手机构成之基础原理——通讯基础Wireless Technology & Services Evolution NATIONAL LOCAL INTER- NATIONAL GLOBAL 1G 2.5G 3G ANALOG 1985 AMPS,TACS,NMT DIGITAL 1992 GSM,NADC CDMA,PDC HSCSD,GPRS,EDGE 1995 WCDMA CDMA2000 ITM-2000 ANALOG SPEECH DIGITAL SPEECH WAP, IMPROVED SPEECH SMS, Multi Media Services
