High level architecture evolved modular federation object model

To improve the agility, dynamics, composability, reusability, and development efficiency restricted by monolithic federation object model （FOM）, a modular FOM is proposed by high level architecture （HLA） evolved product development group. This paper reviews the state-of-the-art of HLA evolved modular FOM. In particular, related concepts, the overall impact on HLA standards, extension principles, and merging processes are discussed. Also permitted and restricted combinations, and merging rules are provided, and the influence on HLA interface specification is given. The comparison between modular FOM and base object model （BOM） is performed to illustrate the importance of their combination. The applications of modular FOM are summarized. Finally, the significance to facilitate compoable simulation both in academia and practice is presented and future directions are pointed out.

Hardware-in-the-loop simulation of communication networks

To enhance the fidelity and accuracy of the simulation of communication networks,hardware-in-the-loop（HITL） simulation was employed.HITL simulation methods was classified into three categories,of which the merits and shortages were compared.Combing system-in-the-loop（SITL） simulation principle with high level architecture（HLA）,an HITL simulation model of asynchronous transfer mode（ATM） network was constructed.The throughput and end-to-end delay of all-digital simulation and HITL simulation was analyzed,which showed that HITL simulation was more reliable and effectively improved the simulation credibility of communication network.Meanwhile,HLA-SITL method was fast and easy to achieve and low-cost during design lifecycle.Thus,it was a feasible way to research and analyze the large-scale network.

Dynamic Multicast Grouping Approach in HLA-Based Distributed Interactive Simulation

In order to improve the efficiency of data distributed management service in distributed interactive simulation based on high level architecture (HLA) and to reduce the network traffic and save the system resource, the approaches of multicast grouping in HLA-based distributed interactive simulation are discussed. Then a new dynamic multicast grouping approach is proposed. This approach is based on the current publication and subscription region in the process of simulation. The results of simulation experiment show that this approach can significantly reduce the message overhead and use fewer multicast groups.

Dynamic Region Updating Strategy in HLA-Based Distributed Interactive Simulation

The HLA(high level architecture)-based distributed interactive simulation uses interest management mechanism to reduce the traffic on network and improve the system scalability. Making region updating occur only when needed can improve the interest management. Typically a static threshold is defined before simulation to trigger the region updating. Now a dynamic threshold is used to trigger region updating , the threshold is adapted by the real-time massage in simulation, named as update lifetime. The result of experiment shows that this policy can overcome the weak point of static threshold and can meet the requirements of bandwidth and simulation correctness.

An Emulating Environment for Network Management of Space Network

An emulating environment for network management of the space network was presented. The emulating environment was developed with node-link model. The nodes of the satellite entities were controlled by the controlling network, which consist of sets of HLA/RTI based federates. These federates described the different aspect of the attributes of the satellites, such as orbit coordinate, routing table and the chain budget. We described the architecture of the emulation environment and the software design of federates. We measured the response time of the protocol data units and verified the detecting of the network topology in the environment. The environment was open that the on board router and the simulator of satellite link which developed by third party could be integrated.

AN EFFECTIVE WAY TO CONTROL CONGESTION FOR RTI WITH HYBRID ARCHITECTURE

Congestions brought by data explosion may suffer system performance or even cause fatal errors in large-scale simulation systems.This paper analyzes the reasons of generating congestion with queuing theory,and proposes a novel congestion control approach for RTI with hybrid architecture,including framework,sampling policy,queue length predicting,and congestion control algorithm.The framework promotes the usage of federate resources,and improves the performance of HLA simulation systems by dynamically distributing loads on RTIG and LRCs(Local RTI Components).At last,experimental results say that the proposed approach is a flexible,simple and efficient way to control congestion in RTI with hybrid architecture.

LoI:Effcient relevance evaluation and filtering for distributed simulation

In large-scale distributed simulation, thousands of objects keep moving and interacting in a virtual environment, which produces a mass of messages. High level architecture （HLA） is the prevailing standard for modeling and simulation. It specifies two publish-subscribe mechanisms for message filtering： class-based and value-based. However, the two mechanisms can only judge whether a message is relevant to a subscriber or not. Lacking of the ability to evaluate the relevance, all relevant messages are delivered with the same priority even when congestion occurs. It significantly limits the scalability and performance of distributed simulation. Aiming to solve the relevance evaluation problem, speed up message filtering, and filter more unnecessary messages, a new relevance evaluation mechanism Layer of Interest （Lol） was proposed by this paper. Lol defines a relevance classifier based on the impact of spatial distance on receiving attributes and attribute values. An adaptive publish-subscribe scheme was built on the basis of Loh This scheme can abandon most irrelevant messages directly. Run-time infrastructure （RTI） can also apply congestion control by reducing the frequency of sending or receiving object messages based on each objects＇ Loh The experiment results verify the efficiency of message filtering and RTI congestion control.