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2.2M
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3 Introduction
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3.1 Teletex service definition
The teletex (Ttx) service is an international telematic service as defined in CCITT F.200-series of recommendations. As an essential characteristic it provides a basic level of compatibility between all terminals participating in the service. Normally the service shall operate on a fully automatic basis and be open con...
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3.2 Context for the Support of Teletex in a GSM PLMN
Considering that a) international roaming of teletex subscribers must be supported; b) all CEPT countries have PSPDNs; c) PSPDNs providing an access unit AU (X.31 case A) support procedures according to CCITT X.32; d) each CEPT country will have an ISDN; e) ISDNs may provide the VCS; f) the teletex service supported by...
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3.3 Reference Configuration of a Teletex Mobile Station
The reference configuration (figure 1/GSM 03.44) is equivalent to those configurations in GSM 07.03. An explicit TA may be used between the R- and the S-interface reference point. The configuration TE1-MT1 can only be supported by means of a specialized TAF including protocol conversion, if necessary, to guarantee the ...
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4 Interworking for Teletex Support
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4.1 Global Network Configuration for Teletex
Presently teletex is offered in the CSPDN, the PSPDN, the PSTN, and in the very next future in the ISDN. Figure 2/GSM TS 03.44 shows the different networks to which a GSM PLMN may have to interwork, when supporting the communication between teletex terminals. ETSI ETSI TR 101 634 V7.0.0 (1999-08) 9 (GSM 03.44 version 7...
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4.2 Network Interworking Scenarios
The following network interworking scenarios may be derived from the global network configuration. Some scenarios allow for different implementations of an IWF. For the interworking functions needed between the PLMN and the different networks refer to GSM TS 09.06 and 09.07. The choice of interworking scenario and the ...
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4.3 Mobile-to-mobile Communication
A communication from a mobile to another mobile is treated like a call from/to a fixed network subscriber, e.g. using the packet functions as per GSM 09.06.
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4.4 Use of GSM Supplementary Services
For supplementary services refer to GSM 09.06 and GSM 09.04.In addition Call forwarding supplementary services may be used to forward a mobile terminated call to a TDS (refer annex). ETSI ETSI TR 101 634 V7.0.0 (1999-08) 11 (GSM 03.44 version 7.0.0 Release 1998)
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4.5 High Layer Compatibility Information Element
Mobile subscribers using the teletex service may code the high layer compatibility information element as described below. Depending on the network implementation this indication may be used by the network for teletex specific requirements. Depending on the signalling capabilities of the fixed network the high layer co...
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1 Scope
The present document defines the interworking between HFC networks on one side and the B-ISDN on the other side.
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2 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. • Fo...
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3 Definitions and abbreviations
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3.1 Definitions
For the purposes of the present document, the terms and definitions in EG 201 400-1 [1] apply.
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3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply: AAL ATM Adaptation Layer AN Access Network ATM Asynchronous Transfer Mode B-BBC Broadband Bearer Control Channel B-ISDN Broadband ISDN DSS2 Digital Signalling System number two HFC Hybrid Fibre Coax MAC Media Access Control NT Network Terminat...
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4 Service Requirements
See ETSI EG 201 400-1 [1]. ETSI ETSI TR 101 686 V1.1.1 (1999-07) 7
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5 Functional requirements
The basic service requirements of an HFC access network connected to a B-ISDN network are defined as follows: a) all requirements as given in EG 201 400-1 [1]; b) all requirements as given in EN 301 005-1 [2] (VB5.1 interface) and EN 301 217-1 [3] (VB5.1 interface).
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6 Reference Configuration and Reference Points
6.1 The HFC access network general architecture and boundaries See ETSI EG 201 400-1 [1].
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6.2 General reference configuration for HFC Access Networks
See ETSI EG 201 400-1 [1]. 6.3 HFC Access Network configuration for the considered network In figure 1, the reference configuration for the interworking between an HFC access network and the B-ISDN network is shown. HFC ACCESS NETWORK HEADEND B-ISDN switch B-ISDN Access Node Cable Network Access Node VB5.x HFC Network ...
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6.4 Reference Points
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6.4.1 Reference points at the user interface side
The following user network interface is the one of the B-ISDN network. • UNI at the TB reference point = B-ISDN UNI.
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6.4.2 Reference points at the network interface side
The following service node interface is the one of the B-ISDN network. • SNI at the VB5 reference point = B-ISDN SNI.
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7 User Interfaces
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7.1 B-ISDN UNI
B-ISDN Terminal (B-TE) B-ISDN Line Interface Functions TB HFC Access Network User Interface Functions Figure 2: Reference configuration at UNI for Broadband ISDN The B-ISDN UNI is the interface between the HFC access network and the B-ISDN terminal. The B-ISDN terminal is a B-TE terminal or any equipment that is compat...
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7.1.2 Interface references
Standard Number (ITU-T Recommendation) Short title I.432.1 [16] B-ISDN UNI: Physical layer specifications: general characteristics I.432.2 [17] B-ISDN UNI: Physical layer specifications: 155 520 kbit/s and 622 080 kbit/s operation I.432.3 [18] B-ISDN UNI: Physical layer specifications: 1 544 kbit/s and 2 048 kbit/s ope...
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7.1.3 User Interface functions - B-ISDN Network Termination
The User interface functions for the B-ISDN services over HFC Access network is fulfilled by a functional grouping called B-ISDN Cable Network Termination. The B-ISDN Cable Network Termination fulfils the interface between the network and the B-ISDN TE or NT-2. ETSI ETSI TR 101 686 V1.1.1 (1999-07) 9 The types of acces...
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7.1.4 Protocol stack and peer communication stack reference
The protocol stacks for B-ISDN signalling and meta-signalling at UNI are the following: I.363.5, Q.2130, Q.2110 AAL layer OSI Layer stack B-ISDN UNI sign. stack I.361 I.432.x Physical layer ATM layer DSS2 signalling Network layer B-ISDN UNI metasign. stack I.361 I.432.x Metasignalling Figure 3: Protocol stack for signa...
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8.1 VB5 functional specification model
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8.1.1 General reference model for the VB5.1 reference point
The general reference model for the VB5 reference point concept is detailed in subclause 5.2 of EN 301 005-1 [2]. NOTE: The general reference model is identical for the VB5.1 and the VB5.2 reference point concept.
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8.1.2 Integration of narrow-band customer access types
The integration of narrowband and other non B-ISDN access types is described in subclauses 4.2 and 4.3 of EN 301 005-1 [2]. Note that these concepts apply to both the VB5.1 and VB5.2 reference point. ETSI ETSI TR 101 686 V1.1.1 (1999-07) 11
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8.2 B-ISDN SNI
HFC Access Network Head End B-ISDN HFC Interface Functions B-ISDN Network Interface Functions VB5 Figure 7: Reference configuration at SNI for Broadband ISDN Requirements for the physical layer interface(s) at the VB5 interface are given in subclause 6.2 of EN 301 005-1 [2]. NOTE: These requirements apply to both the V...
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8.2.1 Interface references
Standard Number Short title EN 301 005-1 [2] Interfaces at the VB5.1 reference point for the support of Broadband or combined narrowband and broadband Access networks; part 1: Interface Specification EN 301 217-1 [3] Interfaces at the VB5.2 reference point for the support of Broadband or combined narrowband and broadba...
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8.2.2 Network interface functions - B-ISDN Cable Line Termination
The Network interface functions for the B-ISDN information over HFC Access network is fulfilled by a functional grouping called B-ISDN Cable Line Termination. The B-ISDN Cable Line Termination is located at the Head End. 8.2.3 Protocol stack and peer communication stack reference configurations
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8.2.3.1 Protocol stacks
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8.2.3.1.1 VB5.1 interface
Figure 8 shows the protocol stack architecture for the VB5.1 interface. The functions performed are defined as follows (more information can be obtained in the VB5.1 recommendation). - Virtual Path links and virtual channel links support for U-plane, C-Plane, and M-Plane. - VB5.1 Real Time Management Plane Co-ordinatio...
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8.2.3.1.2 VB5.2 interface
Figure 9 shows the protocol architecture for the VB5.2 interface. The functions performed are defined as follows (more information can be obtained in the VB5.2 recommendation). - Virtual Path links and virtual channel links support for U-plane, C-Plane, and M-Plane. - VB5.2 Real Time Management Plane Co-ordination (RTM...
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8.2.3.2 Protocol peer configurations
Figure 10 shows the Protocol peer configuration for the User information for B-ISDN. Local Exchange B-ISDN Cable Network Termination B-ISDN Cable Line Termination VB5 CablePMD Cable MAC CablePMD Cable MAC Modulation/demod. Physical layer I.361 Physical layer I.361 Figure 10: Protocol peer configuration for B-ISDN User ...
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8.2.3.2.1 VB5.1 interface
Figures 11, 12 and 13 show different Protocol peer stack configurations for different contexts. I.363.5, Q.2130, Q.2110 Local Exchange I.361 VB5 Physical layer I.363.5, Q.2130, Q.2110 I.361 VB5 Physical layer Access Node VB5.1 VB5.1 System RTMC system VB5.1 System RTMC system Figure 11: Protocol peer configuration for ...
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8.2.3.2.2 VB5.2 interface
Figures 14, 15 and 16 show different Protocol peer stack configurations for different contexts. B-ISDN Local Exchange I.361 I.363.5, Q.2130, Q.2110 Access Node I.361 VB5 Physical layer VB5.2 I.363.5, Q.2130, Q.2110 VB5 Physical layer VB5.2 System RTMC system B-BCC system VB5.2 System RTMC system B-BCC system Figure 14:...
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9 Management Aspects
As any other (sub)network, the HFC access network needs to be managed. This clause indicates reference documents and the reference configuration.
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9.1 Management References
All TMN principles and references to ETSI covering this subject can be found in ETR 230 [5]. These principles are also applicable to HFC access networks. The document fails however to handle Access networks separately, as it does with other networks. Some references with regard to management of access networks are give...
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1 Scope
The present document defines the changes that need to made to ASN.1, SDL and TTCN in order to harmonize these three languages in a consistent and compatible manner. The technical solutions to achieve this harmonization are based on the initial analysis of TR 101 114 [8]. The present document is restricted to documentin...
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2 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. • Fo...
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3 Definitions and abbreviations
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3.1 Definitions
For the purposes of the present document, the following terms and definitions apply: ASN.1:1997: ASN.1 as defined in the 1997 ITU-T Recommendations X.680 [1], X.681 [2], X.682 [3] and X.683 [4]. NOTE: For historical reasons the 1997 version of ASN.1 is sometimes referred to as ASN.1:98. This term is not used in the pre...
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3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply: ASN.1 Abstract Syntax Notation One BER Basic Encoding Rules BNF Backus-Nauer Form SDL Specification and Description Language TTCN Tree and Tabular Combined Notation
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4 Introduction
Historically, ASN.1, SDL, and TTCN have been developed as separate standards. However, it is becoming increasingly common for all three standards to be used in a close relationship. Several tool platforms already provide some form of integrated support of these languages/notations. It is now necessary, from both a user...
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5 Changes to SDL
This clause details the changes necessary to harmonize SDL and ASN.1. Annex A of the present document contains the related proposals submitted to ITU-T Study Group 10/Q6.
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5.1 Summary of SDL issues
The following list summarizes the issues associated with harmonizing SDL-ASN.1: • SDL case-sensitivity; • removal of in-line ASN.1 from SDL; • support for encoding rules and tags in SDL; • support of information objects (classes & sets) and reference to information objects from SDL; • support of open types in SDL (e.g....
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5.2 SDL case-sensitivity
SDL is currently defined as being case-insensitive as follows (ITU-T Recommendation Z.100 [5], p16): "In all <lexical unit>s except <character string>, <letter>s are always treated as if uppercase. (The treatment of <national>s may be defined by national standardization bodies)". This causes many problems when using SD...
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5.3 Removal of In-Line ASN.1 in SDL
Use of in-line ASN.1 in SDL causes many problems (some of which are identified in ITU-T Recommendation Z.105 [6]). Removing in-line ASN.1 from SDL, will provide the following benefits: • provide a cleaner interface between SDL and ASN.1 in accordance with the proposed paradigm; • remove many syntactical restrictions. P...
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5.4 Support for encoding rules and tags in SDL
ITU-T Recommendation Z.105 [6] does not allow the definition of encoding rules. A protocol specified in ASN.1 for which encoding rules are given, needs to have a corresponding mapping in SDL, if a code generator is to work directly from SDL source alone. The other associated problem is with ASN.1 tags. These are used i...
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5.5 Information Objects in SDL
Information objects provide a generic table mechanism within the ASN.1 language. Such a generic table defines the association of specific sets of field values or types. This feature replaces the earlier MACRO construct (available in ASN.1:1990) and is primarily used to fill-in gaps in a type definition dependant on one...
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5.5.1 Support for Defined Useful Information Object Types
Suitable mappings for TYPE-IDENITFIER, ABSTRACT-SYNTAX and INSTANCE OF must be defined, where these are declared in ASN.1 and suitably constrained. The TYPE-IDENTIFIER information object class is defined in ITU-T Recommendation X.681 (Annex A) [2] as: TYPE-IDENTIFIER ::= CLASS { &id OBJECT IDENTIFIER UNIQUE, &Type } WI...
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5.6 Void
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5.7 ASN.1 parameterization in SDL
All ASN.1:1997 concepts (even information object classes) can be parameterized. This feature allows the partial specification of types or values within an ASN.1 module with the specification being completed by the addition of the actual parameters at Instantiation time. The ability to specifying parameterised types and...
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5.7.1 Solution A for ASN.1 parameterization in SDL
Proposed SDL change 5A: Import only fully defined types and values from ASN.1 modules. The user needs to resolve any parameterization of ASN.1 types and values before they can be used in SDL. This could be done by a transformation from ITU-T Recommendation X.683 [4] to X.680 [1] basic ASN.1 (taking care of the compatib...
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5.7.2 Solution B for ASN.1 parameterization in SDL
Proposed SDL change 5B: Use formal context parameters in SDL data types The proposed solution is to translate the ASN.1 parameterized type into an SDL data type with formal context parameters that will preserve the ability to partially specify types. Formal context parameters have been introduced in SDL to parameterize...
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5.7.2.1 Formal Context Parameters in SDL type definitions
In the most simple case (i.e. with no parameterization), a type specification is dependent on the context of where it is defined. To define type specifications independent of their context, SDL allows the user to parameterize type specifications with <formal context parameters>. Parameters can be specified for system t...
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5.7.2.2 Use of Formal Context Parameters in SDL data types
Considering the ASN.1 specification of GenericMsg { MsgDataType } given in section 5.7.1, if we want to use it in SDL, we could do as follows: process myproc; newtype GenericMsg <newtype MsgDataType endnewtype> struct msgCode : INTEGER; msgLength: INTEGER; msgData : MsgDataType; operators makeMsg : INTEGER,INTEGER,MsgD...
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5.7.3 Parameterization issues for further investigation
The preferred solution for supporting ASN.1 parameterized types and values in SDL is solution B, however. The following points need be clarified: • the presence of several levels of parameterization in an ASN.1 type; • the processing of information objects in SDL (addressed in a separate section) has to be coherent wit...
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5.8 Extensibility support in SDL
ASN.1:1997 supports the specification of extensible data types by use of the extension marker. Extensible data types allow the definition of different versions of a given protocol which still preserve backwards and forwards compatibility. Proposed SDL change 6: Extend ITU-T Recommendation Z.105 [6] transformation rules...
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5.8A ASN.1 - SDL Type Equivalence
We need to define a clear interface between ASN.1 and SDL that specifies unambiguously the type correspondence. This will extend ITU-T Recommendation Z.105 [6] appropriately in order to manipulate variables of a type defined in ASN.1 from SDL. ASN.1 provides the subtyping mechanism to limit values of an existing type. ...
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5.9 Support of SDL operators for ASN.1 types
ASN.1 does not support operators and ITU-T Recommendation Z.105 [6] does not give any clean possibility to add them in the SDL specification. Not enabling the use of operators is defying the purpose of encapsulation introduced by object orientation in SDL. This limitation will affect the resulting SDL specification and...
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5.9.1 Inheritance of ASN.1 data types
It should be possible to inherit imported / used ASN.1 data types in the same manner as SDL sorts, and be able to add literals and operators to the new type definition. This would ensure that the only difference in usage between SDL sorts and ASN.1 type definitions is in the use clause, and the rationale for this diffe...
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5.9.2 Multiple references to packages / definitions
It will often be the case that whole packages are imported / used into an SDL specification, but that only some of the definitions require operators associating with them. Given the SDL definition: Use myModule; Use myModule/Expert; This is currently allowed as defined in ITU-T Recommendation Z.100 [5] (the union of re...
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5.10 SDL support for CHOICE, OPTIONAL and DEFAULT
This item is being addressed by ITU-T SG10-Q 6 group.
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5.11 List of proposed changes to SDL
Table 1: List of changes to SDL No. Description Note 1 Change Z.100 [5] to make SDL case sensitive. It is further proposed to define a definite case for keywords (either upper- or lower case). 2 Remove in-line ASN.1 from Z.105 [6] (and thus from SDL). 3 Extend SDL to allow optional encoding reference on signal paramete...
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6 Changes to TTCN
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6.1 Summary of TTCN issues
The following list summarizes the issues associated with harmonizing TTCN-ASN.1: • ASN.1 constraints in TTCN; • additional ASN.1 string types in TTCN; • ASN.1 information objects in TTCN; • ASN.1 type parameterization in TTCN; • ASN.1 extension markers in TTCN; • automatic ASN.1 tagging in TTCN; • ASN.1 exception ident...
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6.2 Support of ASN.1 Constraints in TTCN
This clause is divided into two sections. The first section concerns the specification of values within ASN.1 constraints. The second section describes proposals to allow matching mechanisms to be specified for constraint fields.
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6.2.1 Specification of Constraint Values
This section deals with issues of the TTCN/ASN.1 interface associated with specifying a distinct value to an ASN.1 constraint field. As illustrated below: • the use of TTCN test suite constants in ASN.1 constraints proformas; • the use of expressions in ASN.1 constraints proformas; • the inclusion of ASN.1 field identi...
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6.2.2 Specification of Matching Attributes
The remaining problem is the use of TTCN value constraint types within the ASN.1 PDU constraints declaration to define matching attributes as shown in figure 6. ASN.1 PDU Constraint Declaration Constraint Name : TCON_Class4_2 PDU Type : T_CONNECT1 Derivation Path : Comments : Constraint Value { source ?, connect ?, t_C...
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6.3 Additional ASN.1 String Types in TTCN
ASN.1:1994 introduced the string types: • BMPString • UniversalString And ASN.1:1997 introduces the string type: • UTF8String In order to handle those new string types in TTCN, it is proposed that they are included in the TTCN language. Proposed TTCN change 8: Include the new string types: BMPString, UniversalString an...
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6.4 Information Objects in TTCN
Information objects provide a generic table mechanism within the ASN.1 language. This feature replaces the earlier macro notation and is primarily used to fill-in gaps in a type definition dependant on one or more key fields. There are three operations associated with ASN.1 information objects, Definition, Instantiatio...
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6.4.1 Defining Information Objects
Proposed TTCN change 9: Add new proforma and BNF productions to allow definition of information objects Classes. The format of the information object proforma is shown in figure 14. These proformas should be included in the declarations part of the test suite. The proposed new hierarchy for the declarations part is sho...
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6.4.2 Declaring Information Object Sets
Proposed TTCN change 10: Add new proformas and BNF productions to allow declaration of information objects and information object sets. The proposed proforma for information object declaration is shown in figure 16 with the definition of the information object set proforma in figure 17. These proformas should be placed...
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6.4.3 Referencing Information Objects
The ability to reference types and values from ASN.1 information object from within TTCN is already implicitly included in the existing TTCN language specification. This is because the TTCN BNF specification references the ASN.1 productions Type and Value which in turn give access to the information objects.
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6.5 ASN.1 parameterization in TTCN
Current TTCN supports only a part of the possible ASN.1: 1997 parameterization features. To allow full and consistent use of ASN.1: 1997 parameterization from within TTCN the language must be extended to resolve two major issues. The first issue to resolve is the provision of a unique parameter syntax for TTCN and ASN....
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6.5.1 Parameterization syntax
The current TTCN language defines the syntax of a parameter list in the following way: ( name1: TYPE1; name2: TYPE2 ) whereas in ASN.1:1997 takes the form: { TYPE1: name1, TYPE2: name2 } The proposed solution is to adopt the ASN.1 format for parameter syntax because of the enhanced functionality (for type parameterizat...
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6.5.2 Proforma changes to support parameterization
Currently, parameterization is defined within TTCN in the following: • value parameterization in ASP & PDU constraints; • "partial" type parameterization in ASPs, by being able to define PDUs as parameters; • parameterization of test steps. In contrast, ASN.1: 1997 provides a much broader and more powerful idea of para...
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6.6 Extension Markers in TTCN
ASN.1:1997 allows extensibility to be specified within a syntax definition, either explicitly using the extension marker "…" or globally to an ASN.1 module by assigning an optional field in the module header (ITU-T Recommendation X.680 [1]). The extension marker is visible in some transfer syntaxes such as PER, and so ...
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6.7 Automatic Tagging in TTCN
ASN.1: 1997 introduces the feature of AUTOMATIC tagging. This provides a new tagging mode in addition to the existing IMPLICIT and EXPLICIT. When AUTOMATIC tagging is selected the system will automatically insert any necessary tags within the associated module without the need for user intervention (N.B. the user still...
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6.8 Exception Identifiers in TTCN
It could be of benefit to be able to reference exception cases in ASN.1 type definitions when used in TTCN. Those exceptions would be for handling run-time errors and thus might be useful for feedback to TTCN tools e.g. through record in the log file. The proposed approach is a simplest one that does not impact on TTCN...
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6.9 List of proposed changes to TTCN
Table 2: List of changes to TTCN No. Description 1 Field identifiers are mandatory in all ASN.1 constraints proformas. 2 TTCN Test Suite Constants must be passed into ASN.1 constraints definitions as actual parameters. 3 The use of expressions with ASN.1 constraints definitions shall be forbidden. 4 Only the value nota...
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7 Changes to ASN.1
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7.1 Summary of ASN.1 issues
The following list summarizes the issues for harmonizing ASN.1-SDL/TTCN: • ASN.1 identifiers; • ASN.1 keywords. 7.2 Addition of ‘underscore’ to ASN.1 identifiers Currently, it is possible to use hyphens in ASN.1 identifiers. This is defined in ITU-T Recommendation X.680 [1]: an identifier name "shall consist of an arbi...
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7.2.1 Consequences and migration
The consequence of the proposed change is that ASN.1 modules conforming to the ITU-T Recommendation X.680 [1] series specifications can be written in (or transformed too) a syntax which can be directly used within other high level specification languages. The proposal also retains full backwards compatibility with the ...
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7.3 Alternative syntax for ASN.1 keywords
ASN.1 currently defines the following base types with space separators between the two keywords. • OCTET STRING • BIT STRING • CHARACTER STRING • OBJECT IDENTIFIER • EMBEDDED PDV Whilst doing this slightly reduces the number of keywords required within the language, it is not clear what further benefit it provides. whe...
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7.3.1 Consequences and migration
The consequence of the proposed change is that ASN.1 modules conforming to the ITU-T Recommendation X.680 [1] series specifications can be written in (or transformed too) a syntax which can be directly used within other high level specification languages. The proposal also retains full backwards compatibility with the ...
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7.4 List of proposed changes to ASN.1
The following table lists the required changes to ASN.1(ITU-T Recommendation X.680 [1]) Table 3: List of changes to ASN.1 No. Description 1 Extend the definition of identifier name to allow the use of underscores as well as hyphens 2 Extend the ASN.1 syntax to include an alternative set of keywords containing no space ...
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1 Scope
The present document contains technical performance objectives that should be met for the fixed infrastructure of GSM PLMNs. Concerning transmission delay for the PLMN in clause 4, the requirements should also be met by GSM Mobile Stations (MS)s. These performance design objectives are applicable to all implementations...
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1.1 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. • Fo...
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1.2 Abbreviations
Abbreviations used in the present document are listed in GSM 01.04.
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2 General
For terminology and architecture for GSM PLMNs see GSM 03.02. Interfaces, interface characteristics, connections through an MSC and ancillary functions of the MSC are defined in GSM 11.30. The functions supported by HLRs and VLRs are given in GSM 11.31 and 11.32. Each MSC will be responsible for synchronisation, if req...
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3 Performance design objectives
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3.1 General
Part of the text is taken from CCITT Recommendation Q.543 and part from CEPT Recommendation T/S 64-30.
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3.2 MSCs
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3.2.1 Reference loads
The reference loads are traffic load conditions under which the performance design objectives stated below are to be met. The following reference loads are defined. a) Reference load for incoming inter-exchange circuits; b) Reference load for circuit switched MS calls. Reference load A is intended to represent the norm...
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3.2.1.1 Reference load on incoming interexchange circuits
a) Reference load A - 0,7 Erlang average occupancy on all incoming circuits with 35 call attempts/hour/incoming circuit. This figure assumes 45 % ineffective call attempts. b) Reference load B - 0,85 Erlang average occupancy on all incoming circuits with 42 call attempts/hour/incoming circuit.