1. Use of ITU-T languages in Nokia
Experiences and Challenges
Colin Willcock
Nokia Research Center
ITU-T Workshop
Geneva, July 2004

2. Contents Specification Languages Testing Languages Future Trends MSC
ASN.1
SDL
Testing Languages
TTCN-2
TTCN-3
Future Trends

3. Specification: MSC used in two ways: design and requirements notation
to clarify interactions of components in a system (both in standards and in implementations)
used extensively for the representation of design and requirements for software object interaction with messages
trace output notation
to show how system behaved(in environments that naturally support this (=Telelogic tools))
used with phone trace output to provide a clear representation of the phones behaviour. A number of tools are used to provide MSC representation from phone software trace output.

4. Specification: ASN.1
Used a lot. Partly because it is used in a lot of standards in mobile communication. But also it has been found a convenient means to define protocols and to get codecs generated automatically.
Used extensively in conjunction with TTCN-2 and SDL to define data types used in the protocol software implementation and testing. i.e. both products and product test systems.
Internal CASN compiler tools
SDL. Note: not following Z.105 but defined own mapping of ASN.1 to SDL data.

5. Specification: SDL
SDL is used to create protocol emulators for testers. This is enabled by 3G SDL library project.
Nokia NET has own version of the SDL that is is used quite extensively in some products.
On the NMP side used extensively for the design of many protocol software sub-systems (embedded and workstation based simulation). These models are used as the basis for automatic code generation using various SDL->C code generators.

6. Current Specification Process
Step 1 - System architecture
functional specification: text with embedded MSC diagrams
Stage 2 - Protocol specification
object-oriented analysis and design with UML
detailed protocol specification as an SDL-model
messages and information elements described as ASN.1 protocol data units
layer interfaces described as ASN.1 abstract service primitives
Stage 3 - Protocol implementation
may use code generation from SDL or other methods based on SDL specifications
Step 1 - System architecture
functional specification: text with embedded MSC diagrams
in our case: JAFFA project deliverables
Stage 2 - Protocol specification
object-oriented analysis and design with UML
detailed protocol specification as a SDL-model => needs to pass validation (by human observation) and verification (by computer-aided analysis); the latter serves the same purpose as simulation studies w.r.t. multiple-access method selection on layer 1
messages and information elements described as ASN.1 protocol data units
validation and verification of the specified protocols
layer interfaces described as ASN.1 abstract service primitives
in our case: GUN project deliverables
Stage 3 - Protocol implementation
may use code generation from SDL or other methods
in our case: 3gen product development 7 7 7

7. Introduction of TTCN-2 Testing
Since 1993 TTCN-2 testing has been used in testing of
GSM network elements: MSC/VLR, HLR, BSC, MS
Other 2nd generation mobile phones: D-AMPS
Transmission systems: V5.x
IN systems: SSP, SCP
In-house TTCN-2 tool developed with HUT
first compiler based on DIS version of the TTCN language in
tight integration with Nokia in-house ASN.1 tools

8. Early Experiences on TTCN-2 Testing
testing with several PCOs: some PCOs are used as means for triggering test events to other PCOs
well-designed test suites can be executed and analyzed automatically
TTCN test suites are designed by a test team, which is independent from the product development team
tools for TTCN programming are available
development of an ETS based on TTCN ATS still requires some programming for test adaptors
TTCN based method is not as flexible for interactive probing as protocol emulators
validation of TTCN test suites prior to testing against SUT is a must

9. Evolution of TTCN-2 Testing
Test automation has evolved with TTCN
Modular and Concurrent TTCN in network element testing
Improved integration with other languages => TTCN-2
Modelling of PDUs in ASN.1 also for non-ASN.1 protocols
Cosimulation with SDL as means for test case validation
MSC tracing of test case executions
Standardized test suites, especially by ETSI
Automatic test case generation – still a promise?
TTCN testing has expanded to new systems within Nokia
GPRS: SGSN
UMTS: Node-B, RNC, MSC Server, MGW
VoIP: CPS, HSS

10. Testing: TTCN-2 Summary
Still under development at international bodies, e.g. Bluetooth and the test system for 3G UEs.
Used extensively in Workstation and HW platform test environments for testing protocol software. This includes sub-system integration, system integration, release, regression and conformance testing.
Quite successful in conformance testing but limitations in flexibility and ease of learning have stopped it spreading to other areas of testing

11. Future Testing Challenges
Increasing complexity of products
GSM Specifications 1306
3G Specifications 2290

12. Future Testing Challenges
Pressure to shorten time to market
New systems and services must be available quicker
How can we reduce testing time?
Pressure to improve quality
SW outage average time for Network elements measured in seconds per year
How can we improve testing quality (and quantify it)
New types of testing
IP based protocols
Text based protocols
Unified testing approach for software and protocol testing

13. Why is TTCN-3 Important TTCN-3 More Productive Easier to learn
Easier to use
More Powerful
Extended functionality
Support for IP protocol
Support text-based protocols
More Flexable
Not tied to OSI model
For many types of testing
More Extendable
Extensibility built-in
TTCN-2
Software Testing
Protocol Testing
Function
Module
Layer
Unit
Intergration
TTCN-3

14. TTCN-3
Nokia has been from the very beginning actively involved in the development of the TTCN-3 language at ETSI.
The first product testers using TTCN-3 where introduced in Nokia in 2002.
TTCN-3 especially strong in the text based protocol area like SIP.
Used for almost all new test systems
Investigation about usage in application areas that are not typical protocol testing such as software module testing.
Area of active research and development. Conversion of test systems from TTCN-2 to TTCN-3 already started.

15. Future Trends: Specification
Short term
UML 2.0 tools will mature and the gaps will be filled to enable UML to be used not just at the abstract specifications (requirements) phase but further down towards implementation
Medium Term
As UML 2.0 tools mature and become available there will be a general move from SDL to UML for functional specification
Long Term
UML will become the glue which finally enables MBD to be realised

16. Future Trends: Testing
Short term:
Replacing TTCN-2 in functional and conformance testing as standard language.
Increasing use within the IP world especially for text based protocols
Possible key technology in the IP/telecom convergence.
Medium term:
Expanding from pure protocol testing to software testing and interworking testing.
Possible key technology for unifying testing technology across whole product development.
Long term:
Real time and performance testing? (European INTERVAL project)
Integration with UML (UML testing profile)