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Next-Generation Wireless Communications Networks - From Chips to Architecture

Next-Generation Wireless Communications Networks - From Chips to Architecture. Daniel Foty 1,2,3 , Bruce Smith 2 , Saurabh Sinha 3 , and Michael Schr öter 4 1 Gilgamesh Associates LLC, Fletcher, Vermont, The United States of America

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Next-Generation Wireless Communications Networks - From Chips to Architecture

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  1. Next-Generation Wireless Communications Networks - From Chips to Architecture Daniel Foty1,2,3, Bruce Smith2, Saurabh Sinha3, and Michael Schröter4 1Gilgamesh Associates LLC, Fletcher, Vermont, The United States of America 2Sarissa Radio, Inc., Los Altos, California, The United States of America 3Carl and Emily Fuchs Institute for Microelectronics, University of Pretoria, Pretoria, The Republic of South Africa 4The University of California / San Diego, La Jolla, California, The United States of America Presented at the IASTED-MS Gaborone, Botswana 7 September 2010 IASTED-MS-2010

  2. Outline • Infrastructure, abundance, scarcity… • Wireless bandwidth demand – crisis now • Old model – power-centric, bits/Hz (failing) • New model – bandwidth-centric, bits/watt • Emerging mm-wave technology network ideas • Nuts and bolts (components, architectures, etc.) • Second-generation thoughts • Summary IASTED-MS-2010

  3. Thought For Today “Nothing is easier… than setting some arbitrary goal – preferably based on numbers – and [then going] after it, in utter disregard of the costs or the repercussions.” -- Prof. Thomas Sowell, 2009 IASTED-MS-2010

  4. Beckmann’s Conjecture “In a healthy society, engineering design gets smarter and smarter; in an [unhealthy society], it gets bigger and bigger.” -- Prof. Petr Beckmann, “A History of π,” 1971 IASTED-MS-2010

  5. 1994 “Infrastructure Vision” Source: Adapted from D. Foty and E. Nowak, IEEE Micro, June 1994 IASTED-MS-2010

  6. Abundance and Scarcity “Every economic era is based on a key abundance and a key scarcity.” -- George Gilder, Wired magazine, May 1996(!!) IASTED-MS-2010

  7. Abundance/Scarcity Matrix (Gilder, 1996) (Us, 2010) Abundance Scarcity Power Bandwidth Transistors Time - MIPs Space - Bits Fourteen years on, we’re still stranded in the old paradigm… And its penalties are worsening rapidly!! IASTED-MS-2010

  8. The New Paradigm (Gilder, 1996) (Us, 2010) Abundance Scarcity Bandwidth Power Time Space We need to make bandwidth much more abundant – on present course, dire shortage by… NOW!! IASTED-MS-2010

  9. Bandwidth Demand The Cisco Visual Networking Index (VNI) Forecast for 2007-2012 provides key findings on a variety of consumer and business Internet Protocol (IP) networking trends that are driven by the increasing use of video and Web 2.0 social networking and collaboration applications--AKA visual networking. Projections resulting from the project include: * IP traffic will increase at a combined annual growth rate (CAGR) of 46 percent from 2007 to 2012, nearly doubling every two years. * The resulting annual bandwidth demand on the world's IP networks will be approximately 522 exabytes, or more than half a zettabyte. * In 2012, Internet video traffic alone will be 400 times the traffic carried by the U.S. Internet backbone in 2000. Internet video jumped from 12 percent of the global consumer Internet traffic in 2006 to 22 percent in 2007. * Video on demand, IPTV, peer-to-peer (P2P) video, and Internet video are forecast to account for nearly 90 percent of all consumer IP traffic in 2012. * Global business IP traffic is forecast to grow strongly at a CAGR of 35 percent from 2007 to 2012. Increased broadband penetration in the small-business segment and the increased adoption of advanced video communications in the enterprise are major drivers for business IP traffic growth. * Business IP traffic will grow fastest in the developing markets and Asia-Pacific. In volume, North America will continue to have the most business IP traffic through 2012, followed by Asia-Pacific and Western Europe. * Global IP traffic will reach 44 exabytes per month in 2012, compared to less than seven per month in 2007. * By comparison, global IP traffic in 2002 was five exabytes which means that the volume of IP traffic in 2012 will be 100 times as large. * Monthly global IP traffic in December 2012 will be 11 exabytes higher than in December 2011, a single-year increase that will exceed the amount by which traffic has increased in the eight years since 2000. * Mobile data traffic will roughly double each year from 2008 through 2012. Note: A zettabyte is equal to: 1 trillion gigabytes; 1,000 exabytes; 250 billion DVDs, while an exabyte is equal to: 1 billion gigabytes; 1,000 petabytes; 250 million DVDs. IASTED-MS-2010

  10. Bandwidth Demand • AT&T Wireless – Disaster • iPhones/iPads  “Bandwidth Hogs” • NYC/SF  Can’t even make phone calls mid-day and afternoon (I speak from experience) • Ending unlimited data plans – Re-introducing “caps” beyond which usage becomes metered • iPhone4  Video calls?!?!?!?! (Yeah, right…) • Only allowed via WiFi network – Not over mobile network • Desperate need for more bandwidth IASTED-MS-2010

  11. Network Crisis • Problem • Networks are voice-centric, not data-centric • Need to make a transition to genuinely data-centric networks • Track has been voice-centric networks plus band-aids • Now has reached a crisis point IASTED-MS-2010

  12. The “Iron Triangle” • Shannon Information Theory: C = W log (1 + SNR) • “C”  Data rate • SNR = P/N*W, where P is the signal power and N is the noise power spectral density (one-sided), so that N*W is the noise power • W is the bandwidth • (Thanks to Prof. Toby Berger, University of Virginia) IASTED-MS-2010

  13. Old Model • Old model • High power, • Low bandwidth • Focus on bits/Hz • However, this clearly isn’t working out now • Empirical observation • Back with simple analysis IASTED-MS-2010

  14. Much Thunder, Little Rain PC Magazine, 2 October 2007 “In any technology, reality must take precedence over public relations, for nature cannot be fooled.” -- Richard Feynman, 1986 “You can’t polish a turd.” – Old U.S. Army Proverb IASTED-MS-2010

  15. Northern Reaction IASTED-MS-2010

  16. The Golden Calf • Bits/Hz  Can only increase w/ more power • Shannon: No limit on bits/Hz, but energy/bit… • “Spectral efficiency”  Not best approach • All  High entropy methods IASTED-MS-2010

  17. Bits Per Watt WirelessHD 802.11g 802.11b BT (Cl-2) BT (Cl-1) IASTED-MS-2010

  18. New Model • New model • Low power • High bandwidth • “Power-efficient bandwidth" • Power/bandwidth plane • Move from bandwidth-scarce/power-rich to power-scarce/bandwidth-rich • “Iron Triangle”  Harsh constraints • Need a different way forward IASTED-MS-2010

  19. Need to Expand the Triangle • Only way to get higher data rate at good “cost”? • Implies higher carrier frequencies • Net: mm-wave is the route to power-efficient bandwidth • Escape the tyranny of “bits per Hz”  bits per watt!!  IASTED-MS-2010

  20. Propagation IASTED-MS-2010

  21. Regulatory – mm-Wave • 57 - 64 GHz "ISM"-like allocation • US/Japan/Europe vary slightly, but 5 GHz of overlap • Unlicensed – And “wide/absolute” but not “wide/relative” • US FCC  500 mW maximum EIRP • 71 – 76 GHz  Licensed band for comms • 77 GHz vehicular radar band (R.A.D.A.R for real!!) • 81 – 86 GHz  Licensed band for comms • 92 – 95 GHz VERY licensed band for comms • Big opportunity… But terrible regulatory environment IASTED-MS-2010

  22. Regulatory Help Needed!! • Need for regulatory relief on 92 - 95GHz band • Relax power constraint • Same power limits as 60 GHz – 500 mW EIRP, 2 µW/cm2 @ 3 m (FCC))  Not good for “pencil beams” • Let people use it outdoors IASTED-MS-2010

  23. Tiered mm-Wave Networking • Can divide into three “tiers” • Short range – WP2P, low power, portable (UWB flop) • Medium range (c. 2km) – E.g., building-to-building • Long range (c. 10km) – Backhaul/bulkhaul • Comments on each • Low cost / low power / on-board antenna (UWB space) • Beefier (SiGe bipolar) PA / external antenna • GaN PA / external antenna • Can greatly improve state-of-the-art both technically and cost-wise – on all three IASTED-MS-2010

  24. Three Network Tiers • Long-range (c. 10 km) • Backhaul/bulkhaul story is very promising • Particularly suitable for developing countries (southern Africa) • Medium-range (c. 2 km) • E.g., building-to-building • 70/80 GHz bands – 1.2° “pencil beam” • 90 GHz band would be marvelous • Regulatory relief needed here – Help!! IASTED-MS-2010

  25. Extant mm-Wave Stuff • “BridgeWave gigabit point-to-point wireless links provide fiber-equivalent connections between locations by transmitting data over highly secure 60 GHz & 80 GHz (E-Band) radio frequencies at gigabit and Fast Ethernet speeds with the advantage of add/drop data ports, and optional wire-speed AES encryption built-in.” IASTED-MS-2010

  26. Extant mm-Wave Stuff • “70/80” bands, full-duplex,1.25 Gbps bulk-haul wireless Ethernet • Range  c. 6 km • Produced by Gilland Electronics IASTED-MS-2010

  27. Limiting Factors • Widespread use of 70/80 for bulkhaul/backhaul limited by… • Cost • Power consumption • “Up to”  Problem if you live/operate in a rainy place • Power amplifier technology • Output, cost (TWT & kV power supply, propagation loss limitation (only overcome with power)) • GaN not available yet IASTED-MS-2010

  28. Short Range Networking • Short range • Mobile-device-centric • Requires low power consumption • Driven by… • “Media-rich content” (very data-intensive) • Enormous storage capacity in mobile devices • Obvious market need… but what happened? IASTED-MS-2010

  29. “ETSI” 2004 Forecast IASTED-MS-2010

  30. “ETSI” 2004 Forecast IASTED-MS-2010

  31. “ETSI” 2004 Forecast IASTED-MS-2010

  32. UWB – PR vs. Reality Matches Unit Shipments of Hoverponies During Same Time Period • ETSI 2004 forecast vs. reality • “Where’s the beef??” – Something clearly wrong IASTED-MS-2010

  33. Harsh Reality • “Embarrassed polar bear” • Obvious market need, technology couldn’t reach it • Technological approaches fundamentally flawed • One failure after another • Requires new approaches IASTED-MS-2010

  34. Link Issues - Reality IASTED-MS-2010

  35. Devices • “Devices”  “Semiconductor technology” • Need to make sensible choices here • Avoid “ultimate CMOS” / “SoC” theology • Make good product engineering choices IASTED-MS-2010

  36. IC Technology • Mm-wave has used III-Vs (HBT, HEMT) • Supply limited, very expensive • CMOS is mainstream and inexpensive… • But (despite hand-waving) not capable • Only “real” products on market c. 5 GHz • Been stuck there now for several years  Further CMOS generational scaling doesn’t seem to be increasing the useful RF-CMOS frequency value IASTED-MS-2010

  37. SiGe Technology • SiGe BiCMOS can meet the goals • Available for some time – 200 GHz/220 GHz • Some very cost-effective • Now available – 300 GHz • Delay due to lack of demand – not physics • (SiGe BiCMOS can mix bipolar at will) • Serious development underway for 500 GHz (!!) IASTED-MS-2010

  38. SiGe vs. CMOS - Cost • Cost  CMOS less cost-effective than good SiGe BiCMOS (when including “frequency”) Source: Fabless Semiconductor Association (FSA), Wafer Fabrication Pricing Report, Q2-2004 IASTED-MS-2010

  39. Partition – Two ICs Chip 1: RF SiGe HBT, IF CMOS; Chip 2 – Baseband analog & digital (all CMOS) IASTED-MS-2010

  40. Harnessing the SiGe HBT • Next-generation methods, scaling techniques (Credit: Michael Schröter) IASTED-MS-2010

  41. 'vddvsl.dat' 'vtvsl.dat' 5 4 3 Power Supply Voltage (V) 2 1 ?!?! 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Drawn Lmin of the Process Generation (μm) RF-CMOS “Non-Scaling” Power Supply Voltage Now… Cheating!! Threshold Voltage IASTED-MS-2010

  42. CMOS Theology vs. RF-CMOS • Low power  RF-CMOS = AC path to ground • “Proof” – 802.11g routers • Linksys (all-CMOS chipset) vs. Buffalo (bipolar PA) • Buffalo consumes much less power, runs cooler IASTED-MS-2010

  43. 'gmid2.dat' 'asympt1.dat' 'asympt2.dat' 'iceq1.dat' 'gmxic20.dat' 'gmxic018.dat' 1 Weak Inversion Square Law Asymptote Asymptote Normalized gm/ID SC 0.1 Limit Modern LC 0.001 0.01 0.1 1 10 100 1000 Inversion Coefficient (IC) New Approach to CMOS IASTED-MS-2010

  44. Characterizing gm/Id – 0.18μm Simple unified description across entire spectrum of charge response (L = 20.0 μm, 0.72 μm, 0.36 μm, 0.24 μm, 0.18 μm) IASTED-MS-2010

  45. Critical – Loss of High-End • Loss of strong inversion • Not getting more bandwidth with shrinkage!! 0.13 m 0.18 m 0.5 m IASTED-MS-2010

  46. GaN Power Amplifiers • This is the piece that is needed to make cost-effective 70/80 bulkhaul/backhaul a reality • Conundrum • High-power PAs available – but for < 6 GHz • Cellular base stations • 70/80/90 HEMT-based PAs available – but for 77 GHz automotive radar (350 mW output) • Need to catalyze development of higher-power PAs for 70/80 backhaul/bulkhaul IASTED-MS-2010

  47. Chips, Packaging, Systems • Long-standing RF-IC problem – Stability • Not enough chips “work” • Chips that “work” as chips don’t in package/system • Everything interacts with everything else • Extensive/regular test required  Very expensive • Use expensive (6x) ceramic packaging • Innovation – Electrical tuning • Won’t say more for now here… • Work in progress… IASTED-MS-2010

  48. IASTED-MS-2010

  49. Propagation/Modulation/Antenna IASTED-MS-2010

  50. IASTED-MS-2010

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