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Content for  TS 48.020  Word version:  16.0.0

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1  ScopeWord‑p. 6

The present document defines rate adaptation functions to be used in PLMN Base Station Systems (BSS) transcoders and IWF
  • for adapting radio interface data rates to the 64 kbit/s used at the A-interface in A/Gb mode and
  • for adapting radio interface data rates to the Iu interface in GERAN Iu mode in accordance with TS 43.010.
The number of Base Station System - Mobile-services Switching Centre (BSS - MSC) traffic channels supporting data rate adaptation may be limited. In this case some channels may not support data rate adaptation. Those that do, shall conform to this specification.
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2  References, abbreviations and definitions

2.1  References

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
[1]
TR 21.905: " Vocabulary for 3GPP specifications ".
[2]
TS 22.034: "High Speed Circuit Switched Data (HSCSD) - Stage1"
[3]
TS 43.010: "GSM Public Land Mobile Network (PLMN) connection types".
[4]
TS 23.034: "High Speed Circuit Switched Data (HSCSD) - Stage2".
[5]
TS 44.021: "Rate adaption on the Mobile Station Base Station System (MS BSS) interface".
[6]
TS 24.022: "Radio Link Protocol (RLP) for Circuit Switched Bearer and Teleservices".
[7]
TS 45.003: "Channel coding".
[8]
TS 27.001: "General on Terminal Adaptation Functions (TAF) for Mobile Stations (MS)".
[9]
TS 48.008: "Mobile Switching Centre Base Station System (MSC BSS) interface; Layer 3 specification".
[10]
TS 29.007: "General requirements on interworking between the Public Land Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN)".
[11]
ITU-T Recommendation V.110: "Support of data terminal equipment's (DTEs) with V-Series interfaces by an integrated services digital network".
[12]
ITU-T Recommendation I.460:-Multiplexing, rate adaption and support of existing interfaces.
[13]
TS 48.060: "In-band control of remote transcoders and rate adaptors for full rate traffic channels"
[14]
TS 25.415: "UTRAN Iu Interface user plane protocols".
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2.2  AbbreviationsWord‑p. 7

For the purposes of the present document, the following abbreviations apply:
FPS
Frame Pattern Substitution
FSI
Frame Start Identifier
ZSP
Zero Sequence Position

2.3  Definitions

For the purposes of the present document, the following terms and definitions apply.
Substream:
Stream of data with explicit or implicit numbering between splitter and combine functions.
Channel:
A physical full rate channel on the radio interface (TCH/F) independent of the contents.
A interface circuit:
The 8 bits that constitute one 64 kbps circuit on the A interface.
A interface subcircuit:
One specific bit position or one specific pair of bit positions within the A interface circuit.
EDGE channel:
A general term referring to channels based on 8PSK modulation; i.e. TCH/F28.8, TCH/F32.0, and TCH/F43.2.
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3  General approach

3GPP TS 43.010, clause 6 defines the PLMN connection types necessary to support the data and telematic services in a PLMN operating in A/Gb mode or GERAN Iu mode.
Within the BSS , transcoder and IWF, there are several data rate adaptation functions which are combined as shown in TS 43.010 as part of a connection type.
These functions are RA0, RA1, RA1/RA1' , RA1'' , RA1'/RA1", RA1'/RAA", RA1', RAA", RA1'/RAA', RAA' , RAE and RA2. The RA2 function is equivalent to that described in ITU-T Recommendation V.110. In addition, splitting/combining, padding and inband numbering functions as defined in TS 44.021 and multiplexing as defined herein are used in cases where more than one channel is allowed.
The RA1/RA1', RA1'/RA1", RA1'/RAA" and RA1'/RAA' are relay functions used as indicated in TS 43.010.
The BSS uses the information contained in the ASSIGNMENT REQUEST message on the A-interface (see TS 48.008) to set the "E bits" and to map the "D bits" as shown below, as well as to choose the correct channel coding.
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4  The RA0 Function

The RA0 function is specified in TS 44.021.

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