International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Packet Telemetry Ground Station which receives telemetry data from the Space Station must be able to receive and process various data types including high-rate video, audio, instrumentation, electronic mail, telecommand, and engineering. The Packet Telemetry Ground Station must also be flexible to accommodate changing missions and payloads. Computer simulations of the Packet Telemetry Ground Station provide information about device specifications required to achieve an acceptable level of performance under changing telemetry data traffic configurations. This paper describes a computer simulation model for a Packet Telemetry Ground Station Architecture which was tested using ten different traffic components randomly transmitting data. The Packet Telemetry Ground Station Simulation status and utilization plots are discussed in terms of interpreting the simulation results.

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The lack of analytical models that can accurately describe large-scale networked systems makes empirical experimentation indispensable for understanding complex behaviors. Research on network testbeds for testing network protocols and distributed services, including physical, emulated, and federated testbeds, has made steady progress. Although the success of these testbeds is undeniable, they fail to provide: 1) scalability, for handling large-scale networks with hundreds or thousands of hosts and routers organized in different scenarios, 2) flexibility, for testing new protocols or applications in diverse settings, and 3) inter-operability, for combining simulated and real network entities in experiments. This dissertation tackles these issues in three different dimensions. First, we present SVEET, a system that enables inter-operability between real and simulated hosts. In order to increase the scalability of networks under study, SVEET enables time-dilated synchronization between real hosts and the discrete-event simulator. Realistic TCP congestion control algorithms are implemented in the simulator to allow seamless interactions between real and simulated hosts. SVEET is validated via extensive experiments and its capabilities are assessed through case studies involving real applications. Second, we present PrimoGENI, a system that allows a distributed discrete-event simulator, running in real-time, to interact with real network entities in a federated environment. PrimoGENI greatly enhances the flexibility of network experiments, through which a great variety of network conditions can be reproduced to examine what-if questions. Furthermore, PrimoGENI performs resource management functions, on behalf of the user, for instantiating network experiments on shared infrastructures. Finally, to further increase the scalability of network testbeds to handle large-scale high-capacity networks, we present a novel symbiotic simulation approach. We present SymbioSim, a testbed for large-scale network experimentation where a high-performance simulation system closely cooperates with an emulation system in a mutually beneficial way. On the one hand, the simulation system benefits from incorporating the traffic metadata from real applications in the emulation system to reproduce the realistic traffic conditions. On the other hand, the emulation system benefits from receiving the continuous updates from the simulation system to calibrate the traffic between real applications. Specific techniques that support the symbiotic approach include: 1) a model downscaling scheme that can significantly reduce the complexity of the large-scale simulation model, resulting in an efficient emulation system for modulating the high-capacity network traffic between real applications; 2) a queuing network model for the downscaled emulation system to accurately represent the network effects of the simulated traffic; and 3) techniques for reducing the synchronization overhead between the simulation and emulation systems.

The usage of computer networks has increased enormously recently due to many benefits; it facilitates data distribution speed, long distance communication and industrial system control. Due to these reasons, industry systems have started to use computer networks for system control and data transmission. Meanwhile, the limitations of network devices also raise many challenges for network system configuration. To have the best optimized network system, we need to study the network system by performing experiments. However, experiments on the real systems could be expensive and dangerous. Therefore, we need a model to represent the behaviours of the system. This thesis work uses object-oriented acasual modelling language Modelica to model a local area network system, and the development is performed in OpenModelica, an open source Modelica-based modelling and simulation environment. The simulation results are analysed and verified by using a separate requirement verification model.

ITC/USA 2013 Conference Proceedings / The Forty-Ninth Annual International Telemetering Conference and Technical Exhibition / October 21-24, 2013 / Bally's Hotel & Convention Center, Las Vegas, NV / Distributed Denial of Service (DDoS) attacks have been gaining popularity in recent years. Most research developed to defend against DDoS attacks have focused on analytical studies. However, because of the inherent nature of a DDoS attack and the scale of a network involved in the attack, analytical simulations are not always the best way to study DDoS attacks. Moreover, because DDoS attacks are considered illicit, performing real attacks to study their defense mechanisms is not an alternative. For this reason, using packet/network simulators, such as OPNET Modeler, is the best option for research purposes. Detection of an ongoing DDoS attack, as well as simulation of a defense mechanism against the attack, is beyond the scope of this paper. However, this paper includes design recommendations to simulate an effective defense strategy to mitigate DDoS attacks. Finally, this paper introduces network links failure during simulation in an attempt to demonstrate how the network recovers during and following an attack.

Cyber-physical systems (CPSs) represent a new generation of engineered systems that tightly integrates computations, communications (cyber) and physics. Simulation plays a considerable role in validating CPSs as it substantially reduces the costs and risks in the design-testing cycles. Reliable simulations, however, mandate realistic modeling for both the cyber and the physical aspects. This is especially the case in various networked mobile CPSs (e.g., excavation robots and vehicular networks), where cost and risk may become substantial. Current CPS modeling tools lack complete models of communication. Co-simulation attempts to overcome this limitation by integrating multiple modeling and simulation tools to offer complete models of all aspects of CPSs. In this thesis, we design and implement a co-simulation environment for modeling and simulating networked CPSs. The environment is called AcumenNS3 and it integrates Acumen, a language for modeling hybrid physical systems, with NS-3, a discrete-event network simulator. This environment allows users to augment network simulations with physical models using an easy-to-use modeling language. It provides a seamless integration between network and physics models by providing mobility based on the physical simulation in addition to generic access to the physical state. Using the AcumenNS3 environment, we demonstrate and model example simulation scenarios of networked CPSs. / Thesis (Master, Computing) -- Queen's University, 2014-04-24 14:38:30.039

The Space Mobile Network (SMN) is NASA’s next generation architecture concept for communications services between ground and space-based assets. The SMN calls for a paradigm shift in space communications. The transition will move from an approach based on static, preplanned communications over point-to-point channels to a dynamic, event-driven, and network-based approach that facilitates service-oriented communications. In doing so, the SMN is able to leverage some concepts and technologies present in today’s terrestrial wireless networks, while others must be extended or adapted to the space communications domain. This paper provides background on key SMN architectural concepts and an evaluation of the suitability of terrestrial wireless network modeling tools to be used and applied for proving out SMN concepts.

WirelessSensor Networks have emerged among the different wireless technologies sharingthe ISM spectrum band. This band sharing between the technologies started toraise coexistence issues in accessing the overpopulated spectrum. The WSN powerconstrains make them vulnerable to higher power devices, such as WLAN.Simulation studies are of great importance in predicting the coexistencephenomena in heterogeneous scenarios. Simulations allows us to have aprediction on how a network will behave without the need to physically deploy thenetwork. We address the coexistence phenomena between WSN and WLAN devices and demonstratea performance comparison. We evaluate the capability of the MiXiM simulator to predictthe coexistence issues in heterogeneous networks, raised by WLAN and WSNdevices. We state the importance of having an accurate simulator to predict thephenomena. In this work, we propose a new framework for MiXiM to allow morerealistic simulation results in heterogeneous networks, when evaluating theinterference phenomena between concurrent technologies. We implement a newdefinition of custom transmission power and custom reception filter. Further,we evaluate simulation results provided by MiXiM in simulating WSN homogeneous scenariosand compare its prediction with analytical models. We implement a newsimulation paradigm in MiXiM, cross networks simulation sharing the same ISMspectrum band. We evaluate and analyse the coexistence phenomena of WLAN andWSN devices. Finally, we complete our work with the implementation of a channelsensing module, based on a fixed a priori false alarm probability, for WSNdevices. We evaluate its sensing results by comparing it with MiXiMsimplementation for channel sensing and conclude that our simple analytic modelfor sensing comply with MiXiMs implementation.

Recent research supports the eventual convergence of wireless LAN (WLAN) and cellular systems in order to achieve the IMT-2000 (3G) requirement for 2 Mbps indoor capacities. The WLAN access point can be enhanced to either incorporate or supplant the transmission and packet data capabilities in the cellular network. This research used OPNET™ to design, implement, and test a network system level simulation environment to allow investigators to study the issues and trade-offs for interworking the infrastructure-based WLAN technologies into 3G mobile subscriber cellular systems. The specific contribution of this research was to augment the current OPNET™ model library by creating an enhanced user equipment node (UW) and an enhanced WLAN access point node (UWLAN_AP). The UW was augmented with the capability to selectively gain network access through either a UMTS Node-B or through a 3G-aware WLAN access point. The UWLAN_AP was made 3G-aware by augmenting it with the capability to process UMTS control messages in order to build an access control table to support UMTS authentication and access control. Together, the UW and UWLAN_AP create a simulation framework for interworking the WLAN technology into UMTS as an alternate radio access network for supporting "hot spots." This research is the foundation to allow investigators to identify signaling and data transfer mechanisms that leverage the capabilities of WLAN while supporting cellular service provisioning and accountability requirements for current and future systems. / Master of Science