推荐回答(2个)
CDMA是码分多址的英文缩写(Code Division Multiple Access),它是在数字技术的分支--扩频通信技术上发展起来的一种崭新而成熟的无线通信技术。
GSM80年代兴起于欧洲,1991年投入使用。但GSM系统的容量是有限的,在网络用户过载时,就不得不构建更多的网络设施。
W-CDMA(Wideband Code Division Multiple Access),宽带码分多址,是一种第三代无线通讯技术。
W-CDMAWideband CDMA 是一种由3GPP具体制定的,基于GSM MAP核心网,UTRAN(UMTS陆地无线接入网)为无线接口的第三代移动通信系统。
WCDMA是GSM的升级(GSM是2G技术,其演进是GSM、GPRS、EDGE、WCDMA),同时也是全球3G技术中用户最广(GSM系技术拥有全球85%移动用户)、技术和商业应用最成熟的。
WCDMA运营商遵循WCDMA、HSPA、LTE演进路线。
W-CDMA
也称为WCDMA,全称为Wideband
CDMA,也称为CDMA
Direct
Spread,意为宽频分码多重存取,这是基于GSM网发展出来的3G技术规范,是欧洲提出的宽带CDMA技术,它与日本提出的宽带CDMA技术基本相同,目前正在进一步融合。W-CDMA的支持者主要是以GSM系统为主的欧洲厂商,日本公司也或多或少参与其中,包括欧美的爱立信、阿尔卡特、诺基亚、朗讯、北电,以及日本的NTT、富士通、夏普等厂商。
该标准提出了GSM(2G)-GPRS-EDGE-WCDMA(3G)的演进策略。这套系统能够架设在现有的GSM网络上,对于系统提供商而言可以较轻易地过渡。预计在GSM系统相当普及的亚洲,对这套新技术的接受度会相当高。因此W-CDMA具有先天的市场优势。
CDMA2000
CDMA2000是由窄带CDMA(CDMA
IS95)技术发展而来的宽带CDMA技术,也称为CDMA
Multi-Carrier,它是由美国高通北美公司为主导提出,摩托罗拉、Lucent和后来加入的韩国三星都有参与,韩国现在成为该标准的主导者。这套系统是从窄频CDMAOne数字标准衍生出来的,可以从原有的CDMAOne结构直接升级到3G,建设成本低廉。但目前使用CDMA的地区只有日、韩和北美,所以CDMA2000的支持者不如W-CDMA多。不过CDMA2000的研发技术却是目前各标准中进度最快的,许多3G手机已经率先面世。该标准提出了从CDMA
IS95(2G)-CDMA20001x-CDMA20003x(3G)的演进策略。CDMA20001x被称为2.5代移动通信技术。CDMA20003x与CDMA20001x的主要区别在于应用了多路载波技术,通过采用三载波使带宽提高。目前中国电信正在采用这一方案向3G过渡,并已建成了CDMA
IS95网络。
标准参数:
WCDMA
ARTT
FDD
异步CDMA系统:无GPS
带宽:5MHz
码片速率:3.84Mcps
中国频段:1940MHz-1955MHz(上行)、2130MHz
-2145MHz(下行)
CDMA2000
RTT
FDD
同步CDMA系统:有GPS
带宽:1.25MHz
码片速率:1.2288Mcps
中国频段:1920MHz
-1935MHz(上行)、2110MHz
-2125MHz(下行)
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