iTETRIS simulation Platform
The objective that iTETRIS wants to achieve is the accuracy in simulating communications and behavior of every ITS station making use of cooperative ITS communication systems. This objective is fulfilled in iTETRIS through the simultaneous and combined use of two simulation platforms, each of them addressing the emulation of vehicles movement and wireless communication, respectively.
iTETRIS has opted for integrating two well-known and widely used open source simulation platforms. SUMO (http://sumo.sourceforge.net) is an open-source microscopic traffic platform developed by the German DLR laboratories. For wireless communications simulation, iTETRIS decided to adopt the ns-3 platform (http://www.nsnam.org/). The capability to perform large-scale simulations and to support multi-radio/technology nodes was a key-parameter for the selection. ns-3 resulted to have the best performance in terms of scalability.
The final aspect to address prior to establishing the iTETRIS simulation platform is the way of combining traffic and communication simulators. This combination can be achieved using different coupling approaches, direct coupling, use of middleware architecture for distributed simulations or the adoption of an “in-between” control module used for synchronization and coordination. The rationale to select the best approach for simulation platform coupling is based on several practical considerations. Interoperability of the resulting platform represents one of these aspects - the opportunity has to given to replace one of the simulators by another counterpart. This would ensure wider applicability of the platform and sustainability in case one of the two simulators became obsolete. Also, it is very important that the platform can be extended, maintained and developed within each of its sub-components independently from each other. Finally, if the reusability of the platform beyond the duration of the project is wanted, the possibility has to be given to external users to implement and simulate new applications in a fully flexible way. All the desired features listed above can be resumed in one single world: Modularity. Using a modular approach, the opportunity is provided to the platform to be developed independently in each of its parts, allowing the different developers to use the programming language they are familiar with. Moreover, application developers may, in this way, be free to define their own traffic solutions and test them on iTETRIS, without having a complete knowledge of the internal implementation of the platform. The iTETRIS simulation platform is shown below.
iTETRIS follows a 3-Block approach. The two open source simulation platforms, which are developed autonomously by dedicated experts, do not communicate directly, but are connected with a central module called iTETRIS Control System (iCS). In order to consider simulation efficiency for large scale simulation, the iCS and the simulation platforms components run under the same machine. The applications that can be simulated in iTETRIS are defined as an iCS-assisted external block running on the top of the platform. Thus, platform users can create their application definitions in a “language-agnostic” fashion.
