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OPNET
Technologies OPNET is a
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With OPNET version 10.0, the simulation model of UTRAN R99 has been successively extended based on the OPNET ATM workstation/server model, which represents an ATM node with client-server applications running over TCP and UDP that resides over the IP layer, which in turn resides over the ATM layer. The established UTRAN model is shown in the following figure. This model is capable of representing multi-service scenarios inside the UMTS access network interface, enabling such circuit switch data as voice, video streaming directly transporting over the ATM stack, providing radio interface and related radio protocols such as RLC, MAC and FP layers. In addition, the UMTS Call Admission Control, Radio Resource Management and AAL2 QoS differentiation are implemented inside the model as well. This model is suitable for the performance analysis and dimensioning of the UTRAN Iub interface.
With this simulation model, firstly different traffic source models have been investigated based on specific application mixes. The influence of different protocol stacks, multiplexing and compression techniques were evaluated with respect to delay of voice and data packets and the efficient use of bandwidth. During the ongoing work, in order to obtain a cost-efficient design of the UTRAN network, different dimensioning approaches for transferring both Packet-Switched data and Circuit-Switched data over the costly Iub link are investigated The simulation tool used for all of these investigations is OPNET 10.0. The figure below gives an example of one sepcific simulaiton scenario. This scenario consists of two NodeBs as traffic sources/sink, an intermediate Cisco ATM Switch and an RNC as UMTS peer of the NodeBs. Each NodeB is attached with one single E1 line (2 Mbps) to the ATM switch. On the backbone link between ATM switch and the RNC, the ATM STM-1 line(155 Mbps) is used. Above the physical ATM link, two ATM CBR PVCs are set up from each NodeB to the RNC and AAL2 protocol is used to muliplex several different user connections (voice call, internet connection, etc.) over one PVC. The aggregation of all user traffic of different classes is generated from the application layer of the NodeB and RNC. Depending on the type of the application requested by different users, different transport protocol is selected. For example, the voice is usually over the ATM, Web browsing or FTP traffic is over TCP/IP, etc.
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