Distributed Traffic Load Scheduler based on TITANSim for System Test of a Home Subscriber Server (HSS)
The system test is very significant in the development life cycle of a telecommunication network node. Tools such as TITANSim are used to develop the test framework upon which a load test application is created. These tools need to be highly efficient and optimized to reduce the cost of the system test. This thesis project created a load test application based on the distributed scheduling architecture of TITANSim, whereby multiple users can be simulated using a single test component. This new distributed scheduling system greatly reduces the number of operating system processes involved, thus reducing the memory consumption of the load test application; hence higher loads can be easily simulated with limited hardware resources.
The load test application used for system test of the HSS is based on the central scheduling architecture of TITANSim. The central scheduling architecture is a function test concept, where every user is simulated by a single test component. In the system test several thousand users are simulated by the test system. Therefore, the load application based on central scheduling architecture uses thousands of test components leading to high memory consumption in the test system. In this architecture, the scheduling of test components is centralized which results in a lot of communication overhead within the test system, as thousands of test components communicate with a master scheduling component during the test execution.
On the other hand, in the distributed scheduling architecture the scheduling task is performed locally by each test component. There is no communication overhead within the test system. Therefore, the test system is highly efficient. In the distributed scheduling architecture the traffic flow of the simulated users are described using the Finite State Machines (FSMs). The FSMs are specified in the configuration files that are used by the test system at run time. Therefore, implementing traffic cases using the distributed scheduling architecture becomes simpler and faster as there is no (TTCN-3) coding/compilation.
The HSS is the only node (within Ericsson) whose system test is performed using the central scheduling architecture of TITANSim. The other users (nodes) of TITANSim are using the distributed scheduling architecture for its apparent benefits. Under this circumstance, this thesis project assumes significance for the HSS. When a decision to adapt the distributed scheduling architecture is made for the system test of the HSS, the load application created in this thesis project can be used as a model, or extended for the migration of the test modules for the HSS from the central scheduling architecture to the distributed scheduling architecture.
By creating this load application we have gained significant knowledge of the TITANSim framework; most importantly, the necessary modifications to the TITANSim framework required to create a distributed scheduling architecture based load application for the HSS. The load application created for this project was used to (system) test the HSS by generating load using real system test hardware. The results were analytically compared with the test results from the existing load application (which is based on the central scheduling architecture). The analysis showed that the load application based on distributed scheduling architecture is efficient, utilizes less test system resources, and capable of scaling up the load generation capacity
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