Shulou(Shulou.com)11/24 Report--

Mobile communication has experienced five generations of evolution from Marconi's wireless transoceanic telegram to the hot 5G era.

No.1 beacon smoke-the original state of binary communications, popular that is to exchange information with each other. Human beings invented language for the effective exchange of information. So short-range communication basically depends on roar, what about long-distance communication? Beacon smoke has become a tool to convey information, of course, only 0 and 1 signal that there is no enemy to invade, 1 indicates that there is a war on the border. With the sight distance of wolf smoke, the signal of war can be transmitted from the border to the capital.

However, the information transmitted by the beacon is greatly affected by the environment, and the bit error rate is also very high. The beacon drama princes at the time of the king of Zhou you sent the wrong signal, so that the country died.

So when Athens defeated Persia, in order to accurately and quickly convey the message of victory to the city of Athens, Feidipitz ran a marathon, only conveying the word "victory", and then exhausted. Sent a two-word message at the cost of one life.

In order to exchange information effectively, people have also used the way of flying pigeons to communicate over a long distance. due to the invention of words, the amount of information transmitted has been greatly improved. But the security and accuracy of information is still a challenge. Ma Wencai intercepted the pigeons of Liang Shanbo and Zhu Yingtai, which led to Zhu Yingtai's death.

No.2 Telegraph and telephone-the first time for human beings to use electricity to transmit signals, people's pursuit of communication has not changed. How to transmit information quickly and effectively has become the dream of countless scholars.

In 1832, the American painter Morse (1791-1872) returned to the United States by cruise, during which he met a doctor of electricity named Jackson. Jackson introduced him to electromagnetic knowledge, and Morse was completely fascinated by electricity. He thought: "electricity can be transmitted thousands of miles away in an instant, and electromagnets can react differently when there is electricity and when there is no electricity." So Morse decided to give up painting and invent a way to send messages by telegram. He designed representative symbols for each English letter and Arabic numeral, which are made up of different dots, lines and whitespace, which is the earliest code in the history of telecommunications, and later called it "Morse code". Sometimes interdisciplinary, cross-disciplinary development history is how important.

In 1837, Morse built a Telegraph machine, but its effective working distance was only 500 meters. Later, he improved the Telegraph machine. In order to test the performance of the Telegraph machine in practice, Morse asked the U.S. Congress to fund the erection of a 64-kilometer line between Washington and Baltimore. On May 24, 1844, Telegraph sending and receiving experiments began in the Chamber of the Supreme Court of the Capitol in Washington. Morse sent the first telegram in human history to Baltimore at the appointed time.

The invention of the Telegraph sent the message that people wanted to transmit to the distance at a speed of 300000 kilometers per second. This is an epoch-making initiative in the history of human information. But over time, people are a little dissatisfied. Because to send a telegram, you need to first draft the telegram, then translate it into a code, and then send it to the operator; after receiving the message, the operator of the other party must first translate the code into text, and then send it to the recipient. This is not only a variety of procedures, but also can not exchange two-way information in a timely manner, and it takes a long time to get a call back from the other party.

People's dissatisfaction with the telegram prompted scientists to start new explorations.

The suggestion of long-distance microphone relay transmission information was first put forward. Although this method is not very practical, the name Hughes chose for this way of talking, "phone", is still in use today.

After the 1830s, people began to explore ways to transmit music and voice through electromagnetic phenomena, of which Bell and Gray were the most successful.

Alexander Graham Bell was born in Scotland in 1847. His grandfather devoted his whole life to the education of the deaf-mute. Due to the influence of his family, he had a strong interest in acoustics and linguistics from an early age. At first, he was interested in studying telegrams. Once, when he was doing a telegram experiment, he stumbled upon the phenomenon that a piece of iron vibrating in front of a magnet would make a faint sound, and he also found that the sound could be transmitted to a distance through a wire. This gives Bell a great inspiration. He thought, if you talk to the iron sheet, can't it also cause the iron sheet to vibrate? This was Bell's original idea for the telephone.

Bell's efforts to invent the telephone were encouraged by Joseph Henry, a famous American physicist at that time. Henry said to him, "you have an idea for a great invention. Do it!" When Dambert talked about his lack of knowledge of electricity, Henry said, "learn."

Inspired by Henry, Bell began the experiment, accidentally splashing the sulfuric acid in the bottle on his leg, and he cried out in pain, "Mr. Watson, come and help me!"

Unexpectedly, this very common sentence became the first voice transmitted by human beings over the telephone. Mr. Bell's assistant, Watson, who was working in the other room, was the first person to hear the phone on the phone. Tears welled up in Bell's eyes when he learned that the phone he was experimenting with was able to transmit sound. In a letter to his mother that night, he predicted: "the day will come when friends can stay at home and talk to each other without going out."

Since then, mankind has entered the era of wired communication, and wired telephone has gradually entered thousands of households. Until now, wired telephone is still an inseparable way of communication for many people.

No.3 electromagnetic waves-- Power Communication Wireless Dream in "retaking the electromagnetic Road-- discovering electromagnetic waves", we relearned the course of electromagnetic wave discovery-- from Oster's coil experiment to Faraday's electromagnetic induction, from Maxwell's great prediction to Hertz's electric spark communication-electromagnetic waves, as the most effective carrier of information, are gradually discovered and used by people.

Marconi, who turned 20 in 1894, learned about experiments conducted by Heinrich Hertz a few years ago, which clearly showed the existence of invisible electromagnetic waves that travel through the air at the speed of light.

Marconi soon thought that this wave could be used to send signals over long distances without the need for a line, which made it possible for many communications that could not be completed by telegrams. For example, this means can be used to transmit information to ships sailing at sea.

After a year of hard work, Marconi successfully invented a working device in 1895. He did a demonstration test of the device in England in 1896 and obtained the patent right for the first time. Marconi immediately set up a company and launched the first radio in 1898. The radio signal he sent the following year crossed the English Channel. Although Marconi's most important patent was granted in 1900, he constantly improved his invention and obtained many patents from it. In 1901 he successfully transmitted radio messages across the Atlantic from England to Newfoundland, Canada.

The importance of the invention was dramatically demonstrated in an accident. It was 1909 when the steamer Republic was destroyed by collision and sank to the bottom of the sea, when the radio message played a role, and all but six people were saved. In the same year, Marconi won the Nobel Prize for his invention. The radio message he sent the following year successfully traveled 6,000 miles from Ireland to Argentina.

All this information is transmitted using the dotted line system of Morse code. It was known at that time that sound could also be transmitted by radio, but this was not realized until about 1915. Radio broadcasting for commercial use only began in the early 1930s, but its popularity and significance grew rapidly.

Radio technology is a way of communication that uses radio waves to transmit information. Can transmit sound, text, data and images, etc. Compared with wired communication, it does not need to set up transmission lines, is not limited by communication distance, has good mobility and rapid establishment, but the transmission quality is unstable, the signal is easy to be interfered or intercepted, and the confidentiality is poor.

After the invention of Telegraph and telephone, information spreads many times faster than before. The emergence of telegrams and telephones has shortened the sense of distance between the people of all continents and countries. However, the original Telegraph and telephone rely on electric current to transmit signals in the wire, which makes the communication very limited. For example, in order to communicate, there must be a line first, and the erection of the line is limited by objective conditions. Mountains, rivers and oceans all bring great difficulties to the construction and maintenance of lines. Moreover, the sea ships, which are in great need of communication, and the aircraft invented later, because they are mobile means of transport, they are unable to communicate with people on the ground by cable. The radio communication technology invented in the 19th century makes communication get rid of the way of relying on wires, which is not only a leap in communication technology, but also an important achievement in the history of human science and technology.

Then mobile communication slowly developed into a real wireless era!

No.4 from 1G to 6G1G: analog era 1G represents the first generation of mobile communication technology, cellular radiotelephone systems based on analog technology, such as the now obsolete analog mobile network. 1G wireless system is designed to transmit only voice traffic and is limited by network capacity. The streets of the 1G era are full of public telephone booths and people waiting to make calls, with BB machines attached to their belts. Of course, the standard match for the rich is the mobile phone in the waist.

2G: 2G in the digital age, which is the abbreviation of the technical specification of the second generation mobile phone communication, which is generally defined as unable to directly transmit information such as e-mail, software, etc.; it only has the technical specification of mobile communication such as call and some transmission such as time and date. However, SMS SMS (Short message service) can be implemented in some specifications of 2G.

2G is usually called PCS (Personal Communications Service) in the United States.

2G technology can be basically cut into two kinds, one is based on TDMA, represented by GSM, and the other is based on CDMA specification developed by CDMAOne, a form of Multiplexing.

The main technical specifications and standards for second-generation mobile communication are:

GSM: based on the development of TDMA, originated in Europe, and is now globalized.

IS-95 (also known as CDMA One): based on CDMA, it is the simplest in the United States.

CDMA system, used in some countries in America and Asia.

IS-136 (also known as D-AMPS): based on TDMA, it is the simplest in the United States.

TDMA system for use in America.

IDEN: based on the system developed by TDMA and unique to the United States. It is used by Nextell, an American telecom system provider.

PDC (Personal Digital Cellular): based on TDMA, it is only popular in Japan.

3G: the so-called third generation mobile communication technology in the broadband era, that is, 3G network technology, compared with the first generation mobile communication technology (that is, 1G) and the second generation digital mobile phone communication technology (that is, 2G), 3G mobile phone is mainly a comprehensive combination of wireless communication and Internet and other communication technologies to form a new mobile communication system. This mobile technology can deal with media forms such as images and music. in addition, it also includes some business functions such as teleconference. In order to support the above functions, the wireless network can fully support different data transmission speeds, that is, it can provide data transmission speeds of at least 2Mbps, 384kbps and 144kbps, whether indoors, outdoors, or in a driving environment.

The third generation mobile communication technology (3G), 3G network technology is the necessity of the development of this field. 3G defines the technical standard of mobile communication, uses higher frequency band and CDMA technology to transmit data for related technical support, and has high working frequency band, which is mainly characterized by high speed, high efficiency, signal stability, low cost and good security performance. Compared with the previous two generations of communication technology, the most obvious feature is that 3G network technology fully supports more diversified multimedia technologies.

4G: in the intelligent era, the maximum data transmission rate of 4G exceeds 100Mbit / s, which is 10,000 times higher than that of mobile phones and 50 times that of 3G mobile phones. 4G mobile phones can provide high-performance streaming media content and become personal identification devices through ID applications. It can also accept high-resolution films and television programmes, thus serving as a link in the new infrastructure for merging broadcasting and communications. In addition, some services such as 4G wireless instant connection will be cheaper than 3G. In addition, 4G is expected to integrate different modes of wireless communication-from indoor networks such as WLAN and Bluetooth, cellular signals, radio and television to satellite communications, where mobile users are free to roam from one standard to another.

4G communication technology is not separated from the previous communication technology, but based on the traditional communication technology, and uses some new communication technology to continuously improve the network efficiency and function of wireless communication. If 3G can provide people with a wireless communication environment with high-speed transmission, then 4G communication will be an ultra-high-speed wireless network and an information superhighway that does not need cables. this new network enables telephone users to connect wirelessly and in virtual reality in three-dimensional space.

5G: the era of the Internet of everything

The fifth generation mobile communication technology (English: 5th generation mobile networks or 5th generation wireless systems, 5th-Generation, referred to as 5G or 5G technology) is the latest generation of cellular mobile communication technology, and it is also an extension of 4G (LTE-A, WiMax), 3G (UMTS, LTE) and 2G (GSM) systems. The performance goals of 5G are high data rates, reduced latency, energy savings, reduced costs, increased system capacity and large-scale device connections. The first phase of the 5G specification in Release-15 is to accommodate early commercial deployments. The second phase of Release-16 will be completed in April 2020 and will be submitted to the International Telecommunication Union (ITU) as a candidate for IMT-2020 technology. ITU IMT-2020 specification requires a speed of up to 20 Gbit / s, which can achieve wide channel bandwidth and large capacity MIMO.

6G: interstellar Age

6G, that is, the sixth generation mobile communication standard, a conceptual wireless network mobile communication technology, also known as the sixth generation mobile communication technology. The main promotion is the development of the Internet.

6G network will be a fully connected world with the integration of terrestrial wireless and satellite communications. By integrating satellite communications into 6G mobile communications to achieve seamless global coverage, network signals can reach any remote village, allowing patients in deep mountain areas to receive telemedicine and children to receive distance education. In addition, with the joint support of Global Positioning system, Telecommunication Satellite system, Earth Image Satellite system and 6G ground network, ground-to-air full coverage network can also help human beings to predict the weather and respond to natural disasters quickly. This is the future of 6G. 6G communication technology is no longer a simple breakthrough in network capacity and transmission rate, but also to narrow the digital divide and achieve the "ultimate goal" of the Internet of everything, which is the meaning of 6G.

6G is not the end of mobile communications, the real era of the Internet of everything should come slowly. Let's wait and see.

This article is from the official account of Wechat: radio Frequency School (ID:RF_Center), author: RF Carpenter

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