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13 Specification of constraints using tables
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13.1 Introduction
This clause describes the specification of tabular constraints on Structured Types, ASPs and PDUs. It describes how single constraint tables can be used to specify constraints on flat (unstructured) ASPs or PDUs and how structured constraints can be specified by declaring constraints on Structured Types, defined in the...
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13.2 Structured Type Constraint Declarations
If an ASP or PDU is defined using Structured Types, either as macro expansions or substructures, constraints for these ASPs or PDUs shall be similarly substructured. The following information shall be supplied for each Structured Type Constraint: a) the name of the constraint, which may be followed by an optional forma...
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13.3 ASP Constraint Declarations
The parameter values for ASP constraints shall be provided in the format shown in the following proforma: ASP Constraint Declaration Constraint Name : ConsId&ParList Group : [ASP_ConstraintGroupReference] ASP Type : ASP_Identifier Derivation Path : [DerivationPath] Comments : [FreeText] Parameter Name Parameter Value C...
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13.4 PDU Constraint Declarations
In the tabular format a constraint is defined by specifying a value and optional attributes for each PDU field. The following information shall be supplied for each PDU constraint: a) the name of the constraint, which may be followed by an optional formal parameter list; b) the PDU type name; c) the derivation path (se...
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13.5 Parameterization of constraints
Constraints may be parameterized using a formal parameter list. The actual parameters are passed to a constraint from a constraints reference in a behaviour description. EXAMPLE 53: A parameterized constraint PDU Constraint Declaration Constraint Name : C2 (P1:INTEGER; P2:BOOLEAN) PDU Type : PDU_B Derivation Path : Com...
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13.6 Base constraints and modified constraints
For every ASP, PDU or CM type definition at least one base constraint may be specified. In the case in which an ASP or CM has no parameters or a PDU has no fields, constraints are irrelevant and hence base constraints are unnecessary. A base constraint specifies a set of base, or default, values or matching symbols for...
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13.7 Formal parameter lists in modified constraints
If a base constraint is defined to have a formal parameter list, the following rules apply to all modified constraints derived from that base constraint, whether or not they are derived in one or several modification steps: a) the modified constraint shall have the same parameter list as the base constraint. In particu...
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13.8 CM Constraint Declarations
The field values for CM constraints shall be provided in the format shown in the following proforma: CM Constraint Declaration Constraint Name : ConsId&ParList Group : [CM_ConstraintGroupReference] CM Type : CM_Identifier Derivation Path : [DerivationPath] Comments : [FreeText] Parameter Name Parameter Value Comments ....
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14 Specification of constraints using ASN.1
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14.1 Introduction
This clause describes a method of specifying Type, ASP and PDU constraints in ASN.1, in a way similar to the definition of tabular constraints. The normal ASN.1 value declaration is extended to allow the use of the matching mechanisms. Mechanisms to replace or omit parts of ASN.1 constraints, to be used in modified con...
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14.2 ASN.1 Type Constraint Declarations
Both ASN.1 ASP constraints and ASN.1 PDU constraints can be structured by using references to ASN.1 Test Suite Type constraints for values of complex fields. ASN.1 Test Suite Types are defined in the declarations part of the ATS. The following information shall be supplied for each ASN.1 Type Constraint Declaration: a)...
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14.3 ASN.1 ASP Constraint Declarations
The following information shall be supplied for each ASN.1 ASP Constraint Declaration: a) the name of the constraint, which may be followed by an optional formal parameter list; b) the ASP type name; c) the derivation path (see 13.6 and 14.6), if an ASN.1 Constraint Declaration is a modification of an existing ASN.1 co...
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14.4 ASN.1 PDU Constraint Declarations
The following information shall be supplied for each ASN.1 PDU Constraint Declaration: a) the name of the Constraint, which may be followed by an optional formal parameter list; b) the PDU type name; c) the derivation path (see 13.6 and 14.6); d) the encoding rules to be used for the Constraint, in order to specify exp...
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14.5 Parameterized ASN.1 constraints
ASN.1 constraints may be parameterized (see 13.5).
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14.6 Modified ASN.1 constraints
ASN.1 constraints can be specified by modifying an existing ASN.1 constraint. Portions of a constraint can be respecified to create a new constraint by using the REPLACE/OMIT mechanism. Particular parameters or fields of a base or a modified constraint may be identified through a list of field selectors in order to rep...
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14.7 Formal parameter lists in modified ASN.1 constraints
The requirements of 13.7 also apply to modified ASN.1 constraints. 14.8 ASP Parameter and PDU field names within ASN.1 constraints When specifying a constraint for an ASP or PDU in ASN.1, the parameter or field identifiers defined in the ASN.1 type definition for SEQUENCE, SET and CHOICE types may be used in order to i...
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14.9 ASN.1 CM Constraint Declarations
The parameter values for CM constraints shall be provided in the format shown in the following proforma: ASN.1 CM Constraint Declaration Constraint Name : ConsId&ParList Group : [ASN1_CM_ConstraintGroupReference] CM Type : CM_Identifier Derivation Path : [DerivationPath] Comments : [FreeText] Constraint Value Constrain...
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15 The Dynamic Part
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15.1 Introduction
The Dynamic Part contains the main body of the test suite: the Test Case, the Test Step and the Default behaviour descriptions.
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15.2 Test Case dynamic behaviour
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15.2.1 Specification of the Test Case Dynamic Behaviour table
The title of the table shall be "Test Case Dynamic Behaviour". The header shall contain the following information: a) Test Case name, giving a unique identifier for the Test Case described in the table; b) Test Group Reference, giving the full name of the lowest level to the group that contains the Test Case; that full...
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15.2.2 The Test Case Dynamic Behaviour proforma
The Test Case dynamic behaviour shall be provided in the format shown in the following proforma: Test Case Dynamic Behaviour Test Case Name : TestCaseIdentifier Group : TestGroupReference Purpose : FreeText Configuration : TCompConfigIdentifier Defaults : [DefaultRefList] Comments : [FreeText] Nr Label Behaviour Descri...
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15.2.3 Structure of the Test Case behaviour
Each Test Case contains a precise description of sequences of (anticipated) events and related verdicts. This description is structured as a tree, with TTCN statements as nodes in that tree and verdict assignments at its leaves. In many cases it is more efficient to use Test Steps as a means of substructuring this tree...
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15.2.4 Concurrent Test Case Behaviour Description
If PTCs are used in a test case then the header shall contain the additional entry, Configuration, which shall identify a Test Component Configuration declared in the Declaration Part. The first tree in the Test Case Behaviour table plus all attached trees describe the behaviour of the MTC. The MTC behaviour tree creat...
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15.2.5 Line numbering and continuation
Since lines in the behaviour description, when printed, may be too long to fit on one line it is necessary to use additional symbols to indicate the extent of a single behaviour line. There are two available techniques: a) indicate the beginning of a new behaviour line; an extra line column is added as the leftmost col...
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15.3 Test Step dynamic behaviour
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15.3.1 Specification of the Test Step Dynamic Behaviour table
The dynamic behaviour of Test Steps is defined using the same mechanisms as for Test Cases, except that Test Steps can be parameterized (see 15.7). Test Step dynamic behaviour tables are identical to Test Case dynamic behaviour tables, except for the following differences: a) the table has the title "Test Step Dynamic ...
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15.3.2 The Test Step Dynamic Behaviour proforma
The Test Step dynamic behaviour shall be provided in the format shown in the following proforma: Test Step Dynamic Behaviour Test Step Name : TestStepId&ParList Group : TestStepGroupReference Objective : FreeText Defaults : [DefaultRefList] Comments : [FreeText] Nr Label Behaviour Description Constraint Ref Verdict Com...
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15.4 Default dynamic behaviour
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15.4.1 Default behaviour
A TTCN Test Case shall specify alternative behaviour for every possible event (including invalid ones). It often happens that in a behaviour tree every sequence of alternatives ends in the same behaviour. This behaviour may be factored out as default behaviour to this tree. Such Default behaviour descriptions are locat...
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15.4.2 Specification of the Default Dynamic Behaviour table
Default dynamic behaviour tables are identical to Test Step dynamic behaviour tables, except for the following differences: a) the table has the title "Default Dynamic Behaviour"; b) the first item in the header is the Default name, which is a unique identifier for the Default followed by an optional list of formal par...
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15.4.3 The Default Dynamic Behaviour proforma
The Default dynamic behaviour shall be provided in the format shown in the following proforma: Default Dynamic Behaviour Default Name : DefaultId&ParList Group : DefaultGroupReference Objective : FreeText Comments : [FreeText] Nr Label Behaviour Description Constraint Ref Verdict Comments 1 2 . . . . n . . . [Label] . ...
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15.5 The behaviour description
The behaviour description column of a dynamic behaviour table contains the specification of the combinations of TTCN statements that are deemed possible by the test suite specifier. The set of these combinations is called the behaviour tree. Each TTCN statement is a node in the behaviour tree.
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15.6 The tree notation
Each TTCN statement shall be shown on a separate statement line. The statements can be related to one another in two ways: - as sequences of TTCN statements; - as alternative TTCN statements. Sequences of TTCN statements are represented one statement line after the other, each new TTCN statement being indented once fro...
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15.7 Tree names and parameter lists
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15.7.1 Introduction
Each behaviour description shall contain at least one behaviour tree. In order that trees may be unambiguously referred to (such as in an ATTACH construct) each tree has a tree name. The first tree appearing within a behaviour description is called the root tree. The name of a root tree is the identifier appearing in t...
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15.7.2 Trees with parameters
All trees, except Test Case root trees, may be parameterized. The parameters may provide PCOs, constraints, variables or other such items for use within the tree. Test Case root trees shall not be parameterized. If a tree is parameterized, then a list of formal parameters and their types shall appear within parentheses...
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15.8 TTCN statements
The tree notation allows the specification of test events initiated by the Lower Tester(s) or Upper Tester(s) (SEND and IMPLICIT SEND events), test events received by the Lower Tester(s) or Upper Tester(s) (RECEIVE, OTHERWISE, TIMEOUT and DONE), constructs (GOTO, ATTACH, REPEAT, CREATE, RETURN and ACTIVATE) and pseudo-...
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15.9 TTCN test events
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15.9.1 Sending and receiving events
TTCN supports the initiation (sending) of ASPs and PDUs to named PCOs and acceptance (receipt) of ASPs and PDUs at named PCOs. The PCO model is defined in 11.10 and 15.9.5.3.Concurrent TTCN supports the sending and receiving of CMs to named CPs. The CP model is defined in 11.11. In the simplest form, an ASP identifier ...
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15.9.2 Receiving events
A RECEIVE event line evaluates successfully if an incoming ASP or PDU on the specified PCO matches the event line. A match occurs if the following conditions are fulfilled: a) the incoming PDU can be decoded in accordance with the applicable encoding rules; b) the incoming ASP or PDU is valid according to the ASP or PD...
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15.9.3 Sending events
A SEND event line with a qualifier is successful if the expression in the qualifier evaluates to TRUE. Unqualified SEND events are always successful. The outgoing ASP or PDU that results from a SEND event shall be constructed as follows: a) All ASP parameter and PDU field values shall be of the type specified in the co...
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15.9.4 Lifetime of events
Identifiers of ASP parameters and PDU fields associated with SEND and RECEIVE shall be used only to reference ASP parameter and PDU field values on the statement line itself. In the case of SEND events, relevant ASP parameters and PDU fields can be set, if required, in appropriate assignments on the SEND line. EXAMPLE ...
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15.9.5 Execution of the behaviour tree
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15.9.5.1 Introduction
The test suite specifier shall organize the behaviour tree representing a Test Case or a Test Step according to the following rules regarding test execution: a) starting from the root of the tree, the LT or UT remains on the first level of indentation until an event matches. If an event is to be initiated the LT or UT ...
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15.9.5.2 The concept of snapshot semantics
The alternative statements at the current level of indentation are processed in their order of appearance. TTCN operational semantics (see annex B) assume that the status of any of the events cannot change during the process of trying to match one of a set of alternatives. This implies that snapshot semantics are used ...
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15.9.5.3 Restrictions on using events
In order to avoid test case errors the following restrictions apply: a) a Test Case or Test Step should not contain behaviour where the relative processing speed of the MOT (Means of Testing) could impact the results. To prevent such problems, a RECEIVE, OTHERWISE or TIMEOUT event line shall only be followed by other R...
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15.9.5.4 Precautions when using concurrent TTCN
Precautions should be taken when using concurrent TTCN to avoid unrepeatable results caused by situations in which the order of receipt of events at different PCOs or at different CPs is used to determine verdict assignment. The actual time at which a PDU or CM is received, relative to the receipt of other PDUs or CMs,...
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15.9.6 The IMPLICIT SEND event
In the Remote Test Methods, although there is no explicit PCO above the IUT, it is necessary to have a means of specifying, at a given point in the description of the behaviour of the LT, that the IUT should be made to initiate a particular PDU or ASP (but not CM). For this purpose, the implicit send event is defined, ...
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15.9.7 The OTHERWISE event
The predefined event OTHERWISE is the TTCN mechanism for dealing with unforeseen test events in a controlled way. OTHERWISE is used to denote that the LT or UT shall accept any incoming event that has not previously matched one of the alternatives to the OTHERWISE. The tester shall accept any incoming data that it has ...
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15.9.8 OTHERWISE and concurrent TTCN
In concurrent TTCN, OTHERWISE may be used with CPs as well as PCOs. OTHERWISE on CPs is allowed to provide an efficient way of handling "all other CMs on this CP".
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15.9.9 The TIMEOUT event
The TIMEOUT event allows expiration of a timer, or of all timers, to be checked in a Test Case. When a timer expires (conceptually immediately before a snapshot processing of a set of alternative events), a TIMEOUT event is placed into a timeout list. The timer becomes immediately inactive. Only one entry for any parti...
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15.9.10.1 The CREATE construct
The Main Test Component is started at the beginning of Test Case execution. The Main Test Component starts Parallel Test Components, as needed, by means of the CREATE construct. This construct invokes a set of Parallel Test Components. For each PTC, there are two arguments. The first is the identifier of the PTC that i...
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15.9.10.2 The DONE event
When the MTC terminates, the final verdict is assigned by the MTC, as calculated up to this moment (15.17.5). The DONE event can be used in the MTC and the PTCs to find out whether PTCs have already terminated. Test Components can use this information to determine their own preliminary results and further actions; in p...
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15.10 TTCN expressions
15.10.1 Introduction There are two kinds of expressions in TTCN: assignments and Boolean expressions. Both assignments and Boolean expressions may contain explicit values and the following forms of reference to data objects: a) Test Suite Parameters. b) Test Suite Constants. c) Test suite and Test Case Variables. d) Fo...
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15.10.2.1 Introduction
In order to permit references to components of data objects defined using ASN.1, TTCN provides three access mechanisms: record references, array references and bit references.
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15.10.2.2 Record references
A record reference may be used to reference to a component of a data object of the type SEQUENCE, SET or CHOICE. A record reference is constructed using a dot notation, appending a dot and the name (component identifier) or number (component position) of the desired component to the data object identifier. The componen...
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15.10.2.3 Array references
An array reference may be used to reference a component of a data object of the type SEQUENCE OF or SET OF. An array reference shall be constructed using a dot notation, appending a dot and the index of the desired component to the data object identifier. The index, giving the position of the component within the data ...
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15.10.2.4 Bit references
A bit reference may be used to reference particular bits within a BITSTRING type. For this purpose, data objects of BITSTRING type are assumed to be defined as SEQUENCE OF {BOOLEAN}. Thus, a bit reference may be constructed using the index notation as for array references. The leftmost bit has the index zero. An expres...
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15.10.4.1 Introduction
Test events may be associated with a list of assignments and/or a qualifier. Commas separate assignments and the list is enclosed in parentheses. During execution of an assignment the right-hand side shall evaluate to an element of the type of the left-hand side. The effect of an assignment is to bind the Test Case or ...
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15.10.4.2 Assignment rules for string types
If length-restricted string types are used within an assignment the following rules apply: a) if the destination string type is defined to be shorter than the source string, the source string is truncated on the right to the maximum length of the destination string type; b) if the source string is shorter than that all...
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15.11 Pseudo-events
It is permitted to use assignments, qualifiers and timer operations by themselves on a statement line in a behaviour tree, without any associated event. These stand-alone expressions are called pseudo-events. The meaning of such a pseudo-event is as follows: a) if only a qualifier is specified: the qualifier is evaluat...
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15.12 Timer management
15.12.1 Introduction A set of operations is used to model timer management. These operations can appear in combination with events or as stand-alone pseudo-events. Timer operations can be applied to: - an individual timer, which is specified by following the timer operation by the timer name; - all timers, which is spe...
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15.13 The ATTACH construct
15.13.1 Introduction Trees may be attached to other trees by using the ATTACH construct. Test suite and Test Case Variables are global to both the tree that does the attachment (the main tree) and the attached tree, i.e., any changes made to variables in an attached tree also apply to the main tree. Tree attachment con...
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15.14 Labels and the GOTO construct
A label may be placed in the labels column on any statement line in the behaviour tree. NOTE 1: Whenever an entry is executed in the behaviour tree for which a label is specified, that label should be recorded in the conformance log in such a way that it can be associated with the record of the execution of that entry....
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15.15 The REPEAT construct
This subclause describes a mechanism to be used in behaviour descriptions for iterating a Test Step a number of times. The tree reference shall be a reference to either a local tree or a Test Step defined in the Test Step Library. For the rules of attachment see 15.13. The REPEAT construct has the following meaning: fi...
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15.16 The Constraints Reference
15.16.1 Purpose of the Constraints Reference column This column allows references to be made to a specific constraint placed on an ASP, PDU or CM. Such constraints are defined in the constraints part (see clause 12, 13 and 14). The constraints reference shall be present in conjunction with SEND, IMPLICIT SEND and RECEI...
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15.17 Verdicts
15.17.1 Introduction Entries in the verdict column in Dynamic Behaviour tables shall be either: - a preliminary result, which shall be given in parentheses; - or an explicit final verdict. An entry, of either type, shall not occur on an empty line, or on the following TTCN statements: a) an ATTACH construct; b) a REPEA...
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15.18 The meaning of Defaults
15.18.1 Introduction In many cases Default behaviour will be used to emphasize a set of interesting paths through a test by declaring the less interesting common alternatives (+ their subsequent behaviour) as Default behaviour. The same effect, though less concisely, would be achieved by Test Step attachment (e.g., +DE...
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16 Page continuation
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16.1 Page continuation of TTCN tables
When any TTCN table is too long to fit on a single page the following mechanism shall be used: a) the words "Continued on next page" shall be printed after the table line where the split occurs; b) the words "Continued from previous page" shall be printed before the continued table on the next page. Tables may be split...
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16.2 Page continuation of dynamic behaviour tables
When it is necessary to continue a dynamic behaviour table, then either of the following two mechanisms can be used: a) modularization, where some part of the behaviour of the tree is specified as a library (non-local) Test Step, thereby modularizing the tree and reducing the amount of behaviour for the current proform...
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1 Scope
The present document discusses the issues on the application of Time Division Duplex (TDD) in the Fixed Service bands for Fixed Wireless Access (FWA) Point-to-Multipoint (P-MP) applications. It examines the advantages and disadvantages of applying TDD techniques to such systems, and it discusses the differences between...
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2 References
For the purposes of this Technical Report (TR) the following references apply: [1] SRSP-303.4: "Technical Requirements for Fixed Wireless Access Systems Operating in the Band 3 400 - 3 700 MHz". [2] MII (1998) No.649: "Document of the Ministry of Information Industry, China, Notification on Management Rules of 1,9 GHz ...
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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: fixed wireless access: defined by the ITU as a wireless access application in which the location of the end user terminal and network access point to connect to the end user are fixed. However, throughout the present document the term ...
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3.2 Abbreviations
For the purposes of the present document, the following abbreviations apply: CEPT Conférence Européenne des Postes et Télécommunications CCS Central Controller Station CRS Central Radio Station CS Central Station DECT Digital Enhanced Cordless Telephone ETSI European Telecommunications Standards Institute ETSI ETSI TR ...
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3a Executive Summary
Clause 4 of the present document reviews the attributes of Time Division Duplex (as opposed to Frequency Division Duplex) in the context of in Fixed Wireless Access systems. Whilst identifying several positive features of TDD, it recognizes that FDD claims benefits in simplifying frequency management. Clause 5 discusse...
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4.1 Fixed Wireless Access Systems
ETSI WG TM4 is developing a substantial number of standards for a class of systems which provide duplex telecommunications services to several terminal stations (TS) from a central radio station (CRS) which in turn is connected to a switch or other telecommunications network node. Separate Standards have been, or are b...
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4.2 The TDD technique
Time Division Duplex (TDD) is not a new technique but it is one that is often overlooked in fixed service channel plans and by Regulators. It is a technique widely used in two way digital communications systems where the two directions of traffic (up and down) of one channel are carried on the same carrier frequency bu...
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4.3 Attributes of TDD
Some of the positive attributes claimed for TDD, as compared with FDD, are: 1) simplification of some equipment: for example, the diplexor can be replaced by a lower cost solid state transmit/receive switch, and other components required by a second radio channel such as mixer, oscillator, and synthesizer; 2) because b...
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5 Deployment issues of P-MP FWA systems
The ability of unlike FWA systems to coexist depends as much on deployment issues as it does on their technological attributes. This clause explores how regulatory and deployment characteristics of FWA systems differ from other wireless communications systems.
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5.1 Typical P-MP FWA regulatory regime
It is assumed that the Regulator will wish to delegate the clearance of all stations that comprise a P-MP FWA system to licensed operators. This is because it is supposed that the numbers of stations in a P-MP FWA system is likely to be large and the establishment of stations on customer premises will be carried out at...
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5.2 How FWA differs from P-P and Cellular Mobile systems
Conventional wisdom on the use of traditional FDD techniques to address coexistence issues stems largely from experience of fixed Point-to-Point (P-P) systems and cellular mobile systems. We should be wary of assuming that FDD addresses the coexistence issue of P-MP FWA systems, just because it has been applied in thes...
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6 The interference scenarios
In this clause we report on a number of pieces of independent work investigating the interference scenarios between two Fixed Service systems operating in the same area with adjacent assignments within the same Fixed Service band. In particular, the effects of unlike combination of the chosen duplex methods are being i...
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6.1 Coexistence issues for FDD and TDD P-MP systems
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6.1.1 Introduction
This clause draws upon other work in TM4 on coexistence of different TM4 standards which are now published as TR 101 853 [13]. That TR develops a quantitative analysis of interference scenarios this clause and uses a similar methodology to that developed in that Technical Report. This clause analyses the main coexisten...
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6.1.2 PMP interference classes
When considering the deployment of PMP systems there are four possible classes of interference to be considered. The distinction is based on different pairs of source (interfering system) and destination of interference (victim system) as follows: - Class A1: the interference source is the CRS of the interfering system...
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6.1.3 FDD/FDD scenarios
When considering two FDD systems operating on adjacent (or near, if guard bands are foreseen) channels there are only two possible channel arrangements as depicted in figure 2. In case 1, both systems use the same sub-band for down-link and, consequently, also for up-link while in case 2 they use the opposite sub-band....
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6.1.4 FDD/TDD scenarios
When considering an FDD and a TDD system operating on adjacent (or near, if guard bands are foreseen) channels there are three possible channel arrangement as depicted in figure 3. For simplicity the FDD system up/down arrangement is given in that particular sub-bands but it is the same if the arrangement is the opposi...
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6.1.5 TDD/TDD scenario
When considering two TDD systems operating on adjacent (or near, if guard bands are foreseen) channels there is only one possible channel arrangement as depicted in figure 4: the two channels are adjacent or near. The only difference that could be taken into account is whether the systems are synchronous in transmissio...
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6.1.6 Conclusion of this coexistence work of TM4
From the coexistence and co-ordination point of view FDD/FDD channel arrangements presents some advantages with respect FDD/TDD or TDD/TDD channel arrangements. These advantages do not depend depending on actual scenario, although their significance might do. In particular, if one sub-band is dedicated for CRS transmis...
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6.2.1 One view of co-ordination of FDD or TDD systems
The interference scenarios in P-MP and P-P systems when either FDD or TDD are used are based on an hypothesis of geographical deployment corresponding to several networks operated in the frequency band and belonging to different operators. For the most general case, the links are randomly distributed over a given area ...
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6.2.2 Another view of the possible interference modes
Annex A, which is based on an unpublished paper submitted to SE19, considers the various interference situations between two independently deployed P-MP FWA systems operating in adjacent (or near adjacent) parts of the same fixed service band. It is assumed that the band plan has paired frequencies and so can accommoda...
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6.3 The interference problem in adjacent frequency bands
This clause, and the associated annex F, was drafted by an expert group and was based on material derived from PCS Interference Experts Group on incompatibility issues between FWA and PCS systems. When two systems are allocated in adjacent frequency bands it is probable that devices using the closer carriers to the com...
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6.4 The overlapping cell problem
This clause addresses a specific interference scenario originally developed by EP-DECT in TR 101 370 [15] and has been further developed and adapted to be applied FWA systems in general. The analysis is reported in annex E. This concerns the so-called "overlapping cell problem". annex E considers the potential interfer...
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6.5 A view of FDD/FDD versus FDD/TDD scenarios
This clause is a further ab initio view of the differences and similarities of FDD - FDD and FDD - TDD interference scenarios submitted by an expert group. It is often asserted that the interference scenarios of two FDD systems operating in the same area is significantly less severe and complex to manage than two TDD o...
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6.6 Interference scenarios and results
Using TDD systems alongside FDD systems introduces two additional coupling mechanisms: CRS-CRS and TS-TS. Each coupling has a different significance depending on whether the systems operate in adjacent channels or co-channel. ERC Report 99 [14] contains some analysis of the level of interference for both couplings in b...
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6.6.1 CRS-CRS interference