G网跟C网区别

G网跟C网区别 Mobile is now part of the city G network, E network, EDGE network is now the Olympic City, 3G network operators, is TD-SCDMA Unicom 133 number segment belongs to CDMA network 130.131.132 belongs to the GSM network The move all belongs to the GSM network GSM network standard 800/900/1800/1900MHz generally have three kinds of network frequency, 2G technology, GSM network support mobile phone support GPRS (General Packet Radio Service) belongs to the 2.5 generation of GSM, now black and a EDGE, in fact it is the transitional stage of the third generation GSM networks (also known as 2.75GSM), GSM network technology 3G is the WCDMA network, is one of the development direction of the future GSM; The CDMA network is divided into a total of 3 (CDMA2000/WCDMA/TD-SCDMA), which belongs to the Chinese Unicom's CDMA network CDMA2000, CDMA network standard Qualcomm, divided into several CDMA2000 1x/2x/3x; Chinese Unicom used methods and Japan, Japan is one of the "machine card (i.e. a mobile phone number to bind a number, it must change for mobile phone) in Chinese is" machine card separation "(the user can change the number and do not necessarily need to replace the mobile phone), of course every year to pay royalties to Qualcomm; using the WCDMA network are the main China Hongkong" Hutchison Whampoa "(i.e., and yellow is the use of Hongkong Telecom, Chinese this network, as the network) South Korea is used; the last is TD-SCDMA China and German SIEMENS co developed with independent intellectual property rights, China A 3GSM network. The third generation of GSM network Chinese development direction from two aspects: one is the development of WCDMA, one is TD-SCDMA, the country depends on the government's decision, of course, are most likely to develop the third generation of GSM network is China Mobile, because Chinese Unicom has CDMA2000 1x the 3G network. The difference between c net and G net Whether the GSM mobile phone and CDMA mobile phone radiation power man or difference, to objectively compare actual results, by an international famous CDMA technology company and the authority of a well-known domestic GSM network optimization company engineering and technical personnel in early December 2001 along the two ring road of Beijing city line CDMA and GSM mobile phone transmission power the present network test. The test results show that in the two loop on the CDMA mobile phone average power is 2.4 dBm (1.72mW) GSM, the average mobile phone transmitting power is 28.9dBm (773 mW), taking into account the GSM mobile phone only launched in 1/8 hours, the equivalent of GSM mobile phone at the time of the average transmit power can be reduced to 19.85dBm (96.63mW). As a result, the average transmit power of CDMA handsets is equivalent to 1.78% of the average equivalent transmit power of GSM handsets over time. First, CDMA and GSM system to transmit power requirements of mobile phones Let's first take a look at the requirements of CDMA and GSM related technical specifications on the transmit power of mobile phones. GSM mobile phone 900MHz band maximum transmit power is currently used for 2W (33dBm), maximum transmit power 1800MHz frequency of 1W (30dBm), at the same time specification for GSM900 and 1800 bands, mobile phone communication in the process of minimum transmit power is not lower than 5dBm and 0dBm respectively. CDMA IS-95A specification for maximum transmit power requirements for mobile phone 0.2W ~ 1W (23dBm ~ 30dBm), maximum transmit power at present actually allows for the 23dBm mobile phone network (0.2W), CDMA mobile phone specification has no requirements for the minimum transmission power. In the actual process of communication, in a moment a place, the actual mobile phone transmission power depends on the environment, on the quality of the communication system, many factors such as voice activation, is actually depends on the link budget. In the usual network design and planning, the frame error rate is basically the same as the requirements of the GSM system to mobile phone base station signal carrier to interference ratio is generally about 9dB, because the CDMA system using spread spectrum technology, to gain full rate encoding the spread spectrum gain is 21dB. (more on other low rate encoding gain). So the equivalent before despreading signals the requirement (less than -14dB! CDMA system is usually to despread the signal value is about 7dB). Let's compare the initial values of the transmit power of the GSM and CDMA handsets and the power control mechanism. The communication between the mobile phone and the system can be divided into two stages, one is the access phase, and the other is the communication and communication phase of the two. For GSM system, no mobile phone before entering a special mode in random access stage, there is no power control, in order to ensure the successful access to mobile phone, the maximum power system allows the emission (usually the maximum transmission power of the mobile phone). After assigning a dedicated channel (SDCCH or TCH), the mobile phone adjusts the transmit power of the mobile phone according to the instruction of the base station, and the step length is usually adjusted to 2dB. The frequency is adjusted to 60ms once. For CDMA system, the random access condition, mobile phone will base station according to the received signal level to estimate a smaller value as the initial transmit power to send mobile phone, the first Access Probe, if the response information of the base station are not within the prescribed period of time, will increase the transmission power of mobile phone, send second Access Probe, if within the specified time has not received response information of the base station, the mobile phone will increase transmission power. This process repeats until you receive a reply from the base station or reach the maximum number of attempts you have set. In the call mode, each 1.25ms base station sends a power control command message to the handset, which commands the handset to increase or decrease the transmit power, with a step size of 1dB. See from the above comparison, taking into account the CDMA system other unique technology, such as soft switching, RAKE receiver, multipath diversity is strong on the forward error correction algorithm for uplink budget improvement, transmitting power CDMA system on mobile phone requirements than GSM system on mobile phone transmission power requirements are much smaller. And GSM mobile phone in the process of access to the maximum power transmission, in the process of communication, power control speed is slow, so the mobile phone with high power emission probability. The unique random access mechanism and fast reverse power control of CDMA mobile phones can maintain the average transmit power of mobile phones at a lower level. The above qualitative analysis results are verified in the following actual measurements. Two 、 road test description and result analysis Road test was carried out to test the transmitting power of CDMA and GSM mobile phones in the actual communication process. CDMA test mobile phones and GSM test phones, unplug 1861 at the same time, adjust the car radio to the appropriate volume, analog two-way calls. The speed is about 40km. GSM mobile phones were sampled every 480ms, and CDMA mobile phones were sampled every 20ms. The results of test are: linear CDMA mobile phone the average transmission power of 2.4dBm (1.72 mW), the maximum power (23dBm, 0.2 w) emission probability is 0.2%; the average linear GSM mobile phone transmitting power is 28.9dBm (773 mW), the maximum power (2 Watt W) emission probability is 21.8%. It is worth noting that the current Beijing mobile GSM network in Beijing has been quite mature, the base station spacing, GSM mobile phone can lower power emission, while the CDMA network is in the stage of development, network optimization, CDMA mobile phone to transmit power requirements will be smaller. Three, mobile security radiation standards and mobile phone emission power The effect of mobile phone radiation on the human body is still under constant observation and research. There are a lot of conflicting reports abroad, and there is no comprehensive scientific conclusion. At present, the International (including the United States FCC, NCRP, European CENEIEC) commonly used standard is SAR value (SPECIFIC ABSORPTION RATE), it refers to the quality of human body unit absorbed RF power. (formula omitted) Since the cell phone is close to the person's brain (without headphones), the distance between the antenna and the human brain is usually less than 15cm. The human brain is in the near field of antenna radiation. Because of the complexity of human tissue structure, it is very difficult to calculate the radiation power of antenna in theory and the distribution of field intensity in human body. But according to the theory of electromagnetic field, one thing is for sure, the antenna structure and the mobile phone and the relative position of human body under certain circumstances, the antenna output power is greater, the electric field strength formed in the body of the higher RF radiation power absorbed more. An important method of measuring SAR value is to use the human tissue equivalent model, and use a probe to measure the actual field strength of the human body exposed to radio frequency radiation. The stricter requirement for SAR is the FCC standard, which recommends two types of radiation standards for the 30MHz-15GHz band: 1. controlled radiation limit: 0.4mw/g (human mean), peak 8mw/g (average of 1 grams of human tissue) averaged 6 minutes; 2. uncontrolled radiation limit 0.08mw/g (human mean), peak 1.6mw/g (average of 1 grams of human tissue) averaged 30 minutes. Cell phone radiation belongs to uncontrolled radiation that can not be controlled by a radio frequency source. It is important to point out that the current mobile SAR test results are obtained at the maximum power and full rate mobile phone. The maximum transmission power of the CDMA mobile phone is 0.2W, maximum transmission power of the GSM mobile phone is 2W, but the GSM mobile phone only launch at 1/8 time, and determination of SAR value is the average of a longer period of time, therefore, GSM mobile phone and CDMA mobile phone in the case of the SAR value is close to be not at all surprising. We can't because in this extreme situation, CDMA mobile phones and GSM mobile phone SAR value quite, and arbitrarily believe that in actual communication process, CDMA mobile phones and GSM mobile phone radiation is similar. Because in the actual communication process, GSM phones and CDMA phones are not always delivered at maximum power, especially when CDMA phones are at full rate, with minimal probability of maximum power delivery. The statistical results from the front of the road test, GSM mobile phone with probability high-power emission is far greater than the probability of large power launch CDMA mobile phone, maximum transmit power the average transmit power of CDMA mobile phone CDMA mobile phone is far less than the average transmit power is far less than the GSM mobile phone so that the actual SAR in the actual communication process of CDMA mobile phone radiation on the human body value will be significantly lower than the nominal value of SAR CDMA mobile phone, GSM mobile phone is also much lower than the actual value of SAR. On the other hand, objectively speaking, the widely adopted SAR standard may not be able to comprehensively respond to the impact of mobile radiation on the human body. Because the standard is based on the thermal effects of electromagnetic radiation on the human body. In fact, the electromagnetic wave, especially low-frequency pulsed electromagnetic wave radiation on the human body non thermal effect also attracts more attention, GSM mobile phone emission of low frequency pulsed electromagnetic wave has affected the normal use of sophisticated medical equipment, hearing aids, is also harmful to the human body, there is no conclusion. To avoid these shortcomings of GSM phones, the third generation mobile communications system's terminals will emit radio waves like CDMA phones instead of pulsed waves. Because the transmission power system technology CDMA and GSM on CDMA and GSM of the mobile phone and the requirements of the power control mechanism and take the initial transmit power value is different, in the actual process of communication, the average transmit power the average transmit power of CDMA is much lower than the GSM of the mobile phone mobile phone. The test confirmed that the average transmit power than CDMA mobile phone GSM mobile phone transmitting power 500 times, taking into account the GSM mobile phone only launched in 1/8 time, at the same time, CDMA radiation energy more than GSM mobile phone radiation is 60 times smaller. Mobile phone radiation safety standard SAR value is in the case of mobile phone with maximum power emission, in this case, GSM mobile phones and CDMA mobile phone SAR value is quite normal. Because the maximum transmission power of the CDMA mobile phone average transmit power in the actual communication process is far less than the CDMA mobile phone, the average transmission power is far less than the GSM mobile phone CDMA mobile phone, so the actual radiation on the human body is far less than the maximum transmission power of the mobile phone SAR, but also in the process of low-frequency radio waves, CDMA mobile phone the mobile phone is worthy of the name "green"! CDMA is Access Division Multiple (Code). It is a new and mature wireless communication technology developed on the branch of digital technology spread spectrum communication technology. The principle of CDMA technology is based on the spread spectrum technology, will need to transfer a certain signal bandwidth information data, with a bandwidth is far greater than the signal bandwidth of high speed pseudorandom code modulation, the original data signal bandwidth is extended, and then send out by carrier modulation and. The receiver uses the same pseudo random code to deal with the received bandwidth signal, and the wide-band signal is changed into the narrowband signal of the original information data, namely despreading, so as to realize the information communication. GSM is the abbreviation of Global System for Mobile Communications, As a global mobile communication system, it is one of the main cellular systems in the world. GSM is based on narrowband TDMA, which allows 8 groups of calls to be carried out simultaneously in one radio frequency. The GSM80 era sprang up in Europe and was put into use in 1991. By the end of 1997, it had been operated in more than 100 countries and became the actual standard in Europe and Asia. By 2001, 400 GSM communication networks had been built in 162 countries worldwide. But the capacity of GSM system is limited, and when the network users are overloaded, they have to build more network facilities. Thankfully, GSM has excellent performance in other areas. Besides providing standardized list and signaling systems, it also opens up more intelligent businesses, such as international roaming. The convenience of the GSM phone is that it offers a smart card, which people call SIM card, and the card can be separated, so that the user changes the phone and customized personal information, which is very convenient. GSM phones also allow users to receive short messages with 160 word lengths. CDMA and GSM are the mainstream system of 2G communication. Technically, the difference between them is that the wireless transmission receiving system is different, and the modulation and demodulation methods are different. For users, the difference is that: 1. call quality. CDMA's call quality is higher than GSM, in the same environment, the phone calls, CDMA noise is much smaller than GSM. 2. cell phone radiation. Because CDMA uses excellent power control technology, CDMA phones are much smaller than GSM. 3. high-speed data access. CDMA1x can provide speeds of up to 153.6kbps, much faster than the 20 K a few GSM GPRS. Tariff is actually about the same, the mobile global pass and Unicom new time and space almost, moving Shenzhou line and China Unicom Ruyi line almost, moving dynamic zone and Unicom's UP new forces almost. Explain the following internal classification of CDMA and the classification of GSM. GSM is relatively simple, say GSM first. The so-called "GSM 900/1800/1900" refers to the frequency of GSM mobile phones, namely, China Mobile supported 900MHz, 1900MHz and the 1900MHz used in the United states. In China, the GSM 900/1800 dual band mobile phone that supports 900MHz and 1800MHz is fine. If you want to go to the United States with the support of 1900MHz, must use the mobile phone. CDMA800, this is the working frequency of the CDMA. Unicom's CDMA is working under 800MHz. CDMA2000 is the current 2G CDMA upgrade, is a 3G standard. Compared with the current 2G CDMA, CDMA2000 is able to provide data speeds of more than one trillion bps. And CDMA 1x is the technology that Unicom CDMA network adopts now. It refers to the abbreviation of CDMA2000 1X, that is, CDMA2000 1x. Compared to the real CDMA2000, CDMA 1X, as I said, can only support the data speed of 153.6kbps, so it is called "2.5G" technology, not really 3G technology. 20 answer: drummer_lhp - five