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All of the supported protocol
and simulation support packages are available as optional software modules,
in order to allow the customer to precisely tailor the instrument capabilities
to the test environment where it is to be used; or to keep it up to date
as the requirements evolve or new projects start. Functional diagram
  Drop-Insert Module Functional diagram
The Drop Insert module allows to modify the content of some specific messages that are exchanged between two real network elements. The function works with any HDLC based protocols (LAPx, SS7, Frame Relay, etc) and channel rate. A special syntax has been defined to identify specific message and to describe related modification rules. Main features:
GPRS Modules this is agroup of four modules:
On the top of the SNDCP, the optional UDG (User Data Generator) function can be added in order to build powerful test bed that includes the simulation and the qualitative verification of user data flows. The Frame Relay implementation supports multiple physical links with variable rate. Each physical link can accommodate multiple permanent virtual circuits (PVC) that are mapped to the NSVC (NS Virtual circuits). The user can allocate multiple instances of the Network Service, associated to related BSSGP layers. The LLC/SNDCP layers support up to 10.000 MSs. The current implementation does not support encryption and data compression. The following figure shows the full protocol stack of the Gb interface including the UDG. Functional
diagram
GPRS UDG Module User Data Generator The GPRS UDG consists
of two co-operating modules that simulate the IP data flow on both user and
network side. GPRS Gi-interface Modules Fuctional diagram
GPRS Gi Module IP Interface Simulation — This module provides the Gi protocol stack that simulates the operations of the IP packet data network at the GiIP reference point of the GSM/GPRS Network in case of transparent access. In case of Frame Relay connections, it can handle a pool of physical links at different rates.The implementation supports multiple PVCs. Optionally this layer can be handled through an additional Ethernet connection according to IEEE-802 (an additional network card on the PPU must be added), and the LSU+ will behave as a TCP/IP gateway for the simulated IP traffic. On top of the Gi Packages typically resides the optional UDG/Net module. Functional
diagram
GPRS Abis BTS/MS Simulation PCU FRAMES — This protocol layer transports user data and in-band signalling between the BSC and the BTS related to GPRS traffic channels. As it is not specified by GSM Recommendations, the various manufactures have adopted proprietary solutions. The LSU+ development team can customise this module in conformity with the specific proprietary interface specifications.
- TBF establishment initiated by the MS on PCCCH;.The implementation has two operations modes: debug and automatic. In debug mode the MAC function handling is demanded to the client application, conversely in automatic mode the client application handles MAC internally and it interfaces to the upper layer with the standard GRR-* primitives (GSM 04.07). GPRS Abis BTS/MS Simulation LLC, SNDCP Module — This module provides the remaining upper protocol layers to complete the GPRS Abis protocol stack. The implementation supports up to 10.000 simulated mobiles. It suits an outline of the Abis GPRS protocol stack including UDG. Main features:
GPRS Mobile Commander (RS-232, GSM 07.07, PPP) — This module manages up to 128 real GPRS mobiles, connected to the LSU+ through separate RS-232 ports. It requires the installation of additional multiple RS-232 cards in the PPUs. The software controls the mobiles through the AT command set, and it handles packet data transfer through the PPP protocol (IETF STD 51). On top of PPP the UDG/User can be used to generate and control user data traffic.
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