【资料名称】：3Gpp文档

【资料作者】：刘铭

【资料日期】：2001

【资料语言】：中文

【资料格式】：DOC

【资料目录和简介】：

Figure 4/1. Basic Architecture for UMTS to UMTS TrFO Connection [3].
OoBTC is required to establish Transcoder Free Operation. Out of Band Transcoder Control (OoBTC) is the term used for the capability of a network to negotiate codec types and codec modes for a call with out-of-band signalling procedures.
In [3] these procedures are specified to take place at the call setup phase or possibly later if there is a need to re-negotiate the codec due to e.g. SS interworking. OoBTC is performed between serving core network nodes taking into account transcoding capabilities of all involved parties, i.e. UEs and MGWs under the control of their serving nodes. OoBTC relies on the mechanisms and the architecture defined for an bearer independent circuit switched core network, as specified in [4].
The general principle of Transcoder Free Operation is to enable the support mode operation of the framing protocol defined within [8] not only on the Iu interface but to allow an end to end operation of the support mode procedures on Iu and CN bearers. It shall be possible that the end to end operation of the UP support mode is possible between network nodes that permanently terminate the Iu FP protocol, e.g. between two RNCs in case of a mobile to mobile call or an RNC and a gateway CN node in case of a mobile to fixed call, i.e. it shall not be limited to Figure 4/1.
This principle is enabled due to the agreement during the TrFO workshop to use the Iu UP protocol as a framing protocol within the circuit-switched AAL2/ATM and IP core network for compressed speech and CS data services. (see [10])
Note, that TSG CN WG3, responsible for the definitions of the Nb interface, communicated that the term “Iu UP” is not applicable for the Nb interface. Consequently, instead of using the terms “Iu UP” and “Iu UP protocol”, “Iu framing” and “Iu framing protocol” will be used throughout this TR when applicable, according to wording agreements reached within TSG CN WG4.
Figure 4/2 outlines a network configuration during a mobile to mobile call setup involving certain network entities (RNCs, MGWs, MSC-Servers) and respective protocol entities (RANAP, Iu framing protocol terminations (Iu-UP, Nb-UP) and Transport Independent Call Control (TICC)). Call Contexts, containing terminations (see [11]) with properties that shall be defined within [8] are involved as well (T1-T4).

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