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移动通信系统及技术作为迅速发展的信息化技术手段之一,它为解决日益增长的信息业务需求提供了重要的途径。近20多年来,移动通信技术经历了3个阶段的迅速发展,第一代移动通信系统出现于70年代中期左右,以蜂窝概念的提出为起点,采用模拟调制和频分多址(FDMA)及模拟信令方式,主要提供区域性的话音业务,业务单一、频谱利用率低、系统容量及网络提供的移动性有限。第二代移动通信系统诞生于80年代中期,使用数字调制技术、时分多址(TDMA)/频分多址(FDMA)或者码分多址(CDMA)/频分多址(FDMA)
As one of the rapid development of information technology, mobile communication system and technology provide an important way to solve the increasing demand of information service. In the recent 20 years, the mobile communication technology has undergone rapid development in three stages. The first generation of mobile communication system appeared in the mid-1970s. Based on the proposed concept of cellular, analog modulation and frequency division multiple access (FDMA) and Analog signaling mode, mainly to provide regional voice services, a single business, low spectrum efficiency, system capacity and network to provide limited mobility. The second generation of mobile communication systems was born in the mid-1980s using digital modulation techniques, TDMA / FDMA or FDMA,