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Second Generation Digital Mobile Phone (2G)

What is "GSM"

GSM (Global System for Mobile Communications) network is a global mobile communication system, also known as GSM. Many companies participated in the formulation of the standard, because it was first used in Europe, that is, the European standard, and then most Asian countries had networks (900MHz and 1800MHz), and America began to have PCs (1900 MHz) in the late 1990s. China Mobile adopts 900MHz standard. 9.6kbps data.

GSM adopts digital modulation technology, and one of its key technologies is time division multiple access (each user selects carrier frequency in a certain time slot and can only receive information at a specific time), so the voice is clear, the confidentiality is easy, and more data transmission services can be provided. GSM system has several important features: good anti-theft and copying ability, large network capacity, rich number resources, clear call, strong stability, sensitive information, few dead calls and low power consumption of mobile phones. Therefore, its voice is clear and easy to keep secret, and it can provide many data transmission services. The number of users supported by GSM network is 1.8-2 times that of analog network.

What is "CDMA"?

CDMA (Code Division Multiple Access) is a digital technology first developed by Qualcomm in this exciting new era of wireless communication products and services to provide very clear voice effects. By using digital coding "spread spectrum" radio frequency technology, CDMA can provide better voice effect, confidentiality, system capacity and flexibility, as well as better services, such as short messages, e-mail, Internet access and so on. Better than other wireless technologies.

CDMA network is a wireless cellular network developed by Qualcomm, USA, and its frequency is superior to GSM. American operators Verizon, Sprint and so on. It was adopted first, but it is faster to use the more advanced CDMA 1X system in Korea. Unicom began to operate the only CDMA network in China in 2002.

Compared with GSM mobile phone, CDMA mobile phone has the following advantages: CDMA mobile phone adopts advanced switching technology: soft switch technology (that is, switching is to connect first and then interrupt), which makes CDMA mobile phone call comparable to fixed phone; Using CDMA network, the investment of operators is relatively reduced, which reserves space for the downward adjustment of CDMA mobile phone charges; Because of the modulation multiple access communication mode based on spread spectrum communication, its capacity is 10 times higher than that of analog technology and about 4 times higher than that of GSM network. CDMA based on broadband technology makes the application of video in mobile communication possible, and makes mobile phones move from narrow services such as calling and texting to broadband multimedia applications.

Compared with analog mobile phone voice, GSM digital machine

The voice of GSM digital mobile phone can only be transmitted on the wireless channel after being digitized. It is not as easy to be disturbed as an analog mobile phone, so the voice is clear and the interference is small. However, due to the transmission of digital voice, there are also shortcomings of voice distortion. The speech distortion of analog mobile phone is better than that of GSM digital mobile phone. Now, the relevant departments are studying and developing more advanced speech digital coding technology to reduce the speech distortion of GSM mobile phones.

CDMA digital network: CDMA is the abbreviation of code division multiple access, which is a brand-new and mature wireless communication technology developed on the spread spectrum communication technology, a branch of digital technology. It can meet the market's high demand for mobile communication capacity and quality, and has the characteristics of high spectrum utilization, good voice quality, strong confidentiality, low dropped call rate, small electromagnetic radiation, large capacity, wide coverage and so on, which can greatly reduce investment and operating costs.

Operators in this industry are trying to increase the number of users in their systems, reduce the cost of each user, create greater profits and actively strengthen market penetration. Code division multiple access technology is one of the digital communication technologies to solve this problem.

Its advantages are:

Effective band utilization and greater network capacity.

Simplify network planning

Improve the call quality

Enhance confidentiality

Improve coverage characteristics

Extend the user's talk time

Soft volume and "soft" switching

It's faster to surf the internet.

What is a "GSM/CDMA dual-mode machine"?

The so-called "GSM/CDMA dual-mode mobile phone" means that the mobile phone can support both GSM and CDMA network communication technologies. It can be selected according to the needs of the environment or actual operation. Which network technology can play a more effective role, let the phone switch to which mode to work. If the communication quality of the mobile phone in one mode is not high or there are other bad communication phenomena, you can freely switch to another network mode to work. It actually expands the calling frequency of mobile phones.

What is "TDMA"?

Tdma (time division multiple access) is the abbreviation of time division multiple access, which is a technology to provide wireless digital services through time division multiple access, and it represents a digital signal transmission technology of mobile phone system. TDMA divides a radio frequency into multiple time slots, and then assigns these time slots to multiple groups of calls. In this way, a radio frequency can support multiple data channels at the same time. At present, this technology has become the basis of today's D-AMPS and GSM systems. A digital transmission technology that divides radio frequencies into different time slots and assigns them to multiple calls. )

What is "FDMA"?

FDMA (Frequency Division Multiple Access): FDMA (Frequency Division Multiple Access) is a technology in data communication, that is, different users are assigned to channels with the same time slot but different frequencies. According to this technology, the frequency band controlled centrally in the frequency division multiplexing system is allocated to users as needed. Compared with the fixed allocation system, frequency division multiple access (FDMA) enables the channel capacity to be dynamically exchanged as needed.

In FDMA system, users are assigned a channel, that is, a pair of frequency spectrums, one spectrum is used as a forward channel, that is, a channel from a base station to a mobile station, and the other spectrum is used as a reverse channel, that is, a channel from a mobile station to a base station. The base station of this communication system must transmit and receive multiple signals with different frequencies at the same time, and the communication between any two mobile users must be relayed by the base station, so it is necessary to occupy two channels (two pairs of spectrum) at the same time to realize duplex communication.

In the past, all analog communication systems used FDMA. Frequency division multiple access (FDMA) is a multiple access technology using frequency modulation. Traffic channels are allocated to different users in different frequency bands. Such as TACS system, AMPS system, etc. FDMA (Frequency Division Multiple Access) divides the total frequency band of a communication system into several equidistant channels (also called channels) and distributes them to different users. These channels do not overlap each other, and their width should be able to transmit one digital voice message, and there is no obvious crosstalk between adjacent channels.

Differences among FDMA, TDMA and CDMA

Frequency division multiple access (FDMA) is a multiple access technology using frequency modulation. Traffic channels are allocated to different users in different frequency bands. Such as TACS system, AMPS system, etc.

Time Division Multiple Access (TDMA) is a time division multiple access technology. Traffic channels are assigned to different users at different times. Such as GSM, DAMPS, etc.

CDMA (Code Division Multiple Access) is a code division multiple access technology using spread spectrum. All users obtain service channels at the same time and in the same frequency band according to different codes.

At present, the main multiple access methods of digital mobile communication network are FDMA and TDMA (GSM, DAMPS). The spectrum efficiency is about three times that of the analog system, and the capacity is limited; In terms of voice quality, 13kbit/s coding is also difficult to reach the level of wired telephone. FTDMA system has high service comprehensive ability and can synthesize data and voice, but the terminal access rate is limited (the maximum 9.6kbit/s TDMA system has no soft handover function, and it is easy to drop calls, which affects the service quality Z; The international roaming protocol of TDMA system needs to be further improved and developed. Therefore, TDMA is not the best wireless access for modern cellular mobile communication, while CDMA code division multiple access technology is completely suitable for large capacity, high quality, integrated services, soft handover, international roaming and so on required by modern mobile communication networks.

Transition technology between 2G and 3G-2.5G

At present, the 2.5G mobile communication technology that has been put into commercial use is a connection technology from 2G to 3G, which breaks through the limitation of 2G circuit switching technology on data transmission rate and introduces packet switching technology, thus making a qualitative breakthrough in data transmission rate, which is a super technology between 2G and 3G. GPRS, HSCSD, WAP, EDGE, Bluetooth and EPOC are all 2.5G technologies.

What is GPRS?

GPRS (General Packet Radio Service) is a general wireless packet service in Chinese, which is called 2.5G of GSM. It is a wireless packet switching technology based on GSM system, which provides end-to-end and wide-area wireless IP connection with a speed of 53.6kbps, and has the advantages of "real-time online", "quantity charging", "fast login", "high-speed transmission" and "free switching". Generally speaking, GPRS is a high-speed data processing technology, and the method is to transmit data to users in the form of "packets". Although GPRS is a transitional technology from the existing GSM network to the third generation mobile communication, it has obvious advantages in many aspects.

Because of the use of "grouping" technology, users surf the Internet relatively stably, avoiding unnecessary short-term troubles. In addition, the method of accessing the Internet using GPRS is different from WAP. Using WAP to surf the Internet is like surfing the Internet at home. After surfing the Internet, you can't use the telephone line at the same time, but GPRS is superior. You can download data and talk at the same time. Technically speaking, voice transmission (that is, call) continues to use GSM, while data transmission can use GPRS. In this way, the application of mobile phones will be promoted to a higher level.

Because GPRS has the characteristics of instant online, it is always online for users. GPRS technology also allows service providers to charge according to data transmission volume, rather than simply charging according to online time. This technology cooperates with GSM network, and the transmission speed can reach 1 15kbps.

What is HSCSD?

HSCSD (High Speed Circuit Switched Data Service) This is an upgraded version of GSM network. HSCSD (high-speed circuit-switched data) can be transmitted at the same time through multiple time divisions, not just a single time division, so the transmission speed can be greatly increased to two or three times as usual. At present, both M 1 in Singapore and Singapore Telecom use HSCSD system, and the transmission speed can reach 57.6kbps. HSCSD is an upgraded version of GSM network, which can greatly increase the transmission speed to two or three times of usual.

What is WAP?

WAP (Wireless Application Protocol) Wireless application protocol is a global unified open protocol standard for providing Internet content and advanced value-added services for mobile terminals, and it is a simplified wireless Internet protocol. WAP combines Internet and mobile phone technology, which makes it possible to access rich Internet resources anytime and anywhere. Wap service is a service that mobile phones can directly access the Internet and browse WAP websites through their WAP "browser". You can enjoy news browsing, stock inquiry, e-mail, online games, chat and other application services. Accessing WAP through GPRS network can give full play to the advantages of short access delay (2-second access), high speed, always on-line and convenient switching.

WAP 1.2 is based on WML.

WAP 2.0 is based on WAP-oriented XHTML as programming, which is closer to the WEB.

WAP (Wireless Application Protocol) is a global open standard, which describes in detail how to transmit communication, encode information and apply it to wireless devices. This standard has been supported by more than 200 companies, among which Ericsson, Nokia and Motorola are the initiators of WAP. Relatively speaking, from the understanding, WAP may be called wireless access protocol, or directly called wireless Internet protocol, which regulates the browsing format and communication protocol of web pages, such as TCP/IP. Bluetooth is also a wireless communication protocol, but it standardizes more specific hardware and frequency applications.

WAP (Wireless Communication Protocol) is an open global standard for communication between digital mobile phones, the Internet or other personal digital assistants (PDA) and computer applications. The birth of this standard is the result of the efforts of WAP forum members, which was established by Nokia, Ericsson, Motorola and Wireless Planet in June 1997.

The goal of WAP is to introduce a large amount of information and various services of the Internet into wireless terminals such as mobile phones and handheld computers through WAP technology. Whenever and wherever you need information, you can turn on your WAP phone and enjoy endless online information or online resources.

The WAP protocol includes the following layers:

1, wireless application environment

2. Wireless session layer

3. Wireless Transport Layer Security (WTLS)

4. Wireless Transport Layer (WTP)

The WAE layer includes micro-browser, WML, WMLSCRIPT interpreter, etc. WTLS layer provides basic security functions for wireless e-commerce and wireless encrypted data transmission.

The basic principle of WAP

The AP standard is a set of protocols.

WDP:WAP datagram protocol layer, which is the transport layer for sending and receiving messages.

WTLS: Wireless transmission security layer, which provides security services for e-commerce and other applications.

WTP:WAP transport protocol layer, which provides transport support and increases the availability of datagram services provided by WDP.

WSP:WAP session protocol layer, which provides effective data exchange between different applications.

HTTP interface: supports information retrieval requests of mobile terminals.

What is the edge?

EDGE is called enhanced data rate GSM evolution in English, and Chinese means improving data rate GSM service. It is a bright spot in the data-enhanced mobile communication market based on GSM/GPRS network, including CingularWireless and AT & amp； TelefonicaMoviles in Chile, CSL in China Hong Kong Special Administrative Region and AIS EDGE in Thailand have opened edge-based services. At the same time, some European mobile operators have begun to show interest in EDGE, among which both TIM and TeliaSonera have made it clear that they will adopt EDGE technology. This technology mainly lies in the ability to use broadband services, so that networks using 800, 900, 1800 and 1900MHz bands can provide some functions of the third generation mobile communication network, and can greatly improve the standardized services currently provided on GSM and TDMA/ 136. This technology can provide 384kbps wide-area data communication service and 2Mbps local data communication service, which can fully meet the bandwidth requirements of future wireless multimedia applications.

The concept of edge was first proposed to ETSI by Ericsson in 1997. In the same year, ETSI approved the feasibility study of EDGE, paving the way for the future development of EDGE. Although EDGE still uses GSM carrier bandwidth and time slot structure, it can also be used in other cellular communication systems. EDGE can be regarded as an effective universal wireless interface technology, which provides high bit rate, thus promoting the evolution of cellular mobile system to the third generation function. On this basis, the Unified Wireless Communication Forum (UWCC) evaluated the EDGE technology used in TDMA/ 136 and approved it in 1998+0.

EDGE provides a transition scheme from GPRS to 3G mobile communication, which enables existing network operators to make maximum use of existing wireless network equipment and provide users with personal multimedia communication services in advance before 3G mobile networks are commercialized. Because GDGE is a transitional technology between the existing second and third generation mobile networks, some people call it "second and a half generation" technology. EDGE also makes full use of existing GSM resources and protects the investment in GSM. Most existing devices can continue to be used in EDGE. EDGE can provide three groups of services: EGPRS service: the maximum rate is ≥ 384 kbps/BP; T-ECSD service: transparent enhanced circuit-switched service with the highest rate ≥ 32kbps/BP; NT-ECSD: Non-transparent enhanced circuit-switched service with the highest rate ≥ 28.8kbps.

Specifically, from a technical point of view, EDGE technology is different from GSM in that:

8 PSK air interface mode

Enhanced AMR coding mode

MCS 1~9 nine-channel coding method

Link adaptation

Incremental redundant transmission

RLC window size automatic adjustment

edge

EDGE is the abbreviation of enhanced data rates for global evolution, that is, the global evolution technology of enhanced data transmission, and it is data-enhanced mobile based on GSM/GPRS network.

Communication technology, also known as 2.75 generation technology, is mainly aimed at how the existing GSM operators in the world can benefit from the existing 800/900/1800/1900 MHz GSM network.

Using the existing frequency resources (new frequency resources must be approved by the relevant state departments and pay a certain fee), high-speed data services can be provided (the highest transmission speed can be reached)

474kbps), while improving network capacity and network quality.

From a technical point of view, EDGE provides a new wireless modulation method, which provides three times the air transmission rate of ordinary GSM. On the other hand, EDGE inherits the GSM standard, and the carrier frequency can be based on

The time slot is dynamically switched between GSM and EDGE (based on the type of mobile phone), which supports the traditional GSM mobile phone, thus protecting the investment of the existing network. The edge network can be flexibly expanded step by step,

It provides favorable support for operators to maximize value.

EDGE (Enhanced Data GSM Environment) is a faster version of the Global System for Mobile Communications (GSM) wireless service, which is designed to transmit data at a speed of 384 bits per second and can

Transmit multimedia and other broadband applications to mobile phones and personal computers. EDGE standard is based on existing GSM and cell arrangement standards, which use the same time division method.

Multiple access (TDMA) frame structure.

.

What is EPOC?

EPOC is an operating system, which can transform mobile phones into wireless information devices (such as smart phones) to meet users' demand for data. It supports information transmission, web browsing, office, public utilities and personal information management (PIM) applications, as well as software that can communicate synchronously with personal computers and servers.

Third Generation Mobile Phone (3G)

The so-called 3G, in fact, is the third generation, which means the third generation digital communication in Chinese. 1995, the first generation of digital mobile phones, can only make voice calls; From 1996 to 1997, the second generation of digital mobile phones appeared, adding the function of receiving data, such as receiving mail or web pages; The main difference between the third generation and the first two generations is that the speed of transmitting sound and data has increased.

3G is a new generation mobile communication system that combines wireless communication with multimedia communication such as Internet. It can handle various media forms, such as images, voice and video streams, and provide various information services, including web browsing, teleconference and e-commerce. In order to provide this service, the wireless network must be able to support different data transmission speeds, that is, in any environment, it can support at least 2Mbps (megabyte/second), 384kbps (kilobyte/second) and 144kbps respectively. The bandwidth provided by the 2G network is 9.6Kpbs. 2.5G to 56Kpbs. 3G will have a wider bandwidth and the transmission speed will reach 100-300Kbps, which can transmit not only voice but also data, thus providing fast and convenient wireless applications.

3G technical standard

As early as May 2000, the International Telecommunication Union (ITU) determined three mainstream 3G standards, WCDMA, CDMA200 and TD-SCDMA, and wrote them into the 3G technical guidance document International Mobile Communication Plan 2000 (IMT-2000 for short).

Compared with the first generation analog mobile phones (1G) and the second generation digital mobile phones (2G) such as GSM and TDMA, there are many names for 3G communication. ITU defines it as "IMT-2000" (International Mobile Phone 2000), and European telecom giants call it "UMTS" (Universal Mobile Telecommunication System), which means Universal Mobile Telecommunication System.

The continuous development of this standard is reflected in four versions of UMTS standard of 3GPP: R99, R4, R5 and R6. Formed a huge and relatively independent standard system. WCDMA is the earliest and most perfect preferred air interface, which is widely used by 3G operators in Europe, Asia and America.

3G standard -WCDMA standard

WCDMA: Wideband CDMA, which means Wideband Code Division Multiple Access. Its supporters are mainly European manufacturers based on GSM system, including Ericsson, Alcatel, Nokia, Lucent and Nortel in Europe and America, and NTT, Fujitsu and Sharp in Japan. This system can be set up on the existing GSM network to facilitate the transition of system providers, and Asia, where GSM system is quite popular, will have a higher acceptance of this new technology. So WCDMA has an inherent market advantage. (Japanese mobile communication giant NTT DoCoMo opened the world's first 3G service network based on WCDMA standard on 20011. At present, Asia has become the fastest growing region of 3G, followed by Europe, and the United States is far behind in technical preparation due to lack of enthusiasm. )

WCDMA: The full name of WCDMA is (Wideband Code Division Multiple Access), which is translated as "Wideband Code Division Multiple Access" in Chinese. WCDMA originated from the integration of several technologies in Europe and Japan. It adopts MC FDD duplex mode and has good compatibility and interoperability with GSM network. As a new technology, it is not as mature as CDMA2000, but its advantage is that the widespread adoption of GSM can bring convenience to its upgrade. So it has been favored by major manufacturers recently. WCDMA adopts the latest asynchronous transfer mode (ATM) microcellular transmission protocol, which allows more voice calls to be transmitted on one line, and the number of calls has increased from the current 30 to 300. In densely populated areas, lines will no longer be easily blocked. WCDMA adopts Direct Spread Spectrum (MC) mode with a carrier bandwidth of 5MHz. It can support data transmission rates from 384Kbps to 2Mbps. It can provide a transmission rate of 384Kbps in high-speed mobile state, and the highest transmission rate can reach 2Mbps in low-speed or indoor environment. At present, GSM system can only transmit 9.6Kbps and fixed-line modem only 56Kbps, so WCDMA is wireless broadband communication.

In addition, in the same transmission channel, it can also provide circuit switching and packet switching services, so consumers can answer the phone through switching at the same time, and then access the Internet through packet switching. This technology can improve the efficiency of using mobile phones, and let us go beyond the service limit of transmitting voice or data at the same time.

In terms of cost, WCDMA is based on packet switching technology, so the network use cost is not calculated by the access time, but by the data transmission volume of consumers.

3G standard -CDMA 200 standard

CDMA200: It was put forward by Qualcomm North America Company of the United States, and Motorola, Lucent and Samsung of South Korea all participated. At present, South Korea is the leader of this standard. The standard is derived from the narrow-band CDMA One digital standard, which can be directly upgraded from the original CDMA One structure to 3G with low construction cost. However, there are not many areas using CDMA at present, and there are not as many supporters of CDMA200 as WCDMA. However, the research and development technology of CDMA200 is the fastest among the current standards, and many 3G mobile phones have already taken the lead.

3G standard -TD-SCDMA standard

TD-SCDMA: This standard is a 3G standard independently formulated by China. Proposed by Datang Telecom to ITU on June 29th, 1999. The standard integrates international leading technologies such as smart wireless, synchronous CDMA and software radio, and has unique advantages in spectrum utilization, business support flexibility, frequency flexibility and cost. In addition, due to the huge domestic market in China, the standard has attracted the attention of major telecom equipment manufacturers, and more than half of the equipment manufacturers in the world have announced that they can support the TD-SCDMA standard.

TD-SCDMA

time division synchronous code division multiple access

It is one of the technical specifications of the third generation mobile communication space interface officially released by ITU, and has been fully supported by CWTS and 3GPP.

It is the first complete communication technical standard of China Telecom in the past century, and it is an alternative scheme of UTRA-FDD.

It is a mobile communication technology that combines the advantages of CDMA, TDMA and FDMA, with large system capacity, high spectrum utilization and strong anti-interference ability.

It adopts smart antenna, joint detection, relay switching, synchronous CDMA, low chip rate, multi-slot, variable spread spectrum system and adaptive power adjustment.

Three mainstream WCDMA, CDMA2000 and CDMA -TDD.

CDMA2000

IS-95A = & gt； IS-95B 76.8 kb/s 1 15.2 kb/s

cdma2000

Wideband code division multiple access (WCDMA)

High speed circuit switched data (HSCSD) 1 14.4Kb/s

General Packet Switched Wireless Service (GPRS)384Kb/s

WCDMA is used to realize the final third generation services (2Mb/s data rate and high quality voice and image services within 2*5M bandwidth).

TD-SCDMA

Td-scdma BTS-BSC+-GSM core network

TD-scdma BTS-RNC- third generation core network

Td-scdma base station RNC IP network

TD-SCDMA: The full name of TD-SCDMA is Time Division Synchronous Code Division Multiple Access, which is one of the technical specifications of the third generation mobile communication space interface officially released by ITU, and is fully supported by CWTS and 3GPP. It is the first complete communication technical standard of China Telecom in the last century, and it can replace UTRA-FDD. It is a mobile communication technology that combines the advantages of CDMA, TDMA and FDMA, with large system capacity, high spectrum utilization and strong anti-interference ability. It adopts smart antenna, joint detection, relay switching, synchronous CDMA, software radio, low chip rate, multi-slot, variable spread spectrum system and adaptive power adjustment. Time domain adaptive resource allocation in TD-SCDMA transmission direction can obtain the best utilization ratio of spectrum allocation independent of symmetric traffic load relationship. Therefore, TD-SCDMA can support all 3G services from 8kbps to 2Mbps, such as voice and Internet, through the best adaptive resource allocation and the best spectrum efficiency. In the final version, it is planned to directly connect TD-SCDMA wireless network with the Internet.

Difference between CDMA 1X and CDMA95

CDMA 1X is an upgraded version of CDMA95. Similar to GPRS, it is an upgrade to the original GSM.

▲CDMA 95

CDMA is the abbreviation of Code Division Multiple Access, which is a brand-new and mature wireless communication technology developed on spread spectrum communication technology, a branch of digital technology. It can meet the market's high demand for mobile communication capacity and quality, and has the characteristics of high spectrum utilization, good voice quality, strong confidentiality, low dropped call rate, small electromagnetic radiation, large capacity, wide coverage and so on, which can greatly reduce investment and operating costs. The principle of CDMA technology is based on spread spectrum technology, that is, the information data to be transmitted with a certain signal bandwidth is modulated by a high-speed pseudo-random code with a bandwidth much larger than the signal bandwidth, so that the bandwidth of the original data signal is expanded and then transmitted by carrier modulation. The receiver uses the same pseudo-random code to correlate with the received bandwidth signal, and changes the broadband signal into the narrowband signal of the original information data, that is, despreading, thus realizing information communication.

▲CDMA 1X

CDMA 1X refers to the first stage of cdma2000 (the rate is higher than IS-95 and lower than 2Mbps). The forward link data rate can reach 144Kbps, and packet switching is introduced into the network part to support mobile IP services. W-CDMA and cdma2000 are the most concerned international suggestions on the wireless interface of the third generation mobile communication. Cdma2000 is the proposal of the third generation mobile communication air interface standard put forward by the United States to ITU, and it is the technical system scheme for the evolution of IS-95 standard to the third generation. CDMA 1X adopts the spread spectrum rate of SR 1, that is to say, both the forward channel and the reverse channel adopt the single-carrier direct serial spread spectrum mode, and the chip rate is 1.2288Mbit/s/s ... so it can be easily backward compatible with IS-95(A/B) to realize a smooth transition. Because CDMA 1X adopts new technologies such as reverse coherent demodulation, fast forward power control, transmit diversity and Turbo coding, its capacity has been greatly improved compared with IS-95. Under the same conditions, the capacity of ordinary voice service is roughly twice that of IS-95 system. CDMA 1X network can be used as a bearing platform for voice services and wireless access to Internet packet data, which can provide users with both traditional voice services and end-to-end packet transmission mode data services.

GSM/KOOC-0/X: The so-called GSM/KOOC-0/X refers to dual-mode mobile phones that support two standard networks, mainly GSM/PHS and GSM/CDMA, which greatly improve the Internet access speed compared with GSM/GPRS, among which the GSM/PHS mobile phone is only Sanyo's PDG-G/KOOC-0/000 (that is, J/KOOC-0 sold by Taiwan Province Public Telecom).

GSM 1x can be used as a technical scheme to enable China Unicom to enjoy the benefits of enhanced CDMA 1X services for its existing GSM users on the basis of retaining the characteristics of existing GSM service layers and SIM card users.

GSM 1x integrates the advantages of CDMA 1X and GSM-MAP, which means that GSM operators using any frequency can adopt the solution of providing CDMA 1X services.

GSM 1x can maximize the operator's investment in the existing GSM-MAP network and retain all the main functions and services provided by the system. GSM 1x can improve the voice and data capacity of operators, and at the same time support adding CDMA 1X network to a GSM network, and use GSM/CDMA dual-mode mobile phone based on SIM card to promote global roaming across GSM and CDMA dual networks.

What is 3GPP?

3GPP is a new standard for transmitting multimedia content through high-speed wireless network. 3GPP is designed for mobile devices. It can provide high-quality images and sounds at a lower data rate.

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