OPNET Technologies
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University: Technische Universtität Dortmund, Germany
Professor: Prof. Dr.-Ing. Christian Wietfeld
Department: Communication Networks Institute

Research:

 

In the field of LTE Energy Efficiency Optimization we are working on an efficiency optimized Transmit Power Control Scheme. Therefore, TPC for LTE was introduced to the LTE Opnet model together with an empirically derived energy model that maps the transmission power to the consumed power in a close to reality manner.

First results show, that a large amount of consumed energy can be saved and therefore battery lifetime can be gained, if the observed "High Power Mode" can be avoided. Some methods how to achieve this will be focused in the next month.

In the research unit "Protection And Control Systems For Reliable And Secure Operation Of Electrical Transmission Systems" innovative approaches for the protection and control of wide area transmission systems are investigated and tested in a simulation framework taking into account realistic communication infrastructure. Therefore, the HLA Interface of OPNET is an important feature that allows for the integration of the protocol simulator in an overall framework.

Currently we are working on the integration of OPNET with the other simulation tools. As soon as this work is finished extensive simulation campaings will be performed.

 

Teaching:

 

In the are of Teaching, Opnet is used in several Diploma-, Bachelor- and Master Thesis.

• Martin Skupinski, "Energy Efficient LTE based Sensor Data Transmission"
• Christopher Fromme, "Context Sensitive Transmit Power Control for LTE"
• Alexander Dukat, "Design and evaluation of a hybrid simulation environment for communication networks and power systems for the Smart Grid"

 

Authored Papers:

 

B. Dusza, C. Ide and C. Wietfeld, "Utilizing Unused Network Capacity for Battery Lifetime Extension of LTE Devices", Proc. of the IEEE International Conference on Communications (ICC) Workshop on Novel Approaches to Energy Measurement and Evaluation in Wireless Networks (NovaEnEv), Ottawa, Canada, Jun 2012.

Abstract:

The average operational time of today’s smart phones with one filling of the accumulator is one of the mostimportant performance parameters for the customers of new devices. Nevertheless, this value is remaining constant or even decreasing in the last few years due to the continuously increasing complexity. On the other hand, for ensuring the fulfillment of the high user-requirements even under worst case conditions, novel cellular systems such as Long Term Evolution (LTE) are usually over-dimensioned in terms of the maximum available capacity.

In this paper, a novel approach is presented which allows for trading in unused cell capacity for battery lifetime extension of
the mobile devices. The basic idea in this context is to increase the robustness of the submitted uplink (UL) signal by decreasing the order of the modulation and coding scheme used. If the provided data rate is kept constant, this comes along with an increasing number of allocated Resource Blocks (RB) and therefore a decreased overall cell capacity.

Nevertheless, the more robust signal allows for reducing the uplink transmit power while the Quality of Service (QoS) parameters are still met. The results for exemplary Voice over IP (VoIP) traffic show that for users originally submitting at the maximum available transmit power, the consumed energy of the LTE chip-set can be reduced by up to 27.5 % applying this novel approach.

 

H. Georg, S. C. Müller, C. Rehtanz and C. Wietfeld, "A HLA Based Simulator Architecture for Co-simulating ICT Based Power System Control and Protection Systems", 3rd IEEE International Conference on Smart Grid Communications (SmartGridComm 2012), Tainan City, Taiwan, Nov 2012.

Abstract:

Power systems and especially Smart Grids increasingly apply Information and Communication Technologies (ICT) for exchanging information over wide area networks. Here, the performance of the ICT has become crucial for the development of new Wide Area Monitoring, Protection And Control (WAMPAC) systems. In this context, simulations are a common way for evaluation, but power systems and communication networks are usually analysed with dedicated simulators. Therefore a combined simulation for analysing the dynamics and mutual impacts of both domains is needed.
In this paper we present a generic hybrid simulation architecture based on the IEEE standard 1516 - High Level Architecture to enable a combined simulation of power systems and communication networks in an integrated simulation environment. First, we introduce our hybrid simulator architecture, along with the communication and synchronization process between sub-simulators. Secondly, we present our communication networks architecture for modelling the network traffic caused by the information transmitted by control and protection algorithms within the electrical transmission system. Finally, we introduce our modelling approach for mapping entities between the power systems and the communication networks. For this purpose, we introduce our concept of a Substation Data Processing Unit, which represents entities on substation level by providing an IEC 61850 based model for mapping logical functions for local process control, implementing decentralized protection and control algorithms and providing additional components for the power systems (e.g Phasor Measurement Units (PMUs)).

 

S. C. Müller, H. Georg, C. Rehtanz and C. Wietfeld, "Hybrid simulation of power systems and ICT for real-time applications", 3rd IEEE PES Innovative Smart Grid Technologies (ISGT) Europe Conference, Berlin, Germany, Oct 2012.

Abstract:

With the rise of smart grid technologies, the interdependencies of ICT and power systems become increasingly important in both transmission and distribution networks. For the design of time-critical applications, simulation tools for an integrated analysis of these domains are needed. In the case of electrical transmission systems, high-performance ICT solutions and fast controllable power equipment enable a new era of dynamic power system operation whereas applications for this purpose need to be investigated with a special focus on their real-time performance. This paper presents a novel, modular co-simulation environment for comprehensive analysis of mutual effects, taking into account communication networks, IT processing and power system response. This hybrid simulation environment has been developed with a focus on the evaluation of the real-time performance of wide-area monitoring, protection and control (WAMPAC) applications, nonetheless, it is applicable to a variety of smart grid applications in transmission and distribution networks. The simulator architecture takes into account various standards from different areas of research - such as IEEE 1516-2000 (High-Level Architecture), IEC 61850, OPC and CIM - in order to provide a highly flexible simulation environment and to enable development of applications close to industrial implementation.

 

H. Georg, N. Dorsch, M. Putzke, C. Wietfeld, "Performance Evaluation of Time-critical Communication Networks for Smart Grids based on IEC 61850", 2013 IEEE INFOCOM Workshop on Communications and Control for Smart EnergySystems (INFOCOM'2013 CCSES), Torino, Italy, April 2013.

Abstract:

Driven by the increasing application of Smart Grid technologies in today's power systems, communication networks are becoming more and more important for exchanging monitoring, control and protection information on local and wide area level. For communication the IEC 61850 standard is a candidate for the Smart Grid and has been introduced for Substation Automation Systems (SAS) some years ago. IEC 61850 provides interoperability among various manufactures and enables system-wide communication between intelligent components of future power systems. However, as IEC 61850 addresses Ethernet ISO/IEC 8802-3 family) as network technology, especially high performance aspects of Ethernet have become increasingly important for time-critical communication within substation automation systems. In this paper we introduce the generic architecture of IEC 61850 and present our modelling approach for evaluating high performance and real-time capability of communication technologies for future smart grid application. First, we give a short overview of the IEC 61850 protocol and present communication flows in substation automation system according to the standard. Here we focus on substation automation at bay level, located inside an exemplary substation node taken from the IEEE 39-bus power system network. Afterwards we demonstrate our modeling approach for communication networks based on IEC 61850. For performance evaluation we developed a simulation model along with an analytical approach on basis of Network Calculus, enabling to identify worst case boundaries for intra-substation communication. Finally results are provided for two bay level scenarios, showing the applicability of Network Calculus for real-time constrained smart grid communication, verified by simulative evaluation.

 

OPNET Technologies, Inc. is a leading provider of solutions for managing networks and applications. OPNET's best-in-class solutions address application troubleshooting, application monitoring, network monitoring, network configuration management, network planning , and network simulation. OPNET’s solutions have been operationally proven in thousands of customer environments worldwide, including corporate and government enterprises, government and defense agencies, network service providers, and network equipment manufacturers. For more information about OPNET and its products, visit www.opnet.com.