In (66) the strength of the carrier signal is varied to represent binary 1 or 0. (67) is a system that can map a name to an address and conversely an address to al name. (68) is a three-way handshaking authentication protocol that it’s packets are encapsulated in the point-to-point protocol. (69) is an approach that enables an ATM switch to behave like a LAN switch. (70) is an guided media which is made of glass or plastic and transmits signals in the form of light.

A．NAT

B．NCP

C．DDN

D．DNS

a）S国某网络运营商要求使用5M频谱资源实现主体S4/4/4站型配置，可使用频点是：26～50（不考虑保护频点），其中26～37用于BCCH载频，38～50用于TCH频点。请分析能否实现1×3或者1×1频率规划并且同基站内不存在同邻频。如果能实现，请说明具体实现方法；如果不能实现，请说明具体原因并给出你的解决建议。