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OPNET Technologies
OPNET
Technologies, Inc. |
Research: 1. Crossing Layer Location-Aided Wireless Routing Protocol for Ad Hoc Networks Recently, many location-aided routing protocols have been proposed for the mobile ad hoc networks. The efficiency of the routing protocols can be improved by considering the location information of the mobile nodes. However, the major assumption is that other than the destinations position, each node only knows its own position and the position of its nearest one hop neighbours in order to forward packets. In this work, a cross layer approach is considered for location-aided wireless routing protocol for mobile ad hoc networks. PHY-layer cooperative location estimation algorithm will offer the position of the node own and another node with a line-of-sight link. Routing protocols then aim on finding the best path according to factors including delay, bandwidth and route stability. Results: TBC 2. IEEE 802.11p Protocol Performance in ITS Systems The aim of this project is to estimate the performance of IEEE 802.11p protocol in ITS systems using OPNET. 802.11p, an amended draft to IEEE 802.11, has been chosen to support V2X communications. An interactive network simulation based-on HLA is designed in order to couple Car-2-X related simulators (e.g. a car traffic, application and communication simulator). With this combination, an 802.11p protocol would be simulated in real world scenarios and high efficiency realistic results would be achieved. Results: TBC 3. Impact of WSN Traffic on Mobile Access Networks Mobile access networks such as UMTS are designed to support voice or data traffic generated by nomadic users with various QoS requirements. Today, new technologies are emerging where devices such as sensors generate traffic for users in different locations. In such circumstances, mobile access networks can be used to establish/provide the communication path between the sensors and the users, with/without the support of the Internet. This work will study the impact of wireless sensor networks' (WSN) traffic on mobile access networks and propose additional entities/functionalities needed to support/enhance the performance of WSN traffic via mobile access networks. The simulation study will be performed using the OPNET simulator. Results: TBC 4. Directional routing protocol performance in mesh networks
Hamadani, E
The SMART-Net project is based on a decentralised vision where nodes are equipped with directional antennas. A key objective of the project is to make available, comprehensive and configurable experimental facilities for the investigation into future wireless networks, by deploying simulation and real-life testbeds based on advanced Radio Access Technologies. OPNET is used to evaluate the performance of directional routing protocol in mesh networks using 802.11 d/e technologies. Results: Using OPNET ODB we have realized there is a strong cross layer interaction between TCP and 802.11 MAC. In particular, due to channel unfairness experienced by some users in multihop ad hoc networks, TCP will react inappropriately by cutting its congestion window size dramatically and entering slow start. In addition, we concluded that in order to increase the performance of TCP in ad hoc networks, TCP should dynamically adjusts its window size to avoid overloading the network. Simulation results in OPNET suggested a congestion window size between 1 to 2 packets will be optimum for different size of ad hoc networks. 5. Synchronized Data Aggregation Policy (SDAP) For the purpose of practical delay optimization and practical network coding, we will propose the Synchronized Data Aggregation Policy(SDAP). SDAP is a practical resource management policy for data aggregation which provides an efficient framework for distribution of traffic in the network. In this framework the distribution of traffic on different paths will be controlled to synchronise the delay of data coming from different paths towards the sink node. The proposed protocol uses the delay on different paths as the criterion for selecting a best path on which data can arrive. We will show that the SDAP will provide a solution in which the delay on each path is synchronised. The practical expected average delay for the data coming from different paths is minimised, and the information flow is maximised. Finally we will simulate the SDAP on the Ethernet and IEEE 802.11 Mac using OPNET. Results: TBC 6. Spectrum Sharing Schemes & Cognitive Radio This Research starts with understating of the cognitive radio (CR) concept and specifying a cognitive cycle for sharing in UMTS cellular topology and defining practical protocols for both spatial and temporal sharing. This is based on defined assumptions in terms of available frequency bands (licensed and unlicensed). The proposed protocols will be modelled in OPNET, using a suitable cellular simulation environment which includes multiple systems with different statuses (primary or secondary), frequency bands and traffic profiles. The performance of the spectrum sharing protocols will be evaluated in different scenarios and achievable gains will be compared with theoretical results. Results: TBC 7. Advances in Micro-Mobility Management using a Mobility-Aware Routing Protocol
Georgiades, M, Chew, K. A. and Tafazolli, R
Abstract: Several micro-mobility schemes have been proposed to augment Mobile IP and provide a faster and smoother handoff than what is achievable by Mobile IP alone, the majority of which can be categorized into either ″network prefix-based″ or ″host-specific forwarding″ mobility management protocols, depending on the routing method used. This paper proposes a mobility-aware routing protocol (MARP) which makes use of both of these routing methods using dynamic IP address allocation. Its performance was evaluated and compared against hierarchical Mobile IP (HMIP) and Cellular IP based on handoff performance, end-to-end delivery delay, and scalability using OPNET. The results demonstrate that MARP is a more robust, flexible, and scalable micro-mobility protocol, minimizes session disruption, and offers improvements in handoff performance. 8. Admission Control Module for heterogeneous next-generation networks Abangar, H, Wang, M , Georgiades, M and Tafazolli, R Simultaneous access to different wireless networks is available in many places and multi-mode mobile devices are becoming more popular. Integration of heterogeneous radio technologies into one multi-radio access environment opens the potential to provide access to any network in an ″Always Best Connected″ fashion. Combining cellular wireless networks and high bandwidth WiFi for accommodating voice telephony services as well as internet browsing has already changed the user experience and consequently the user expectation. Optimum selection of the network and timely and efficient movement between different networks is of particular importance. We are proposing an Admission Control Module to tackle this issue. We assume the connectivity between mobile nodes and the proposed module is provided by a heterogeneous middle-ware that means the mobile nodes don't need additional network infrastructure support to connect to the Admission Control Module. We are considering WiFi, WiMAX and UMTS networks in our current research and we assume that mobile nodes are equipped to be able to connect to at least one of the mentioned wireless network technologies. When a mobile node is turned on in the operators network, the Admission Control Module is responsible for selecting the access network for the mobile node to attach to, maintain the status of the mobile node, select best access network and trigger the hand-over between available networks. The Admission Control collects some metrics from the mobile nodes and the available wireless network technologies, and this information will be used by proposed algorithms to assist in the handover decision. The handover decision can be the result of different user or network scenarios, e.g., Users willingness to experience a better QoS, resource management, availability of higher bandwidth, lower cost, bad coverage. We are using an in-house developed WiFi Simulator, OPNET's UMTS and WiMAX modules. HLA is being employed to enable co-simulation between different simulators. The simulation results will be used to investigate and then improve the effectiveness of the proposed algorithm. 9. Mobile VCE Ubiquitous Project Sheng, Y Hierarchical Mobile IPv6 (HMIPv6) is a protocol that enhances Mobile IPv6 (MIPv6) with faster handovers and reduces the signaling at the same time, with the introduction of the Mobility Anchor Point (MAP). From security point of view, HMIPv6 protocol does not provide ways to authenticate roaming mobile nodes, although visited networks (foreign network) will need to check if mobile nodes can be granted the network access. Also, the handover process is not secured. With the DIAMETER servers in place in both of the home domain and foreign domain, the authenticated access control scheme and securing handover process scheme are provided for HMIPv6 in my work. The security effect of these two mechanisms on HMIPv6 performance, in terms of the handover latency and signaling load on MAP, will be evaluated by OPNET. The MIPv6 modules in OPNET will be used and modified to build up the HMIPv6 module with the security mechanisms enabled. Three scenarios, the standard HMIPv6 scenario (micro-mobility handover, macro mobility handover and inter-domain handover), the multiple MAPs scenario and the hierarchical MAPs scenario will be used for evaluations. And the future simulations will also be based on these scenarios as well. 10. Interworking WiMax & Satellite Hincapie Yepes, G With interworking projects operators are faced with operational challenges before the end-to-end implementation of the service is complete, in our case study among other problems Mobility Management of the final user is our main concern. This project will examine the Interworking between WiMax and DVB-RCS technologies and implement a simulation for the analysis of Mobility management in such hybrid architecture. 11. Multicast Bearer Selection in Heterogeneous Wireless Networks
Gluhak, A, Chew, K. A., Moessner, K and Tafazolli, R
Abstract: Network scenarios beyond 3G assume the cooperation of operators with wireless access networks of different technologies in order to improve scalability and provide enhanced services to their mobile customers. While the selection of an optimised delivery path in such scenarios with multiple access networks is already a challenging task for unicast delivery, the problem becomes more severe for multicast services, where a potentially large group of heterogeneous receivers has to be served simultaneously via shared resources. In this paper we study the problem of selecting the optimal bearer paths for multicast services with groups of heterogeneous receivers in wireless networks with overlapping coverage. We propose an algorithm for bearer selection with different optimisation goals, demonstrating the existing tradeoff between user preference and resource efficiency. 12. Network-Centric User Assignment in the Next generation Mobile Networks
Huang, L, Liu, Y, Thilakawardana, S and Tafazolli, R
Abstract: This letter addresses the user assignment problem for multimedia streaming applications in heterogeneous wireless networks using a network-centric strategy. The optimal problem is mathematically formulated and proven to be Non-deterministic Polynomial-time (NP)-hard. An efficient heuristic algorithm is then proposed to find sub-optimal solutions in practical systems. Simulation results demonstrate the improved performance of this heuristic in comparison to a conventional user-centric algorithm. 13. Efficient Group-Based Multimedia-on-Demand Service Delivery in Wireless Networks
Huang, L, Chew, K. A., Thilakawardana, S, Liu, Y, Moessner, K and Tafazolli, R
Abstract: Recently, an upsurge of interest has been observed in providing multimedia on-demand (MoD) services to mobile users over wireless networks. Nevertheless, due to the rapidly varying nature of mobile networks and the scarcity of radio resources, the commercial implementation is still limited. This paper presents an efficient group-based multimedia-on-demand (GMoD) service model over multicast-enabled wireless infrastructures, where users requesting the same content are grouped and served simultaneously with a single multicast stream. The grouping is fulfilled through a process named "batching". An analytical model is derived to analyse a timeout-based batching scheme with respect to the tradeoff between user blocking probability and reneging probability. Based on the deduced analytical model, an optimal timeout-based batching scheme is proposed to dynamically identify the optimal tradeoff point that maximizes the system satisfaction ratio given a particular system status. The proposed scheme is evaluated by means of simulation and compared with two basic batching schemes (timeout-based, size-based), and two hybrid ones (combined-for-profit, combined-for-loss). The simulation results demonstrate the proposed approach can ensure significant gains in terms of user satisfaction ratio, with low reneging and blocking probabilities. 14. Network Selection for One-to-Many Services in 3G-Broadcasting Cooperative Networks
Huang, L, Chew, K. A. and Tafazolli, R
Abstract: Beyond 3G or 4G mobile systems envisions heterogeneous infrastructures comprising diverse wireless systems, e.g., 2G, 3G, DVB, WLAN, and various transmission approaches, e.g., one-to-one and one-to-many. In this context, a network selection (NS) problem emerges regarding the determination of the appropriate Access Network (AN), as users are reachable through several different ANs. This paper addresses the issue of provisioning one-to-many services over heterogeneous wireless networks in terms of how to choose the AN that satisfies the bandwidth requirement of services, while maximizing the system profit obtained in the combined network. A heterogeneous network comprised of Multicast Broadcast Multimedia Service (MBMS) of the third generation mobile terrestrial network and the digital video broadcasting transmission system for handheld terminals (DVB-H) is adopted in this study. Both networks cooperate and complement each other to improve the resource usage and to support one-to-many services with their multicast and broadcast transmission capabilities. Based on this architecture, an algorithm framework is defined and proposed to solve the NS problem for the one-to-many services. Six schemes based on the algorithm framework are then evaluated by simulation. 15. Resource Management over Interworking of 3G and Digital Broadcasting Networks
Huang, L,Chew, K. A. and Tafazolli, R
Abstract: A resource management (RM) framework is proposed for the efficient delivery of the mobile multimedia-on-demand services in a Beyond 3G (B3G) environment where the enhanced version of the third generation mobile terrestrial network for multicast and broadcast multimedia service (MBMS), and the digital video broadcasting transmission system for handheld terminals (DVB-H) work together cooperatively and complementarily. Their inherent "one-to-many" transmission capabilities are exploited to stream multimedia services to a group of users. Furthermore, network selection and qualities of service (QoS) adaptation are developed to allocate radio resources adaptively to network conditions and users personalities to benefit overall utility of the system and loss probability. Simulation results confirm the benefit of the proposed RM framework. 16. Optimal Approach Of Achieving Group-Based MObile Multimedia-On-Demand Services
Huang, L,Chew, K. A. , Thilakawardana, S and Tafazolli, R
Abstract: This paper addresses a group-based bandwidth-efficient mobile multimedia-on-demand (GMMOD) service over wireless networks, e.g. multimedia broadcast multicast system (MBMS) and digital video broadcasting network (DVB). In this service model, user s requests are first aggregated or batched and then served over a shared multicast or broadcast channel to achieve the objective of high system satisfactory ratio. We first analyze the tradeoff between service blocking probability and users reneging probability for a basic timeout-based batching approach. A theoretical model is developed. From this model, we propose an optimal timeout-based approach that is able to identify the optimal tradeoff point that maximizes the system satisfactory ratio at a particular cell status, traffic and user profile. The optimal timeout-based approach is then compared with the previously studied approaches: (1) two basic approaches (timeout-based, size-based), and (2) two hybrid approaches (combined for profit, combined for loss) by simulation. The simulation results demonstrate that the proposed approach gives the better performance in improving the satisfactory ratio and reducing the reneging probability while maintaining a small blocking probability. 17. Performance of VoIP Call Set-up Over Satellite-UMTS Using Session Initiation Protocol
Kueh, V Tafazolli, R and Evans, B
Abstract: Session Initiation Protocol (SIP) is an application layer signalling protocol used in the IPbased Universal Mobile Telecommunication Systems (UMTS) network for establishing multimedia sessions. With a satellite component identified to play an integral role in UMTS, there is a need also to support SIP-based session establishment over Satellite-UMTS (S-UMTS) to achieve end-to-end seamless IP-based terrestrial/satellite network integration. Due to the inherent characteristics of SIP, the performance of SIP-based session set-up is largely compromised when transported over an unreliable wireless link with a large propagation delay. This paper presents the work done in incorporating a link layer retransmission based on the UMTS Radio Link Control acknowledgement mode (RLC-AM) mechanisms to improve the call set-up performance. Specifically, our investigation focuses on the impact of the poll prohibit timer on the system performance and via simulations in OPNET, some insight into the configuration of this timer is identified. 18. Quantitative analysis of restricted reliability protocols for constant rate traffic
Howarth M. and Sun Z.
19. Context Transfer Extension to Mobility Protocols for All-IP Based Infrastructures
Georgiades M., Chew K. and Tafazolli R.
20. IST EVOLUTE Multilayer Mobility Management Architecture Evaluation
Chew K., Politis C. and Tafazolli R.
21. SIP-based Session Establishment over an Integrated Satellite-Terrestrial 3G Network
Kueh V., Tafazolli R. and Evans B.
22. Multilayer Mobility Management for All-IP Networks: Pure SIP vs. Hybrid SIP/Mobile IP
Politis C., Chew K. and Tafazolli R.
23. Comparison of Micromobility Management Protocols
Chew K., Politis C. and Tafazolli R.
24. W-CDMA Random Access Channel Transmission over Satellite-UMTS
Kueh V., Capellacci A., Tafazolli R. and Evans B.
25. W-CDMA Random Access Channel Transmission Enhancement for Satellite-UMTS
Kueh V., Capellacci A., Tafazolli R. and Evans B.
Abstract: The random access channel (RACH) is an uplink shared channel for initial channel access to the network as well as for short data bursts. In this paper, we propose modifications to the RACH preamble for satellite-UMTS using higher order of Hadamard codes, and it is shown that these enhancements have a better performance than that of the current Third Generation Partnership Project (3GPP) specifications and the European Telecommunications Standards Institute (ETSI) proposal. 26. MAC Protocol for Supporting QoS in All-IP HiperLAN2
Politis C. and Tafazolli R.
Abstract: The demand for high-speed Internet access and the emergence of multimedia applications are leading towards a new area of broadband wireless networks. This paper focuses on HiperLAN2 air-interface standard based on an all-IP network architecture. An appropriate QoS framework is proposed, based on which, classification and scheduling mechanisms of traffic classes are investigated. These could be considered as potential enhancements and compliments to the MAC protocol of HiperLAN2 for providing end-to-end QoS. 27. Performance Analysis for GPRS with Prioritized and Non-Prioritized Mobility Management Procedures
Chew K. and
Tafazolli R.
Abstract: GPRS is part of the evolution path towards 3G. This paper investigates the effect of user mobility on packet transmission in GPRS. A simulator was developed to study the end-to-end behaviour of data transmission between a mobile client and a fixed server via GPRS and Internet. Simulation results show interruption in data delivery when MS executes a routing area update procedure. A fair queuing algorithm is proposed to minimise update delay and packet loss. In addition, we give priority to all the mobility management-related packets to ensure that all MM-related packets are processed and reach its destination with minimal delay. The obtained simulation results demonstrated that the proposed techniques give better routing area update performance than FIFO service. 28. Internet Traffic Evaluation for Satellite Networks
Cruickshank H. and Sun Z.
Abstract: This paper presents the research works carried out in the BISANTE project funded within the European ESPRIT programme. The objective of this project is to develop simulation methodology and framework with a prototype workbench, which can be used to evaluate broadband and Internet traffic over satellites at network level. The framework includes traffic models, satellite constellations and network models and protocol architecture models. The capability of the simulation workbench is demonstrated by using it to study the performance of Internet traffic such as FTP and HTTP with simulation scenarios taking GEO satellites and LEOs such as Iridium and Teledesic satellite constellations as examples. The simulation results can give good indications on performance and QoS provisioning to applications for the given simulation scenarios and can be useful to network dimensioning and traffic management. 29. Error Performance Aspects of IP Multicast over Satellites
Howarth M. The last few years have seen an explosive growth in the use of the Internet. In addition to email and browsing the world-wide web, it is now used for interactive videoconferencing, information distribution, audio and video streaming, and real time applications. Satellites have significant potential to support these applications at a large scale by using IP multicast, and satellites with on-board processing and switching are currently being developed to carry IP-based traffic. In this context the characteristics of IP multicast in networks that include satellite links are of significant interest. This thesis begins by describing the principles of multicast routing protocols and reliable multicast protocols, and illustrates how the introduction of a satellite link into a network results in a number of aspects where the behaviour of multicast protocols differs from that in a terrestrial network. 30. Evaluation of TCP and Internet traffic via Low Earth Orbit (LEO) Satellites
Chotikapong Y. and Sun Z. The prospect of the Internet as the fastest growing satellite communication application coupled with satellite based multimedia networks have generated vast interest about the performance of TCP/IP over satellite networks. The paper presents network architecture for supporting services based TC/IP (and ATM) over satellite and support for IP telephony. Issues of using Low Earth Orbit (LEO) satellites to provide Internet services will be discussed as many studies have been done on GEO satellite already. With advantages that LEO satellite can offer, the paper will discuss the possibility of using it to expand the Internet. Finally, performance study, from simulations, of TCP over a LEO satellite constellation model transmitting HTTP and FTP traffics between client and server will be presented. 31. Network Architecture and Performance Evaluation of Broadband Satellite Systems
Chotikapong Y., Cruickshank H., Sun Z. and Evans B.,
For broadband access, satellites offer substantial bandwidth that can support transmission at Gbps rates. At the same time, significant difficulties arise at these rates that stem mainly from the delay and error characteristics of the satellite channel. In a network environment, these characteristics impact adversely some of the broadband network protocols from ATM to TCP and the network security. This paper presents some broadband satellite applications and details the technical challenges in implementing ATM, TCP and security systems to support such applications.
32. BISANTE - Traffic Evaluation Tool for Broadband Satellite Networks
Sun Z., Cruickshank H., Cheng B. and Evans B.,
33. LEO Satellite Networks Modelling and Traffic Evaluation
Sun Z., Cheng B., Cruickshank H. and Evans B., 34. Simulation studies of TCP/IP Performance over Satellite
Chaisompong C., Chotikapong Y. and Sun Z.
35. Network Architecture and Performance Evaluation of TCP/IP and ATM over Satellite
Chotikapong Y., T.Ors and Evans B.,
36. Evaluation of application performance for TCP/IP via satellite links
Chotikapong Y. and Sun Z. This paper presents performance results of simulation studies on TCP/IP over satellite using OPNET simulation software. Transmission Control protocol (TCP) is the main transport layer protocol in the TCP/IP protocol suite for today's Internet. It provides connection oriented reliable delivery of data over network paths by its congestion control algorithms. With the TCP congestion control algorithms, satellite channels of high bit error rate and long delay severely affect TCP performance. These lead to poor bandwidth utilization and response. Research and studies have been done in order to improve TCP performance over satellite channel. Many proposals have been made such as increasing initial window size, time stamp, window scaling and Selective Acknowledgment (SACK). The paper aims to give an overall review of the problems that TCP faces and its performance over satellites based on well defined scenarios using simulation results produced on the OPNET environment, and highlight the issues for further research.
37. Channel modelling and error control strategies for the LEO satellite channel
Sweeney P. OPNET was used in simulating the performance of the SR sliding window protocol, which was incorporated in the PACSAT protocol suite. The research aimed at investigating the optimal hybrid-ARQ scheme based on punctured Reed Solomon codes for varying LEO satellite channel conditions.
38. Satellite-ATM networking and call performance evaluation for multimedia broadband services
Mertzanis, I., Sfikas, G., Tafazolli, R. and Evans B., 39. Service mapping and radio resource management in multimedia non-GEO satellite networks
Mertzanis, I., Tafazolli, R. and Evans B.,
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. |
