SS7 or SIP Signalingnotified, typically via SS7 or SIP Signaling

Cellular Telephony - OperationMobile to Wired callCellular Telephony - OperationMobile to Wired call

Mobile transmits # to BS/MTSOMobile transmits # to BS/MTSO Uses Control ChannelUses Control Channel

Unused voice RF channel is assigned Unused voice RF channel is assigned Mobile tunes to assigned channelsMobile tunes to assigned channels

BS & MTSO coordinate BackhaulBS & MTSO coordinate Backhaul MTSO places call via CO to wired unitMTSO places call via CO to wired unit

Could be via PSTN or VoIPCould be via PSTN or VoIP

Cellular Telephony - Operation Wired to Mobile callCellular Telephony - Operation Wired to Mobile call

Signaling info shipped to home MTSOSignaling info shipped to home MTSO Home MTSO checks databaseHome MTSO checks database

Mobile in home area? Mobile is pagedMobile in home area? Mobile is paged Mobile not in home area? Mobile not in home area?

Signaling info is forwarded to local MTSO Signaling info is forwarded to local MTSO Local MTSO database indicates Mobile's cellLocal MTSO database indicates Mobile's cellMobile is paged & tunes to assigned RF channelMobile is paged & tunes to assigned RF channel

End-to-End Voice channel is set upEnd-to-End Voice channel is set up BS & MTSO coordinate BackhaulBS & MTSO coordinate Backhaul MTSO & CO coordinate Long HaulMTSO & CO coordinate Long Haul

Cellular Telephony - OperationCellular Telephony - Operation HandoffHandoff

MTSO/BS/Mobile decides signal gettingMTSO/BS/Mobile decides signal gettingtoo weaktoo weak

Adjacent cells are polledAdjacent cells are polledUnused voice RF channels in the newUnused voice RF channels in the new

cell is assignedcell is assignedMobile tunes to assigned channelMobile tunes to assigned channelMTSO reroutes traffic: MTSO reroutes traffic:

Old BS Old BS MTSO to New BS MTSO to New BS MTSO MTSO

Wireless MAN DataWireless MAN Dataso

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Advanced Mobile Phone System (AMPS)Advanced Mobile Phone System (AMPS)

1st Generation U.S. Cellular1st Generation U.S. Cellular Analog FDMAAnalog FDMA

30 KHz FM channels30 KHz FM channels # of subscribers peaked in 1999# of subscribers peaked in 1999 February 18, 2008February 18, 2008

FCC no longer required carriers to supportFCC no longer required carriers to support Should now be called OMPSShould now be called OMPS

RIP

1G AMPSFDMA1G AMPSFDMA

frequency

tim

eDifferent channels use some of the frequency all of the time.

1 32 4Cell 1Cell 2

AMPS

1G Backhaul1G Backhaul

Typically a T-1 Typically a T-1 23 calls23 calls 1 signaling channel1 signaling channel

14.4 Kbps data per user14.4 Kbps data per user Voice Backhaul Voice Backhaul

Moving a little data on the sideMoving a little data on the side

2G Mobile Wireless (MAN) 2G Mobile Wireless (MAN)

Time Division Multiple AccessTime Division Multiple Access U.S. TDMA, 2G, gone U.S. TDMA, 2G, gone → GSM→ GSM GSM, 2G, Data Speeds GSM, 2G, Data Speeds << 14.4 Kbps 14.4 Kbps

ObsoleteObsolete

RIP

2G GSM2G GSMfrequency

tim

eCombo of TDM & FDM

1

2

3

1etc.

4

5

6

4

7

8

9

7

10

11

12

10

Cell 1Cell 2

2G Mobile Wireless (MAN) 2G Mobile Wireless (MAN)

Time Division Multiple AccessTime Division Multiple Access U.S. TDMA, 2G, gone U.S. TDMA, 2G, gone → GSM→ GSM GSM, 2G, Data Speeds GSM, 2G, Data Speeds << 14.4 Kbps 14.4 Kbps

ObsoleteObsolete

Code Division Multiple Access Code Division Multiple Access TIA-95 CDMA (a.k.a. IS-95 or CDMA1), 2GTIA-95 CDMA (a.k.a. IS-95 or CDMA1), 2G

Data Speeds Data Speeds << 14.4 Kbps 14.4 KbpsObsoleteObsolete

RIP

+1

-1time

time

time+1

-1-1-1

+1 +1 +1

Traffic(9 Kbps)

SpreadingSignal27 Kcps

TransmittedSignal27 Kcps(mappedonto hi freq)

+1 +1+1

-1 -1

DSSS - Transmit Side

Wireless Wireless

X

27 KcpsSquare Pulses

cos(2πfct)

BPSK output27 Kcps90% of power in 54 KHz BW

centered at fc Hertz

X

cos(2πfct)

BPSK input27 Kcps+ noise

27 KcpsSquare Pulses+ filtered noise

RCVR Front End

RF Transmitter

Low PassFilter

time

time+1

-1-1-1

+1 +1 +1DespreadingSignal27 Kcps

ReceivedSignal27 Kcps

+1 +1+1

-1 -1

+1

-1

timeRecoveredTraffic9 Kbps

DSSS-Receiver

time+1ReceivedSignal #227 Kcps

-1 -1

timeRecoveredGarbage from 2ndsignal -1 -1

+1

+1 +1+1

time

-1-1

+1 +1 +1DespreadingSignal #127 Kcps

+1 +1

-1

DSSS-Receiver2nd Signal active

-1

Input toMatchedFilterDetector(sum)

+1

-1

timeRecoveredTraffic9 Kbps

timeRecoveredGarbage from 2ndsignal -1 -1

+1

+2

+1

-1

+1

-2

time

DSSS-Receiver2 Signals active

ReceiverMatchedFilterDetectorOutput

Additional signals transmitting at the same time increase the apparent noise seen by our system.

Message (voice) BER will increase.

+1

-1 time

Input toMatchedFilterDetector(sum)

+2

-2

time

TBit

CDMACDMAfrequency

tim

eDifferent channels use all of the bandwidth all of the time.

Channels use different codes. Other channels cause noise-like interference.

CDMA: 3D ViewCDMA: 3D View

code #1

code #2

code #3

frequency

time

Multiplexing SchemesMultiplexing Schemes

Frequency Division MutiplexingFrequency Division Mutiplexing Time Division MultiplexingTime Division Multiplexing Statistical MultiplexingStatistical Multiplexing Code Division MultiplexingCode Division Multiplexing

2G Backhaul2G Backhaul

Still Frequently T Carrier Still Frequently T Carrier T1's, Fractional T3's, or a maybe a T3T1's, Fractional T3's, or a maybe a T3

14.4 Kbps Data Initially14.4 Kbps Data Initially << 200 Kbps data with later add ons 200 Kbps data with later add ons

Primarily Voice Backhaul Primarily Voice Backhaul Moving a little more data on the sideMoving a little more data on the side

Mobile Wireless EvolutionMobile Wireless Evolution

Developmenthalted in 2005

2G: Voice! Voice!2.5G: One eye

on data.3G: Voice & Data4G: Hi Speed Data

LTE(4G)

WiMax

Sprint2012-2013

3G Mobile Wireless (MAN)3G Mobile Wireless (MAN) Universal Mobile Telephone Service (UMTS)Universal Mobile Telephone Service (UMTS)

3G GSM, Data Rates from 384 Kbps to 2+ Mbps3G GSM, Data Rates from 384 Kbps to 2+ Mbps Wideband CDMA, 5 MHz BWWideband CDMA, 5 MHz BW

High Speed Packet Access (HSPA)High Speed Packet Access (HSPA) 3G GSM, UMTS upgrade, data 3G GSM, UMTS upgrade, data << 2(4+) Mbps up(down)link 2(4+) Mbps up(down)link W-CDMA: more codes & higher M-Ary for dataW-CDMA: more codes & higher M-Ary for data

Code Division Multiple Access 2000 (CDMA 2000)Code Division Multiple Access 2000 (CDMA 2000) 3rd Generation 3rd Generation Data Rates 200 Kbps to maybe 3+ Mbps Data Rates 200 Kbps to maybe 3+ Mbps

3G Backhaul3G Backhaul

T3's & SONETT3's & SONET ATM or IP BasedATM or IP Based

Some Carrier EthernetSome Carrier Ethernet Mixed Traffic EnvironmentMixed Traffic Environment

FDMFDMAFDMFDMA

frequency

tim

eDifferent channels use some of the frequency all of the time.

1 32 4

Orthogonal FDMOrthogonal FDMfrequency

tim

e

Channels split into sub-channelsBits parceled out to sub-channels

Advantage:Sub-channel bit rates can be modified to cope with narrow band interferenceLess susceptible to multipath

Channel 1

FDM with Multi-pathFDM with Multi-path

XMTR

RCVRdirect path

bounce path

direct path pulsesbounce path pulses

Signal sum seen by Receiver

T2 T3 Symbol decision intervals at Receiver.The third bit is obliterated by multi-path.

T3time

delay

T1

OFDM with Multi-pathOFDM with Multi-path

direct

T3

bounce

directbounce

directbounce

T2T1

Matched filter detector will work OK.

delay

Slower symbol rate over each subchannel.

Automatic ReQuest RepeatAutomatic ReQuest Repeat Standard ARQStandard ARQ

Use "Hard Decision" symbol detectorUse "Hard Decision" symbol detector Throw away contents of corrupted packetThrow away contents of corrupted packet Request a retransmissionRequest a retransmission

TCP does thisTCP does this

Hybrid ARQHybrid ARQ Use "Soft Decision" symbol detectorUse "Soft Decision" symbol detector Save contents of corrupted packetSave contents of corrupted packet Request a retransmissionRequest a retransmission Combine ResultsCombine Results

Standard ARQStandard ARQ Hard Decision Matched Filter Bit DetectorHard Decision Matched Filter Bit Detector

Sample Bit Multiple TimesSample Bit Multiple Times Compute an AverageCompute an Average If Average > Threshold, Call it a Logic 1If Average > Threshold, Call it a Logic 1 If Average < Threshold, Call it a Logic 0If Average < Threshold, Call it a Logic 0

Suppose 00101100 flunks CRCSuppose 00101100 flunks CRC Suppose 00011100 retrans also flunks CRCSuppose 00011100 retrans also flunks CRC

Pretty sure of 1st, 2nd, & 5th – 8th bitsPretty sure of 1st, 2nd, & 5th – 8th bits Are 3rd and 4th Bits 1's or 0's?Are 3rd and 4th Bits 1's or 0's?

Hybrid ARQHybrid ARQ

Soft Decision Matched Filter Bit DetectorSoft Decision Matched Filter Bit Detector Sample Bit Multiple TimesSample Bit Multiple Times Compute an AverageCompute an Average How Far From Threshold?How Far From Threshold?

Barely Above? Could Say "It might be a Logic 1"Barely Above? Could Say "It might be a Logic 1" Above? Could Say "It's probably a Logic 1"Above? Could Say "It's probably a Logic 1" Well Above? Could Say "It's very likely a Logic 1"Well Above? Could Say "It's very likely a Logic 1" Far Above? Could Say "I'm positive it’s a Logic 1"Far Above? Could Say "I'm positive it’s a Logic 1"

Ditto for Voltages Below ThresholdDitto for Voltages Below Threshold

Hybrid ARQHybrid ARQ Soft Decision Matched Filter Bit DetectorSoft Decision Matched Filter Bit Detector Suppose 00Suppose 0010101100 flunks CRC1100 flunks CRC

Suppose Average for 3rd bit barely aboveSuppose Average for 3rd bit barely above Suppose Average for 4th bit barely belowSuppose Average for 4th bit barely below

Suppose 00Suppose 0001011100 retrans also flunks CRC1100 retrans also flunks CRC 3rd bit average far below → Positive it's a Logic 03rd bit average far below → Positive it's a Logic 0 4th bit average barely above → Iffy Logic 14th bit average barely above → Iffy Logic 1

Byte probably is 00Byte probably is 00000011001100 We're pretty sure 3rd bit is a Logic 0We're pretty sure 3rd bit is a Logic 0 4th bit can't be a 1, as 00011100 flunked CRC4th bit can't be a 1, as 00011100 flunked CRC

4G requires higher SNR4G requires higher SNR

source: Yuan, Y., et al, "LTE-Advanced Coverage Enhancements", IEEE Communications, October 2014

Need more Need more battery powerbattery power

Smaller Cell SizesSmaller Cell Sizes

4G Backhaul4G Backhaul

Frequently SONETFrequently SONET IP & MPLS BasedIP & MPLS Based

Some Carrier EthernetSome Carrier Ethernet Bursty Data EnvironmentBursty Data Environment

Hauling a little Voice over IP on the sideHauling a little Voice over IP on the side

Data Rate Roll-OffData Rate Roll-Off

Signal power decrease is proportional toSignal power decrease is proportional to1 / (distance)1 / (distance)22

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4G Wireless (MAN)4G Wireless (MAN) Long Term Evolution (LTE)Long Term Evolution (LTE)

OFDM, MIMO, Data Rates OFDM, MIMO, Data Rates >> 60 Mbps 60 Mbps Back to the Future: TDMA → CDMA → TDMABack to the Future: TDMA → CDMA → TDMA Initially Deployed in 2011. Initially Deployed in 2011.

LTE-AdvancedLTE-Advanced Seeing initial deployment in 2013Seeing initial deployment in 2013 1-2 Gbps speeds claimed on downlink1-2 Gbps speeds claimed on downlink Some Trade Pub articles → Don't need a LANSome Trade Pub articles → Don't need a LAN

Speeds ↓ as distance from BS ↑ & BW sharedSpeeds ↓ as distance from BS ↑ & BW shared

WiMax (IEEE 802.16)WiMax (IEEE 802.16) OFDM, MIMO, Data Rates OFDM, MIMO, Data Rates << 10 - 70 Mbps 10 - 70 Mbps Deployed by Sprint & Clearwire. Sprint moved to LTE. Deployed by Sprint & Clearwire. Sprint moved to LTE. Alternative to LTE? No. Used as back haul, fixed wireless. Alternative to LTE? No. Used as back haul, fixed wireless.

5G Cellular5G Cellular IP Wireless TrafficIP Wireless Traffic

3 Exabytes in 2010 (exabyte = 103 Exabytes in 2010 (exabyte = 101818)) Projected to exceed 500 exabytes by 2020Projected to exceed 500 exabytes by 2020 4G Cannot Handle4G Cannot Handle

Goals Goals Aggregate Data Rate (bps/unit area) 4G x 1000Aggregate Data Rate (bps/unit area) 4G x 1000 Edge Rate (Worst Case speed seen by 5%)Edge Rate (Worst Case speed seen by 5%)

1 Mbps → 100 Mbps1 Mbps → 100 Mbps Average Round Trip Time: Reduce by x 15Average Round Trip Time: Reduce by x 15 Energy Use: Don't Let It Increase Energy Use: Don't Let It Increase

source: Andrews, J;, et al, "What Will 5G Be?", IEEE Journal on Selected Areas in Communications, June 2014

Meeting 5G GoalsMeeting 5G Goals Extreme DensificationExtreme Densification Mix of few large cells and Mix of few large cells and manymany small cells small cells

Including pico cells (range < 100 meters)Including pico cells (range < 100 meters) Including femto cells (< 10 – 20 meters)Including femto cells (< 10 – 20 meters) Highest Bit Rates from Smallest CellsHighest Bit Rates from Smallest Cells

Increasing # of protocolsIncreasing # of protocols Smart RadiosSmart Radios

Improved Mobility SupportImproved Mobility Support Smart NetworkSmart Network Seamless Merging of Large & Small CellsSeamless Merging of Large & Small Cells

source: Andrews, J;, et al, "What Will 5G Be?", IEEE Journal on Selected Areas in Communications, June 2014

Meeting 5G GoalsMeeting 5G Goals Increased BandwidthIncreased Bandwidth "Beach Front" BW is taken"Beach Front" BW is taken

XXX MHz and X GHzXXX MHz and X GHz Propagates and Penetrates Reasonably WellPropagates and Penetrates Reasonably Well

Must go to Higher Carrier FrequenciesMust go to Higher Carrier Frequencies mmWave Frequencies XX to XXX GHzmmWave Frequencies XX to XXX GHz

Do Not Propagate as WellDo Not Propagate as Well Electronics Not So Good & ExpensiveElectronics Not So Good & Expensive

mmWave Not So Good for Large CellsmmWave Not So Good for Large Cells Potentially Good for Femto & Pico CellsPotentially Good for Femto & Pico Cells

Meeting 5G GoalsMeeting 5G Goals Increased Spectral Efficiency (bps per Hz)Increased Spectral Efficiency (bps per Hz)

Massive MIMOMassive MIMO Including 3D BeamformingIncluding 3D Beamforming

Cloud Based Control?Cloud Based Control? BackhaulBackhaul

Fiber Deployments ContinueFiber Deployments Continue Wireless Point-to-Point Speeds ImprovingWireless Point-to-Point Speeds Improving

mmWave more feasible for static outdoor linksmmWave more feasible for static outdoor links

Localized Caching of High BW Video Localized Caching of High BW Video

source: Andrews, J;, et al, "What Will 5G Be?", IEEE Journal on Selected Areas in Communications, June 2014

IEEE 802.11 ComparisonIEEE 802.11 Comparison

Source: "IEEE 802.11ac: From Channelization to Multi-User MIMO", IEEE Communications Magazine, October 2013

802.11 Sales802.11 Sales

WiFi Speed vs. DistanceWiFi Speed vs. Distanceso

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802.11 Flow Chart (Simplified)802.11 Flow Chart (Simplified)

Packet to Send?

ACKreceived?

No

Yes

No

YesNo

Binary ExponentialBack-off Used(Similar to 802.3)Min Wait: 0Max Wait: 51.2 msec

Back-off

Media Quiet?

Media Quiet?

Yes

Transmit

NoQuiet

for IFS?Yes

No