The modeling and simulation (M&S) landscape for systems engineers is complex. This complexity is due to a variety of factors including the diversity of system components over a range of domains which are modeled at multiple scales using varied modeling formalisms. There is a need to chain system models developed using varying formalisms, resolutions or scales. An ideal Multiformalism, Multiresolution, Multiscale Modeling (M4) environment would provide a singular (or small set of) modeling formalisms from which to derive representations (models) across formalism, resolution and scale. This paper describes a research activity to translate Systems Modeling Language (SysML) models to the Joint Communications Simulation System (JCSS). A deliverable from this activity will aid the Department of Defense (DoD) in the design and analysis of the Joint Information Environment (JIE).

OTC, together with the JTRS JPEO and PEO-I MSO, funded a Small Business Innovative Research (SBIR) Phase 2.5 Technology Transition effort, with SNT as the contractor, to develop the JTRS Network Emulator (JNE) to support GMR LUT and MOTE test activities. The accuracy of the JNE, to a large extent, depends upon the accuracy of its constituent models. Consequently, OTC funded an effort to verify and validate the performance of the QualNet WNW and SRW waveform models. The purpose of this paper is to report on the status and results generated to date for the QualNet WNW and SRW V&V activities that are scheduled through the end of Fiscal Year 2012.

Abstract : The DoD is pursuing an end-to-end, seamless, network-centric enterprise communications infrastructure to support a wide range of operating conditions and network topologies. Evaluating the achievable performance of this communications infrastructure, as it evolves, is essential to the user community in order to guide their ongoing requirements, design, and procurement activities. Tactical edge applications present significant challenges to network evaluation methods since they often include mobile ad-hoc networks (MANETs) that employ a wide range of platform types (ground-based, air-based, and satellite-based), traffic types (data, voice, video, and multimedia), delivery methods (unicast and multicast), offered traffic loads (kilobits/sec through megabits/sec), and numbers of nodes (from 10s to 1000s). The complexity exhibited by tactical edge applications typically demands the use of Modeling and Simulation (M&S) techniques, supported by high-fidelity models, to adequately quantify achievable performance on an end-to-end basis. However, these high-fidelity models often have very long runtimes, and restrictive limitations on scenario sizing. We investigate the application of the DoD High Level Architecture (HLA) and High Performance Computing (HPC) platforms to address the performance demands associated with analyzing tactical edge applications. A federation comprised of two Soldier Radio Waveform (SRW) federates and one Wireless Network after Next (WNaN) federate is developed and executed within an HPC environment at Aberdeen Proving Grounds (APG). High-fidelity OPNET models are used to represent the SRW and WNaN waveforms. Situational Awareness (SA) multicast traffic is delivered among the nodes represented within each of the three federates. Unicast traffic is exchanged between the SRW federates, in the presence of this SA background traffic, using the WNa

The rapid deployment requirements, limited infrastructure, and mobile nature of tactical edge networks have led the Department of Defense (DoD) to investigate and implement Mobile Ad-hoc Networks (MANETs) to support its mission needs. MANETs rely on spectrum as the transmission medium, and their performance depends heavily on the electromagnetic environment (EME) where they operate. Traditional methods of assessing MANET performance have been focused on link capacity and network throughput, without adequately accounting for the effects of the EME. The Joint Spectrum Center of the Defense Spectrum Organization (DSO/JSC) has developed the Spectrum Simulation Testbed to adequately account for spectrum impacts on MANET performance. As part of the DSO/JSC Spectrum Simulation Testbed development, a number of capability gaps were identified, specifically in areas of quantifying the relationship between spectrum requirements and MANET performance. The purpose of this paper is to report the results of a survey to identify the current capabilities to address MANET performance within the context of accounting for available spectrum and to describe two capabilities that were developed to help bridge the analysis gap in the area relating spectrum requirements to system performance predictions.

-Quantifying the end-to-end performance of evolving DOD communication networks is highly desired by the component and network designers during all phases of the development process. Analytical techniques, inlab testing and field demonstrations are all necessary toward this end but all have limitations in addressing this need. Simulation remains a primary method with which to generate end-toend performance. However, simulation often results in unacceptably long runtimes for these types of networks. The purpose of this paper is to report on the results generated in the second year of a 2-year IR&D program to investigate methods to improve simulation runtime performance when simulating mobile ad-hoc communication networks.

With the conventional modeling and simulation (M&S) of networks, simulations are usually executed from beginning to the end without interruption, and results are available only at the end of the simulation runs. These results typically consist of various statistics for some measures of performance (MOPs) that attempt to quantify the network's performance. Although these results can capture the timing of significant events and performance transitions, they generally capture neither their causes nor the transient behavior that leads to their occurrence. This paper presents an approach to operate a simulated network similar to an actual network where the simulated network can be monitored in real-time and better, and, if appropriate, be stopped for explorations of the network state. A console equipped with a GUI interrogates the simulated network during the run and displays the relevant characteristics of the network, which allows experimenters to monitor the network's behavior and performance. Experimenters can use the console to stop and query the simulation to obtain detailed information from each node or protocol layer within each node. Examples of such information are route forwarding tables at a node, node position, or some protocol attributes configured at a node. Further, experimenters can use the console to change network configuration during the simulation run and observe its impact on the performance of the network. Our solution is built using OPNET Modeler as the simulation engine and its cosimulation facility to interconnect the experimenter's console with the simulation.

Quantifying the end-to-end performance of evolving DOD communication networks is highly desired by the component and network designers during all phases of the development process. Analytical techniques, in-lab testing and field demonstrations are all necessary toward this end but all have limitations in addressing this need leaving simulation as a primary method with which to generate end-to-end performance. However, simulation often results in unacceptably long runtimes for these types of networks. The purpose of this paper is to report on the results generated in the second year of a 2-year IR&D program to investigate methods to improve simulation runtime performance of mobile ad-hoc communication networks

This paper evaluates the performance of several alternative reliable unicast transport mechanisms in a hybrid network. Options investigated include end-to-end TCP (different flavors), end-to-end space communications protocol standards-transport protocol (SCPS-TP), and performance enhancing proxies (PEPs) (also called transport layer proxies). Our approach is to analyze these options in a specific scenario using modeling and simulation (M&S). We describe this scenario and the corresponding OPNET network model, our experiment plan, and the results obtained. Finally, we identify several areas for further analyses

Mobile ad-hoc networks (MANETs) are a major component of all DoD tactical networks. MANETs must be carefully analyzed to ensure integrated DoD networks perform properly on an end-to-end basis. Simulation is generally used to evaluate these networks before their actual deployment. We have identified the routing table calculation to be a major contributor to the excessive run-time and have employed an algorithm based on the breadth-first search to improve the simulation run-time. Our results show that employing the new algorithm will result in a lower run-time for the simulation

The complexity of the issues involved in the evolving DoD communications infrastructure requires the use of simulation techniques to fully quantify achievable performance on an end-to-end basis. To date, the application of simulation techniques have been hampered because of excessive run-times and large memory footprints. The purpose of this paper is to report on the results of an internal R&D effort in which we are quantifying methods to improve the run-time and memory footprint performance in large scale simulations related to the evolving network-centric DoD paradigm

: The future DoD transport vision is for the Global Information Grid (GIG) to provide an internet-like capability that meets the mobility, security, and reliability needs of a wide spectrum of DoD users. A variety of services must be provided to the users including management of resources to support QoS, a transition path from IPv4 to IPv6, and efficient networking across heterogeneous networks (i.e., wired/wireless, fixed/mobile, GND/Air/Space, etc.). Due to the complexity of the issues involved with the integrated GIG, it is only possible to quantify end-to-end GIG performance via modeling and simulation (M&S) techniques using component models having adequate fidelity. The purpose of this paper is to describe the End-to-End M&S Testbed (EMAST) that has been developed to address these issues.

This paper describes an M&S Environment that was developed and is currently being used in support of the DARPA Future Combat System Communications (FCS-C) technology program and the Joint Tactical Radio System (JTRS) program, and an example of its application. This M&S Environment supports the performance evaluation of the full range of emerging communications technologies against the backdrop of operational scenarios having traffic profiles comprised of IERs and threads and accounts for foliage and terrain-induced path attenuation. For the example analysis, we evaluate a sample device model, which includes both a unicast and a multicast routing protocol, along with 802.11, for a given scenario and show some of the types of results available. We discuss the scenario evaluated, the OPNET network model generated by the M&S Environment, its execution and results.

The purpose of this paper is to describe a communications analysis tool, referred to as OPAR, that can be used in support of both in-field demonstrations and large-scale simulation activities. Using overhead imagery as a backdrop, OPAR provides a graphical user interface that allows the user to quantify the source/destination path attenuation in a mobile, ad-hoc communications network, taking into account obstructions due to foliage and buildings.

This article describes an approach for providing dynamic quality of service (QoS) support in a variable bandwidth network, which may include wireless links and mobile nodes. The dynamic QoS approach centers on the notion of providing QoS support at some point within a range requested by applications. To utilize dynamic QoS, applications must be capable of adapting to the level of QoS provided by the network, which may vary during the course of a connection. To demonstrate and evaluate the dynamic QoS concept, we have implemented a new protocol called dynamic resource reservation protocol (dRSVP) and a new QoS application program interface (API). The paper describes this new protocol and API and also discusses our experience with adaptive streaming video and audio applications that work with the new protocol in a testbed network, including wireless local area network connectivity and wireless link connectivity emulated over the wired Ethernet. Qualitative and quantitative assessments of the dynamic RSVP protocol are provided.

This paper looks at issues involved in providing quality-of-service (QoS) support in a dynamic environment. We focus on a resource reservation-based approach, which we believe is attractive for military applications but is especially difficult in a dynamic network environment. This is because resources reserved for a particular flow may contract after they have been “committed” to the flow, causing the reservation to be dropped. Our approach is to expand the semantics of the reservation so that instead of being a single value indicating the level of service needed by an application, it becomes a range of service levels in which the application can operate, together with the current reserved value within that range. This provides flexibility so that reservations can be maintained as network conditions change. Rather than being forced to make a binary “admit/fail” decision for each flow, the network provides feedback to applications on the current reservation level. Based on this feedback, applications can adapt their behavior to what the network can support. We have developed a prototype implementation of this concept by extending the Reservation Setup Protocol (RSVP) protocol. We are currently evaluating the implementation in a testbed network where we can vary the link bandwidth. The testbed also includes several adaptive applications (audio, video, data transfer) running over the User Datagram Protocol (UDP). The paper discusses our approach, testbed, experiences to date, and current plans

This paper describes an approach for providing dynamic Quality of Service (QoS) support in a variable bandwidth network, which may include wireless links and mobile nodes. The QoS approach centers on the notion of providing QoS support at some point within a range requested by applications. The applications must be capable of adapting to the level of QoS provided by the network, which may vary during the course of a connection. The paper describes a new protocol called dynamic RSVP (dRSVP) that we have implemented to demonstrate and evaluate the dynamic QoS concept. The protocol and a new application programming interface (API) for this dynamic QoS are described. Finally, we briefly discuss our experience with adaptive streaming video and audio applications that work with the new protocol in a testbed network.

This paper describes a simulation-based evaluation of several unicast routing protocols tailored specifically for mobile ad hoc networks. Four protocols were evaluated: the wireless Internet routing protocol (WIRP), a link state (LS) algorithm with constrained LS updates, a distance vector variant of WIRP, and temporally ordered routing algorithm (TORA). The goal was to determine how well these routing protocols worked in specific tactical conditions, supporting a given mix of traffic. Factors varied included tactical scenario, network size, and loading. Tactical scenario included different connectivities (e.g., "dense" versus "sparse") and link fluctuation rates (e.g., "high" versus "low"). Metrics collected included average end-to end delay per application, path length, total efficiency, and fraction of user messages received. We found that certain protocols performed better in densely connected networks than in sparser networks (e.g., TORA), while some performed better in sparser networks (e.g., LS). One protocol, WIRP, performed well in both types of networks over the scenarios evaluated, Several remaining issues and areas for continued research are identified.

This paper presents an approach to supporting quality-of-service (QoS) in a dynamic network environment. With this approach, resource reservations represent ranges, and applications adapt to an allocated level of QoS provided by the network at some point within the requested range. To explore this approach, we have implemented a new protocol called dynamic RSVP (dRSVP), which is an extension to RSVP.