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LPB 110, a System for Controlled Test Traffic Bengt Jansson, Kent Johansson and Tommy Ostlund In the testing of telecommunication systems demands are made for shorter test times and at the same time the equipment being tested becomes increasingly complex. Powerful and efficient aids are therefore required, primarily for the testing of whole systems. Ericsson has developed such a test system. LPB 110, which has been designed to generate and terminate test traffic. The authors describe LPB 110 and how it can be used for design, production and installation testing of Ericsson systems and also other systems. UDC 621 395.2/ 3.001 4 Fig. 1 Test equipment developed during the 1930s, 1950s and 1970s Over the years various types of devices have been used for testing telephone equipment at system level. These test devices have often been developed for specific applications, fig. 1. The need for more general test equipment has arisen for various reasons, partly because of the rapid technical development in the field of telecommunications. New demands have been made on existing test equipment, and new test requirements have arisen for newly developed system parts. Demands from the users have led to a modular structure, so that the equipment can easily be modified for different requirements, and the same facilities for man-machine communication as in stored program controlled telephone exchanges. In order to exploit design resources efficiently they were brought together in a project, in which all requirements were formulated in collaboration with representatives from the system and installation testing departments The test system developed in accordance with these requirements, LPB 110, can be used for all autonomous testing at signal interfaces towards telephone equipment, for example towards MDF, where LPB 110 can simulate the environment of a telephone exchange, fig 2. Test facilities LPB 110 has been designed to generate and terminate controlled test traffic, primarily in connection with design, production and installation testing, including acceptance testing, but it can of course also be used for testing equipment in service, for example for traffic route testing. LPB 110 can simulate the functions of the subscriber and junction lines in the surrounding network and hence can simulate all connection types, i.e. local, incoming, outgoing and transit calls.
BENGTJANSSON KENT JOHANSSON TOMMY OSTLUND Public Telecommunications Division Telefonaktiebolaget LM Ericsson Each connection can be controlled and checked both at the originating and the terminating side. The test object can be a telephone exchange, a telex exchange, a data switch or any other telecommunication system, regardless of type. The traffic functions and signalling systems that can be simulated by the equipment are: - Subscriber line signalling (dial or push-button) - Conventional junction line and register signalling systems (e.g. d.c. loop, E&M, MFC or decadic signalling) - PCM signalling, of the first and second order and for I/O channel - Common channel signalling (CCITT nos. 6 and 7) - Digital subscriber line signalling - Signalling in mobile telephone networks - Signalling in telex and data networks (AXB20and AXB30). The system can easily be adapted to new signalling systems since the basic system permits the connection of equipment to the AXE 10 device bus interface (the EM bus). This means that equipment (e.g. IT and OT) developed for AXE 10 can also be used in LPB 110. This will reduce the cost of adapting LPB 110 to special signalling systems considerably. Applications LPB 110 is an efficient aid for - traffic case testing in an exchange - individual testing of line equipment - operational testing - acceptance testing. Traffic case testing Traffic case testing means systematic testing of all permitted traffic combinations between incoming and outgoing lines. Such functions as digit analysis, route analysis and tariff analysis are checked, and, of course, also all general functions, such as B answer, speech connection, time supervision and disconnection. Individual testing of line equipment Only a few lines are normally tested during traffic case testing, which means that each individual line must be tested separately. The individual testing is basically the same as traffic case testing, but fewer functions are tested. Operational testing The purpose of operational tests is to verify that the equipment is satisfactory for connection to the network. A number of tests are carried out in which normal operating conditions are simulated. This requires controlled test traffic, preferably generated by an LPB 110 system. The connections of the system are then distributed over the test object so that the greatest possible part is activated. Acceptance testing The Ericsson policy for the acceptance of a plant is that the customer will accept the equipment when the service quality has reached the level specified in the contract. This quality level can be verified with the aid of controlled test traffic from an autonomous LPB 110 system. In an acceptance test a large number of connections 0.5-1 million) have to be generated in a fairly limited time. Fig. 2 Test facilites IT OT LI KK Incoming junction line Outgoing junction line Subscriber line Main distribution frame. MDF
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Page 21 and 22: Fig. 11 Part of an urban and trunk
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Page 41 and 42: 37 Fig. 10 LPB 110 used in an AXE 1
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