What are the main standards in the world in the 2g era?

The first generation standard was commercialized worldwide in the 1980s, and 1987 entered China, mainly focusing on voice services. 1G is an independent system in the world, and major developed countries have introduced their own standards, such as AMPS, E-TACS, NMT, J-TACS, etc.

China's institutional choice has technical, economic and political considerations. TACS and AMPS are relatively mainstream systems of 1G, and the technical level and commercial scale of the two systems are not much different. The biggest difference between them is the different channel spacing. TACS is 25kHz, while amperes are 30kHz. It is said that TACS was chosen because its channel spacing better matched the channel spacing of various radio communication equipment used in China at that time.

However, even if the whole country is unified as TACS, there are AB networks which are not connected with each other. Motorola equipment is the main equipment in the north, a system is implemented in the south, and Ericsson is the main equipment. It was not until 1995 that the national analog mobile phone roamed automatically.

At that time, mobile communication was still a luxury for the public. Not only do you need to pay an initial installation fee of more than 10 thousand yuan, but there are also tens of thousands of mobile phones, and there are very few styles to choose from. The initial network capacity is small, even if you have money to buy it, you have to wait for several months.

Bosses in the south like to grab purses by hand, install mobile phones called mobile phones and expose long whip antennas, which is a common way to show off their wealth. Mobile communication has also brought revolutionary changes to social interaction. For example, once the director answered the mobile phone in front of us and said that he was on a business trip in Hainan and was not available. Wait a minute.

The main reason for the small network capacity is that the network equipment is monopolized by multinational companies, and China's domestic industry is seriously backward and lacks bargaining power, so the price is very expensive. For example, a four-unit directional base station antenna is tens of thousands, and the supporting materials of Ericsson equipment include garbage shovel, dust sweeper, cable ladder and other materials. Predictably, the price is more than ten times that of local materials. The labor cost of foreign companies is also many times higher than ours. In the early days, Ericsson's installation personnel were mainly Malaysians and Pakistanis, and some were from Sweden. In the early 1990s, when the annual income of most people was less than 6.5438+0 million, the annual salary of a base station installation engineer in Sweden was equivalent to 400,000 RMB, and he could stay in the best local hotel for business trip. This shows the high gross profit and the heavy burden on consumers in China.

We can refer to the case of Ericsson's winning the bid for 65,438+000 TACS base stations in Vodafone, UK. The total project price is 30 million pounds, that is, the average price of single-station equipment plus engineering is 300,000 pounds, which is at least ten times the current single-station cost of 4G or even 5G, not to mention the single-user cost. In contrast, in March 2020, China Mobile just announced the bidding results of the second phase of 5G base stations in its 28 provinces, and the average price of each 5G base station was1.8000 RMB.

Network construction cost restricts the scale and speed of network construction. After 14 expansion, Guangdong tacs * * completely stopped network expansion in about 1998, but the network capacity only reached10000000. To solve the problem of larger user capacity, the next generation standard is needed.

In the era of 1G, it was generally difficult to locate the base station. At that time, local governments were asking mobile companies to build base stations, and some towns would publicize them in local media after opening the base stations. At that time, most of the base stations were located in the office buildings of post offices, and even many of them were rented by public institutions.

02

Technical defects and network equipment of 1G

1G adopts analog modulation, and the signaling is both analog and digital, but the data rate is very low. For example, TACS is only 8kb/s, so it cannot be used as business data.

Technically 1G determines that it only supports voice service, and the service is single, and the anti-interference of analog modulation is poor. Crosstalk is a common problem, so the carrier-to-interference ratio is higher than that of digital system, which leads to low frequency reuse efficiency and low user capacity under the same frequency bandwidth.

Poor confidentiality, easy to be eavesdropped. At that time, Guangdong Province used Ericsson's RBS 883 base station, and the audio of the call could be output on each carrier. At that time, I heard that the duty officer took pleasure in eavesdropping on the phone at night.

However, 1G is more deadly. For example, at the electronic wholesale market of Guangzhou Cultural Park at that time, you could buy a modified mobile phone ROM for about 1000 yuan. As long as we know the IMEI number and telephone number of the legitimate mobile phone body, the tariff of this number can be stolen by the grid, and the legitimate mobile phone cannot be authenticated by the network management. Whoever has good signal and fast access speed is preferred;

Of course, a considerable number of mobile phone numbers are intentional. For example, a boss intends to change multiple mobile phones for employees through his mobile phone number. These phones are only used for dialing, but it is a low-cost mobile communication scheme with pagers. In view of the serious phenomenon of number theft, local public security organs have set up task forces to crack down on number theft, and even sent special police officers to post offices around the country.

TACS*** all over the country bought two equipment vendors to build two networks, namely Motorola's A network coverage 2 1 provinces and cities, and Ericsson's B network coverage 15 provinces and cities. This is because China has a vast territory and many provinces. If only one manufacturer's equipment was used at that time, the supply would definitely be delayed and the price would be high, but roaming between two networks requires a long time of manual operation.

TACS network is attached to PSTN network, and each mobile exchange is equivalent to an end office of PSTN. The indirect renewal of mobile exchange needs to be completed through PSTN, and the telephone number of mobile users is equivalent to a local telephone number, and the exchange number is 90.

At that time, Guangdong used Ericsson's equipment, and the analog equipment was bulky and consumed a lot of electricity. Therefore, each station is equipped with 1~2 bulky power cabinets and extremely heavy spare battery packs. At that time, the computer rooms were basically selected in local high-rise buildings, and some even in the mountains. It is conceivable that if there were no elevators, there would not even be roads to transport these nearly one ton of batteries.

The maintenance of the base station is also inconvenient, such as the battery is not maintenance-free; On the equipment side, because the voice from the transceiver board is still analog, its return adopts 2Mbps E 1 circuit, and it needs to jump frames to collect 30 voices into one E 1. This kind of earth-dense jumping frame does not match the tall image of mobile communication.

Unlike RRU, which is widely used now, the base stations at that time were all indoor equipment. For a large site with more than 32 carriers per sector, the indoor area of the base station needs almost 40 square meters, and the distance from the base station antenna sometimes reaches hundreds of meters. Radio frequency cable has high cost, great loss and great difficulty in lightning protection.

Due to the frequency division multiple access (FDMA) mechanism, when the earliest base station is turned on, it needs to tune the frequency of the combiner (also called combiner, which is composed of filters with different resonance frequencies) of the RF front end according to the assigned frequency points, in addition to the conventional definition of channel frequency points. If network optimization involves frequency point replacement, it needs to be replaced on site, which is not only cumbersome, but also requires expensive and bulky equipment.

Later, Ericsson base station introduced an automatic tuning combiner, which saved manual tuning. The combiner combines up to 32 channels into one antenna. When there are more than 32 channels, it is necessary to add transmitting antennas, and the transmitting and receiving antennas are still independent. Therefore, for base stations with large traffic, each sector needs at least two transmitting antennas and two receiving antennas for diversity reception. For a site with three sectors, a total of 65,438+02 antennas are needed. Moreover, due to the adoption of single-polarized antennas, there is a strict minimum distance requirement between antennas, so there is room in the sky.

Generally speaking, compared with the current base station, 1G base station equipment works indoors, with large floor space, high energy consumption, many interconnection lines, large space requirements and high opening and maintenance costs.

03

Industrial situation in 1G period

In terms of mobile communication main equipment, China's 1G era is a foreign investment era represented by Motorola and Ericsson. Different from Motorola, Ericsson saw the development prospect of the mobile communication market from the fixed-line switches at that time, and expanded to the mobile communication field in the early 1980s.

Ericsson has cultivated in China for many years, and has already started localization in the 1G era. By cooperating with Nanjing Panda and Guangzhou Wireless Power Plant to produce and maintain base station equipment, the cost is greatly reduced and the competitiveness is improved.

In terms of mobile phones, the domestic market is basically monopolized by Motorola, which entered the China market earlier. Motorola's 8800/8900 series is synonymous with mobile phones. After the 8000 series,

Motorola later introduced the first flip 9900, which can prevent the keys from being pressed by mistake. Compared with the 8800/8900 series, the size and weight of the mobile phone were greatly reduced, and it became a famous machine at that time and a special pet for women, but the price was as high as 20,000 RMB, almost catching up with the small houses in the third-tier cities at that time.

The machine flip is easy to be damaged, and the earliest maintenance cost is as high as several thousand, but after all, it is an injection-molded part, so there are many non-genuine parts, and the maintenance cost is obviously reduced. Compared with Motorola's size,

Ericsson also introduced mobile phones represented by EH237 and EH238, and Nokia's 12 1. Compared with Motorola, these mobile phones are more compact and exquisite, giving people a refreshing feeling, and can be put in your trouser pocket.

Because the user number of 1G is one-to-one corresponding to each mobile phone, the mobile phone sales are basically contracted by the post and telecommunications departments, and the available models are very limited. I lost my mobile phone, so I have to go to the post office to report the loss and re-do the user information.

Compared with now, at that time, mobile phone maintenance was a high-level occupation with high fees and high technical threshold. The maintenance points of the scale are basically contracted by the tertiary industry of the post and telecommunications department, and most of its maintenance personnel are undergraduates.

The integration of RF and IF parts of analog mobile phones is far less than now, and the failure rate is also very high. If you don't invest in expensive spectrometer or comprehensive tester, it is difficult to locate this fault. It is a high investment to equip ordinary individual shops with oscilloscopes with the highest frequency of several hundred KHz, so it is difficult to compete with the deep-pocketed post and telecommunications departments in maintenance business.

In the era of 1G, the participation of domestic industries is very low, and the main equipment and mobile phones are completely foreign. At present, Huawei's main force is still private branch exchange, but its switching equipment only appears in small-capacity office rooms in rural areas.

The huge mobile communication market in China is very asymmetrical with the complete lack of domestic brands, and this situation can only be changed after 2G.

Domestic brands can be seen sporadically on individual non-core supporting components, such as Guangdong Jingxin of low-power repeater, Guangdong Tongyu Communication of individual repeater antennas and individual omni-directional base station antennas, and spare batteries of individual stations like Guangyu in the later period. The domestic mobile phone industry is dominated by accessories and batteries, and some brands of mobile phone accessories similar to Scud have also been cultivated.

The present situation of domestic industry in the era of 1G is mainly related to the industrial base of China at that time, and the lack of global standards and the disunity of network element interfaces in1g.

The main equipment of mobile communication needs high-intensity continuous R&D investment and has the ability to integrate long-term industrial chain. At that time, mainstream equipment manufacturers all had their own chip departments, and the key processing chips needed self-research.

Visible, can undertake the main equipment R&D and manufacturing must be large companies, and China in the 1980s and 1990s, the scale of enterprise units is mainly state-owned enterprises and scientific research units under ministries and commissions, so it is difficult to break through among the multinational giants within the system, while China was seriously lacking in chip design and manufacturing capabilities (although there are chip processing enterprises similar to Wuxi Huajing, it is far from satisfactory).

Therefore, it is an inevitable choice for domestic enterprises to start with low-value non-core accessories. Even so, they can make a lot of profits and indeed cultivate a number of enterprises.

Wireless communication was a very popular university major in the late 1980s, but few people were able to engage in wireless communication research and development after graduation, and more people chose the post and telecommunications system at that time or non-core technical posts abroad. The major of radio frequency is even more embarrassing. At that time, except for a few radar and aerospace institutes, it was difficult to find corresponding R&D jobs outside the system, which reflected the serious lack of R&D industry and talent base for main equipment in China.

Finally, in terms of localization, it is worth mentioning that pager, a one-way mobile communication tool, appeared earlier than1g. At that time, the account was about1000 ~ 3,000 yuan, and the monthly rent was very low, which was within the range of ordinary people at that time. Combined with public telephones all over the streets, the mobility of communication can be solved at a low cost to a great extent. Early paging stations were mainly manual. For example, the most staff in the mobile sub-bureau are the so-called call girls. In the development of automatic paging, domestic equipment occupies the main force, which is a successful example of localization of communication equipment memory.

04

End of 1G

The first generation standard is backward in technology and only provides voice services, with single service type, insufficient technical capacity, inconsistent standards and poor confidentiality inherent in analog standards. However, as the first large-scale commercial network in China, cellular technology and the network operation and maintenance have been verified and exercised, and the huge mobile communication market potential has been tapped and ignited, which officially opened the prelude to the cellular mobile market. Therefore, the 2G network will be launched soon after the construction of 1G scale.

Developed countries and regions began to withdraw and transfer analog networks in the middle and late 1990s. For example, Hong Kong requires all analog networks to be converted into digital networks before 1 July, 9971day.

At the end of 1990s, there were basically no new users in China analog network, and the network expansion was stopped, and even the operating cost was reduced through network integration. Finally, it completely withdrew from the market at the end of 200 1, and some equipment was supported to Africa, and the corresponding spectrum was also allocated to the GSM network of China Mobile.

China analog network quit late, which is also determined by many factors, such as the great difference in China, the backwardness of economy and communication industry.

2G

0 1

System introduction

Although the mainstream standard of 1G technically supports roaming, it can't be realized due to the different standards of different countries. The next generation of standards urgently needs unified standards, so the formulation of standards also needs a cross-country organization to implement.

In the 2G era, there are still several standards in the world. The mainstream includes D-AMPS in the United States, narrow-band CDMA as a rising star, PDC in Japan and GSM in Europe. However, due to its early start and many supporting countries, GSM stood out in the 2G era and eventually occupied 80% of the world.

Except CDMA, the other three methods are based on TDMA, which is also the mainstream technology in the 2G era.

In order to achieve a unified European standard, Group Private Mobile (GSM) under the Technical Committee of the European Telecommunications Standards Institute (ETSI) was established in 1982, and began to formulate the GSM standard.

This is also the internal rhythm of technological evolution, that is, after the previous generation has completed the standard formulation and started commercial use, it will start the next generation's evolution technology research and standard project establishment.

When the standard organization of GSM was established, it was not decided whether to use digital or analog. But for 1G mobile communication, the standards are not uniform and the frequency spectrum is not uniform. As a standard to consider the global roaming demand, first unify the 900M spectrum; In the mid-1980s, TDMA was finally chosen for various multiple access technologies. Under the impetus of ETSI, the first version of GSM standard was frozen at 1992 and accepted by the industry.