An Illustrated Guide to Mobile Technology pdf pdf

AN ILLUSTRATED GUIDE TO MOBILE TECHNOLOGY

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BISAC Category: TEC061000 TECHNOLOGY & ENGINEERING / Mobile & Wireless Communications

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To my wife Aditi, and son Nikhil,

Without your help and support, this book would have remained just an idea in my mind.

CONTENTS

PART I: HISTORY OF THE MOBILE PHONE

On January 9 2007 the world witnessed the first Apple iPhone. This was the day Steve Jobs showcased the iPhone at the Macworld Conference in San Francisco, California in what is considered to be one of the most significant product launches of all times. Later that year – June 29 to be precise – people in the United States got their hands on their first ever iPhone. Within three months Apple had sold its one millionth iPhone in the US.

At one point during this sales blitzkrieg, 270,000 iPhones were sold in a 30 hour time span; an average of 150 iPhones getting sold every 60 seconds! Since its launch in June 2007 Apple has sold more than half a billion iPhones. Seldom has something so expensive that occupies such a small volume sold so many units.

The iPhone, followed by the Google Android Phone that was launched in 2008 have together changed the way we use our phones in such a fundamental manner that we would be excused in believing that these two devices have changed mobile phone history in ways that nothing else has.

However the roots of mobile technology penetrate much deeper into the annals of history.

Over the past six decades, government bodies, international standards bodies, giant corporations and individual innovators have each pushed the envelope on what is possible in mobile technology. Innovations have come out of university labs, corporate labs, government labs, workshops & conferences, and from people’s homes and garages. This evolution has been a tight interplay between the evolution of mobile networks and the mobile phones that use them. Our mobile phones have evolved to meet our ever growing expectations of them, and the networks have evolved to support what people want to be able to do with their phones.

While the evolution of mobile technology has been complex and multifarious, if you step back a bit from all the complexity, you can spot some pretty remarkable trends and milestones. These milestones have fundamentally shaped the evolutionary history of the mobile phone and the mobile network.

In the first part of this book, I shall take you through what I hope will be a fascinating tour of the history of mobile telephony. In doing so, we will uncover some astounding

"connect the dots" on the path that has led to the creation of the modern smart phone. So let’s roll the tape back – all the way to the 1800s!

The history of wireless communication goes as far back as we can look into modern human history. For thousands of years people have been inventing ways of communicating over long distances using all kinds of techniques ranging from fireworks to carrier pigeons! The early forms of wireless telegraphic systems actually did use things such as fireworks, and smoke or light signals to transmit information in the form of a string of encoded symbols. All of this off course looks hopelessly primitive compared to what the smart phone sitting in our pockets can do today. But as you will soon see, the DNA of that very phone were manufactured in this early era.

The Photophone

A fascinating invention in the early days of wireless telephony was the Photophone created by Alexander Graham Bell and his assistant Charles Sumner Tainter in February 1880.

Figure 1: Technical Drawing of the Photophone appearing in Alexander Graham Bell and Sumner

Tainter’s USA patent 235496 titled “Photo phone-transmitter” published on 14 December 1880.

The Photophone was remarkably elegant in its simplicity.

A beam of light was focused into a parabolic mirror which reflected the light right out. One spoke into the back side of such a mirror. The mirror flexed back and forth ever so slightly in response to the varying pressure of the sound waves hitting it on its back side. This flexing of the mirror’s surface caused the light that was being reflected by the mirror to be proportionately modulated, i.e. its frequency was altered in proportion to the amount and frequency of the flexing of its surface. Thus the light waves that were reflected out from the mirror effectively encoded the speech of the person who was speaking into the backside of the mirror! The receiver consisted of another parabolic mirror which focused the received light waves into a special material known as transducer which converted light back into sound.

Alexander Graham Bell used Lampblack as the trans-ducting material in his original design.

Figure 2: Left: Alexander Graham Bell (1847-1922). Right: Charles Sumner Tainter (1854-1940)

Bell was enormously proud of the Photophone, proclaiming it to be his greatest invention, and also wanting to name his second daughter “Photophone”! Mrs. Bell is said to have wisely discouraged her husband from taking this step. Bell’s Photophone was subsequently enhanced by himself as well as several other adopters of the device in many important ways. The direct sound-to-light coupling of the original device was changed into a sound-to-electrical-to-light coupling. The range of the Photophone was increased to several miles. The light source was changed from sunlight to a variety of artificial light sources including infrared light. The Photophone was also adopted in battlefields during the 1930s and 1940s for communicating between battlefield field units. A very useful advantage that the Photophone enjoyed in the battlefield was that its light based transmission mechanism could not be easily eavesdropped upon.

By the turn of the 19 century the advent of radio telegraphy and radio telephony, with their much longer range and the high degrees of reliability they offered under adverse weather conditions proved to be the beginning of the end for the Photophone as a practical wireless communication system.

The Photophone proved to be a lens into the future of communication in a number of ways. For example, the principles of sound-to-electricity-to-light and vice-versa conversion used by the Photophone were astoundingly similar to the fiber-optic based communication systems that came into use almost a century after the Photophone’s invention in 1880.

The advent of radio communication

While Alexander Bell’s Photophone in the 1880s provided a magnificent portal into the future of optical communication, a revolution of an entirely different kind was brewing in Europe and in the United States in the area of radio frequency communications. Radio waves are the portion of the electromagnetic spectrum between 3 Kilo Hertz and 300 Giga Hertz. The corresponding wavelengths range from 100 Kilometers down to 1 millimeter. Their use as the medium for sending telegraphic messages proved to be a significant up-shift in what was possible in the field of long distance wireless communication. In fact the genesis of radio as a method of communication goes all the way back to the early 1800s.

From the early 1800s through the 1860s several scientists in Europe, Russia and the USA devised experiments which demonstrated the various ways in which electricity and magnetism were connected to each other. Out of this experimentation was born much of the path breaking work on electromagnetic theory that would go on to form the basis for all forms of modern radio communications including the cell phones that we use today and the wireless networks that they operate over. Some of the early pioneers in the field of electromagnetic theory during the 1800s were Hans Christian Ørsted, André-Marie Ampère, Peter Barlow, Johann Salomo Christoph Schweigger, William Sturgeon, Francesco Zantedeschi, Michael Faraday, Heinrich Lenz and Joseph Henry.

Much of this work on electromagnetism culminated in the ground breaking publication in 1865 titled “A Dynamical Theory of the Electromagnetic Field” by a 34 year old Scottish physicist by the name James Clerk Maxwell. In his paper, Maxwell presented a grand unification of several properties of electricity, magnetism and light.

Figure 3: Left: Plaque showing Maxwell’s Equations affixed to the statue of Maxwell in Edinburgh,

Scotland. Right: James Clerk Maxwell (1831-1879)

Among other things, Maxwell’s theory predicted that electromagnetic waves can travel through space at the speed of light.

This crucial discovery has been the bed-rock of the field of mobile communications ever since.

Figure 4: The Electromagnetic Frequency Spectrum. The Y-axis shows frequency in Kilo Hertz on a

logarithmic scale (powers of 10). The colored vertical bars indicate the frequency range for various radio

frequency phenomena such as short wave radio, MW Radio, FM Radio, the frequency range that the zero-

G networks (MTS, and IMTS) of the 1940s and 50s used to operate in, the frequency spectrum that

modern day cellular phone networks occupy and so on.

In the years following Maxwell’s death in 1879, a brilliant German physicist by the name Heinrich Rudolf Hertz performed experiments that proved beyond any doubt Maxwell’s assertion that electromagnetic waves can actually travel through space. In doing so, the 28 year old physics professor at the University of Karlsruhe, Germany also created a method to intentionally transmit and receive radio waves in the Ultra High Frequency

(UHF) range. This would be the world’s first deliberately performed radio-frequency transmission and reception!

Figure 5: Left: Heinrich Rudolf Hertz (1857-1894), Right: Line drawing of the apparatus used by Hertz

for transmitting and receiving radio signals through air.

Unfortunately Professor Hertz, in whose honor the unit of frequency, Cycles Per Sec a.k.a. Hertz is named, utterly failed to realize the sheer importance of his achievement. When asked by one of his students what use could be made of his discovery he replied, “It's of no use whatsoever. This is just an experiment that proves Maestro Maxwell was right—we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But they are there." When the same student persisted by asking what else could be achieved from this discovery, Hertz replied, "Nothing, I guess." Nothing could have been further from the truth.

The birth of radio telephony

As other scientists around the world came to hear about Hertz’s experiments they sought to replicate them and to perform their own experiments in the deliberate transmission and reception of electromagnetic signals. From 1890-1895, scientists such as Édouard Branly, Nikola Tesla, Roberto Landell de Moura, Oliver Lodge, Thomas Edison and Jagdish Chandra Bose built upon the work of Hertz and furthered the field of wireless radio communication. In doing so several among them demonstrated some of the first experimental telegraphic systems operating in radio frequencies.

Figure 6: Graphic from Thomas Edison’s 1891 United States patent application # 465,971 illustrating a

means to do radio frequency communication between ships and between ship and shore.

However, in spite of the several patents that were granted in this field, nobody had yet managed to create a commercially viable radio frequency telegraph system.

That task was to lie with a dynamic Italian engineer and inventor named Guglielmo Marconi.

Figure 7: Guglielmo Marconi (1874-1937) Marconi was able to successfully build upon the work of others before him to create a practically workable and a commercially viable method of radio transmission and reception. Marconi obtained a British patent for his invention in 1897, his first of over 35 patents which he received in the field of radio transmission. The same year the Marconi Company was established. Marconi soon set up the first radio station at Niton, Isle of Wight, England and successfully transmitted a radio message to Bournemouth, England over a distance of 22 Kilometers. Later that year wireless radio telegraph signals were sent over a distance of 34 miles from Salisbury Plain to Bath, England using Marconi’s radio telegraph technology. In the following decade wireless telegraph stations popped up all across the landscapes of Britain and the United States. During the early 1900s the Marconi Company also succeeded in commercializing wireless transmissions across the Atlantic and from ship to shore.

Figure 8: Radio transmission (red arrow) by Marconi in 1898 from his first permanent station on the Isle

of Wight, England to Bournemouth, England over a distance of 22 Kilometers.

Newfoundland, Canada

Figure 10: A schematic of spark gap based radio frequency transmitter of the kind used by Marconi to

perform telegraphic transmissions.

Figure 11: Photograph of an actual spark gap based radio frequency transmitter used by Marconi to make

long distance telegraphic transmissions in the late 1890s and early 1900s .

By 1920s wireless telegraphy had become a global system of communication. In many places it replaced the physical cable based telegraph lines that were in widespread use at that time. Radio frequency wireless telegraphy became especially invaluable for ship – to

– ship and ship – to – shore communications; an area where cable based telegraphic systems could not be used.

While radio frequency telegraphy was gaining widespread acceptance by the early 1900s, the transmission of sound over a radio frequency channel wasn’t far behind.

The credit for the first sound transmission over a radio channel is said to lie with the Canadian inventor Reginald Aubrey Fessenden.

Figure 12: Reginald Aubrey Fessenden (1866-1932)

Fessenden believed that the future of radio lay not in the on-off nature of the spark transmitters that Marconi’s telegraphy systems used, but instead in a more continuous wave kind of transmission. To achieve that, Fessenden used a modified version of the spark transmitter known as the rotary transmitter which produced a more continuous radio signal that was necessary for the transmission of sound.

Figure 13: Top: Photo of the rotary gap transmitter used by Fessenden at the Brant Rock transmitting

station, Brant Rock, Massachusetts, USA (c1906). Bottom: Photograph of the Brant Rock station in 1912,

taken from Blue Fish Rock. The tall stacks exiting from the building's roof are for the steam engine's

boiler.

On December 23 1900 Fessenden successfully made the first long range audio transmission over radio frequencies over a distance of 1 mile from Cobb island in the Potomac River in Maryland, USA. Fessenden spoke the following words over the radio channel to his associate at the end other: "One - two - three - four, is it snowing where you are Mr. Thiessen? If it is, would you telegraph back to me?" His associate replied in the affirmative and the rest is history! The age of radio telephony was born.

During the early part of 1900s Fessenden’s system was extended, modified and augmented through his work and the work of several others in the field. The operating frequencies were increased. The methods of transmission and reception underwent significant changes from Fessenden’s original spark transmitter based design. The transmission range went up from dozens of miles to hundreds of miles and the reliability of the equipment improved significantly. Radio telephony began to be used not just for specialized uses such as by the US Weather Bureau to communicate weather data among their weather stations, but also for the public broadcast of signals.

Up through the 1940s radio telephony proliferated in Europe and North America. It was used for Ship – to – Ship and Ship – to – Shore communications, on the battlefields in the form of “portable” trans-receiver sets (or walkie-talkies as they came to be called) and on trains for placing ”pay phone calls” within a certain radial range. Some of the early experiments in train based telephones were carried out in 1918 by the German National Railway, the Deutsche Reichsbahn. By 1926 Deutsche Reichsbahn had installed “pay- phones” in the first class compartments of trains on the Berlin to Hamburg route.

In the early years of the 1900s the use of radio frequency based voice communication proliferated in many parts of Europe and North America. However it hardly resembled what might pass for a modern telephone system. For example, except in a very small highly specialized set of cases, you could not simply place a call by dialing somebody’s telephone number. Besides the radio sets were anything but portable. Each telephone set weighed several dozen Kilograms! It wasn’t until the 1940s that mobile telephony advanced from these early uses of radio frequency transmission to something resembling the modern mobile telephone system.

FROM TRAINS, SHIPS AND TANKS TO THE MOTOR CAR – THE

ERA OF ZERO-G

The first large scale rollout of a metropolitan mobile telephone network took place during the mid to late 1940s. Amazingly, the rollout completely skipped the hands and pockets of people and went straight on to get installed in people’s motor vehicles in the form of the Car Phone.

There are a couple of important reasons why the first mobile phone roll out in the United States during the 1940s was also the first car phone rollout of the world. For starters each “mobile” phone unit weighed around 80 pounds (36 Kilograms). It was hardly the kind of device that you could lug around on the street. The mobile phone of the 1940s needed the pulling power of your car’s internal combustion engine to move itself around! Secondly, the mobile phone system of the 1940s was targeted towards an American population that was becoming increasingly dependent on automobiles as their primary mode of transport rather than trains. What better place to put a phone in than in their car! This system in the United States was called by the rather uninspiring name “Mobile Telephone Service” or MTS for short.

MTS & IMTS

MTS was rolled out by AT & T Bell Laboratories. AT & T was already the principal operator of the Public Switched Telephone Network a.k.a. the land based telephone system in the USA at that time. The telephone equipment was designed by Bell Labs but initially supplied by Western Electric Corporation and later by General Electric and Motorola.

Figure 14: One of the earliest attempts of using a car mounted phone. Notice the transmitter-receiver unit

and the enormous antenna mounted on top of it. This picture was taken circa 1924, four decades before

the rollout of the first commercial car phone network in the United States.

In radio communications, the length of the antenna is inversely proportional to the transmission frequency. You need a long antenna for transmitting or receiving low frequency (long wavelength) signals. The MTS system operated in the Very High Frequency a.k.a. VHF range (30-300 Mega Hertz). In comparison modern cell phone networks operate in the 850 MHz to 2100 MHz Ultra High Frequency a.k.a. UHF range. UHF frequencies are anywhere from 3 to 70 times higher than VHF frequencies. This in turn leads to a short stubby antenna design like the one found on some of the modern cell phones. In fact these days, engineers have found a way to pretty much embed the entire antenna inside the cell phone unit thereby making it completely invisible to the user. On the other hand, since the MTS system of the 1940s used VHF, one needed to mount a ridiculously long antenna on top of your vehicle to get any kind of reception on your car phone in the MTS network. On the plus side the use of VHF meant that MTS required lower power to transmit and it operated over longer distances. Both characteristics were desirable at the time. The whole concept of radio telephony during the better part of the

20 century was based upon the notion of one base station serving a very large geographical area situated around it. The concept of cellular networks, in which mobile towers located inside small “cells”, would seamlessly hand off calls to towers in neighboring cells as you moved around, had yet to become a practical reality until much later in the century.

Figure 15: ‘Zero-G’ mobile phone systems such as AT&T’s Mobile Telephone Service were based on the

concept of one large tower serving a large geographical area around it.

Bell Labs designed MTS to operate in two modes – a highway mode and an urban mode. The urban mobile car phone network in America went live on June 17, 1946 when a truck driver in St. Louis, Missouri made the first telephone call from his truck. The highway mode went live shortly thereafter in August of the same year.

The MTS system required operator assistance to make any out-bound call from your vehicle. Moreover the system was strictly half-duplex i.e. basically similar to a walkie- talkie. This meant that you needed to push a button on the handset to talk and then let go to listen. The phone equipment mounted inside the vehicle consisted of a transmitter- receiver unit (also known as a transceiver), which took up most of the trunk space of your vehicle, a large antenna that would be mounted on the roof and a handset that was mounted just underneath the dashboard. The entire equipment drew power from the car’s battery. The MTS car phone also had a very curious feature called a call decoder. The call decoder sat inside the trunk of the vehicle as part of the rest of the trunk mounted unit. Each time someone called into the base station so as to try to reach a specific car phone user, a wheel fitted inside this call decoder would mechanically click in response to the electrical pulses sent out by the base station. Interestingly, this clicking happened inside the decoder of every single vehicle lying within the base station’s range! So when you heard the trunk of your vehicle start clicking, you knew that someone was trying to reach someone else around you on the MTS network. However, exactly one of these decoders – the one whose phone number matched the one that the base station operator was trying to reach – would click all the way through and that would trigger the call ringer inside

Figure 16: The illustration shows how the MTS and IMTS car phone equipment that AT&T supplied to its

customers during 1940s-70s, was laid out inside the customer’s vehicle.

The MTS equipment was heavy, power hungry and came with very few channels – which meant that only a few people could call at one time within a base station’s network. And it was also very expensive. Still, MTS proved to be dramatically popular within North America. The initial rollout itself covered 60 cities in the USA in its urban mode and 85 cities in its highway mode. The system handled more than 4000 mobile subscribers and 117,000 calls a month. The waiting lists grew longer by the day. During 1940s, 1950s and into the early 1960s MTS was improved upon iteratively. Miniaturization was implemented and the telephone equipment in the vehicle became less bulky. The system began to support full duplex operation, i.e. the person could talk and listen at the same time. In some cases the person could also directly dial the number from their car phone instead of going through operator assistance. The direct dial feature was seen to be a tremendous advancement at the time.

Figure 17: Motorola TLD 1100 MTS Car Phone (1964). Source: National Electronics Museum, Maryland,

USA

In 1964, this later feature of direct i.e. non-operator assisted dialing from your car phone was mainstreamed by the next generation of MTS. AT&T once again rather un- imaginatively named the improved version of the Mobile Telephone Service as...the Improved Mobile Telephone Service a.k.a. IMTS.

From 1964 through the early 1980s, IMTS flourished in North America. Full duplex direct dialing from the car phone became a reality for most North American car phone users. During this time, the invention of the electronic solid state transistor also enormously helped the cause of mobile telephony. As a result phone units were further miniaturized and by early 1970s, Motorola was already manufacturing completely solid state versions of phone units.

During the 1960s another car phone based mobile telephone service called the Radio Common Carrier (RCC) was introduced in the United States by companies that competed with AT & T’s MTS and IMTS based car phone systems. RCC continued to operate up until the 1980s.

All through the 1940s to 1980s, MTS, RCC and the IMTS compliant mobile phones were still too bulky to leave the vehicles that they were mounted in. A possible exception was the introduction of “attaché-phones” in the late 1960s. These units were IMTS compliant mobile phones which were small enough to fit inside a stylish brief case that you could carry around with you. It would make quite a picture to be seen carrying around such a briefcase sized mobile phone today. In the late 1960s it was the state of the art for mobile telephony, and a fashionable thing to be seen lugging around one of these ‘attaché phones’.

Figure 18: The Trigild Gemini 2 briefcase phone

The growth of zero-G systems outside North America

During the 1940s through the 1980s, while the USA and Canada were going all out in their roll outs of car phones, the rest of the world wasn’t far behind.

The A-Netz mobile telephone network that was launched in West Germany in 1958 quickly became one of the world’s largest mobile phone networks of that time. A-Netz was superseded by the B-Netz network in 1972 which among other things offered direct dialing in place of operator assisted dialing.

In 1950s, the USSR began the development of the Altai mobile car phone service. The service was first introduced in Moscow in 1963 and soon spread to major metropolitan areas of the USSR. Finland launched the ARP car radio phone service in 1971 and by 1978 it had covered 100% of that country. Norway launched its first public mobile telephone network called OLT in 1966.

One of the largest zero-generation analog mobile telephone network rollouts happened in Sweden during the 1950s through the 80s, when the country launched the MTA, MTB and MTD mobile telephone networks. At its peak, MTD had over 20000 mobile phone subscribers and over 700 phone operators switching calls between users.

The Nordic countries would continue to remain at the forefront of mobile telephony in the decades to come.

Drawbacks of the earlier mobile networks

All of the mobile telephony systems described in this chapter, irrespective of the country that they operated in, were hobbled by several common drawbacks. They operated mostly in the VHF range and rarely in the UHF range. This meant long antennae on mobile units. The long range of VHF signals as compared to UHF used by cellular networks, meant that

VHF frequencies could not be reused by base stations in adjacent areas, due to excessive signal interference. Therefore the available VHF spectrum could accommodate only a small number of phone subscribers. Network congestion happened quickly, and often. The mobile telephone equipment weighed several dozen kilograms and literally required a motor vehicle to be carried around. The transmission was done via analog signals and therefore was very easy to be eavesdropped upon. Furthermore, the whole system worked on the concept of central base stations serving geographical areas around them. Therefore coverage was basically on a line-of-sight basis. This meant that if you went behind a tall building, a hill or any other large object you immediately lost the signal. Furthermore, the long wavelength VHF signals don’t get reflected very well back to earth by the earth’s atmosphere. Due to the earth’s curvature, you could lose the signal even on absolutely obstruction-less ground when you travelled “over the horizon” with respect to your base station. These early mobile phone systems could not, and did not, scale well to large geographies. The concept of roaming, although existent at the time, rarely worked seamlessly for the user.

The advent of cellular telephony in the 1980s, along with further miniaturization of the mobile telephone equipment began to finally address many of these constraints. Mobile phones started freeing themselves of the motor vehicles that they used to be trapped in. The 1980s saw the concept of the mobile pocket-phone truly become a reality.

– THE ERA OF 1G

Cellular phone networks are based on the concept of adjacently located coverage areas known as cells. Each cell contains a transmitting tower. As the user moves from one cell to another cell the user’s cell phone collaborates with the transmitting towers of the source and destination cells to “handoff” the user from one cell to the next. The beauty of this handoff procedure lies in its working completely unbeknownst to the user even when a phone call is in progress.

Figure 19: The black hexagons in the graphic represent the geographical cells of a cellular network. Each

cell contains a mobile tower at the center of the cell (towers T1, T2, T3, T4 in the illustration). Each tower

transmits into its cell using three different frequencies in three different directions that are 120 degrees

apart (shown by the blue double headed arrows). The actual cell in the cellular network is therefore the

red colored hexagons in the graphic. Each of these red colored cells is divided into three regions (R1, R2,

R3). Each cell tower services one region within a red cell. When the mobile phone M1 shown in the

graphic is switched on, it will scan for signals from all neighboring towers. Since it lies in region R1 it will

in theory find the strongest signal coming from tower T1 and begin communicating with it.

A cellular phone network enjoys several important advantages over the “zero-G” hub-and- spoke networks described in the previous chapter. Since each cell covers a geographically small area, much less power is needed to transmit and receive signals. This makes the cell phone batteries smaller and less heavy. This in turn reduces the overall size and weight of the mobile phone. Cellular networks also operate in the Ultra High Frequency (UHF) band leading to short stubby antenna designs on the phones instead of the out-sized antennae that were needed by the Very High Frequency (VHF) based car phone systems of the 1940s, 50s and 60s. The cellular nature of the network also means that the “over- the-horizon” issue faced by the zero-G networks is very elegantly avoided. A cellular network can scale virtually infinitely over and across mountains, around tall buildings, and across rivers and lakes simply by adding more cells to the network. Finally, and very importantly, on a cellular network two subscribers can talk on the same frequency band as long as they are in different cells. This enormously increases the number of simultaneous conversations that the network can support, and thereby addresses the network congestion problem that plagued the hub-and-spoke based zero-G networks.

Birth of cellular telephony concepts

The genesis of cellular telephony began as early as 1940s in Bell Labs, USA. However, cellular networking concepts continued to be researched upon all the way through to late 1970s, i.e. in parallel with the large scale roll outs of zero-G networks that were happening world wide as described in the previous chapter.

On 11 December 1947, Bell Labs researcher Douglas H. Ring together with his colleague W. Rae Young dispatched an internal Bell Labs technical memo that introduced the concept of utilizing adjacently located cellular coverage areas so as to increase the coverage of the mobile telephone service across the nation. While the memo was detailed enough in the description of how the cellular network would function in theory, the technology to actually make it work did not exist at the time. Neither had the Federal Communications Commission (FCC) in the United States opened out the frequency channels that such a cellular system would need. Given this situation, the field of cellular telephony would languish for another 20 years. Meanwhile, AT & T continued to petition the FCC for additional frequency allocations. Researchers at Bell Labs and Motorola as well as ones outside the United States would also continue to make progress in cellular telephony research.

Figure 20: The concept of the cellular network described by Bell Labs researcher Douglas H. Ring in his

1947 memo to Bell Labs was remarkably similar to the structure of modern cellular phone systems. The

concept described in D. H. Ring’s memo involved an area that was to be served by a large number of radio

stations using ‘n’ different frequencies. The service radius of each station is fixed. The stations are

arranged in such a manner that each station is surrounded by 6 other equidistant stations.

In the 1960s another set of Bell Labs researchers, Richard H. Frenkiel, Joel S. Engel and Philip Thomas Porter built upon the work of Ring and Young and gave it the full technical rigor that would later form the basis for AT & T’s first commercially deployed cellular phone service in America called the Advanced Mobile Phone System (AMPS).

Field trials for AMPS began in 1978 in Chicago, Illinois and Newark, New Jersey. AMPS was launched as the United States’ first cellular mobile telephone service in Chicago, IL in 1983. AMPS was operated by the Ameritech Corporation.

World’s first hand held cell phone

Motorola was a major equipment supplier to AT & T for the MTS and IMTS car phone systems during the 1940s through the 1980s. During this time the company became deeply entrenched in the field of mobile telephony and particularly in the manufacturing of state-of-the-art telephone handsets.

Figure 21: Left: Motorola car phone dialer unit (c1960). Right: Car phone dialer unit mounted under the

dashboard of a 1968 Cadillac Fleetwood Brougham.

During the 1960s, while Frenkiel, Engel and others at Bell Labs continued their work on the development of cellular phone networks, Motorola invested in the development of cell phones that would be hand held and truly portable. This feat had started becoming a reality due to factors such as the advent of solid state electronics. The solid state device versions of the mobile phones were lighter and less power hungry than their vacuum tube and mechanical relay based cousins. They also required a smaller, lighter battery. Overall the phone could be made smaller and lighter than the briefcase sized and car trunk size units that were manufactured in the 1940s and 50s.

Martin Cooper who headed Motorola’s communication systems division created the Motorola DynaTAC portable cell phone.

Figure 22: The Motorola DynaTAC8000x cell phone

The original DynaTAC created by Cooper and his team was more than 10 inches long and weighed almost 2 pounds. Most of the weight of the phone came from its battery. It had a talk time of 20 minutes after which it needed to be charged for 10 hours. Cooper has since quipped that the talk time was never an issue since you couldn’t actually hold the phone to your ear for 20 minutes straight due to its sheer weight! On April 3 1973, Motorola gave a famous street demonstration of the DynaTAC phone when Cooper and his manager John F. Mitchell demonstrated the phone to the media in mid-town Manhattan. Cooper went on to dial Dr. Joel Engel at Bell Labs and spoke the first words on the world’s first truly portable cell phone: “Joel, this is Marty. I'm calling you from a cell phone, but a real cell phone, a handheld, personal, portable cell phone”.

Unfortunately the size and weight of the DynaTAC quickly earned it the nickname “the brick”.

Over the next 10 years Motorola invested heavily in the development of the “brick phone” and the first commercial version was launched in 1984. It was called as the DynaTAC 8000X and it cost USD 3,995. It was available for use on the AMPS cellular network which was launched in the US just a year earlier.

The 8000x was somewhat smaller and lighter than the “brick”.

The growth of cellular telephony outside the United States

The USA rolled out its 1G cellular network in the 1980s, but this time they were beaten to the line by Japan and the Nordic countries.

The world’s first fully automated cellular network was launched not in the USA, but in Japan in 1979 by Nippon Telephone and Telegraph (NTT). It operated over the 400 and 800 MHz ranges. The network was launched initially in metropolitan Tokyo. Within the next five years it spread all across Japan making it one of the first countries of the world with 100% 1G cellular coverage.

Two years later in 1981, the fully automated Nordic Mobile Telephony (NMT) cellular network was launched in Sweden and Norway, followed by a launch in Denmark and Finland in 1982 and Iceland in 1986. Interestingly the first commercial service of NMT was started in Saudi Arabia in 1981 even before the network began operation in Sweden. The initial “user equipment” a.k.a. the phone used on NMT continued to be the heavy car phone based system. However NMT’s specifications were open and therefore encouraged widespread competition among mobile phone manufacturers. This raised the fortunes of companies such as Nokia (called Mobira at that time) and Ericsson in Europe, and further enhanced the global reach of established players such as Motorola. A wonderful feature that NMT came with was the ability to roam freely on it across all the Nordic states that implemented it. During the 1980s, NMT spread into several Eastern European Countries and Russia. During the same period AMPS spread its wings across North America, and its variants – the TACS (Total Access Communication System), JTACS (Japanese Total Access Communication System) and ETACS (Extended Total Access Communication System) – spread into the United Kingdom, Ireland and Japan.

The 1G analog based cellular networks of the 1980s such as AMPS, NMT, TACS, JTACS and ETACS were a significant improvement over their non-cellular 0G cousins who had prevailed from 1940s to 1970s.

1G mobile phones

The 1G mobile phones of the 1980s started out as large, bulky and power hungry. As the

The 1980s had begun with the famous introduction in 1984 of the Motorola DynaTAC described earlier. However, there were a few other noteworthy examples of 1G cell phones during the 1980s that have shaped the field of cell phone design and cell phone capability through the 1980s and into early 1990s.

Consider just some of the following phones introduced by Nokia around this time and one gets a feel for how fast mobile phone technology was developing during the 80s.

In 1982 Nokia introduced its first 1G cellular car phone: the Nokia Mobira Senator 450. It operated over the 450 MHz NMT network and weighed a whopping 10 Kilograms.

Figure 23: Nokia Mobira portable cellular phones of the 1980s

1984 through 1989 saw the introduction of the Nokia Mobira Talkman series phones such as the Talkman 320F, 450, and 900. The Talkmans weighed in just under ½ a kg. The Talkman was considered to be quite portable by 1980s standards. The Nokia Cityman Series was manufactured from 1987 to 1990. This series saw the introduction of five Cityman Series phones from Nokia – the Cityman 1320, 900, 150, 190 and 100.

Figure 24: (Left) Nokia Cityman 100 ETACS version announced in January 1990, (Right) Cityman 150

announced in 1989. The Nokia 1100 launched in 2003 is also shown at extreme right for comparison.

The 1987 Cityman 1320 was a direct competitor to the Motorola DynaTAC introduced in 1984. The Cityman 1320 was also Nokia’s first truly hand held phone. Soon after its launch the Cityman 1320 received a huge publicity boost when it was used by Mikhail Gorbachev to make a public phone call from Helsinki, Finland to his communications minister in Moscow. That soon earned the phone the nickname “Gorba”.

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