evolution of microwave communications - a brief history · pdf fileevolution of microwave...

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PRESENTED BY RICHARD U. LAINE, PEPRINCIPAL ENGINEER, AVIAT NETW ORKS, SANTA CLARA, CA 95054

EVOLUTION OF MICROWAVECOMMUNICATIONS - A BRIEF HISTORY

JULY 2011

Agenda

• Historical Perspective, not without controversy

• “Wireless” in its Infancy—the Intertwining of Edison, Marconi, andTesla

• Propagation—the Intertwining of Huygens, Newton, Fresnel, andEinstein

• Microwave Radios—The Early Days: PPM “digital,” Analog FM-FDM

• Evolution of the U.S. Microwave Communications Industry

• Evolution to Aviat Networks

• Upgrade from Analog to Digital Microwave Hops

• Digital Microwave Attributes—A Media Comparison

JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY2

Wireless Communications – The Early Days

Excerpt from the Scientific American July 1892

In the specification to one of his recent patents,

Thomas A. Edison says:

“I have discovered that if sufficient elevation be obtained to

overcome the curvature of the earth’s surface and to reduce to

the minimum the earth’s absorption, electric signaling between

distant points can be carried on by induction without the use of

wires.”

MICROWAVE PATH ENGINEERING 117 YEARS AGO!


Thomas A. Edison (1847-1931)Ohio

The First Wireless Communications Age

The radio is one hundred years old, but it doesn’t look it!

... it is interesting to note that Samuel F. B. Morse’s telegraph was followed

only 40 years later by the increasingly remarkable invention of radio

frequency transmission.

Thomas Edison experimented with signals that could be generated and

detected at a distance in 1883, but did not appreciate the importance of

“the Edison Effect.” Edison received a patent for wireless telegraphy in

1885, but was preoccupied with other projects. Edison sold the patent “for

a song” to Marconi, who put extensive effort into the technology. By 1901,

he sent Morse Code from Massachusetts to Cornwall, England.

Roger Rusch

Applied Microwave & Wireless Fall 1995


Samuel F. B. Morse (1791 – 1872) Scotland

Wireless – Marconi Inventor of the Radio?

January 1897An invention which promises to be of the greatest practical value in the world of telegraphy hasreceived its first public announcement at the hands of Mr. William H. Preece, the telegraphicexpert of the London post office. During a lecture on "Telegraphy Without Wires" recentlydelivered in London, Mr. Preece introduced a young Italian, a Mr. Marconi, who, he said, hadrecently come to him with such a system. Telegraphing without wires was, of course, no newidea. In 1893, telegrams were transmitted a distance of three miles across the Bristol Channel byinduction. Young Marconi solved the problem on different principles, and post office officials hadmade a successful test on Salisbury Plain at a distance of three-quarters of a mile.

Scientific American - January 1897

The roots of modern radio-links can be perceived in the first experiments carried out by Marconi,as he used very high frequencies—practically in the field of microwaves—and had recourse toparabolic-cylinder reflectors. Here is the first invention which Marconi anticipated. Many scientistsbefore Marconi had devoted their work to the electric and magnetic phenomena, takingadvantage of the extraordinary synthesis which James Clerk Maxwell’s equations had giventhem. In 1894, when he was only twenty, the young man from Bologna set up his first laboratoryat Villa Griffone, about fourteen kilometers from his native city. Marconi’s basic contribution, forwhich he deserves the name of “inventor of the radio”, was, first of all, that he modulated by asignal the electromagnetic waves that a spark produced in a Hertz oscillator sent in space.

Gian Carlo Corazza 1996 European Conference for Radio-Relay, Bologna


Guglielmo Marconi(1874-1937) Italy1909 Nobel Prize for Wireless Telegraphy

James Clerk Maxwell(1831-1879) Scotland

Wireless – Marconi Inventor of the Radio? Or Not!!

On 11 June 1943, the U.S Supreme Court overturned most of Marconi’s

wireless communications patents thus upholding Nikola Tesla’s earlier

September 1897 patent for radio, that in 1904 was reversed by the U.S. Patent

Office and awarded to Marconi, based upon Tesla’s wireless communication

demonstrations in 1894.

This Supreme Court decision—five months after he died impoverished, alone

in a New York hotel room—in effect recognized Tesla (who, shortly after

arriving in the U.S. in 1884, had worked for Thomas Edison for $18 per week)

as the inventor of the radio.

This added to Tesla’s remarkable credentials as the inventor and architect of

alternating current machinery and long-distance electrical distribution, this

rendering obsolete his adversary Edison’s direct current electrical

powerhouses that had been built up and down the Atlantic seaboard.


Nikola Tesla (1856-1943) Austrian Empire“The Man who Invented the 20th Century”

Propagation – Huygens’ Principle? Or Not!!

Christiaan Huygens, a contemporary of Sir Isaac Newton, is said to have gained most of his insights into wave motion by

observing waves in a canal. In 1678, this great Dutch physicist wrote the treatise Traite de la Lumiere on the wave theory of

light, and in this work he stated that the wavefront of a propagating wave of light at any instant conforms to the envelope of

spherical wavelets (Huygens’ “Combination Wavefront” of separate waves) emanating from every point on the wavefront at

the prior instant, with the understanding that the wavelets have the same speed as the overall wave.


Augustin-Jean Fresnel(1788-1827) - France

Albert Einstein(1879-1955) - Germany

Christiaan Huygens(1629-1695) - Netherlands

Sir Isaac Newton(1643-1727) - England

Propagation – Huygens’ Principle? Or Not!!

An illustration of this idea, now

known as Huygens' Principle, is

shown. Disbelieving, Newton

continued to push his “Corpuscular

Theory” of particle propagation of

light, so because of that it was not

until some 100 years later when

Augustin-Jean Fresnel of “Fresnel

lens” and “Fresnel zone” fame

revisited Huygens’ Principle in 1815

that his term “diffraction” was

reintroduced.*

JULY 20118 EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY

Einstein and others opine the dualitythat light functions as both a particle(per Newton) and a wave (perHuygens) depending on how theexperiment is conducted and whenobservations are made.

Illustration of Huygens’ Principle.The pinholes in the mask act assecondary point sources of radioenergy.

Microwave Radio Links - The Early Days

2 GHz PPM “Digital” Radios

6 Bays!! 24xVF or 24x300 baud data channel capacity!! General Electric’s

2 GHz “radar-like” pulse position modulated (PPM, used during WW2 then

declassified) hot standby terminal. Many hundreds of similar GE and ITT

PPM radio hops were deployed in long pipeline, power and turnpike

systems in the 1940s-50s, some up to 75 hops in length with no end-to-

end noise buildup (like modern digital systems), all over the U.S. and

worldwide for the military.


Microwave Radio Links - The Early Days

AT&T Long-Haul Analog Routes Deployed 35,000 TD2 Repeaters

The San Francisco-New York transcontinental route of hundreds of 4 GHz

TD2 analog FM-FDM hops completed in 1951 for all long distance VF and

TV was upgraded with high-capacity L6 GHz TH1 radios in 1955 and

improved TD3 radios in 1962.

The performance of analog hops was far more

affected than later generation digital radio hops

to equipment nonlinearities, interference,

thermal noise, multipath distortion,

waveguide echoes and moding,

and fading.


U.S. Microwave Industry Evolution Through 1991

The Early DaysU.S. Microwave CommunicationsManufacturers from 1931 (ITT) through 1991

Farinon/Harris MCD (1958) andDMC/Stratex Networks (1984) merged to formHarris Stratex Networks (2007), which changed names toAviat Networks (2010)


EXTINCT

50EXTINCT

50EXTANT

20(growing rapidly)

EXTANT

20(growing rapidly)

How We Evolved into Aviat Networks


1963

1982

1984

Jan 1984San Jose

2002

Microwave CommunicationsDivision (MCD)

1980Merger

1981

1998

Feb 1958San Carlos

Jan 26, 2007 Merger

SiemensTransmission Systems

Lenkurt Electric Company

GTE Network Systems

Len EricksonKurt Appert*

1959 Merger

1944 San Francisco1947 San Carlos, CA

1983

Siemens Information andCommunications Networks

Boca Raton* Bancroft Library Oral history: http://www.archive.org/search.php?query=kurt%20appert

Bill Farinon

Bill Gibson

)(

2010

The Migration from Analog to Digital Microwave Links

It’s Been a Challenge!

• Canadian Marconi delivered the first PCM digital radios to privatemicrowave users in North America in 1970, some hops remaining inservice into the millennium, thus triggering the rapid development anddeployment of higher capacity (first 1152 VF ch/78 Mbit/s, then 1344 VFch/90 Mbit/s) digital radios for LOS (line-of-sight) radio-relay hops.

• This culminated in 1980 with the realization that the alarm/networkmanagement systems and adaptive equalization in these trailblazingdigital radios were often found totally inadequate to accommodate thefragile, bursty characteristics of many high capacity digital microwaveradios and spectral distortion caused by dispersive fading in hops notbefore seen in FM-FDM analog radio systems.


The Migration from Analog to Digital Microwave Links

It’s Been a Challenge!

• The 1980s thus brought about dramatic improvements in digitalmicrowave modulation efficiencies and, with new adaptive equalizationand powerful error correction, robustness to the dispersive (spectrum-distorting) fade activity that so degraded digital radio hop performance inthe 1970s.

• The mid-1990s heralded DSP equalizers that replaced discrete devicesin far more robust advanced asynchronous (PDH) and 2016/1890 chSONET/SDH point-to-point TDM digital radios. The FCC’s relocation ofanalog microwave hops from 2 GHz in the late 1990s to accommodatecellular deployment sped this digital migration.

• These new PDH and SDH digital technologies supported the explosivebirth of new high-performance terrestrial Fixed Wireless Systems andFixed Wireless Access networks in all of their forms, e.g. Point-to-Pointand Point-to-Multipoint, in synergism with fiber optics and FSO (free-space optical) networks.


Digital Microwave Attributes - a Media Comparison

• Superior availability (“uptime”) —route security (no fiber optics cable cuts)

• Rapidly expandable and upgradeable, in-service if protected

• High quality—no multihop “noise” addition as in analog microwave hops

• Rapid deployment over difficult terrain and into urban areas, unlike cable

• Economical and secure—no copper or fiber optic cable deployment withright-of-way and security issues, and very high costs

• Robust to fading and interference compared to analog microwave hops

• Much less sensitive to antenna feeder system and long-delayed ,on-pathechoes compared to analog microwave hops

• Highly efficient data and broadband transport

• Exacting in-service visibility of radio hop performance with NMS, PCR

• Seamless interconnectivity to an ever-expanding digital transport (fiberoptics and other), PABX/MSC switch, and LAN/IP world


FavorsMicrowave

Microwave or Fiber

FavorsFiber

Required Transport CapacityLow

Long

Transport ChoicesShort

Turn

-Up

Tim

e

High

Radio Fiber

Availability/security Payload (transport) Cost effectiveness Implementation time Terrain considerations

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