Basic knowledge of GPRS [Repost]

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Basic knowledge of GPRS [Repost] [Copy link]

Basic knowledge of GPRS [Repost]

What is GPRS? GPRS is the English abbreviation of General Packet Radio Service, which is a new packet data bearer service developed on the existing GSM system. The most fundamental difference between GPRS and the existing GSM voice system is that GSM is a circuit switching system, while GPRS is a packet switching system. Therefore, GPRS is particularly suitable for intermittent, sudden or frequent, small amounts of data transmission, and is also suitable for occasional large amounts of data transmission. This feature is suitable for most mobile Internet applications. What are the advantages of GPRS? Compared with the original GSM dial-up circuit switching data transmission method, GPRS is a packet switching technology with the advantages of "real-time online", "pay-as-you-go", "quick login", "high-speed transmission" and "free switching". 1) Real-time online ? "Real-time online" means that users can keep in touch with the network at any time. For example, when a user accesses the Internet, the mobile phone sends and receives data on the wireless channel. Even if there is no data transmission, the mobile phone is still connected to the network. Not only can the user initiate data transmission, but also push services can be started from the network at any time. Unlike ordinary dial-up Internet access, you have to dial again to surf the Internet after being disconnected. 2) Pay-as-you-go ? Users can be online all the time, and the fee is charged according to the number of data packets received and sent by the user. When there is no data traffic transmission, the user is free even if he is online. Let me give you a very vivid and interesting example: being idle is free. 3) Quick login 　　GPRS users are always attached to the GPRS network as soon as they turn on the phone. Each time they use it, they only need an activation process, which generally only takes 1-3 seconds to log in to the Internet immediately. Fixed dial-up access to the Internet requires dialing, verifying the username and password, logging in to the server, etc., which takes at least 8-10 seconds or even longer. 4) High-speed transmission ? GPRS uses packet switching technology, and the theoretical maximum data transmission rate can reach 171.2kb/s, but the actual speed may be different due to the limitations of encoding and mobile phone terminals. Circuit-switched data service has a rate of 9.6K bits per second, so the relationship between circuit-switched data service (CSD) and GPRS is like the difference between 9.6K modem and 33.6K and 56K modem. 5) Free switching 　　GPRS also has the advantage that data transmission and voice transmission can be carried out simultaneously or switched. That is to say, users can receive voice calls while surfing the Internet with their mobile phones. For example, the original telephone dial-up Internet access, after access, can no longer make calls or receive calls, while GPRS is similar to the concept of ISDN for fixed telephones, which allows both telephone and Internet access.

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What can GPRS bring to users? Especially the application services that are different from the existing GSM? GPRS mobile data services can provide users with a wealth of application services, such as: (1) Mobile commerce: including mobile banking, mobile financial management, mobile transactions (stocks, lottery), etc. (2) Mobile information services: information on demand, weather, travel, services, yellow pages, news and advertising, etc. (3) Mobile Internet services: web browsing, email, etc. (4) Virtual private network services: mobile office, mobile medical care, etc. (5) Location-based services: location query, hotel and similar service industry navigation, etc. (6) Multimedia services: videophone, multimedia information transmission, online games, music, video on demand, etc. (7) Personal service services: PIM and other services tailored for individuals, etc. It is worth noting that although the above services themselves are not limited to using GPRS as a network carrier to achieve implementation, different carrier characteristics can provide users with better services. We know that GPRS has the characteristics of "real-time online", "pay-as-you-go", "fast login", "high-speed transmission", "switching freely", resource sharing, rich bandwidth, etc. It is not a service itself, but a better network carrying method. Therefore, even the same application will be improved due to the above characteristics of GPRS. Of course, due to the technical characteristics of GPRS itself, there are also some application services that are particularly suitable for GPRS network, such as online chatting, mobile stock trading, remote monitoring, remote counting and other data services with small traffic and high frequency transmission. The following are several application examples: ??Mobile stock trading-now you don't have to go to the securities trading department. The market index, individual stock market, K-line chart analysis, etc. can be received and displayed in real time by mobile phones, and online transactions can also be carried out. For stock traders, it is really a mobile phone in hand, and you don't have to worry about crossing thousands of mountains and rivers. ??Mobile shopping-you can see the appearance of clothes clearly through mobile phones or wireless handheld computers. Ladies are blessed! ??Mobile leisure-traveling to a new city with Honey, want to go to the nearest restaurant for dinner, no problem! Check the GPRS mobile phone, there is a detailed local map on the screen, and there are instructions for your location and the restaurant. Wow! We are here! What about the restaurant? Just turn right, left, and left again and you will be there. ??Mobile office - Arrived at the airport, wow? The plane is late and will take off in two hours. Let's continue working. Take out the laptop with GPRS PC card, send and receive emails, and continue to discuss problems and work together with colleagues through video conference. Two hours have passed unknowingly, and it is time to board the plane. Look, what an efficient two hours. What is the concept of "always online"? "Always online" means that users can stay connected to the network at any time. For example, when a user accesses the Internet, the mobile phone sends and receives data on the wireless channel. Even if there is no data transmission, the mobile phone is still connected to the network. When data transmission is to be carried out again, it does not need to be re-initiated, unlike ordinary dial-up Internet access, which has to be dialed again after disconnection to surf the Internet. How fast can GPRS reach? The theoretical maximum rate supported, how can it be truly achieved? The theoretical maximum rate supported by the GPRS network built by CMCC is currently 171.2kbps, which is achieved when the coding method is CS-4, the wireless environment is good, and the channels are sufficient. When GPRS reaches the theoretical maximum value of 171.2kbps, it can fully support some multimedia image transmission services and other application services that require high bandwidth, but the actual data transmission rate is affected by factors such as network coding methods and terminal support. Currently, users' access speeds are roughly divided into several levels: 20k, 40k, 60k, and 115.2k. How long does GPRS access time take? A GPRS mobile phone can attach to the GPRS network as soon as it is turned on, that is, it has established a connection with the GPRS network. The attachment time is generally 3-5 seconds; when using GPRS data services, an activation process is required, which is generally 1-3 seconds. After activation, it is fully connected to the Internet. Will using GPRS affect normal calls? No. When using GPRS to surf the Internet, you can also receive calls and make calls normally.

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Can GPRS be used to make calls and surf the Internet at the same time? It depends on the support of the mobile phone. GPRS mobile phones are divided into three levels: A, B, C: Class A mobile phones can still browse the Internet, send and receive emails, etc. while making voice calls, that is, voice calls and data transmission can be carried out at the same time; Class B and Class C terminals cannot make data transmission while making calls, and need to switch between data transmission and voice calls. Class B terminals can switch automatically, temporarily suspending GPRS data transmission when making calls, and continue data transmission after the call ends. Class C terminals need to be switched manually. Class B mobile phones are the most common in the market. What are the technical advantages of GPRS over WAP? The existing WAP bearer is circuit switching (CSD), while GPRS is packet switching for data transmission. Circuit switching cannot carry data and voice at the same time, and the charging model is also charged according to the length of time. Because GPRS is packet switching, the utilization rate of network resources has been greatly improved compared with circuit switching. In addition, GPRS can transmit voice and data at the same time, and can be charged completely according to the generated traffic. ??In fact, WAP itself is not comparable to GPRS. The content on the existing WAP can also be browsed and used on GPRS. It's just that GPRS makes the existing CSD-based WAP faster, more convenient and more reasonably charged. The service content of WAP will also be greatly promoted and improved due to the technical progress of the network. Will GPRS replace WAP? WAP currently uses CSD (circuit switched data) GSM data services. In the future, WAP can use GPRS, a new GSM network, as a bearer. ??GPRS will not replace WAP. The two belong to different categories. GPRS and the current CSD-based GSM data services are roads, while WAP is the car on the road. WAP now runs on two lanes, while GPRS has increased the data transmission speed and has 8 lanes. It can be said that GPRS has enhanced the WAP service. The content on the existing WAP can also be browsed and used through GPRS. What are the technical advantages of GPRS compared with GSM? GPRS is a packet-switched data carrying and transmission method developed on the basis of GSM. Compared with the original GSM, GPRS has very obvious advantages in carrying and supporting data services: it makes more effective use of wireless network channel resources, and is particularly suitable for sudden and frequent small-volume data transmission; it supports higher data transmission rates, with a theoretical peak of 115kbps; the billing method is more flexible, and can support billing based on data traffic; GPRS can also support voice calls while data transmission is in progress, etc. What is the relationship between GPRS and WAP and HTTP? We can give an example, two users use ordinary fixed-line phones and mobile phones to make a call. Here, GPRS is equivalent to the telephone line and telecommunications network for transmitting voice, and WAP and HTTP are equivalent to the Cantonese or Mandarin spoken by the user. The content of the user, such as "Have you eaten?", is the specific content transmitted on WAP and HTTP. Therefore, GPRS and WAP are concepts of different categories. What is the relationship between GPRS and 2G and 3G? GPRS is developed on the basis of the second generation wireless communication system GSM. It adds network system equipment that supports packet switching to the transmission of data streams in the GSM network. The third generation wireless communication system will make further technological progress and development on the basis of GPRS, and fully support high-speed and broadband multimedia data transmission for the network. In other words, GPRS is a network technology between the second generation and the third generation, which is generally called 2.5 generation. How long is the life of GPRS? Is it just a transitional product? If the transitional product lasts for several years or even longer, it can be regarded as a phased mainstream product. At present, the world is more cautious about the development of the third generation network. It is believed that Chinese operators will also steadily develop the third generation network according to the number and demand of data users. In the vacuum period of several years, GPRS is undoubtedly the first choice for the development of mobile data services. GPRS is a packet switching data bearer and transmission service developed on the basis of the GSM system. It is a 2.5 generation network product, but it does not mean that GPRS is just a transitional product. On the contrary, GPRS is a very important and indispensable step and milestone in the evolution from the second generation to the third generation network. Because GPRS has made a qualitative leap from circuit switching to packet switching in data transmission compared to GSM, it has greatly promoted mobile Internet and data services. At this stage, the road to 3G is not very clear, and the technology development and market demand are not very mature. GPRS will become the main carrier of mobile data services in the next 4-5 years. In addition, all new technology network products and services are backward compatible. That is to say, even if the 3G network already exists, GPRS will coexist with 3G for a long time due to network costs and market gradualness. What are the characteristics of GPRS compared with CDMA? Strictly speaking, GPRS is a mobile data network based on 2.5G technology developed on the basis of GSM network, which realizes data transmission through packet switching. The main advantages of GPRS are "always online" and "charged by traffic". In other words, GPRS can access the Internet at any time without dialing, keep in touch with the network at any time, and the billing is more reasonable, charging completely according to the actual traffic used. Moreover, GPRS is developed on the basis of the original GSM on the wireless side of the network, so the network coverage of GPRS should be said to be relatively mature; in addition, the original GSM users do not need to change their mobile phone numbers when upgrading to GPRS users, and can directly activate the GPRS service on the GSM mobile phone number. ??CDMA has several types such as IS-95A, IS-95B and CDMA2000. IS-95B is the narrowband CDMA that everyone usually talks about now. It is a network technology based on 2G, and the data transmission method used is also the same circuit switching type as GSM. IS_95A (CDMA 2000 1x) is a 2.5-generation CDMA technology, and CDMA2000 is a 3-generation network technology. Now most operators and the CDMA to be built in China are IS-95B, which means it is only a 2-generation CDMA network.