Semiconductor Laboratory Zhao Gong Semiconductor Engineer 2022-01-20 07:58
█ Embryonic period: the birth of modern communication
Around 600 B.C., the ancient Greek philosopher Thales was idle and rubbed a kitten with an amber stick from his home. Rubbing and rubbing, he found that the amber rod sucked up the kitten's hair.
Now we all know that this is because of static electricity. However, the people at the time (including Thales) did not know.
Thales believed that this and magnets were a principle, and he called this unknown mysterious force "electricity."
In fact, the record of "electricity" in human civilization can be traced back to earlier. In ancient Egyptian books written in 2750 BC, a creature called electric fish (actually electric rays) was recorded, and these fish were called "thunder messengers of the Nile".
Neither the ancient Egyptians nor the ancient Greeks would have thought that this "electricity", thousands of years later, would have completely changed the fate of mankind.
In 1600, William Gilbert, the Englishman, the Imperial Physician of Queen Elizabeth I of England, used the Latin word "electricity" to describe the force exerted when certain substances rubbed against each other. He also wrote a famous book, "On Magnetism". In the book, he argues that the generation of electricity requires friction, while magnets are not used, so electricity and magnetism are two different things.
This idea persisted for many years, and people have been studying electricity and magnetism separately as unrelated disciplines.
Later, more and more people began to study electricity, and made good progress. One of the greatest discoveries was Benjamin Franklin's "kite experiment."
Kite Experiment – Franklin places the kite with the key in a metal wire into the clouds, and lightning strikes the key, which is sensed by Franklin's hand along the metal wire.
By 1820, the Danish Hans Christian Oersted discovered the magnetic effects of electric currents and re-established the connection between electricity and magnetism.
In 1821, the Englishman Michael Faraday invented the electric motor. Ten years later, in 1831, he discovered the law of electromagnetic induction and built the world's first generator that could generate a continuous current.
faraday
Great times, constantly giving birth to great inventions.
In 1837, the American Morse invented Morse code and wired telegraph.
Morse and his telegraph machine
The emergence of the wired telegraph is of epoch-making significance - it has given mankind a new way of transmitting information, which is "invisible", "untouchable", "inaudible", completely different from the previous letters, slogans, trumpets, and beacons.
In 1865, the Englishman James Clerk Maxwell proposed Maxwell's system of equations, established classical electrodynamics, and predicted the existence of electromagnetic waves.
In 1876, the American Alexander Bell applied for a telephone patent and became the father of the telephone. Although the real father of the telephone should have been Antonio Meucci, he was picked up by Bell because he was too poor to have the money to apply for a patent.
In 1888, the German Heinrich Rudolf Hertz experimentally demonstrated the existence of electromagnetic waves. At this point, the classical electromagnetic theory building was officially completed.
In 1896, the Italian Guglielmo Marchese Marconi achieved the first radio communication in human history, with a communication distance of 30 meters (up to 2 miles the following year).
The father of radio, Galielmo Marconi
From this moment on, human beings have officially opened the door to the era of wireless communication.
█ Dormant period: wait, wait patiently
For a long time after that, wired communication and wireless communication developed on their own tracks and did not get very close to each other.
Let's start with wired communications.
After the invention of the telephone, people's voices could spread on wires. In fact, the acoustic signal is converted into an electrical signal, the electrical signal is transmitted through the wire, and finally the electrical signal is converted into an echo signal. For communication networks, the main problem to be solved is how to lay and connect these wires.
In the beginning, it was connected by means of a manual switch.
Operators and manual switches
As the number of users increases, the telephony network becomes more and more massive. Telephone lines went from a few hundred to thousands, tens of thousands.
Telephone poles at the end of the 19th century, with thousands of telephone lines on them
In this case, the manual switch is obviously no longer enough. In addition to the unbearable workload, the error rate is also high.
In 1891, a funeral home owner named Stefan Joe suffered a big loss from the artificial switch.
A.B. End Joe, Almon Brown Strowger
He found that business calls to his shop were always transferred to another funeral home by the operator. Later, I learned that the local operator was the cousin of the owner of the funeral home. So he got angry and vowed to invent a switch that didn't require human intervention.
As a result, he actually did.
In his garage, he made the world's first step telephone exchange.
In his honor, this switch is also known as the "End Joe Switch"
This is a mechanical switch with the imprint of the mechanical industry era. Although it has achieved the replacement of labor, there are still many disadvantages, such as the contact is sliding, poor reliability, easy to damage, slow action, complex structure, large volume, etc.
In 1919, the Swedish engineers Betaland and Palmgren jointly invented a new type of selector for a "longitudinal and horizontal connector" and applied for a patent for it.
Cross-sectional wiring
This connector changes the sliding type to the point-and-touch type in the past, thereby reducing wear and increasing service life.
On the basis of the "vertical and horizontal connector", in 1926, the world's first large-scale vertical and horizontal automatic telephone exchange was put into use in the Swedish city of Sundsvall. By 1938, the United States opened the No. 1 vertical and horizontal automatic telephone switching system. Subsequently, France, Japan and other countries have also produced and used such systems.
Since then, human beings have officially entered the era of vertical and horizontal switches. By the 1950s, the vertical and horizontal switching system was very mature and perfect.
Crossbar switch
"Vertical and horizontal system" and "step system" are wired by electromagnetic mechanical action, so they both belong to the "electromechanical automatic telephone exchange".
After all, machinery is mechanical, with low efficiency, small capacity, and high failure rate, which is difficult to meet the growing communication needs of human beings. As a result, people expect a new way of dealing with exchanges.
In December 1947, a research team of Schockair, Bardeen and Bratton from Bell Labs in the United States invented the transistor.
The world's first transistor
The birth of the transistor set off a wave of microelectronics revolution, and also sounded the clarion call for the birth of integrated circuits later.
With the rapid development of semiconductor technology and electronic technology, people began to consider the introduction of electronic technology in telephone exchanges.
Because the performance of electronic components at that time could not meet the requirements, there was a combination of electronic and traditional mechanical switching technology, known as "semi-electronic switch" and "quasi-electronic switch".
Later, microelectronics technology and digital circuit technology were further matured, and finally there was an "all-electronic switch".
In 1965, Bell of the United States successfully produced the world's first commercial storage program control switch (that is, a "program-controlled switch"), model No.1 ESS (Electronic Switching System).
No.1 ESS program-controlled switch
In 1970, France opened the world's first program-controlled digital exchange system E10 in Lannion, marking the beginning of a new era of digital exchange for mankind.
The essence of the program-controlled switch is the switch controlled by the electronic computer.
NEC program-controlled switch
It controls the switching action with a pre-programmed program, and the advantages are very obvious: fast connection speed, multi-function, high efficiency, clear sound, reliable quality, and large capacity.
Before we enter the '80s, let's stop. Let's go back and look at the pace of development of wireless communication.
For a long time after Marconi invented wireless telegraphy, wireless communication was in a state of one-way communication (simplex communication).
Simplex communication, only one-way communication
That is, the sender sends the message and the recipient receives the message in a one-to-many way. Anyone can receive the radio waves emitted by the sender, and only those who have the codebook can decrypt the contents of the radio waves.
If it is an unencrypted plaintext radio wave, then anyone can know the content of the message.
Broadcasting is such a "one-to-many" simplex way of working. After the advent of broadcasting, it replaced newspapers to a certain extent and became the quickest way for people (the rich) to get news.
The world's first radio station
War is a catalyst for high technology, and so is communication technology.
During World War II, Motorola (founded in 1928) developed a cross-era product, the SCR-300 military walkie-talkie, which enabled long-distance wireless communications over distances of up to 12.9 kilometers.
The SCR-300 uses FM FM technology, which has a certain degree of anti-interference ability and stable signal quality, but it is not light (16 kg), requiring a special signal soldier to carry, or installed on a car or aircraft.
In 1946, Bell Labs built the world's first so-called "mobile communication telephone" on the basis of a battlefield walkie-talkie. However, although called a mobile phone, it is so large that researchers can only put it on a shelf in the laboratory, and soon after, it is forgotten.
Since then, the communication technology, like the situation encountered in the previous wired communication, has been limited by the technical bottleneck of electronic components, and there has been no major breakthrough.
After the gradual maturity of semiconductor technology, wireless communication equipment began to have a basis for rapid development.
In 1958, the Soviet engineer Leonid V. Kuprijanovich invented the ЛК-1 mobile phone. The phone is still mounted on a car to use.
Leonid. Kupriyanovich is testing the portable mobile phone type ЛК-1 (Source: Soviet magazine За рулем, 1957)
In the 1960s, technology companies such as Motorola and AT&T began to regain interest in developing mobile phones.
In the 1970s, there was finally an explosion of wireless communication technology.
One day in April 1973, a man stood on the streets of New York, pulled out an equipment about the size of two bricks, and spoke to it, dancing with excitement that attracted the eyes of passers-by.
This person is the inventor of the mobile phone, Martin Kupa. He is an engineer at Motorola.
Martin Cooper and his mobile phone invention
The world's first mobile phone was made to a rival of Martin Kupa's at Bell Labs. The other party was also working on a mobile phone at the time, but it was not yet successful. Cooper later recalled: "I called him and said, 'Joe, I'm talking to you on a portable cellular phone right now.' I heard the 'gritted teeth' on the other end of the earpiece—though he had maintained considerable courtesy. ”
The mobile phone invented by Martin Kupa is the world's first mobile phone in the true sense, which can be carried by a single person and can talk on the move.
The invention of mobile phones marks that human beings have knocked on the door of the era of national communication, and also marked the beginning of wireless communication to surpass wired communication.
█ Outbreak period: From 1G to 4G, the rise of mobile communications
The beginning of mobile communications is rightly called the 1G era. The dominant 1G era is Motorola. The symbol of the 1G era is the big brother mobile phone like a brick.
After 1980, Big Brother gradually entered people's lives. People started using it, communicating over long distances.
1G uses analog communication technology, poor confidentiality, low capacity, poor call quality, and unstable signal.
In the late 1980s, with the maturity of large-scale integrated circuits, microprocessors and digital signal technologies, people began to study the transformation of analog communications to digital communications.
So, soon, we ushered in the 2G era.
2G is the shining debut of digital mobile communication technology.
At the beginning, in order to get rid of the monopoly of communication standards in the 1G era by the United States, Europe planned to develop a communication standard by itself. Therefore, in 1982, the European Post and Telecommunications Regulatory Commission established the "Mobile Expert Group" to be responsible for the study of communication standards.
This "mobile expert group", abbreviated groupe in French as Groupe SpécialMobile, was later changed to "Global System for Mobilecommunications", also known as GSM.
The core of 1G technology is FDMA (Frequency Division Multiple Access). As the name suggests, different users use channels of different frequencies to achieve communication.
At the heart of 2G GSM is TDMA (Time Division Multiple Access). It is characterized by an average distribution of one channel to eight callers, with only one person speaking at a time, and each person taking turns to use 1/8 of the channel time.
Unexpectedly, the American company Qualcomm has developed a third system, that is, CDMA.
At the heart of CDMA is code division multiple access. Compared with GSM, CDMA has a larger capacity, better immunity to interference, and higher safety.
However, CDMA started late, and GSM has already occupied most of the global market share, forming a de facto global mainstream standard. Coupled with the use of Qualcomm's CDMA, it is necessary to pay a huge patent licensing fee. Therefore, although it belongs to the same 2G standard, cdma's influence and market size cannot be compared with GSM.
"Patent Wall" at Qualcomm's headquarters
In the period before the rise of 2G, there was another important thing happening, that is, the explosion of the Internet .
In the 1980s, computer technology became more and more mature, computer network technology also flourished, and related basic theories were gradually improved, and eventually gave birth to a powerful Internet (Internet).
After the rise of the Internet, the demand for data communication between computers exploded.
Prior to this, the main transmission content of people's communication was voice . Now, people are starting to think about how to transmit computer data packets. These data messages, that is, the carriers of images, audio, video and other files.
Transmission of data packets, also known as "packet-switched services". In contrast, telephony belongs to the "circuit-switched service".
The direct consequence of the rapid growth of packet switching services is the huge impact on channel capacity.
As we mentioned earlier, in the 1970s, wired communications developed into program-controlled switching. Program-controlled switching, to put it bluntly, is still a circuit switch with voice service as the main purpose. The bearing mode is also based on TDM circuits (you can understand it as cables), which cannot well meet the needs of packet-switched services.
So Ethernet was introduced, network cables were introduced. Network cable is the most suitable transmission medium for transmitting IP packet messages.
On the left is the E1 cable (a type of copper core cable), and the right is the network cable (twisted pair)
The transmission medium has changed, of course, the transmission equipment and switching equipment must also change.
Thus, in the 80s and 90s, transmission equipment evolved from PDH/SDH to MSTP and PTN. Switching equipment evolved from program-controlled switching to NGN (Next Generation Network) and Softswitch.
It doesn't matter if you don't understand it, you just need to remember that in this period, the key development direction of communication technology is from analog to digital, from circuit to IP, from voice to multimedia.
The main pain point at this stage is that for operators, the lack of communication system capacity and the high price of communication equipment. Such high costs are also passed on to ordinary users, resulting in the consumption level of communication products is still high and cannot be completely popularized.
However, the price ice is constantly being broken, and more and more people are beginning to use landline telephones and dial-up Internet access.
Back to mobile communication.
After the mobile phone reaches 2G, more and more users are beginning to use mobile phones. The needs of users, from being able to make phone calls, extend further to being able to access the Internet.
In order to access the Internet and provide support for packet data services, 2.5G, also known as GPRS, General Packet Radio Service, and universal packet radio services, has evolved.
GPRS has a very low Internet speed of only 115Kbps, which obviously cannot meet the needs of users.
As a result, in order to speed up the network, communication manufacturers began to introduce 3G technology.
The three major standards of 3G are the European-led WCDMA, the Us-led CDMA2000, and the TD-SCDMA launched by China.
As can be seen from the name, the three major technologies are closely related to CDMA, which also makes Qualcomm earn a lot of money.
The speed of the 3G network has been greatly improved compared to 2.5G, reaching 14.4Mbps (WCDMA theoretical downstream rate). It can already meet the basic multimedia business needs.
At the same time, Apple's Jobs launched the iPhone just right. Smartphones, represented by the iPhone, have completely changed our lives.
Jobs and the iPhone
After that, it's 4G LTE. The story of this stage is believed to be very familiar to everyone.
From 1G to 4G, from the user's point of view, 1G has appeared mobile calls, 2G has popularized mobile calls, 2.5G has realized mobile Internet access, 3G has achieved faster rate Internet access, 4G has achieved faster rate Internet access, and basically meets all people's Internet needs.
From the perspective of operators and mobile communication networks themselves, from 1G to 4G, it is analog to digital, frequency division to time division to code division to synthesis, low frequency to high frequency, low speed to high speed. The capacity of the system continues to increase, so does the security and stability, and the cost is decreasing. Eventually, communication was transformed from the privilege of a few into the well-being of all.
The same is true of the development ideas of wired communications.
Almost forgot to say, there is another major invention, which greatly alleviates the capacity bottleneck of the communication system, that is, optical fiber.
In 1966, Chinese scientist Kao Kun pioneered the application of optical fibers in communication, which opened the door to the world of optical communication.
Kao Kun (1933.11.4-2018.09.23)
For decades, optical fiber has become an irreplaceable and important part of the communication system with ultra-high capacity and ultra-low cost, and has also made earth-shaking changes in our lives. If it were not for optical fiber, we would not have had such a fast network speed as we have now, and there would be no so-called mobile Internet life.
So far, with the efforts of countless communicators, we have made good achievements in the field of communications, with the current advanced communication technology, developed communication network, to provide support for the global social and economic development.
█ Looking to the future: where is the communication path?
The pace of human progress will not stop, and the development and evolution of communication technology will not stop.
Today, we are once again at a turning point in the times.
On the surface, this is a turning point between 4G and 5G, and we have ushered in an exciting 5G era.
But in the real sense, now is the turning point in the era of the Internet of People and the Internet of Things, and our goal is the sea of stars where everything is interconnected.
Will the future really be as exciting as imagined? Will IoT applications usher in a second golden age?
No one knows the answer. All we can do now is bury our heads in hard work and wait patiently.
However, for the communication technology and network in front of us, there are really not many directions that we can work towards.
The main direction of wireless communication is still the bandwidth of the wireless air interface. The potential of electromagnetic waves is further drained by 5G's Massive MIMO enhanced antenna arrays, beamforming, and enhanced coding.
On the wired communication side, optical fiber seems to have been able to meet the bandwidth requirements (at present, optical fiber has reached the Pb/s level, 1Pb = 1024Tb), and there is no technical bottleneck in the processing power of switching equipment. The main focus is on how to achieve lower costs, greater flexibility, scalability and security, and how to find the perfect balance between performance, demand and cost.
The introduction of AI artificial intelligence, as well as the maturity of cloud computing big data technology, is likely to help the next upgrade of communication systems and help achieve the above goals.
All in all, electromagnetics, as the theoretical foundation of modern communication technology, has a history of more than 130 years. Mr. Shannon, the grandfather of the ancestors, proposed the Shannon formula, which has also been more than 70 years. Under the relay of countless communicators, we are already approaching the limit. I believe that in the near future, there will be great scientists who will break through the dome and bring the dawn of a new world.
As a communicator, I look forward to the day coming soon.
Source: Old Zagu
Semiconductor engineer
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