数据库系统中， DBA 使用的数据视力用（ ）描述。

在通信系统中，SDN 是网络虚拟化的一种实现方式，其英文全称是 ( )。当前接入互联网的重要手段之 WiFi 的英文全称是 ( ) 。

Recently,telecommunication carriers has been building ( ) core networks in order to effectively support various kinds of fixed and mobile broadband services.

When we use VolP service，the voice packets over the Internet arrive at their destination in a（ ） stream.

SMS was originally designed as part of ( )，but is now available on a wide range of networks ，including 3G and 4G networks.

（ ）was frozen in December 2008 and this has been the basis for the first wave ofLTE equipment.LTE specifications are very stable，with and added benefit of enhancements having been introduced in all subsequent 3GPP Releases.