The Research On Simulation And Modeling Methods Based On OPNET

Nowadays, information technology developes quickly, the network structures and scales become complicated. With continuously extending in scope and scale of the applications, it is difficult to program and design the network, the development of the network protocols, and the design of the network equipments also. So there has an urgent needs of means in science urgently to reflect and predict the function of the network, the system simulation technique emerge with the tide of the times.Is 20 near in the last years the system simulation technique develops particularly, the network simulation, the intelligence programming, network optimizing and managing become hot issues of the data network domain. The application of system simulation techniques can raise the credibility and accuracy of the network programming and designs, forthermore it can lower the network investment risk clearly, and reduce the investment waste.System simulation technique will become the link of the programming and designing of network indispensability.The modeling techniques are mainly discussed in this paper. The point of the paper is how to model a network protocol and how to carry out it by OPNET software.Then analyzes the performance of the standard model system provided. The IEEE802.11 standard MAC layer function is introduced, the detailed analysis is under the environment that the network stations increment, the the main factors influenced network circulates are the increment of conflict and the spare time segments witch waste resources of wireless channel. And then some measures can be taken on the improvement to the MAC, to acquire the better performance.The OPNET software provides the strong development environment for the simulation of network, but there are some problems of OPNET to carry out distributing cosimulation with other simulation system or the application procedure.High Level Architecture(HLA) is a general architecture,witch can satisfy the need of the large-scale and complicated system simulation.Theremarkable characteristic of HLA is to support kinds of system simulation, provides the general-purpose data commutation agreement and the general, open mutual opration of the data , HLA will separate the general support environment from the function of simulation software, so HLA makes great improvement in the co-operation and the reuse of different and distribute, models and simulation system. It is discussed lots of the HLA system structure, the run-time infrastructure (RTI), and also how co-simulate based on HLA.