دانلود رایگان مقاله مدل سازی تعاملی برنامه های زمان واقعی در VANETs با با ارزیابی عملکرد

Abstract

Vehicular Ad-Hoc Network (VANET) is an emerging technology, which provides intelligent communication between mobile vehicles. Integrating VANET with Ubiquitous Sensor Networks (USN) has a great potential to improve road safety and traffic efficiency. Most VANET applications are applied in real time and they are sensitive to delay, especially those related to safety and health. Therefore, checking the applicability of any proposed application is very important. One way to achieve that is by calculating the Round Trip Time (RTT), which is the time taken by a VANET application starting from the initiator node (source vehicle) sending a message until receiving a response from the core network. In this paper, we present a new complete analytical model to calculate the RTT of VANET applications. Moreover, we introduce a novel detailed network architecture for VANET applications using the IP Multimedia Subsystem (IMS) as a service controller in the USN environment. To the best of our knowledge, there is no previous published work that either studied the RTT of VANET applications or developed a complete architecture to implement them by integrating VANETs with USNs and IMS. The RTT is calculated by combining two analytical models. Firstly, we developed an analytical model to calculate the time needed for the communication between two nodes on a road. Secondly, we developed a queuing model using Baskett Chandy Muntz Palacios (BCMP) queuing network for the IMS servers to calculate the application's execution time in the core network. These models are general enough to be applied to any VANET application. Finally, to assess the validity and the accuracy of the proposed architecture and models, we used three different tools: C++, MATLAB, and OPNET. The analytical results were compared to the simulation results to evaluate their consistency.

6. Conclusions

In this paper, we proposed a complete model, including signaling flows, which uses the IMS as a service controller sub-layer for VANET applications due to its benefits and features. Additionally, the use of IMS provides the ITU-T service requirements of USN applications and services. On the other hand, safety applications are time sensitive. Therefore, there is a need to test the validity of the proposed model. One way to achieve this is by calculating the Round Trip Time (RTT), which is the time taken by a VANET application starting from the initiator node (source vehicle) sending a message until receiving a response from the core network. For the validity of our proposal, we developed two analytical models for the proposed architecture. First, we modeled the vehicles link connectivity on roads to estimate the reporting delay of events until reaching the closest RSU using the connectivity queuing model GIx/D/∞. The analytical model validity is proved in the performance section. It achieves a perfect performance when comparing its results with those obtained from the simulation. Second, we modeled the behavior of the IMS servers using BCMP networking. The performance of the developed model is validated and it shows to be more accurate when compared with the simulation results. These models are general enough to be applied to any VANET application. Finally, we calculated the RTT to test the reliability of the proposed application model. As a conclusion from the results, the average RTT of the proposed model is less than a second, which proves the applicability of using the IMS as a sub-layer controller for VANET applications. This work will be used as a base for further work. We plan to derive models for more sophisticated vehicular communication scenarios and to incorporate beam-forming based broadcast technique.