Features & Benefits- Monitoring and Simulation/Emulation of Signaling Protocols at theIu, Iub, Iur, Iu-BC, Iu-PC, Nb, Mc, and Nc Interfaces Ensure QualityImplementation of Protocol Definition and Behavior
- Powerful Tools for Development and Test of UMTS Network Elements AllowEarlier and Cost Effective Availability of Adjacent Network Node Functions
- Simultaneous Handling of AAL2 and AAL5 Virtual Channels Allows SimultaneousTesting of Control and User Plane Protocols
- More than 1800 protocols and variants according to 3GPP R99, R4, R5,and R6
- Vendor specific protocol decoding (Nortel, Nokia)
- Call Generation for MOC (Mobile Originated Calls) and MTC (MobileTerminated Calls)
- Handover Tests (3G-3G HO, 3G-2G HO) and Location Service Test capabilities
- Data Generation of IP Traffic Enables QoS and End-to-End Tests
- Test Scenarios with AMR coded voice
- Supports Interface Boards ATM E1/DS1 (Rx/Tx and Rx/Rx) and ATM STM1/SONETOC3 Optical (Rx/Tx and Rx/Rx) to Cover the Needs of UMTS Networks
- Seamless Access to PCM Lines Using IMA (Inverse Multiplexing OverATM) and Fractional ATM
- Test solution for TDD LCR (Time Division Duplex, Low Chip Rate) R4
Applications- Functional Testing of Protocol Implementations
- System Testing of Network Nodes
- Simulation of RNC, CN (SGSN/MSC), Media Gateway Controller, MediaGateway, and Node B
- All-IP UTRAN Test Application
- Calltrace for Iub, Iu-CS and Iu-PS
- Iub Deciphering
- Iu-PS Capacity Tests
UMTS SoftwareAs the third-generation mobile standard, UMTS allows sophisticated servicesthrough the latest CDMA and network technologies. Extensive simulationand monitoring test tools are required more than ever, due to the advancesand complexity of developing, deploying, and operating these mobile networks.As a leader in the mobile measurement business, Tektronix offers solutionsto meet Protocol Test challenges. Software for the K1297-G20 Protocol Tester supports functional testsin UMTS R99, R4, R5, and R6 system development, and system tests for systemintegration. Monitoring, Simulation, and Emulation functions are providedfor relevant UMTS signaling protocols and user plane protocols. Solutionsare available for the most challenging test functions such as PER encodedRANAP, NBAP, and RNSAP protocols. UMTS Iu, Iub, and Iur test software allows the RNC or CN at both sidesof Iu interfaces, as well as RNC and Node B, to be simulated and tested.The software enables telecommunication equipment manufacturers to verifythe software implementation of the RNC, CN, and Node B, ensures productdevelopment quality, minimizes development time, and reduces the risksfor UMTS projects. Continuous protocol version upgrades are made available in order to complywith the latest 3GPP specifications. For fast trouble ticket resolutionthe K1297-G20 base SW offers Single-Interface Calltrace for Iub, Iu-CSand Iu-PS interfaces. A Calltrace captures all relevant messages on oneinterface related to a certain subscriber or to a certain transaction.A mobile operator may be interested in singling out all transactions relatedto a certain network problem, like congestion or temporary failures. The software packages support the following test functions (selection): - Monitoring and simulation of Iu UP (TS25.415)
- Monitoring and simulation of Iub FP (TS25.427, TS25.435)
- Monitoring and simulation of MAC (TS25.321)
- Monitoring and simulation of RLC (TS25.322)
- Monitoring and simulation of RANAP (TS25.413)
- Monitoring and simulation of NBAP (TS25.433)
- Monitoring and simulation of RNSAP (TS25.423)
- Monitoring and simulation of SABP (TS25.419)
- Monitoring and simulation of RRC (TS25.331)
- Monitoring and simulation of MM/CC/RR/GPRSMM/SM (TS24.008)
- Monitoring and simulation of SMS (TS23.040, TS24.011)
- Monitoring and simulation of BMC (TS25.324)
- Monitoring and simulation of PCAP (TS25.453)
- Monitoring and simulation of Supplementary Services (TS24.080)
- Monitoring, simulation, and emulation of M3UA and SCTP
- Monitoring, simulation, and emulation of ALCAP (Q.2630.1, Q.2630.2,and Q.2150.1/2)
- Monitoring, simulation, and emulation of GTP (TS29.060)
- Monitoring, simulation, and emulation of PDCP (TS 25.323)
- Monitoring and simulation of BICC
- Monitoring and emulation of RTP/RTCP
- Send and receive speech on interfaces such as UMTS Iu. Iub, Nb, GSMA, and PSTN
- Emulation of IPv6
- Mobile originated call generation for circuit and packet switchedcalls by simulating RNC or CN at the Iu interface
- IP packet generator and comparator on top of GTP-emulation
UMTS Reference Model
Figure 1. UMTS reference model.
UMTS architecture can be seen as the next step beyond the 2G and 2.5Gtechnologies (GSM and GPRS). Thus, UMTS will not replace these technologiesand their network elements, but will extend the network architecture.UMTS R99 introduced new network elements, such as the Radio Network Controller(RNC) and Node B, as shown in Figure 1. These two new network elementswill form three new UMTS specific interfaces: - The Iu interface between RNC and MSC/SGSN, with the Circuit Switched(CS) and Packet Switched (PS) part
- The Iub interface between RNC and Node B
- The Iur interface between RNCs
UMTS R4 introduced new network elements such as the MSC Server and theMedia Gateway (MGW), as well as new interfaces Nc, Nb, and Mc, as shownin Figure 1. In addition, new functionalities have been added to alreadyexisting UMTS/GPRS protocols. These new elements, the interfaces between them, and the great numberof new protocols create a huge demand for test applications. Examplesof test configurations that can be handled with the K1297-G20 UMTS solutionare described below. UMTS R5 introduced an All-IP architecture, end-to-end support for VoIP,the Stand-alone A-GPS SMLC (SAS) and new features (e.g. HSDPA) that willenable new services and reduce operating costs. The Iu-PC interface connectsthe SAS with the RNC. Further, support of the TD-SCDMA technology hasbeen included in UMTS R5. UMTS Release 6 supports key features such as Multimedia Broadcast/MulticastService (MBMS), Network Sharing, Priority Service, Wireless LAN/UMTS Interworking,IMS Phase 2, Push Services, and Presence.
Figure 2. K1297-G20 simulating a Radio Network Controller (RNC).
Figure 2 shows a K1297-G20, which simulates the RNC network element towardsthe MSC and SGSN. Depending on the test purpose, the protocol layer willbe simulated or emulated. The message flow for the protocol to be simulatedis usually defined in a simple way with the Message Sequence Chart (MSC)Tool offered by the K1297-G20 Base Software. Emulations, which behaveaccording to the standards, are used for all layers below the simulated
Figure 3. K1297-G20 simulating a MSC towards RNC and SGSN.
In Figure 3, the K1297-G20 simulates a MSC towards the SGSN and the RNC.This configuration requires the appropriate GPRS packages for Gsinterface simulation. Applications, such as the Call Generator, help totest the basic call handling.
Figure 4. K1297-G20 monitoring the Iu interface.
Monitoring UMTS interfaces adds additional test challenges. As the physicallayer is often optical in nature (e.g., STM1 optical) it is not possibleto hook the unit to an interface without disconnecting the lines betweenthe network nodes unless there are special monitoring points. In addition,an optical coupler (each direction) may be necessary to allow passivemonitoring. The K1297-G20 in Figure 4 monitors the complete Iu interface(Iu-CS and Iu-PS) at the same time.
Figure 5. K1297-G20 monitoring of Iub and Iur interface.
Figure 5 shows a K1297-G20 monitoring the Iub and the Iur interface. Iu-PS Capacity TestsThe SGSN in the UMTS core network is tested from both the Gi and IuPSinterface by the test unit. The test unit emulates many RNC抯 supportingmultiple UEs at IuPS. The UEs and RNC抯 are modeled as performing realworld mobile procedures, like: - Attach
- Detach
- PDP Context Activation
- PDP Context Deactivation
- PDP Context Modification
- Intra/Inter-SGSN RAU with simultaneous data transmission
- PTMSI Reallocation
- Paging PS
- Uplink/Downlink Data Send
- Uplink/Downlink Data Receive
- SMS Send
- SMS Receive
A K1297-G20 with one AP-4/ATM-Board is able to simulate up to 100.000mobile subscribers. Testing the SGSN at the Gi interface is valuable because: - It allows for sending of traffic in both directions better simulatingreal world up-link and down-link traffic.
- Gathering payload metrics at Gi allows for analysis of the SGSN抯performance in processing user plane traffic generated at IuPS.
- These metrics can include total packet, good packet, lost packet andbad packet counts.
- Down link traffic can be generated at Gi to test the SGSN抯 user planein the reverse direction.
For more detailed information refer to the Iu-PS Capacity Test ApplicationNote 2FW-17575-0. Dynamic allocation of AAL2 links with a K1297-G20 on the Iub interface.The Iub interface protocol architecture consists of two functional layers,as shown in Figure 6: - The radio network layer defines procedures related to the operationof Node燘. It consists of a radio network control plane and a radionetwork user plane
- The transport layer defines procedures for establishing physical connectionsbetween Node燘 and the RNC
Figure 6. Iub interface protocol structure.
In order to decode the dynamically opened Signaling Radio Bearers (SignalingRABs) from and towards the User Equipment (UE), the signaling on Iub ControlPlane (NBAP) and Transport Network Control Plane (ALCAP) must be traced. Each connected Node燘 requires configuring at least one pair ofNBAP and ALCAP links. An appropriate application analyzes this signaling, and opens the appropriateCommon and Dedicated Control Channel.
Figure 7. Set of common transport channels.
One Node燘 serves a certain number of cells. For each cell thereis a complete set of Common Control Channels, such as PCCH, BCCH, andCCCH. These channels are called Logical Channels. See Figure 7. Iub DecipheringCiphering in UMTS is performed between UE and RNC over Air and Iub-Interface.For the structure of the Iub protocol stack refer to Figure 8. The ciphering function is performed either in the RLC sublayer or inthe MAC sublayer, according to the following rules: - If a radio bearer is using a non-transparent RLC Mode (AM, UM), cipheringis performed in the RLC sublayer.
- If a radio bearer is using the transparent RLC Mode (TM), cipheringis performed in the MAC sublayer (MAC-d entity).
In effect, if a protocol tester without Deciphering application is usedon Iub-Interface and Ciphering is activated, all RRC messages and aboveplus all User Data cannot be decoded anymore.
Figure 8: Iub protocol stack with Ciphering.
Ciphering will be activated after exchange of securityModeCommand andsecurityModeComplete (see Figure 9). The deciphering application of theK1297-G20 works in automatic and manual mode. In order to capture theciphering key CK in automatic mode, access to the Iu Interface is required.The manual mode is designed for test labs that are able to manipulatethe ciphering key CK. For this use case no access to the Iu-Interfaceis necessary. The Iub Deciphering application will trace up to 1000 (automaticmode) or 50 (manual mode) different connections on Iu- and Iub-Interfaces.
Figure 9: Ciphering activation.
The recording shown in Figure 10 shows an authentication and call setupprocedure (MOC) on Iu- (blue color) and Iub-Interface (black color). AllNAS-messages after the security procedure are encrypted on Iub-Interface.Therefore without deciphering application, the SETUP, CPROG messages aredecoded on Iu-Interface, but not on Iub-Interface anymore. The K1297-G20 deciphering application works in online and offline modeand also tracks complex procedures, like Softer-Handover and Channel TypeSwitching.
Figure 10: Ciphering authentication and key agreement.
Seamless Access to IMAThe requirements for higher bandwidth and the need to reduce investmentsin mobile radio network infrastructure were the driving factors for thedefinition of IMA. The standard was defined in the late 1990s by the ATMForum and describes how to use links with lower bandwidth (such as E1and DS1) to form a 搗irtual?link with higher bandwidth. In order to save costs during the early years of 3G network deployment,operators will try and re-use as much infrastructure from existing networksas possible by using this IMA technology. Using this technology successfullyrequires a tool for non-intrusive monitoring, which examines all lineswithout utilizing additional test equipment. By combining innate protocolmonitoring for the lub interface with seamless access to IMA links, Tektronix抜nnovative new IMA monitoring software enables users to perform upper-layerprotocol analysis in addition to retrieving information (statistics, alarms,etc.) from the lower-layer IMA links. While most IMA monitoring toolsactually interrupt physical lines carrying active network traffic (cuttingoff traffic on the link while the connection is being made), the new IMAsolution is the only one to monitor passively.
Figure 11: G20 System Concept for passive IMA Monitoring
Connection to the E1/DS1 lines of interest (those using IMA) is possibleat any time without affecting live traffic. There is no need to disconnector re-start the links being monitored. Tektronix?IMA software automaticallydetermines whether the links that make up an IMA group are correctly connected.Links that do not belong in the group are revealed in real-time. Thisautomation dramatically simplifies the task of connecting E1/DS1 cablesand reduces the risk of incorrect connections. See Figure 12.
Figure 12: An IMA Pool is correctly configured and the IMA Groupis operational
As soon as all cables are correctly connected to the PCM lines and theconfiguration is set up (IMA Pool is operational) all the higher protocollayers are decoded 揳s usual? Applications like Iub-Monitoring work asexpected. In case of IMA state changes (e.g. add/remove of an IMA link)these events will be displayed as layer 1 alarms in the recording file.Furthermore there are dozens of IMA specific counters that allow a detailedanalysis of the IMA protocol states. Fractional ATMFractional ATM is a technology that allows Network Operators to minimizetheir infrastructure costs, especially during the UMTS deployment phasewhen the network load is low. The UMTS UTRAN and the GSM BSS share thesame physical medium and exchange User and Control information over thismedium with the Core Network. The K1297-G20 time slot editor (See Figure13) allows the assignment of an ATM Fraction in any combination. ThisATM section forms the monitoring part for the UMTS Iub-Interface. Theremaining time slots can be used for conventional PCM-30 monitoring, e.g.for GPRS/GSM A-Interface monitoring.
Figure 13. Fractional ATM time slot editor.
Fractional ATM is part of the K1297-G20 Base SW. It supports E1 and T1connections. |
