Cdma Switching And Routing System Set Up And Exchange Network Optimization

CDMA is the abbreviation of Code Division Multiple Access, it is the new and mature radio communication technique which develops from the branch of digit technique—Spread Spectrum. CDMA bases on Spread Spectrum. It modulates the signal required to transmit with the high speed pseudo-random code, bandwidth much wider than the original signal, so as to expand the bandwidth of original data information. The resulting signal modulates a carrier and the modulated carrier is transmitted. The receiver uses the same pseudo-random code to correlate the received signal, extracting the narrow band information data from the wideband signal to complete the communication of information.Mobile communication system has many ways to classified. For example, analog and digital according to property of signal; Frequency Modulation, Phase Modulation and Amplitude Modulation according to method of modulation; FDMA, TDMA and CDMA according to the means of multiple access. The GSM networks, which are used in China Unicom and China Mobile, are the combination of FDMA and TDMA. The GSM network has many advantages to the analog system, but it's capacity is limited and it's spectrum effectiveness is only 3 times of the analog system. It's voice quality can not have the same level with fixed phone. The maximum access rate of TDMA terminals is only 9.6kbit/s. The TDMA system has no the soft-handoff function, so the calls are easy to be dropped to decrease service quality. Therefore, the TDMA system is not the best radio access method in today's radio mobile communication. The CDMA system are favoured by the more and more service provider and customers for its large capability, high voice quality, integrated services, soft-handoff function and so on.CDMA technology was derived from the demands of higher endless wireless communications technology of the people. Because of the demand of war during the Second World War, CDMA technology was exploitured, the original intention was to prevent the disturb from the enemy. During the war it was widely used in military affairs. The Qualcomm company modified it to be commercial. Many advantages of CDMA technology theory have been verified since the first commercial CDMA system run on 1995. CDMA systems have gotten the rapid spread and applied in North America, South America and Asian. There are some commercial CDMA networks in many countries and regions including China Hongkong, South Korea, Japan and USA. CDMA technology has been the main mobile communication technology in Japan and USA.