From 0G to 5G, a century of mobile communications Time flies, and the years are wasted.

During World War II, Motorola's SCR series of walkie-talkies were successful on the battlefield, showing the world the magic of wireless communication and arousing people's desire to apply it to the civilian market. After the war, in 1946, AT&T officially launched MTS (Mobile Telephone Service) for civilian use by connecting wireless transceivers to the public switched telephone network (PSTN). In MTS, if a user wants to make a call, he or she must first manually search for an unused wireless channel, then talk to the operator's operator and request a secondary connection through the PSTN network. The entire call is half-duplex, which means that only one party can speak at the same time. When talking, the user must press the "push-to-talk" switch on the phone. The billing method of MTS is also very primitive. The operator would listen to the entire call between the two parties and manually calculate the charges and confirm the bill at the end of the call. Although MTS may seem very different now, it is indeed the first commercial cell phone system ever developed. Wait a minute! I thought cell phones were invented in the 70s? How could it have existed in the 1940s? Don't panic, MTS refers to Mobile Telephone (Mobile Telephone), not cell phones, but Mobile Vehicle Telephone (Mobile Vehicle Telephone). To be more precise, it is a vehicle mounted semi-duplex manual intercom. With the electronic technology and battery technology at that time, it was impossible to invent a cell phone. It was already very good to be able to create a car phone. At that time, the "base station" was also very large, somewhat like a radio and television tower, only one in a city, located in the center of the city, covering a radius of 40 kilometers, with very high power. In December 1947, Douglas H. Ring (Douglas H. Ring), a researcher at Bell Labs, pioneered the idea of the "cellular (honeycomb). He believes that instead of increasing the signal transmission power, it is better to restrict the signal transmission range to a limited area (cellular). In this way, different cells can use the same frequency without affecting each other, and enhance the system capacity. Douglas' paper, entitled "Mobile Phones - Wide Area Coverage Although the idea of cellular communication was good, it was also limited by the electronic technology at that time (especially the switching technology), and could not be realized. Bell Labs had to put it on the shelf. By the 1950s, more countries began to build car phone networks. For example, in 1952, West Germany (the Federal Republic of Germany) introduced the A-Netz. In 1961, the Soviet engineer Leonid Kupriyanovich invented the ЛК-1 cell phone, which was also installed in a car. Later, the Soviet Union introduced the Altai car phone system, which covered more than 30 cities in the country. In 1969, the United States introduced an improved MTS in-car telephone system called IMTS (improved MTS). IMTS supported full duplex, automatic dialing and automatic channel search, and could provide 11 channels (later 12), which was a quantum leap from MTS. In 1971, Finland launched the public cell phone network ARP (Auto Radio Puhelin, puhelin means Finnish phone), working in the 150MHz band, still manual switching, mainly for car phone service. Whether it is Altai, IMTS or ARP, it is later called "0G" or "Pre-1G" mobile communication technology. 1G After the 1970s, with the development of semiconductor technology, the conditions for the birth of cell phones were finally ripe. In 1973, Motorola engineers Martin Cooper and John F. Mitchell finally wrote history by inventing the world's first true cell phone (handheld personal cell phone). The phone was named DynaTAC (Dynamic Adaptive Total Area Coverage), was 22cm high, weighed 1.28kg, could talk for 20 minutes, and had an eye-catching antenna. In 1974, the Federal Communications Commission (FCC) approved a portion of the radio spectrum for cellular network trials. However, the trial did not officially begin until 1977. At that time, AT&T and Motorola were the two archrivals participating in the experiment. AT&T was "stripped" of the commercial use of satellite communications by the U.S. Congress in 1964. They had no choice but to set up a mobile communications division at Bell Labs to look for new opportunities. Between 1964 and 1974, Bell Labs developed an analog system called HCMTS (High Capacity Mobile Telephone System). The system's signaling and voice channels were modulated using FM with a 30 kHz bandwidth and a signaling rate of 10 kbps. Since there was no standardization organization for wireless mobile systems, AT&T created its own standard for HCMTS. Later, the Electronic Industries Association (EIA) named the system Interim Standard 3 (IS-3). In 1976, HCMTS was given a new name - AMPS (Advanced Mobile Phone Service). AT&T is the use of AMPS technology, in Chicago and Newark for the FCC trial. Let's look at Motorola. In the early days, Motorola engaged in a RCCs (Radio Common Carrier) technology, making a lot of money. Therefore, they have been strongly opposed to the FCC to cellular communications spectrum release, so as not to affect their RCCs market. But at the same time, they are also desperately researching and developing cellular communication technology to carry out technology reserve. This led to the birth of DynaTAC. After the FCC released the spectrum, Motorola based on DynaTAC, in Washington, D.C., to conduct trials. While they were still slowly experimenting, other countries were already ahead of them. In 1979, Nippon Telegraph and Telephone (NTT) launched the world's first commercial automated cellular communication system in the Tokyo metropolitan area. This system was later considered to be the world's first 1G commercial network. At that time, the system had 88 base stations and supported fully automatic call switching between sites in different areas without manual intervention. The system used FDMA technology with a channel bandwidth of 25KHz in the 800MHz band and a total of 600 duplex channels. Two years later, in 1981, the Nordic countries of Norway and Sweden established Europe's first 1G mobile network, NMT (Nordic Mobile Telephones). Soon after, Denmark and Finland joined them, and NMT became the world's first cell phone network with international roaming capabilities. Later, Saudi Arabia, Russia, and several other Baltic and Asian countries also introduced NMT. In 1983, the United States finally remembered to start its own 1G commercial network. In September 1983, Motorola released the world's first commercial cell phone, DynaTAC 8000X, which weighed 1kg, could talk for 30 minutes and took 10 hours to fully charge, but was priced at US$3,995. On October 13, 1983, Americitech Mobile Communications (from AT&T) launched the nation's first 1G network in Chicago, based on AMPS technology. This network could be used with both car phones and DynaTAC 8000X. The FCC allocated 40 MHz of bandwidth in the 800 MHz band for AMPS. With this bandwidth, AMPS carries 666 duplex channels with a single uplink or downlink channel bandwidth of 30 KHz, and later, the FCC allocated an additional 10 MHz of bandwidth. As a result, the total number of duplex channels in AMPS became 832. In the first year of commercial operation, Americitech sold about 1200 DynaTAC 8000X handsets and accumulated 200,000 subscribers. Five years later, the number of subscribers was 2 million. The number of subscribers was much larger than the AMPS network could handle. Later, to increase the capacity, Motorola introduced a narrowband version of AMPS technology, NAMPS, which divided the existing 30KHz voice channel into three 10KHz channels (the total number of channels became 2496), thus saving spectrum and expanding capacity. In addition to NMT and AMPS, another widely used 1G standard is TACS (Total Access Communication Systems), which was first introduced in the UK. In February 1983, the UK government announced that BT (British Telecom) and Racal Millicom (the predecessor of Vodafone) would build a TACS mobile network based on AMPS technology. On January 1, 1985, Vodafone officially launched the TACS service (equipment bought from Ericsson) with only 10 base stations covering the entire London area. TACS has a single channel bandwidth of 25KHz, using 890-905MHz for uplink and 935-950MHz for downlink, with a total of 600 channels for voice and control signals. The TACS system was mainly developed by Motorola and is actually a modified version of the AMPS system. The two systems are identical except for differences in frequency bands, channel spacing, frequency bias and signaling rates. Compared with the Scandinavian NMT, the performance characteristics of TACS are distinctly different; the NMT is suitable for the sparsely populated rural environment of the Scandinavian countries (Scandinavia) and uses a frequency of 450 MHz (later changed to 800 MHz) with a larger area. The advantage of TACS is capacity, not coverage distance, and the lower transmitter power of the TACS system is suitable for countries with high population density and large urban areas like the UK. As the number of users increased, TACS was later supplemented with some frequency bands (10 MHz) and became ETACS (Extended TACS). Japan NTT made JTACS on the basis of TACS. It is worth mentioning that the first mobile communication base station built in Guangzhou, China in 1987, used TACS technology, and the partner was Motorola. In addition to AMPS, TACS and NMT, 1G technologies also include C-Netz from Germany, Radiocom 2000 from France and RTMI from Italy. These blossoming technologies announced the arrival of the era of mobile communication. (In fact, there was no such name as 1G at that time, only after the emergence of 2G technology, they were called 1G for differentiation.) 2G In 1982, the European Postal Regulatory Commission established the "Mobile Expert Group", which is responsible for the study of communication standards. The French acronym for this group is GroupeSpécialMobile, which was later changed to Global System for Mobile communications (GSM), the most famous name for GSM. The purpose of GSM was to establish a new pan-European standard for the development of a pan-European public land mobile communications system. They set forth requirements for efficient use of spectrum, low-cost systems, handheld terminals, and global roaming. In the following years, the European Telecommunications Standards Organization (ETSI) completed the specification of GSM 900 MHz and 1800 MHz (DCS). In 1991, the Finnish company Radiolinja (now part of ELISA Oyj) launched the world's first 2G network based on the GSM standard. It is well known that 2G uses digital technology instead of analog technology of 1G, resulting in a significant improvement in call quality and system stability, more security and reliability, and a significant reduction in equipment energy consumption. In addition to GSM, another widely known 2G standard is CDMA, introduced by Qualcomm in the U.S. To be precise, it is IS-95 or cdmaOne. There are two versions of IS-95, IS-95A and IS-95B, with the former supporting peak data rates of up to 14.4kbps and the latter up to 115kbps. In addition to IS-95, the US also developed IS-54 (North America TDMA Digital Cellular) and IS-136 (1996). In fact, 2G is not only GSM and CDMA. The Cellular Telephone Industries Association of the United States developed a digital version of AMPS based on AMPS technology, called D-AMPS (Digit-AMPS), which is actually also considered a 2G standard. Digital Cellular), also belongs to the 2G standard. 2.5G At the end of the 20th century, with the explosion of the Internet, there was a strong demand for mobile Internet access. As a result, GPRS (General Packet Radio Service) began to emerge. We can think of GPRS as a "plug-in" to GSM. With the help of GPRS, the network can provide data service rates of up to 114Kbps. GPRS was first proposed in 1993 and the first phase of the protocol was released in 1997. Its emergence was a turning point in the history of cellular communications. It meant that data services started to emerge as the main development direction of mobile communications. 2.75G After the launch of GPRS technology, telecom operators also came up with a faster technology called Enhanced Data-rates for GSM Evolution (Enhanced Data-rates for GSM Evolution), which many people may be more familiar with as EDGE. The E often seen on the side of the cell phone signal, is EDGE The biggest feature of EDGE is that it can provide two times the data service rate of GPRS without replacing the equipment.