From 0G to 5G, the ups and downs of mobile communications over the past century

During World War II, Motorola's SCR series walkie-talkies made great achievements on the battlefield, showing the world the magical charm of wireless calls and arousing people's desire to apply them to the civilian market.

After the war, in 1946, AT&T of the United States connected the wireless transceiver to the public switched telephone network (PSTN) and officially launched the MTS (Mobile Telephone Service) mobile phone service for civilian use.

In MTS, if a user wants to make a call, he must first manually search for an unused wireless channel, and then talk to the operator to request the other party to make a secondary connection through the PSTN network.

The entire call is half-duplex, that is, only one party can speak at a time. To speak, the user must press the "push-to-talk" switch on the phone.

MTS's billing method is also very primitive. The operator will listen to the entire conversation between the two parties and manually calculate the charges and confirm the bill after the call.

Although MTS seems very different now, it is indeed the first commercial mobile phone system in human history.

Wait! Aren’t mobile phones invented in the 1970s? How come they were invented in the 1940s?

Don't panic, the Mobile Telephone (MTS) refers to is not a mobile phone, but a Mobile Vehicle Telephone (mobile vehicle telephone). More precisely, it is a vehicle-mounted half-duplex manual walkie-talkie.

With the electronic and battery technology at the time, it was impossible to invent a mobile phone. Being able to make a car phone was already very good.

The "base stations" at that time were also very large, a bit like radio and television towers. There was only one in a city, located in the city center, covering an area of ​​40 kilometers and with extremely high power.

In December 1947, Douglas H. Ring, a researcher at Bell Labs, first proposed the concept of "cellular".

He believes that instead of blindly increasing the signal transmission power, it is better to limit the range of signal transmission and control the signal within a limited area (cell).

In this way, different cells can use the same frequency without affecting each other, thus improving system capacity.

Douglas's paper at the time was titled "Mobile Telephones - Wide Area Coverage"

Although the idea of ​​cellular communication was a good one, it was also limited by the electronic technology at the time (especially the switching technology) and could not be realized. Bell Labs had to put it aside.

In the 1950s, more and more countries began to build car phone networks. For example, in 1952, West Germany (Federal Republic of Germany) launched A-Netz.

In 1961, Soviet engineer Leonid Kupriyanovich invented the ЛК-1 mobile phone, which was also installed in cars. Later, the Soviet Union launched the Altai car phone system, covering more than 30 cities in the country.

In 1969, the United States launched an improved MTS car telephone system, called IMTS (improved MTS).

IMTS supports full-duplex, automatic dialing and automatic channel search, and provides 11 channels (later 12), which is a qualitative leap compared to MTS.

In 1971, Finland launched the public mobile phone network ARP (Auto Radio Puhelin, puhelin means telephone in Finnish), which operated in the 150MHz frequency band and was still manually switched, mainly serving car phones.

Whether it is Altai, IMTS or ARP, they were later called "0G" or "Pre-1G" mobile communication technology.

1G

After entering the 1970s, with the development of semiconductor technology, the conditions for the birth of mobile phones finally matured.

In 1973, Motorola engineers Martin Cooper and John F. Mitchell finally made history by inventing the world's first true mobile phone (a handheld personal mobile telephone).

This phone is named DynaTAC (Dynamic Adaptive Total Area Coverage). It is 22cm high, weighs 1.28kg, can hold calls for 20 minutes, and has a striking antenna.

In 1974, the Federal Communications Commission (FCC) approved a portion of the radio spectrum for cellular network trials. However, the trials did not officially begin until 1977.

Participating in the experiment at that time were two arch-rivals, AT&T and Motorola.

AT&T was "deprived" of its commercial use of satellite communications by the U.S. Congress in 1964. In desperation, they established a mobile communications department at Bell Labs to look for new opportunities.

During 1964–1974, Bell Labs developed an analog system called HCMTS (High Capacity Mobile Telephone System). Both the signaling and voice channels of this system used FM modulation with a bandwidth of 30kHz and a signaling rate of 10kbps.

Since there was no standardization organization for wireless mobile systems at the time, AT&T developed its own standard for HCMTS. Later, the Electronics Industries Association (EIA) named this system Interim Standard 3 (IS-3).

In 1976, HCMTS changed its name to AMPS (Advanced Mobile Phone Service).

AT&T is using AMPS technology to conduct FCC trials in Chicago and Newark.

Let’s look at Motorola.

In the early days, Motorola developed RCCs (Radio Common Carrier) technology and made a lot of money. Therefore, they have been strongly opposed to the FCC's allocation of spectrum for cellular communications to avoid affecting their own RCCs market. But at the same time, they are also working hard to develop cellular communication technology and make technical reserves. This is how DynaTAC was born.

After the FCC released the spectrum, Motorola conducted experiments in Washington based on DynaTAC.

While they were still slowly conducting experiments, other countries had already taken the lead.

In 1979, Nippon Telegraph and Telephone (NTT) launched the world's first commercial automated cellular communications system in the Tokyo metropolitan area. This system was later considered the world's first 1G commercial network.

At that time, the system had 88 base stations and supported fully automatic call switching between different cell sites without the need for human intervention.

The system uses FDMA technology, with a channel bandwidth of 25KHz, located in the 800MHz frequency 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. NMT became the world's first mobile phone network with international roaming capabilities.

Later, Saudi Arabia, Russia and some other Baltic and Asian countries also introduced NMT.

In 1983, the United States finally realized the need to build its own 1G commercial network.

In September 1983, Motorola released the world's first commercial mobile phone - DynaTAC 8000X, which weighed 1kg, could make calls continuously for 30 minutes, took 10 hours to fully charge, but was priced at US$3,995.

On October 13, 1983, Americach Mobile Communications (from AT&T) launched the first 1G network in the United States in Chicago based on AMPS technology.

This network can be used with both the car phone and the DynaTAC 8000X.

The FCC allocated 40MHz bandwidth in the 800MHz band to AMPS. With this bandwidth, AMPS carries 666 duplex channels, and the bandwidth of a single upstream or downstream channel is 30KHz. Later, the FCC allocated an additional 10MHz bandwidth. Therefore, the total number of duplex channels of AMPS became 832.

In the first year of commercial use, Americatech sold about 1,200 DynaTAC 8000X phones and accumulated 200,000 users. Five years later, the number of users reached 2 million.

The rapidly growing number of users far exceeded the capacity of the AMPS network. Later, in order to increase capacity, Motorola launched the narrowband version of AMPS technology, namely NAMPS. It divides the existing 30KHz voice channel into three 10KHz channels (the total number of channels becomes 2496), thereby 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 launched in the UK.

In February 1983, the British government announced that BT (British Telecom) and Racal Millicom (the predecessor of Vodafone) would build the TACS mobile communications network based on AMPS technology.

On January 1, 1985, Vodafone officially launched the TACS service (equipment purchased from Ericsson). At that time, there were only 10 base stations covering the entire London area.

The bandwidth of a single channel of TACS is 25KHz, with 890-905MHz used for uplink and 935-950MHz for downlink. A total of 600 channels are used to transmit 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 the frequency band, channel spacing, frequency deviation and signaling rate.

Compared with the Nordic NMT, the performance characteristics of TACS are significantly different. NMT is suitable for the sparsely populated rural environment of the Nordic countries (Scandinavia), using the 450MHz frequency (later changed to 800MHz), with a larger cell range.

The advantage of TACS is capacity, not coverage distance. The transmitter power of the TACS system is relatively small, which is suitable for countries like the UK with high population density and large urban areas.

As the number of users increased, TACS later added some frequency bands (10MHz) to become ETACS (Extended TACS). Japan's NTT developed JTACS based on TACS.

It is worth mentioning that the first mobile communication base station built by China in Guangzhou in 1987 adopted TACS technology, and the cooperative manufacturer was Motorola.

In addition to AMPS, TACS and NMT, 1G technologies also include Germany's C-Netz, France's Radiocom 2000 and Italy's RTMI. These flourishing technologies announced the arrival of the mobile communication era. (In fact, there was no such thing as 1G at the time. It was only after the emergence of 2G technology that they were called 1G to distinguish them.)

2G

In 1982, the European Postal and Telecommunications Administration established the "Mobile Expert Group" to specifically study communication standards.

This "Mobile Experts Group" has the French abbreviation Groupe Spécial Mobile. Later, the meaning of this abbreviation was changed to "Global System for Mobile communications", which is the famous GSM.

The purpose of GSM was to establish a new pan-European standard and develop a pan-European public land mobile communication system. They proposed requirements such as efficient use of spectrum, low-cost system, handheld terminals and global roaming.

In the following years, the European Telecommunications Standards Institute (ETSI) completed the specification of GSM 900MHz and 1800MHz (DCS).

In 1991, the Finnish company Radiolinja (now part of ELISA Oyj) launched the world's first 2G network based on the GSM standard.

As we all know, 2G uses digital technology to replace 1G analog technology, which greatly improves call quality and system stability, makes it safer and more reliable, and significantly reduces equipment energy consumption.

In addition to GSM, another well-known 2G standard is CDMA launched by Qualcomm in the United States. To be precise, it is IS-95 or cdmaOne.

There are two versions of IS-95, IS-95A and IS-95B. The former can support a peak data rate of up to 14.4kbps, while the latter reaches 115kbps.

In addition to IS-95, the United States also developed IS-54 (North America TDMA Digital Cellular) and IS-136 (1996).

In fact, 2G is not just 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 a 2G standard. In 1990, Japan launched PDC (Personal Digital Cellular), which is also a 2G standard.

2.5G

At the end of the 20th century, with the explosion of the Internet, people had a strong demand for mobile Internet access, so GPRS (General Packet Radio Service) began to appear.

We can regard GPRS as a "plug-in" of GSM. With the help of GPRS, the network can provide a data service rate 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, because it meant that data services began to rise and became the main development direction of mobile communications.

2.75G

After the launch of GPRS technology, telecom operators also developed a faster technology called Enhanced Data-rates for GSM Evolution, which is EDGE that many people may be familiar with.

The E you often see next to mobile phone signals is EDGE

The biggest feature of EDGE is that it can provide data service rates twice as fast as GPRS without replacing equipment. Because it has been favored by some operators, the world's first EDGE network was deployed by AT&T in the United States on its own GSM network in 2003.

3G

In 1996, Europe established the UMTS (Universal Mobile Telecommunications System) Forum, which focused on coordinating the research of European 3G standards. The European camp represented by Nokia, Ericsson, and Alcatel clearly recognized the advantages of CDMA, and thus developed the W-CDMA system with similar principles.

It is called W-CDMA (Wide-CDMA) because its channel bandwidth reaches 5MHz, which is wider than the 1.25MHz of CDMA2000.

Many people are confused about the relationship between UMTS and WCDMA. In fact, UMTS is the general term for 3G in Europe. WCDMA is an implementation of UMTS, generally referring to the wireless interface part. TD-SCDMA, which we will mention later, also belongs to UMTS.

In order to compete with the United States, European ETSI also jointly established the 3GPP organization (3rd Generation Partnership Project) with Japan, China and other countries to jointly develop global third-generation mobile communication standards.

On the other hand, there are differences of opinion within the North American camp.

Companies such as Lucent and Nortel support WCDMA and 3GPP. Another group of forces, represented by Qualcomm, joined South Korea to form the 3GPP2 organization to compete with 3GPP. The standard they launched is the CDMA2000 standard developed based on CDMA 1X (IS-95).

Although CDMA2000 is a 3G standard, its peak rate was not high at the beginning, only 153kbps. Later, through the evolution to EVDO (EVolution Data Optimized), the data rate has been significantly improved, providing a peak download speed of up to 14.7Mbps and a peak upload speed of 5.4Mbps.

During this period, China also launched its own 3G standard candidate (also known as TD-SCDMA) to participate in international competition.

After fierce competition and negotiation, the ITU International Telecommunication Union finally confirmed the three major global 3G standards, namely WCDMA dominated by Europe, CDMA2000 dominated by the United States, and China's TD-SCDMA.

In terms of 3G commercialization progress, Japan's NTT is again in the lead.

On October 1, 1998, NTT Docomo launched the world's first commercial 3G network (based on WCDMA) in Japan.

3.75G

Based on UMTS, ETSI and 3GPP developed HSPA (High Speed ​​Packet Access), HSPA+, dual-carrier HSPA+, and HSPA+ Evolution. The speed of these network technologies is significantly higher than that of traditional 3G, and people call them 3.75G.

Because HSPA+ has a very high speed, even exceeding the early LTE and WiMAX, some operators (such as T-Mobile in the United States) did not immediately start the construction of LTE, but upgraded the existing HSPA network to HSPA+. China Unicom in our country also had a similar idea at the time.

4G&5G

In 1999, the IEEE Standards Committee established a working group to develop wireless metropolitan area network standards. In 2001, the first version of IEEE 802.16 was officially released, which later developed into IEEE 802.16m.

IEEE 802.16, which later became widely known as WiMAX (Worldwide Interoperability for Microwave Access).

WiMAX has introduced advanced technologies such as MIMO (multiple antennas) and OFDM (orthogonal frequency division multiplexing), which has greatly improved the download rate and brought great pressure to 3GPP.

Therefore, 3GPP launched LTE (which also introduced MIMO and OFDM) based on UMTS to compete with WiMAX. Later, LTE-Advanced (2009) was further evolved, with a several-fold increase in speed.

In 2008, the ITU International Telecommunication Union released the requirements that the 4G standard should follow and named it IMT-Advanced. The only ones that really meet the requirements are 3GPP's LTE-Advanced, IEEE's 802.16m, and TD-LTE-Advanced submitted by China's Ministry of Industry and Information Technology. In other words, they are the real 4G standards.

On December 14, 2009, the world's first public LTE service network (under the name of 4G) was launched in Stockholm, the capital of Sweden, and Oslo, the capital of Norway. The network equipment came from Ericsson and Huawei, while the user terminals came from Samsung.

After a fierce industry battle, LTE finally defeated WiMAX and gained global support and recognition. WiMAX quickly lost its position and was relegated to the cold palace. (If you are interested, you can read this article: The history of WiMAX's pitfalls)

Later, 3GPP launched 5G (IMT-2020) and unified the world. I don’t need to say more about the story here, right? Each of us is a witness to the new history.

Time flies, and years pass by. After nearly a century of development, mobile communication networks have grown from nothing to something, from weak to strong. It has pushed the wheel of history and accelerated social changes.

Where will the future of mobile communications go? Let us wait and see!