6.2 TTCN-2 Testing architecture
34.123-33GPPPart 3: Abstract test suite (ATS)TSUser Equipment (UE) conformance specification
A unique testing architecture is shown in Figure 6.2.
Figure 6.2: A unique testing architecture
6.2.1 Lower Tester (LT)
The Lower Tester (LT) provides the test means for the execution of the test cases for CC, SM, MM, GMM, SMS, RRC, RLC, MAC, PDCP, BMC, RAB, IR_U/G, A-GPS, HSD_ENH, HSU_ENH, MBMS, HSPA7_ENH, HSPA8_ENH and HSPA9_ENH. The LT provides also the RLC, MAC and PHY emulators to communicate with the UE. The configuration and initialization of the emulators are control by the TTCN via ASPs.
6.2.2 Configuration and initialization
A number of TTCN test steps are designed for the generic setting.
1) Configuration of L1 of the tester, such as the cells, Physical channels and common transport channels via CPHY-PCO, configuration of MAC via CMAC-PCO and configuration of RLC layer via CRLC-PCO.
2) Sending system information via TR-PCO.
3) Establishment RRC connection via AM or UM-PCO.
4) Assigning a radio bearer via AM-PCO.
5) MM /GMM registration via Dc-PCO.
6) Establishment of a CS call or a PDP context via Dc-PCO.
7) Setting security parameters and control of integrity via CRLC- and ciphering via CRLC- and CMAC‑PCO.
6.2.3 Upper Tester (UT)
An Upper Tester (UT) exists in the test system. The UT interfaces toward UE with any optional EMMI (3GPP TS 34.109 [4], clause 7). TTCN communicates with the UT by passing coordination primitives via a Ut PCO. The primitives can either contain AT commands aiming at the automatic tests, or some informal commands as MMI, in order to request the UE for certain actions and to provide simple means for observations of UE.
6.2.4 TTCN-2
TTCN-2 is used as specification language based on TR 101 666 [27] (TTCN 2++). The importation of ASN.1 modules and modular TTCN-2 are two of the most important features used in the design of the ATSs.
The TTCN test suites have been designed to maximize the portability from the language TTCN-2 to TTCN-3.
6.2.5 Model extension
If a test case needs to handle a concurrent situation two or more LTs can be configured at the same time. The following test scenarios identified may require multiple testers in the test configuration.
6.2.6 Multiplexing of RLC services
For the RRC and NAS testing, the TTCN RRC test steps (on RB1 and RB2) and the RRC emulator (on RB3 and RB4 for the NAS messages) share the same service access point (AM SAP). The RLC emulator shall provide separate message queues (buffers) for the TTCN RRC test steps and the RRC emulator for the TTCN NAS test cases, according to the signalling radio bearer identities.