Telefonaktiebolaget Lm Ericsson (publ)

Hans Magnus Broberg

Lars-G&ouml;ran Petersen

Lars-Göran Petersen

Anders Olof Lindstrom

Anna Kristina Bostrom

An asynchronous transfer mode (ATM) switch ( ) has plural switch ports ( ) connected by respective bidirectional links ( ) to a switch core ( ). Connected to each switch port is a corresponding row column unit ( ), each row column unit managing the writing of service cells to one row of cross point units ( ) and the reading of service cells from one column of cross point units. The bidirectional links between each switch port and its corresponding row column unit of the switch core carry both service cells and control cells. An interactive exchange of control cells is implemented to sequence operation of the switch core. The operations particularly dependent upon control cell generation include transmission of service cells from the switch core; transmission of pollstate control cells from the switch core; retrieval of contents of certain control registers maintained by the switch core; and synchronization procedures. Pollstate information, indicative of &ldquo;occupied&rdquo;/&ldquo;free&rdquo; status of selected ones of the cross point units, is transmitted in pollstate control cells. The pollstate control cells are generated and transmitted either (1) in response to a particular control cell evocative of the pollstate information, or (2) upon a change of absence/presence (e.g., free/occupied status) of a predetermined number of the affected cross point units.

Asynchronous transfer mode switch providing pollstate status information

In the connection of a number of telephone sets to a private branch exchange, control information is communicated between the telephone sets and the exchange set in such a way that a bidirected conversion unit is required. In order to provide a high degree of service at a reasonable cost the telephone sets are collected in groups which share a generally smaller number of conversion units. By way of suitable control devices and switch units in the forwarding of control information, a suitable non-occupied conversion unit can be selected.

Apparatus for communication between a telephone exchange and connected

A device for testing line connections at a telephone exchange includes a combined generator and comparator for generating a bit sequence of pseudo-random type and for comparing a received bit sequence to a generated bit sequence. A generated bit sequence is through a line connection forwarded to a telephone set and back again to the generator and comparator, where the received sequence is compared to the forwarded one. The number of bit errors occurring in the transmission is a measure of the transmission quality of the connection. A selector device selects one of several line connections which is to be tested. Only one testing device is required for testing a number of line connections which through the same pair of one serial output line and one serial input line are connected to a telephone exchange.

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Hagersten, Sweden

Hans Magnus Broberg