Simulation And Modeling Of Interactive 3G HF Email System

Network simulation technology could rapidly build up network model and conveniently modify the model to forecast network performance, shorten estimation time and save the network construction spend. Discrete-event-driven mechanism is similar with the characteristic of occurrence of network events. Thus it is the most popular simulation method of current network simulation software. However, with the requirements of simulation getting deeper, single simulator could not satisfy the users any more。The occurrence of distributing simulation enables several simulators to cooperate and simulate more complex environment. And also, it provides a solution to build interactive network simulation system.The implementation of interactive network simulation imports the architecture of distributed simulation. Simulators and user controllers join a same federation as federates. The Run-time infrastructure (RTI) could interchange information between them and an interactive network simulation could be built.HF Email simulation system is built to research the performance of MIL-STD-188-141B protocol in Email scenario. To simulate the user operation and forecast the protocol performance more realistically, it is needed to be built interactively.Interactive HF Email simulation system comprises two parts: user interface which is provided by OPNET and HLA; and the HF Email system implemented in OPNET. The controller, HLA interface and Run-time infrastructure constitutes the interface with users. HF Email system in OPNET comprises application layer/transfer layer, network layer, data link layer and physical layer. The highest layer takes charge of the sending and receiving of Email in HMTP and HPOP module which adopt pipeline extended Simple Mail Transfer Protocols (SMTP) and Post Office Protocol (POP3) to reduce the influence of large delay of HF channel. Network layer and data link layer adopt 141B protocol to implement the network controller and the function of data link layer. The simulation of physical layer adopts the simulation method of wireless channel in OPNET to model the HF wireless channel. All of these steps implement the whole interactive simulation system based on 3G HF.