The test bed for simulation over a Gb interface was
developed initially to emulate SGSN behaviour when testing a BSC element
in GPRS and EDGE networks. In this case, the LSU was used to inject packet
traffic at the Abis interface and to collect it after the Gi interface.
In addition the LSU is used to test the SGSN directly, simulating a
population of BSS and originating various types of data at the Gi interface.
The Gb interface can be simulated/monitored over frame relay
and Ethernet for R99, R5 and R6. Signalling procedures and data
traffic can be fully controlled by the use of scripts running on
top of the Test Manager, dedicated external application used to
schedule testing activities such as:
Simulation of one or more SGSNs with Gi interfaces towards
a set of BSSs
Simulation of one or more BSSs with associated UE population
performing signaling procedures and data transfer
Data traffic generation of real internet applications like
HTTP, HTTPS, FTP
There is complete implementation of Gb interface over frame relay and
Ethernet for both BSS and SGSN side, for R99 and R5. Signalling procedures
and data traffic can be fully controlled by means of scripts. BSSs with
associated UE population performing signalling procedures and data transfer
are simulated, as are one or more SGSNs with Gi interfaces towards a set
of BSSs. Data traffic generator simulates user activity with real Internet
applications like HTTP, HTTPS, FTP. A monitoring function is integrated.
The SGSN/BSS under test is closed
via the PCM physical interfaces towards the LSUv3 (up to 196 PCM lines
can be terminated).
The LSUv3 simulates one or more BSSs with
different UE population or more SGSNs with Gi interface Ethereal monitoring
provides logging for Gb interface protocol stack on PCM/Ethernet.
The Test Manager provides the scriptable environment used to control
the tests and the UE behavior.
The Test Commander provides the graphical environment for the test
scheduling and results collecting.
For Gb interface load and stress purposes, it is important to simulate
data traffic functions as close as possible to the real world.
What is really needed? Something resembling "real user traffic", like
web browsing, FTP to different sites.
For this purpose the Test Manager can generate sequence of actions driven
by state machine including timers, on top of the common IP applications.
Actions include HTTP GET/POST, FTP GET/PUT.
The actions are placed in scripts associated to a group of terminals.
The Test Manager core activates the various procedures according to the
scheduling rules defined by the user.
Test Manager provides timing functionalities that enable the creation
of complex scenarios.
Client Applications
The LSU is dedicated to network protocol management relating to real-time
behaviour of the BSC. Protocol decoding and simulation intelligence are
external client applications running on multiple instances on a remote
site.
The LSU can perform monitoring concurrently with simulation (both
on the simulated interfaces and on those connected between real
node elements), thus avoiding the need of a separated instrument
and allowing a significant cost reduction.
Monitoring
The LSU has a powerful and user-friendly GUI for protocol decoding.
It is based on the popular open source protocol analyser Ethereal,
modified by PRISMA Engineering to support many telecom manufacturers'
proprietary protocols, such as: Abis Signalling, Abis O&M, TRAU frames,
PCU frames (GPRS and EDGE). The interface between LSU and the monitoring
client is open, allowing customers to develop their own applications
for special purposes.
Simulation
Test Manager by PRISMA Engineering is a client application able
to run several tests in parallel over all the different data and signalling
links connected to the LSU.
A large number of protocol libraries are available to simulate every
protocol stack at every interface on the GSM/GPRS/EDGE network. Ready
to run solutions based on the Test Manager allow to perform complete
simulation of the behaviour of network elements such as BSS (more BTS
and BSC) or SGSN/GGSN.
Testing people in a telecom lab can:
define scenarios with a lot of BTS and mobile phone calling in
parallel.
programming test scheduling.
trigger actions at particular events or abnormal conditions.
collect statistical data to analyze network behavior in real-time
or by post-processing for QoS verification.
