In this Issue:
TESTING APPLICATIONS
m500 Mesh Architecture for Scalable Load Generation
WHAT’S NEW….
Structured STM-1/OC-3 Highlights
J1/E1/T1 (JET) Interface Card Now Available
TECHNICAL TIPS
Catapult News is issued periodically by Catapult Communications. Covering a variety of test
topics, we hope that you find this e-newsletter to be informative and helpful.
PESQ – A Closer Look
Perceptual Evaluation of Speech Quality (PESQ) provides an objective measure that predicts the results of subjective listening tests on telephony systems. PESQ uses a sensory model to compare the original unprocessed signal with the degraded version at the output of the communication system. PESQ can be used with confidence to assess end-to-end speech quality as well as the effect of individual elements such as codecs.
PESQ takes into account coding distortions, errors, packet loss, delay and variable delay, and filtering in analog network components as sources of signal degradation. It does not take into account the subjective effect of level changes in the network, echo, and the effects of round-trip delay on conversation.
PESQ requires two inputs: the original, unprocessed test signal (speech-like signals) and the degraded version that has been passed through the device under test (DUT). In addition, the model needs to know the sampling rate of these files.
Operations performed by PESQ:
- Level Alignment
- Input Filtering
- Time Alignment
- Auditory Transformation
- Equalization
- Disturbance Processing
Catapult’s Implementation of PESQ:
PESQ implementation is supported on both MGTS and DCT2000 network diagnostics systems. A typical MGTS or DCT2000 UMTS Iu test scenario with PESQ involves a simulated UTRAN node and a Core Network DUT. The UTRAN node simulates Mobile Originating Calls (MOC) and Mobile Terminating Calls (MOT).
Traffic generator utility and DCPL scripts are use on MGTS and DCT2000 respectively to send and receive the voice payload for both originating and terminating calls. To record calls for PESQ, the terminating side must have the PESQ feature enabled (see figure 1).
QoS Server. The QoS server is responsible for decoding the received degraded speech files and performing PESQ analysis on the files. When the analysis for a channel is completed, a message is sent to the QoS client with the PESQ score. The degraded speech file is saved as a speech (.spc) file. The file contains channel information as well as a degraded WAV file. In order to extract the WAV file from the speech file, the QoS client must be used. The QoS server must run on a Linux platform (see figure 2).
QoS Client. The QoS client (PESQ GUI application) is used to display PESQ analysis results. It runs on Linux (either MGTS or DCT) or Solaris (MGTS admin) platforms. By default, on the DCT2000 the QoS server launches the QoS client automatically on the machine where the PESQ test is run. On the MGTS PESQ is activated through the utility menu (see figure 2).
Wave Converter Application. The wave converter application converts a .wav file into a desired encoded speech format such as Adaptive Multi-Rate (AMR) narrow-band codecs. The input .wav file must be encoded in 16 bit samples and must be 8 Khz.
Speech samples for all supported codecs are supplied with Catapult’s PESQ test systems. Users have the flexibility of customizing their test scenario with a different language or dialect by supplying their own speech samples that can be converted to coded speech with the wave converter application.
MGTS uses the Traffic Generator to take the AMR file and generate traffic to the device under test. DCT2000 uses a DCPL script file to provide the same functionality. QuickStarts are available on both the DCT2000 and MGTS to ensure ease of feature activation.
For more information on PESQ and Catapult’s implementation please contact your local Catapult representative.
Parts of this article are included with the permission of Psytechnics Limited.
m500 Mesh Architecture for Scalable Load Generation
With its efficient mesh architecture, the m500 platform can connect up to 17 processing cards to a single physical link. This allows the m500 platform to provide unprecedented load performance and scalability. The m500 platform is also well suited for testing scenarios that require running a variety of protocols simultaneously over various types of interfaces.
Determining test equipment performance is often a difficult task. This is because performance is dependent on the type of applications being tested as well as a variety of network and environmental factors.
Catapult’s test systems provide users the ability to configure the various parameters including call hold times (CHT), simultaneous calls, busy hour call attempts (BHCA), and packet sizes to stress the device under test.
Below are examples of actual UMTS load test results using the m500 platform with only one mesh computing interface card (mCU2):
Note that these numbers are based on specific configurations and will vary with changes in parameters and tested devices. Additionally, with Catapult’s new mCU5 processing card the load numbers increase dramatically.
Catapult Expansion Continues
Catapult Expansion Continues.
Catapult has opened two additional support offices, one in Bangalore, India and another in Aachen, Germany. These openings continue the Company’s worldwide expansion plan that most recently saw sales and support offices being opened in Sweden and China. The contact information for these new facilities is listed below.
Catapult Communications Bangalore Pvt. Ltd.
908, Level 9, Raheja Towers
M.G. Road, Bangalore - 560 001
Tel: +91 80 4180 0853
Fax: +91 80 4180 0900
Email: india@catapult.com
Catapult Communications
C 2.03
Pauwelsstr. 19
D-52074 Aachen
Germany
Tel: +49 (0) 24 19 63 23 55
Fax: +49 (0) 24 19 63 23 59
Structured STM-1/OC-3 Interface Highlights
Catapult announced the general availability of a new Structured STM-1/OC-3 (SSTM-1) card in July 2006. This card represents a major improvement for high capacity testing applications, minimizing the need for multiple E1/T1 cards to run the same level of traffic. The SSTM-1 is being paired with a Rear Transition Module (RTM) card to provide a mesh interface riding on the m500 platform.
The SSTM-1 card supports up to four simultaneous optical interfaces to simulate channelized 64kb/s TDM data transported over T1 or E1 carried over a SONET STM-1 communication link.
As part of the m500 mesh architecture, the SSTM-1 card provides one of the most scalable high load testing capabilities in the industry. By generating traffic for up to 8064 channels, this card is ideal for SS7 and media gateway testing.
For more information on this new card please contact your local Catapult representative.
J1/E1/T1 (JET) Interface Card Now Available
Catapult’s new JET card is available for use with MGTS or DCT on the p-series and m500 platforms. The JET interface card is a four-port card interfacing to test links at a data rate of 2.048 or 1.544 Mb/sec. Each card is configurable over the full range of 96 (T1 or J1) or 124 (E1) channelized timeslots. Its flexibility also allows the support of fractional, unchannelized and ATM operation.
New Datasheets Available
New product datasheets are available on the product literature section of Catapult’s website (www.catapult.com):
- m500 High Performance Mesh Architecture Platform
- m500 STM-1c/OC-3c ATM Mesh Interface
- m500 Gigabit Ethernet Mesh Interface
- J1/E1/T1 Interface Card
What’s New on DCT2000 Releases 11.1 - 11.3
- New and updated protocols:
- New Utility Tool: X·Stream Packet Generator on DCT-LINUX
- Generates maximum packet data load rates
- Gathers high-level transmit and receive statistics
- Estimates integrity of connection pathways
- DCT2000 QuickStart Enhancements:
- IuCS QuickStart with PESQ
- Upgraded SIP+RTP QuickStart
- CATTgen Enhancements:
- New entries in the CATTgen/Launcher for Va, b variant formats
- Easier to import and export CATTgen protocol in the launcher context
- Defined port/protocol info in launcher context
- Macro selection with alphabetical buckets
What’s New on MGTS Releases 14.0 and 14.2
- m500 Structured STM-1/OC-3 Interface Card
- Supports SS7 (MTP2)
- TDM traffic over a 155Mb/s optical link
- COT/DTMF
- Conformant to ITU-T, ETSI, ANSI and TTC
- Level 2 Conformance on JET Card
- Provides a pass or fail result for each test
- CCITT Blue book recommendation Q.781
- MTP2 Level 2 test specifications, recommendation Q.782
- SS7 monitoring on p-series platforms (high speed and low speed links)
- ATM protocols (AAL0, AAL2, AAL5) on J1/E1/T1 interface
- SS7 monitoring on p-series platforms (high speed and low speed links)
- Wave Converter Application
- Converts user-specified input files from .wav format to any of the following formats:
° Adaptive Multi-Rate (AMR) narrow band
° AMR TFO - The standalone wave converter application is available using the Real User Plane or PESQ on all p-series and m500 platforms.
- Converts user-specified input files from .wav format to any of the following formats:
- PESQ GUI enhancements for easier reporting
For a complete set and details of all supported capabilities and technical specifications please consult with your Catapult sales representative.
DCT2000 Technical Tip
Customizing PESQ QuickStarts
Users may customize the PESQ QuickStarts by replacing the audio files in the QuickStart directory with ones created using the wave converter application and by modifying a few lines of code.
Step 1: Record the reference .wav file that needs to be encoded.
Step 2: Use the DCT wave converter to create the necessary .tar file.
Step 3: Copy the QuickStart to the user directory.
Example: cp -R /home/dct2000/11.3/QuickStart/Iu/CS
Step 4: Copy the .tar file created from the wave converter into the PESQ subdirectory. Example: cp new_reference.tar CS/PESQ
Step 5: Untar the new reference file.
Example: cd CS/PESQ ; tar vxf new_reference.tar
Step 6: Modify the scripts to use the new files. The file is located under:
CS/common/Traffic/traffic_PESQ.d
Convert all references to the PESQ_test_file to the new file name.
Step 7: Recompile and run the QuickStart.
File Management Time Savers
Managing Protocol Flavors: Modifying .installedFlavors file.
A standard MGTS user installation creates a file called “.installedFlavors “in the user’s $HOME. The installedFlavors file contains information about the protocol flavors available to the user. When launching MGTS, the protocol window lists the flavors found in this file for the user and requests a selection. The flavor selection from this menu decides the user environment variables, such as $MGTS_DECODE. If the user consistently uses only one or a few flavors, this file can be edited to remove the extraneous flavors’ lines.
Decoding when point codes are present: Modifying pointCode.rules file.
This file instructs the system how the bits break out into the point code notation when decoding any layer that may contain point codes, such as MTP or M3UA. A system administrator can access the “pointCode.rules” file in the $MGTS_BASE/config/SigStd directory.
The first line advises that "$MGTS_DECODE is used as the default." In the absence of any other information about which point code rule should be used, the flavor selected in the protocol window at MGTS initialization will be used.
Other sections of the pointCode.rules file give the instructions for point code handling. Each section contains:
As an example, the entry for Whitebook SS7:
NAME=WHITE-SS7 COLUMNS=11
STRING=%u-%u-%u
MIN=0 MAX=7 BITS=3
MIN=0 MAX=255 BITS=8
MIN=0 MAX=7 BITS=3
In the example above, point codes with up to14-bit range are displayed as 3 unsigned integers, separated by hyphens.
Default values in this file can be modified. For example, if UMTS point codes are desired to be presented in ITU format, the UMTS and UMTS-CCITT entries may be edited as follows:
NAME=UMTS COLUMNS=7
STRING=%u
MIN=0 MAX=16383 BITS=14
This allows the 14-bit range of point codes to be demonstrated as 1 unsigned integer.
Creating a backup of the original file before modification is always advised. Modifying this file affects all users that decode with that installation.
Changing colors in the message decoder layer: Modifying ColorDecode.cfg
This file is used to set the colors for the various layers in the message decoder. A system administrator can access this file in the $MGTS_BASE/config/SigStd directory. The format of the file is:
LAYER=< layer name > COLOR=< color name >
The layer name is the descriptive name of the layer as shown in the message editor and elsewhere. If the descriptive name of the layer is not known, you can peruse the list available to each flavor by checking its layer.trv file, found at $MGTS_BASE/config/SigStd/
Either the specified color name or hex format may be used. Useful information about available names and hex triplets can be found on Wikipedia at:
http://en.wikipedia.org/wiki/Web_colors#X11_color_names
As an example, to create entries for distinctive color-decoding of Iu-PS messages: First, look over the file containing available descriptive layer names at
$MGTS_BASE/config/SigStd/UMTS/layer.trv.
Next, examine the lines of interest:
PROTOCOL=SCTPP VISIBLE=T DESCRIPTION=SCTP Primitive
PROTOCOL=M3UA VISIBLE=T CODING=ltor DESCRIPTION=M3UA (M3UA)
PROTOCOL=SCCP VISIBLE=T VERSION=2 DESCRIPTION=SCCP (SCCP)
PROTOCOL=RANAP VISIBLE=T CODING=ltor DESCRIPTION=RANAP Sig
Protocol (RANAP)
After deciding on colors, the next step is to modify the ColorDecode.cfg with new color entries:
LAYER= SCTP Primitive COLOR= DodgerBlue
LAYER= M3UA (M3UA) COLOR= MediumSeaGreen
LAYER= SCCP (SCCP) COLOR= PeachPuff
LAYER= RANAP Sig Protocol (RANAP) COLOR= Salmon
Modifying this file affects all users that decode with that installation.
Catapult Communications is a leading provider of advanced digital telecom test systems to global equipment manufacturers and service providers. Catapult delivers test systems for over 700 of protocols and protocol variants in the following telecommunication standards: 3G UMTS, cdma2000, VoIP, IMS, GPRS, SS7, and Intelligent Network and more. For more information about Catapult products, please contact your local Catapult office or visit our website at http://www.catapult.com
Sincerely,
Catapult Communications
®2006 Catapult Communications
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