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Technical Description


The LSU+ connects to the Telecom equipments with PCM E1/T1 configurable interfaces, with selectable synchronisation source. The system is provided with a suite of 256 SCCs (Serial Communication Controller) with separately configurable speed (8-2048Kb/s).
These channels constitute the basic elements on which most of the features of the system are built; they can be employed either in HDLC (packet mode) or in transparent mode. The system has four analog connections for phone handsets complete with CODECs (D-phone).  A switch matrix, with 256 x 256 channels, entirely configurable, allows the PCM line timeslots, the SCC, and the D-phone to be connected. The switch matrix logic allows some extra features, as real time sampling of any channel and the fixed pattern forcing.

The LSU+ can monitor signalling channels, simulate protocol stacks, generate network traffic and add asynchronous events representing either failures or abnormal conditions, both for physical interfaces and protocols.

Hardware Architecture

The Line Server Unit Plus (LSU+) is built on top of an high performance hardware architecture.

  • Multi-processor system (3 CPU Pentium III);
  • Internal Fast Ethernet connection (100 Mb/s);
  • High performance PCI cards (Musycc) specifically designed to handle 256 serial channels;
  • 16 PCM E1/T1 lines at 2Mb/s;
  • MVIP bus;
  • Distributed real time operating system (QNX).
The CPU cards use Pentium III processors.
The SCCs are implemented in a PCI card, which is based on the Musycc IC (Bt8474), designed and produced by PRISMA Engineering S.r.l.
The MVIP bus interconnects data flows between the different cards (16 2Mb/s lines and 2 SCC cards with 128 channels each).

The LSU+ is a multiprocessor system with three CPUs: the Main Processing Unit (MPU), that manages the console, the mass storage and external LAN, and two Protocol Processing Units (PPUs, that are diskless unit equipped with the PCI Musycc card), linked together by an internal Fast Ethernet (100 Mb/s).

Both the MVIP bus and the distributed switch matrix circuits allow the connection of channel with a capacity multiple of 64 Kb/s (without restrictions about the PCM line timeslots), of the Musycc card serial channels and of the D-Phone resources. The system can be equipped with E1 and T1 PCM lines at the same time.

The entire equipment is managed by the QNX operating system, which in particular hadles the communication between the different processes running on the three CPUs, creating an homogeneous pool of resources that can be used transparently through Posix primitives.
The most demanding software packages were developed using the Pentium III processor's MMX functions.
The user can work directly on the system console with the graphic Photon interface, or the system can be controlled from remote in one of the different ways QNX supports (e.g.: Telnet, Ditto, Photon client on a Windows host, etc.).

MPU (Main processing unit)
  • 4 Line interface cards, each one providing 2 E1/T1 PCM, a D-Phone codec, MVIP bus;
  • Processor card based on a PENTIUM III at a minimum clock frequency of 400 MHz;
  • Fast Ethernet PCI interface card Hard disk, 17 Monitor and keyboard.

PPU (Protocol processing unit)
  • Processor card based on a PENTIUM III at a minimum clock frequency of 400 MHz;
  • Fast Ethernet PCI interface card;
  • High Performance multi-channel protocol controller PCI card (Musycc), with 128 channels, in packet mode (HDLC) or transparent mode (i.e. Pcu/TRAU Frames, V.110) with a transfer rate of up to 2048 Kb/sec and MVIP bus.

The system is contained in a 19 rack container with two handles for easy transportation.
The front cover hosts the keyboard.
The system is shipped complete of a 17"monitor.

Software Architecture

The LSU+ basically handles the hardware interfaces and the low level communication protocols and allows other hosts to operate at higher level through appropriate communication primitives. The communication between LSU+ and its clients is based on Ethernet, TCP/IP and sockets. Each LSU+ service access point corresponds to a predefined port number. Each protocol server supports a set of primitives in terms of messages and codes that is compliant to what defined in the ETSI/ITU/GSM specifications.


The LSU+ has a very modular structure, both from the hardware and from the software point of view: 3 standard hardware versions are available for applications ranging from the "personal" instrument to the multi-user server, to the load & stress equipment.

From the software point of view this equipment is entirely modular: the basic software included consists of configuration and managing modules and some general functions. All the other software functions are supplied as add in modules. 

The basic software includes:

The modules listed below can be used to reach the different test configuration the LSU+ supports:

The development activity of new software modules is in continual. New modules will be available soon and others are due within the end of this year:
  • Update of existing GSM/GPRS Modules to the latest version of the specification

  • GPRS Mobile commander (Multiple RS-232, GSM 07.07, PPP)

  • H.323 Basic Module (Frame Relay or ATM or Ethernet, UDP/IP, H.225.0, RTP, RTCP)

  • UMTS UTRAN Iub Interface: Signalling transport Module (ATM, AAL5, SSCOP, SSCF-UNI)

  • UMTS UTRAN Iub Interface: Transport management signalling Module (ATM, AAL5, SSCOP, SSCF-UNI, Q.2150.2, ALCAP)

  • UMTS UTRAN Iu/Iur Interface (CS): Signalling transport Module (ATM,  AAL5, SSCOP, SSCF-NNI, MTP3-b, SCCP)

  • UMTS UTRAN Iu/Iur Interface (PS): Signalling transport Module (ATM, AAL5, UDP/IP, SCTP, ITUN, SCCP)

  • UMTS UTRAN Iu/Iur Interface (CS): Transport management signalling Module (ATM, AAL5, SSCOP, SSCF-NNI, MTP3-b, Q.2150.1, ALCAP)

  • UMTS UTRAN CS-Domain User Plane Data Module (ATM, AAL2, Transparent/Support Mode)

  • UMTS UTRAN PS-Domain User Plane Data Module (ATM, AAL5, IP, UDP, GTP-U, Transparent/Support mode)

  • UMTS UTRAN User Plane Data Application Module (Uplink-Downlink Loop, Test patterns player/recorder)

  • H.323 Application specific Modules.
The release of a new line interface card at 51/155 Ms/s for ATM and UMTS applications is planned.

In the following pages you can find the list of the available software modules ans some examples of common applications.

Info: lsu@prisma-eng.it