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目前在世界上许多国家运营的蜂窝式移动电话系统如北欧四国的 NMT、美国的AMPS、联邦德图的 C 网、英国的 TACS、日本的 NAMTS,我国在北京、上海和广州运营的 TACS 和爱立克森系统都属第一代模拟式移动电话系统。为了满足更多用户的要求,建立符合统一技术标准的系统,欧州许多国家在移动通信专业组(GSM)组织协调下,提出了多种系统方案,即第二代数字蜂窝式移动电话系统试验系统方案。本文对这几种系统,重点对 CD900、S900D,作了全面介绍。并从多址技术、信道编码、语音编码、调制技术以及经济性等方面进行了分析和评估。
Cellular cellular telephone systems currently operating in many countries around the world, such as NMT in Northern Europe, the United States, AMPS in the United States, C Network in the Federal Republic of Germany, TACS in the United Kingdom, NAMTS in Japan, TACS and Love in China operating in Beijing, Shanghai and Guangzhou The Lexus system is the first generation of analog mobile phone systems. In order to meet the requirements of more users and establish a system that conforms to uniform technical standards, many European countries have proposed various system solutions under the coordination of the GSM organization, that is, the second generation digital cellular mobile phone system test system Program. This article on these types of systems, focusing on the CD900, S900D, made a comprehensive introduction. And from the multiple access technology, channel coding, speech coding, modulation and economic aspects of the analysis and evaluation.