Overview
GSM stands for Global System for Mobile Communication and is an open, digital cellular technology used for transmitting mobile voice and data services.
A GSM network is made up of multiple functional entities and interfaces that facilitate sending and receiving of signaling and traffic messages. It is a collection
of transceivers, controllers, switches, routers, and registers.
The GSM network can be divided into following broad parts.
- The Mobile Station(MS)
- The Base Station Subsystem (BSS)
- The Network Switching Subsystem (NSS)
- The Operation Support Subsystem(OSS)
The MS and the BSS communicate across the Um interface, also known as the air interface or radio link. BTS and BSC will communicate across Abis interface
and The BSS communicates with the Network Service Switching center across the A interface.
The Abis interface is used between the BTS and BSC. At this level, the radio resources at the lower portion of Layer 3 are changed from the RR to the Base
Transceiver Station Management (BTSM). The BTS management layer is a relay function at the BTS to the BSC.
The RR protocols are responsible for the allocation and reallocation of traffic channels between the MS and the BTS. These services include controlling the
initial access to the system, paging for MT calls, the handover of calls between cell sites, power control, and call termination. The RR protocols provide the
procedures for the use, allocation, reallocation, and release of the GSM channels. The BSC still has some radio resource management in place for the frequency
coordination, frequency allocation, and the management of the overall network layer for the Layer 2 interfaces.
Message Automation & Protocol Simulation™ (MAPS) – GSM Abis Interface
GL’s Message Automation & Protocol Simulation™ (MAPS) is a powerful Protocol Test platform-supporting a wide range protocols such as GSM over A
interface, A-bis interface, SS7, ISDN, MGCP, and others.
GL’s GSM Abis Interface Emulator is an advanced protocol simulator/tester for GSM simulation over Abis Interface that can simulate BTSM messages
and signaling specification as defined by 3GPP standards. The tester supports testing network elements BTS and BSC, Error tracking, regression testing,
conformance testing, load testing/call generation and generation of high volumes of GSM traffic. It is able to run pre-defined test scenarios against GSM Abis
interface test objects in a controlled & deterministic manner.
GSM Abis Interface Emulator supports powerful utilities like Message Editor, Script Editor and Profile Editor which allow new scenarios to be
created or existing scenarios to be modified using BTSM messages and parameters.
GL also provides an independent GUI based GSM protocol analyzer (optional application – XX150) for online capture and
decode of the signaling in real-time both during tests and as a stand-alone tracer for live systems.
Protocol Standards
This test tool can also be used to perform protocol conformance testing as per the following specifications -
- 3GPP TS 24.008 – Contains Mobility Management (MM) procedures and Circuit Switched Call Control (CC) procedures
- 3GPP TS 08.58 – Contains Radio Link Layer (RRL), Dedicated Channel (DCH) , Common Channel (CCH), and Transmission (TRX) Management procedures
- 3GPP TS 04.18 – Contains Radio Resource Management procedures
GSM Abis Testing Features
- GSM Abis Interface simulation over TDM (E1/T1)
- MAPS can be configured to act as either BSC or BTS
- Multiple E1/T1 line interfaces supported
- User-friendly GUI for configuring the LAPD Layer
- Supports DCM, RLM, CCM message groups.
- Configure AGCH, ACCH, SDCCH, BCCH and other logical channels.
- Supports all Call Control, Mobility Management, and Radio Resource messages.
- Access to all BTSM Message Parameters like CM Service Request, Paging, call Control messages like Release messages, and more.
- User controlled access to optional parameters such as timers.
- Supports Authentication, TMSI Reallocation, Encryption and other optional procedures.
- Ready scripts for Mobile Originating, Mobile terminating and Location Updating procedures.
- Logging of all Messages in real time.
- Save and Load Configurations.
- Supported on Windows® 2000/XP/Vista operating systems.
Automatic Simulation Behavior (Generate and respond to calls/ messages):
- Call Generation Configuration: Allows independent outgoing communications. The Call Generation interpretation of establishing call is to invoke the required
scripts for call transfer.
- Editing utilities allow access to Mandatory Fixed, Mandatory Variable and Optional parameters using Message Templates, Import, and Export files
- Change or assign parameter value using Profile Editor window
- Impairments can be applied to messages to simulate error conditions
- High volume traffic options
- Retransmission of messages with specific interval
- Provides protocol trace with full message decoding, custom trace, and graphical ladder diagrams of call flow with time stamp while simulation is running
- Option to run the test for multiple iterations
- Quick configurations to create multiple entries
- Interactive GUI to view status, results, call information, total iterations to be done, and number of completed iterations
- Provides the associated captured events and error events during call simulation
- Call Reception Configuration: Allows configuring incoming communications to handle all possible signaling and call control messages for responding to the
call requests.
- Automatic response to incoming messages - Processes the BTSM messages received based on the script specified in the script configuration
window
- Provide the result of the test with detail protocol decode and ladder diagram
Software Architecture
- Script based & protocol independent software architecture
- Quick-testing to complex testing
- Customization of call flow and messages
- Generate and respond to calls/ messages
- Monitor the call flow graphically (ladder diagrams)
Working Principle
The message templates form the backbone of MAPS application. The Message Editor is a powerful utility of MAPS application, which allows users to create
any number of message templates with user-selected protocol fields and default values for each protocol field.
The protocol fields in message templates are classified as Mandatory fixed, Mandatory variable and Mandatory Optional Parameters and these can be
accessed by scripts as variables using import/export files.
The scripts comprises of sequence of commands that performs the required operation using pre-defined message templates. The Script Editor is another
powerful utility of MAPS, in which sequences of message templates can be grouped together in an order to create call flow.
Profile consists of values assigned to the variables. Profiles can be created using a utility called Profile Editor where the values can be assigned to the
variables. The original value of the variables in the message template is replaced with these assigned values.
MAPS provide the ability to create any number of scripts to simulate a real-time scenario with GSM A Interface Emulator and DUT. Prior to script execution,
the test bed configuration allows configuring T1/E1 server and MTP server, to communicate with the DUT.
Buyer's Guide:
Specifications are subject to change without notice.
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