EXPERIMENT N0: 06 AIM:TO DESIGN UMTS NETWORK USING OPNET MODELER APPARATUS: OPNET MODELER 14.0

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1 EXPERIMENT N0: 06 AIM:TO DESIGN UMTS NETWORK USING OPNET MODELER APPARATUS: OPNET MODELER 14.0 THEORY:Universal Mobile Telecommunications System (UMTS) is a Third Generation (3G) wireless protocol that is part of the International Telecommunications Union's IMT-2000 vision of a global family of 3G mobile communications systems. UMTS is expected to deliver low-cost, high-capacity mobile communications, offering data rates up to 2-Mbps. The UMTS model suite allows you to model UMTS networks to evaluate end-to-end service quality, throughput, drop rate, end-to-end delay, and delay jitter through the radio access network and core packet network. It can also be used to evaluate the feasibility of offering a mix of service classes given quality of service requirements. This model is available as part of the specialized model library. The UMTS model of the packet wireless network is based on 3 rd Generation Partnership Project (3GPP) Release 1999 standards. The network architecture of this release is divided into the radio access network (RAN) and the core network as shown in figure. The UMTS module models the UMTS RAN and the UMTS functionality of the core network (see highlighted elements in figure). The radio access network for UMTS contains the User Equipment (UE), which includes the Terminal Equipment (TE) and Mobile Terminal (MT), and the UMTS Terrestrial Radio Access Network (UTRAN), which includes the Node-B and Radio Network Controller (RNC). UMTS uses Wideband Code Division Multiple Access (W-CDMA) access scheme. This version of W-CDMA uses direct spread with a chip rate of 3.84 Mcps and a nominal bandwidth of 5 MHz. The model supports one of W-CDMA's two duplex modes: Frequency Division Duplex (FDD). Time Division Duplex (TDD) is not supported. In FDD mode, uplink and downlink transmissions use different frequency bands. The radio frame has a length of 10 ms and is divided into 15 slots. Spreading factors vary from 256 to 4 for an FDD uplink and from 512 to 4 for an FDD downlink. With these spreading factors, data rates of up to 2 Mbps are attainable. The packet domain core network includes two types of network nodes: serving GPRS support nodes (SGSNs) and the gateway GPRS support node (GGSN). The GPRS support nodes (GSNs) include all GPRS functionality needed to support GSM and UMTS packet services. SGSNs monitor user location and perform security functions and access control. The GGSN contains routing information for packet-switched (PS) attached users and provides interworking with external PS networks such as the packet data network (PDN). The model's CN nodes include both SGSN and GGSN functionality. 1

2 The circuit switched (CS) core network, which is not currently modeled, includes the mobile switching center/visitor location register (MSC/VLR). The MSC/VLR is used in the packet domain architecture to efficiently coordinate PS and CS services and functionality. The Home Location Register (HLR) contains GSM and UMTS subscriber information. The Charging Gateway Functionality (CGF) collects charging records from the SGSN(s) and GGSN. The Equipment Identity Register (EIR) stores information about user equipment identity. The HLR, CGF, and EIR are included in this description for completeness, but are not currently modeled. Creating a UMTS Network Topology The node models shipped as part of the UMTS specialized model library are grouped in the UMTS and UMTS_advanced object palettes. 2

3 Node model Table 2 Node Models Description UE umts_station General client node that includes UE and generic traffic generation functionality. This node can only send traffic to (and receive traffic from) other umts_station nodes served by the same SGSN. umts_wkstn umts_server UTRAN umts_node_b umts_node_b_3_sector umts_rnc General workstation node (with full OSI stack) that includes UE and client/server application functionality. General server node (with full OSI stack) that includes UE and client/server application functionality. Node-B portion of the UTRAN. Node-B portion of the UTRAN. This node_b model has 3 directional antennas, which handle connections with the UEs in their sector. RNC portion of the UTRAN. CN umts_sgsn Simple CN node has core network functionality, but does no IP routing. Routes packets to and from umts_station nodes, exclusively. umts_ethernet_slip8_gtwy umts_ethernet_slip8_large_gtwy umts_ggsn_slip8 umts_ggsn_atm8_ethernet8_slip8 umts_ggsn_ethernet2_slip8 umts_sgsn_ethernet_slip umts_sgsn_atm_ethernet_slip Gateway CN node general gateway node that includes SGSN and GGSN routing functionality and Ethernet and SLIP interfaces. Used only in networks with umts_wkstn and umts_server nodes. Not used with umts_station nodes. GGSN portion of the CN SGSN portion of the CN 3

4 Supported Configurations You can configure your UMTS network model to use either of the following configurations: UMTS workstation nodes routing application traffic ( , ftp,...) through one or more CN nodes to other UMTS workstation or server nodes, or to workstations and servers running over other technologies, such as Ethernet or WLAN. UMTS station nodes sending generic data traffic to other UMTS station nodes though a single or multiple SGSN nodes. You cannot send application traffic to a UMTS station node, nor can you send traffic generated by a station node to a UMTS workstation or server node. When using the UMTS workstation nodes, use the application models to generate traffic as you would for any workstation node. See the application model documentation for additional information on configuring application traffic. Using the station and SGSN nodes allow you to configure a traffic generation pattern that is not application-based. This avoids the need to use the application models when you are not interested in application-specific performance in the UMTS network. Consider using the station nodes and SGSN nodes when the following apply: You want to model raw traffic data within the UMTS network. You are not interested in the external IP network. You are not modeling CN to CN data transfer. 4

5 The following diagrams illustrate the supported types of UMTS network configurations: Figure3: Simple UMTS Network Using Application Traffic Figure 4 Simple UMTS Network Using Raw Traffic Generation 5

6 Model Architecture The GPRS network architecture is shown in Figure 5. This section describes the nodes shown in Figure 5, including their process and node models. Figure5: UMTS Network Architecture When a user powers-on, the model assumes that synchronization and a PS signaling connection are established. This PS signaling connection is kept for the entire simulation. Because of this, when a user powers-on it can immediately do a UMTS GPRS attach with the SGSN(s) to access to GPRS services. Packets are queued when they are received from higher layers. Since each user supports four QoS profiles, the traffic is queued on one of four QoS queues. If no PDP context has been activated for that QoS profile, an Activate PDP Context Request is sent to the SGSN(s). This PDP context activation message includes the QoS requested. The model assumes that the SGSN(s), after consulting the RNC, either grants the QoS requested by the user in its entirety or rejects it. No negotiation by the SGSN/GGSN or RNC of the requested QoS is done at this stage. On receipt of the Activate PDP Context Request, the SGSN(s) sends a RAB Assignment Request to the RNC along with the QoS requested. The UTRAN performs admission control to determine if the request can be granted. If the uplink and downlink have sufficient capacity toaccommodate the request, the request is granted. If the request can be granted, the RNC sends a Radio Bearer Setup request to the UE. 6

7 On receipt of the Radio Bearer Setup request, the UE sets up the channel as specified in the request and send a Radio Bearer Complete to the RNC. On receipt of the Radio Bearer Complete, the RNC sends a RAB Assignment Response, which includes the granted QoS, to the SGSN/GGSN. The SGSN(s) then sends the Activate PDP Context Accept message, which also includes the granted QoS. The UE can send packets to the destination on receipt of the Activate PDP Context Accept message from the SGSN(s). Before reaching their destination, these packets are first tunneled through serving the RNC and SGSN/GGSN, then routed through the IP cloud. If the destination network is also a UMTS network, then they are finally queued at the destination SGSN/GGSN node. Once a channel is set up at the destination, the packets are forwarded to the destination UE. CONCLUSION: In this experiment the UMTS NETWORK was designed using the different UMTS modules consisting of UMTS workstation, UMTS SGSN, GGSN nodes. 7