Post on 29-Jan-2021
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
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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/
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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
Copyright Prof. Gregory D. Durgin 8
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/
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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WHAT IS THE MOST IMPORTANT EQUATION?
Copyright Prof. Gregory D. Durgin9
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?
Copyright 2010-present 10
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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
Copyright 2010-present 11
SIMO Channel Capacity n SIMO = Single Input, Multiple Output n Beam-forming produces channel gain, which
enhances capacity
Copyright 2010-present 12
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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:
Copyright 2010-present 13
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
Copyright 2010-present 14
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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MIMO Processing Visualization
Copyright 2010-present 15
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”
Copyright 2010-present 16
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
9
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
Copyright Prof. Gregory D. Durgin 17
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
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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
Copyright Prof. Gregory D. Durgin 19
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
Copyright 2010-present 20
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.
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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]
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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Single- or Multi-User MIMO
Copyright 2010-present 23
[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
Copyright Prof. Gregory D. Durgin24
From Apple Computer
A Brief History of Space-Time Radio By Prof. Gregory D. Durgin
IEEE Student Seminar
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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
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