摘要：
The Global System for Mobile Communication (GSM) and Code Division Multiple Access (CDMA) systems are digital mobile phone services consisting of base-station antennas which communicate with the mobile phone via radio frequency (RF) transmission. In turn the base-station antenna is connected to the wired telephone system directly or via a further RF communication link.
The mobile phone system is often referred to as cellular telephone technology because the regions being covered are bro 阅读全文
posted @ 2006-02-28 16:14 freshventure 阅读(1379) 评论(0) 推荐(0) 编辑