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OPNET is being used within the following projects: Title: Vertical handover based on SIP The aim of this project is to implement vertical handover for multimedia session over an all-IP mobile network based on Session Initiation Protocol (SIP) and the triggers form the lower layers. As SIP is becoming the leading protocol for multimedia call control in IP networks and is expected to be widely deployed in the near future. We are developing OPNET SIP Model by adding the re-invite function so that it can support the mobile node when it moves between different networks, such as WiFi, WiMax and 3G. We also plan to model the smart triggers that are generated by L2.5 in the mobile node, to improve the handover time and reduce the packet loss. Title: Optimisation of user specific packet scheduling in HSDPA/HSUPA Transport layer performance affect heavily on packet scheduler in RNC. HSDPA/HSUPA provides new dedicated channels, higher bit rates etc. Packet scheduling can be optimized to provide the better performance of transport layer protocols like TCP. Using Opnet currently we are studying the effect of using different channels and data rates under different conditions. Analysis of different types of application, performance of application level and TCP level end to end performance effects under softer, soft and hard handovers are also studied. We are using Opnet's UMTS and Wireless modules for this study. Title: Cross Layer Design to Improve TCP Performance The reliable transport protocol for the Internet has been engineered to perform well in traditional wired networks where packet loss is mainly due to congestion. TCP performance degrades on wireless links which are characterized by high bit error rate and intermittent connectivity. On wireless links, the performance seen by the TCP layer can be improved by the use of cross layer algorithms at the link level that interact with the TCP state machine. To investigate more in this area OpNet is being used to simulate the whole layered interaction. Hence Implementing the algorithms in OpNet and examine on the behavior of the protocol stack can give a support to this issue.
Title: Network Mobility and Quality of Service The demand for data communications on the move has shown rapid growth in recent years, and with it, a greater expectation of reliable and consistent services at any time and anywhere. Such expectations are exemplified in the frustration expressed by users when they experience a dropped connection on a public transport vehicle as it moves through a tunnel or at high speed. Whilst many of the causes of unreliability stem from issues at the radio and media access layers, a considerable number are as a result of inefficiencies at the network layer, due mainly to congestion caused by signaling storms upon IP handovers. To address issues of efficiency and scalability, it is necessary to redesign many network-layer protocols to be able to provide session continuity to users within a moving network without necessarily burdening the scarce resources of the network with control signaling. Accordingly, OPNET is being used to evaluate the performance of existing quality of service mechanisms when used within a moving network, a particular network-layer aspect on which this research is focused. We are currently involved in, amongst other things, extending the in-built Mobile IPv6 functionality of OPNET to support the NEMO Basic Support protocol (RFC 3963).
Title: Energy Efficient Wireless Sensor Network Current project implements the protocol stack of a wireless sensor node within OPNET based on the ideas inspired from state of the art Wireless Sensor Network protocols. Further Analysis and cross-layer optimization is done using this implementation.
Title: Coverage-based Common Radio Resource Management The project is to evaluate the coverage-based CRRM to support non-real-time traffic in a heterogeneous environment. Two cellular systems: UMTS and GSM are considered in this evaluation. Our results has show the potential of coverage-based CRRM to increase the non-real-time traffic throughput in this scenario.
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