A Brief History of Space-Time Radio...A Brief History of Space-Time Radio By Prof. Gregory D. Durgin...

A Brief History of Space-Time Radio By Prof. Gregory D. Durgin

IEEE Student Seminar

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A Brief History of Space-Time Radio

Prof.GregoryD.Durgin,GeorgiaTechSchoolofECE

or “The Past, Present, and Future of How Your Smart Phone Works”

Personal History

n  Ph.D. at the end of 2000 from Virginia Tech n  Doctoral research at the Mobile & Portable Radio

Research Group (MPRG) n  American researcher visiting Morinaga Laboratory

(Osaka University) for 1 year n  Professor in Georgia Tech School of ECE n  Research program at

http://www.propagation.gatech.edu



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Outline of Talk n  The Challenge with Mobile Radio n  Using Multiple Antennas n  The Most Important Equation? n  LTE and 4G Cellular n  mm-Waves and Beyond

Copyright Prof. Gregory D. Durgin 3

Cellular Industry Circa 1983 n  First cellular system

deployed in Chicago, 1983

n  Had been on the drawing board since 1960s

n  Antenna is a long metal rod sticking out up top

Copyright Prof. Gregory D. Durgin4

MOTOROLA DYNATAC 8000X depicted by “The Evolution of Cell Phone Design from 1983-2009”, https://www.webdesignerdepot.com/2009/05/the-evolution-of-cell-phone-design-between-1983-2009/



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Transmission Line Analogy

Copyright 2010-present 5

Small-Scale Fading n  Constructive or

destructive wave interference

n  Leads to a random, unpredictable signal strength

n  PDF characterizes typical power or envelope levels

Copyright Prof. Durgin6



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Elitzur-Vaidman Experiment n  Waves constructively/destructively interfere even

when amplitudes drop below photonic coherence n  Demonstrated in optics with apparatus similar to

diagram below [Eli93]:

Copyright Prof. Durgin7

Cellular Industry Circa 1992 n  Launch of digital, personal

communications systems n  Phones get smaller n  Antenna is now a dual-

mode monopole whip/stub-loaded helix


Nokia 1011 depicted by “The Evolution of Cell Phone Design from 1983-2009”, https://www.webdesignerdepot.com/2009/05/the-evolution-of-cell-phone-design-between-1983-2009/



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WHAT IS THE MOST IMPORTANT EQUATION?


The Most Important Equation? n  Schrodinger’s equation n  Maxwell’s equations n  Newton’s laws of motion n  E=mc^2 n  Ohm’s law n  Shannon channel capacity n  Nyquist sampling theorem n  Laws of Thermodynamics n  Any suggestions?




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SISO Channel Capacity n  SISO = Single Input, Single Output n  Power is the show-stopper, but there are

diminishing returns on investment


SIMO Channel Capacity n  SIMO = Single Input, Multiple Output n  Beam-forming produces channel gain, which

enhances capacity




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Beam-forming Channel Capacity n  Multiple antennas at both transmit and receive

could provide very large gains, increase in channel capacity

n  Gains are always “squashed” by the logarithm:


MIMO Signal Processing n  Transmitter and Receiver signal vector processing

can be represented by unitary matrix operations, V and U.

n  Unitary matrices add no power, so any improvements will be genuine with respect to SINR




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MIMO Processing Visualization


MIMO Channel Capacity n  For an M x M system, there are now M separate

data channels or streams n  Aggregate channel capacity is the sum of each

individual stream capacity n  Brings M “outside the logarithm”




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Cellular Industry Circa 2004 n  Electronics are getting

smaller, allowing the phone to get thinner

n  Incorporation of Planar F and similar antenna types allow hidden radiators


MOTOROLA RAZR depicted by “The Evolution of Cell Phone Design from 1983-2009”, https://www.webdesignerdepot.com/2009/05/the-evolution-of-cell-phone-design-between-1983-2009/

First Textbook on Space-Time Radio

Book Title: Space-Time Wireless Channels Prentice-Hall Inc. October 2002



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Cellular Industry Circa 2008 n  First iPhone introduced

in 2007 n  New “brick” form factor n  Enabled by small, PCB/

multimode antennas


APPLE IPHONE 3G depicted by “The Evolution of Cell Phone Design from 1983-2009”, https://www.webdesignerdepot.com/2009/05/the-evolution-of-cell-phone-design-between-1983-2009/

Migration of Antenna in Phones n  PCB or thin substrate

area across end of phone q  Mechanically stable q  Low profile q  Minimal user effects q  Allows metal housing &

ground plane protrusion

n  True for 1 or 2 antennas


T.W. Kang, K-L Wong, L-C Chou, M-R Hsu. “Coupled-Fed Shorted Monopole With a Radiating Feed Structure for Eight-Band LTE/WWAN Operation in the Laptop Computer.” IEEE Transactions on Antennas and Propagation, Feb 2011.



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LTE/E-UTRA MIMO Support n  MIMO Uplink

q  2 x 2 antennas q  SC-FDMA – Single Carrier Frequency Division

Multiple Access

Copyright 2010-present21

n  MIMO Downlink: q  (2 or 4) x (2 or 4) antennas q  OFDMA – Orthogonal Frequency Division Multiple

Access

OFDMA-MIMO Transmission

n  Multiple users assigned various subcarriers n  Pilot subcarriers transmit/receive coordination

information n  MIMO on each subcarrier (effectively

narrowband) Copyright 2010-present 22

[Wikipedia, OFDMA, 2011]



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Single- or Multi-User MIMO


[Li10] Q. Li, G. Li, W. Lee, M. Lee, D. Mazzarese, B. Clerckx, “MIMO Techniques in WiMAX and LTE: A Feature Overview.” IEEE Communications Magazine. May 2010.

Cellular Industry Circa 2017 n  Antennas now excite

waveguide modes inside a metal case with slots

n  Multiple slots allow different “antennas” for MIMO and diversity


From Apple Computer



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The Future n  More functionality in “5G” cellular

q  Higher data rates for High-Def video q  Low latency for new types of mobile applictions

n  Move to higher frequencies, mm-Wave spectrum q  Studies suggest high-rate links are possible q  More propagation losses means more spectral reuse q  Issues involving power consumption and practicality

n  Massive MIMO q  Dozens or hundreds of base station antenna elements q  Lots of multi-user channels, highly directional links


A Brief History of Space-Time Radio...A Brief History of Space-Time Radio By Prof. Gregory D. Durgin...

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