在ATM信元中，UNI信头和NNI信头的差别是，(61)，当网络出现阻塞时，交换机要(62)，信元路上传输时，ATM信元要装配成传输帧，如果高层没有数据发送，则必须插入空信元或(63)，以便将ATM层信元速率适配成传输线路的速率。ATM网络是基于(64)方式的数据交换网络，若要实现IP Over ATM，则需要(65)技术。

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(66)

(64)

(65)

(62)

Bluetooth is a universal radio interface in the(71)frequency hand that enables portable electronic devices to connect and communicate wirelessly via short-range, ad hoc networks. Each unit can simultaneously communicate with up to(72)other units per piconet. Moreover, each unit can simultaneously(73)to several piconets. Eliminates the need for wires, cables and connectors for and between cordless or mobile phones, modems, headsets, PDAs, Computers, printers, projectors, local area networks, and so on, and paves the way for new and completely different devices and applications. Technology Characteristics(74)symbol rate exploits maximum available(75)bandwidth。

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