ECEN5553 Telecom Systems Dr ECEN5553 Telecom Systems Dr. George Scheets Week #13 [27] "5G Wireless Access: Requirements and Realization" [28a] "Why Wi-Fi Stinks- and How to Fix It" [28b] "What's Next for Wi-Fi?" [28c] "Old-School Wi-Fi is Slowing Down Networks"= [29a] "What to Expect from 11ac’s Next Big Deal: Multiuser MIMO" [29b] "Worries Mount over Upcoming LTE-U Deployments Hurting Wi-Fi" [29c] "Is it Safe to Use Public Wi-Fi Networks?" [29d] "How the Wi-Fi industry is adapting to keep up with the IoT" Exam #2 Results Hi = 90.1, Low = 54.2, Ave = 78.94, σ = 9.44 A > 81, B > 72, C > 59, D > 50 Term Paper: Late Fee = -1 point per working day Final Exam Monday, 5 December, 2:00 – 3:50 pm (Live) < 12 December (Distance Learning)

Bit Error Rate Unsatisfactory? System designer has several options: Use FEC codes Increase received signal power Crank up transmitter power out Use directional antennas Use more effective modulation technique Slow down the transmitted symbol rate Use less noisy receiver electronics

Techniques to Increase Bit Rate (Per Channel Basis) Use FEC Increase Received Signal Power Increase transmitter power out Use directional antennas Change Modulation Technique Go to higher "M" in M-ary Build a Quieter Receiver Slow Down Transmitted Bit Rate Increase Available Bandwidth Compress the Application Signal Increases apparent bit rate

Voyager II Deep Space Probe Used all of previous techniques on downlink: 2:1 FEC Coding (different code than in previous examples) Increasingly sophisticated earth receive antennas Binary PSK signaling Reduced bit rates Cryogenically cooled receiver electronics Flight history Launch , August 1977 Jupiter fly-by, July 1979, Message bit rate: 115.2 Kbps Saturn fly-by, August 1981, Message bit rate: 44 Kbps Uranus fly-by, January 1986, Message bit rate: 29.9 Kbps Neptune fly-by, August 1989, Message bit rate: 21.6 Kbps Now well past Pluto. NASA is still in contact.

Pre-Cellular Mobile Telephony source: Telecommunications by Warren Hioki, 1st Edition

0th Generation Mobile Phones Source: http://www.wb6nvh.com/MTSfiles/Carphone1.htm

Cellular Telephone System source: Telecommunications by Warren Hioki, 1st Edition

Cellular Telephony Advantages: Frequency Reuse Reduced Transmitter Power Out Reduced Multipath Problems Reduced brain damage? Subdividing Cells increases System Capacity More Reliable due to cell overlap

Cellular Telephony Disadvantages: More complex More installation hassles BS to MTSO link (Backhaul) & switching requirements can get out of hand

1987 Mobile Phone source: September 1987 Electronic Design Magazine

One Big Cell 30 Channels could support 30 users

Seven Smaller Cells Set #2 10 Channels Can Set #1 Support 10 Channels 70 Users with same Channel set. Set #3 10 Channels

Mobile Traffic Source: "The Great Spectrum Famine", IEEE Spectrum Magazine, October 2010.

London, 1995

Hidden Cell Towers sources: businessweek.com mobilitydigest.com

Cellular Telephony - Operation Power Up & Intermittently Thereafter Mobile tunes to strongest control channel Mobile communicates with BS/MTSO Local MTSO notes in database mobile is active & which cell it's in If mobile is roaming, Home MTSO is notified, typically via SS7 or SIP Signaling

Cellular Telephony - Operation Mobile to Wired call Mobile transmits # to BS/MTSO Uses Control Channel Unused voice RF channel is assigned Mobile tunes to assigned channels BS & MTSO coordinate Backhaul MTSO places call via CO to wired unit Could be via PSTN or VoIP

Cellular Telephony - Operation Wired to Mobile call Signaling info shipped to home MTSO Home MTSO checks database Mobile in home area? Mobile is paged Mobile not in home area? Signaling info is forwarded to local MTSO Local MTSO database indicates Mobile's cell Mobile is paged & tunes to assigned RF channel End-to-End Voice channel is set up BS & MTSO coordinate Backhaul MTSO & CO coordinate Long Haul

Cellular Telephony - Operation Handoff MTSO/BS/Mobile decides signal getting too weak Adjacent cells are polled Unused voice RF channels in the new cell is assigned Mobile tunes to assigned channel MTSO reroutes traffic: Old BS  MTSO to New BS  MTSO

Where is this MTSO? Could be anywhere Increased Computer Power Co-located with a Central Office In the Cloud Elsewhere Increased Computer Power What used to be done at MTSO can now be accomplished at other locations Widespread Internet Availability Traffic could flow thru ISP & bypass MTSO Depends on the carrier

Advanced Mobile Phone System (AMPS) 1st Generation U.S. Cellular Analog FDMA 30 KHz FM channels # of subscribers peaked in 1999 February 18, 2008 FCC no longer required carriers to support Should now be called OMPS RIP

1G AMPS FDMA 1 2 3 4 Cell 1 Cell 2 AMPS time Different channels use some of the frequency all of the time. frequency 1 2 3 4 Cell 1 Cell 2 AMPS time

1G Backhaul Typically a T-1 14.4 Kbps data per user Voice Backhaul 23 calls 1 signaling channel 14.4 Kbps data per user Voice Backhaul Moving a little data on the side

2G Mobile Wireless (MAN) Time Division Multiple Access U.S. TDMA, 2G, gone → GSM GSM, 2G, Data Speeds < 14.4 Kbps Obsolete RIP

2G GSM Combo of TDM & FDM frequency 1 4 7 10 Cell 1 Cell 2 2 5 8 11 3 6 9 12 time 1 4 7 10 etc.

2G Mobile Wireless (MAN) Time Division Multiple Access U.S. TDMA, 2G, gone → GSM GSM, 2G, Data Speeds < 14.4 Kbps Obsolete Code Division Multiple Access TIA-95 CDMA (a.k.a. IS-95 or CDMA1), 2G Data Speeds < 14.4 Kbps Obsolete RIP

DSSS - Transmit Side +1 Traffic (9 Kbps) time -1 Spreading Signal 27 Kcps +1 +1 +1 time -1 -1 -1 Transmitted Signal 27 Kcps (mapped onto hi freq) +1 +1 +1 +1 time -1 -1

Wireless RF Transmitter RCVR Front End 27 Kcps Square Pulses X BPSK output 27 Kcps 90% of power in 54 KHz BW centered at fc Hertz cos(2πfct) RCVR Front End BPSK input 27 Kcps + noise Low Pass Filter 27 Kcps Square Pulses + filtered noise X cos(2πfct)

DSSS-Receiver +1 +1 +1 +1 time Received Signal 27 Kcps -1 -1 Despreading Signal 27 Kcps +1 +1 +1 time -1 -1 -1 Recovered Traffic 9 Kbps +1 time DSSS-Receiver -1

DSSS-Receiver 2nd Signal active Received Signal #2 27 Kcps +1 +1 +1 +1 time DSSS-Receiver 2nd Signal active -1 -1 Despreading Signal #1 27 Kcps +1 +1 +1 time -1 -1 -1 +1 +1 Recovered Garbage from 2nd signal +1 time -1 -1 -1

DSSS-Receiver 2 Signals active +1 Recovered Traffic 9 Kbps time -1 +1 Garbage from 2nd signal +1 time -1 -1 -1 Input to Matched Filter Detector (sum) +2 time DSSS-Receiver 2 Signals active -2

Additional signals transmitting at the same time Input to Matched Filter Detector (sum) +2 time -2 TBit Receiver Matched Filter Detector Output +1 time -1 Additional signals transmitting at the same time increase the apparent noise seen by our system. Message (voice) BER will increase.

CDMA Channels use different codes. Other channels cause Different channels use all of the bandwidth all of the time. CDMA frequency Channels use different codes. Other channels cause noise-like interference. time

CDMA: 3D View frequency code #3 code #2 code #1 time

Multiplexing Schemes Frequency Division Mutiplexing Time Division Multiplexing Statistical Multiplexing Code Division Multiplexing

2G Backhaul Still Frequently T Carrier 14.4 Kbps Data Initially T1's, Fractional T3's, or a maybe a T3 14.4 Kbps Data Initially < 200 Kbps data with later add ons Primarily Voice Backhaul Moving a little more data on the side

Mobile Wireless Evolution 2G: Voice! Voice! 2.5G: One eye on data. 3G: Voice & Data 4G: Hi Speed Data LTE (4G) Sprint 2012-2013 WiMax Development halted in 2005

3G Mobile Wireless (MAN) Universal Mobile Telephone Service (UMTS) 3G GSM, Data Rates from 384 Kbps to 2+ Mbps Wideband CDMA, 5 MHz BW High Speed Packet Access (HSPA) 3G GSM, UMTS upgrade, data < 2(4+) Mbps up(down)link W-CDMA: more codes & higher M-Ary for data Code Division Multiple Access 2000 (CDMA 2000) 3rd Generation Data Rates 200 Kbps to maybe 3+ Mbps

3G Backhaul T3's & SONET ATM or IP Based Mixed Traffic Environment Some Carrier Ethernet Mixed Traffic Environment

FDM FDMA 1 2 3 4 time Different channels use some of the frequency all of the time. frequency 1 2 3 4 time

Orthogonal FDM time frequency Channel 1 Channels split into sub-channels Bits parceled out to sub-channels Advantage: Sub-channel bit rates can be modified to cope with narrow band interference Less susceptible to multipath time

FDM with Multi-path T3 bounce path XMTR direct path direct path pulses time bounce path XMTR direct path direct path pulses RCVR delay bounce path pulses Signal sum seen by Receiver Symbol decision intervals at Receiver. The third bit is obliterated by multi-path. T1 T2 T3

OFDM with Multi-path Slower symbol rate over each subchannel. delay bounce direct bounce direct direct bounce Matched filter detector will work OK. T1 T2 T3

Automatic ReQuest Repeat Standard ARQ Use "Hard Decision" symbol detector Throw away contents of corrupted packet Request a retransmission TCP does this Hybrid ARQ Use "Soft Decision" symbol detector Save contents of corrupted packet Combine Results

Standard ARQ Hard Decision Matched Filter Bit Detector Sample Bit Multiple Times Compute an Average If Average > Threshold, Call it a Logic 1 If Average < Threshold, Call it a Logic 0 Suppose 00101100 flunks CRC Suppose 00011100 retrans also flunks CRC Pretty sure of 1st, 2nd, & 5th – 8th bits Are 3rd and 4th Bits 1's or 0's?

Hybrid ARQ Soft Decision Matched Filter Bit Detector Sample Bit Multiple Times Compute an Average How Far From Threshold? Barely Above? Could Say "It might be a Logic 1" Above? Could Say "It's probably 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" Ditto for Voltages Below Threshold

Hybrid ARQ Soft Decision Matched Filter Bit Detector Suppose 00101100 flunks CRC Suppose Average for 3rd bit barely above Suppose Average for 4th bit barely below Suppose 00011100 retrans also flunks CRC 3rd bit average far below → Positive it's a Logic 0 4th bit average barely above → Iffy Logic 1 Byte probably is 00001100 We're pretty sure 3rd bit is a Logic 0 4th bit can't be a 1, as 00011100 flunked CRC

4G requires higher SNR Need more battery power Smaller Cell Sizes source: Yuan, Y., et al, "LTE-Advanced Coverage Enhancements", IEEE Communications, October 2014

4G Backhaul Frequently SONET IP & MPLS Based Bursty Data Environment Some Carrier Ethernet Bursty Data Environment Hauling a little Voice over IP on the side

Signal power decrease is proportional to 1 / (distance)2 Data Rate Roll-Off source: Zander, J., Mahonen, P., "Riding the Data Tsunami in the Cloud: Myths and Challenges in Future Wireless Access", IEEE Communications Magazine, March 2013. Signal power decrease is proportional to 1 / (distance)2

4G Wireless (MAN) Long Term Evolution (LTE) LTE-Advanced OFDM, MIMO, Data Rates > 60 Mbps Back to the Future: TDMA → CDMA → TDMA Initially Deployed in 2011. LTE-Advanced Seeing initial deployment in 2013 1-2 Gbps speeds claimed on downlink Some Trade Pub articles → Don't need a LAN Speeds ↓ as distance from BS ↑ & BW shared WiMax (IEEE 802.16) OFDM, MIMO, Data Rates < 10 - 70 Mbps Deployed by Sprint & Clearwire. Sprint moved to LTE. Alternative to LTE? No. Used as back haul, fixed wireless.

5G Cellular IP Wireless Traffic Goals 3 Exabytes in 2010 (exabyte = 1018) Projected to exceed 500 exabytes by 2020 4G Cannot Handle Goals Aggregate Data Rate (bps/unit area) 4G x 1000 Edge Rate (Worst Case speed seen by 5%) 1 Mbps → 100 Mbps Average Round Trip Time: Reduce by x 15 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 Goals Extreme Densification Mix of few large cells and many small cells Including pico cells (range < 100 meters) Including femto cells (< 10 – 20 meters) Highest Bit Rates from Smallest Cells Increasing # of modulation techniques Smart Radios Improved Mobility Support Smart Network Seamless 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 Goals Increased Bandwidth "Beach Front" BW is taken XXX MHz and X GHz Propagates and Penetrates Reasonably Well Must go to Higher Carrier Frequencies mmWave Frequencies XX to XXX GHz Do Not Propagate as Well Electronics Not So Good & Expensive mmWave Not So Good for Large Cells Potentially Good for Femto & Pico Cells

Meeting 5G Goals Increased Spectral Efficiency (bps per Hz) Massive MIMO Including 3D Beamforming Cloud Based Control? Backhaul Fiber Deployments Continue Wireless Point-to-Point Speeds Improving mmWave more feasible for static outdoor links 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 Comparison Source: "IEEE 802.11ac: From Channelization to Multi-User MIMO", IEEE Communications Magazine, October 2013

802.11 Sales