FR2791836A1 - ISDN line establishment of communication uses signalling channel to exchange data about transmitter and receiver prior to use of main transmission channel - Google Patents

Abstract

The system uses the signalling channel in initial communications, prior to use of the transmission channel. The procedure provides transmission on a digital network comprising at least one transmission channel and one signalling channel. The signalling channel transmits frames containing at least one sub-sequence defining the nature of the service to activate at the destination channel, and at least one further sub-sequence containing information to determine the origin of the call. Before transmission of the frame, the caller records the nature of the message which is defined by the predefined functionalities of the called station, within the second sub-sequence which is nominally destined to contain the information about the origin of the message. The called station proceeds to read this message, before completely opening the link.

Description

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  TRANSMISSION OF INFORMATION OVER AN ISDN NETWORK.

  The invention relates to the transmission of information over digital networks, in particular over

  integrated service digital networks (ISDN).

  On ISDN networks, the protocol channel or signaling channel is separated from the information transmission channels. Connection establishment requests are made with a remote site via the signaling channel and the site is actually in dialogue with the transmission channels after the connection is established. These transmission channels allow voice (telephone mode), images or

any digitized data.

  The signaling channel, also called channel D in the ISDN standard, can have a reduced bandwidth compared to the information transmission channels called B channels and H channels. It is only used sporadically to allow dialogue during the connection. Devices seek to optimize the transit of information on these different channels. We can cite the request W09824078 which uses a digital transmission channel present on the network link to make requests to remote sites. The responses are partially encrypted and returned by the digital transmission channel to the central station. In this particular case, the D channel makes it possible to transmit the necessary information to the central site without disturbing the communications which are carried out on the transmission channels. Using the X25 function in the channel

D is planned.

  This device, as well as those generally used, has the major drawback of operating with services having a charge for communication. They

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  do not allow information to be transmitted

  basic for a low cost.

  The object of the invention is to reduce these costs when transmitting predefined information and to free up the transmission channels for the transfer of unpredictable information flows such as real-time video. The invention relates to a method for transmitting information over a digital network comprising at least one transmission channel and one signaling channel. The signaling channel transmits frames comprising at least one customizable sequence comprising at least a first sub-sequence defining the nature of the service to be activated by

  the destination station, and at least a second sub-

  sequence intended to contain information intended to determine the origin of the call. Before the transmission of the frame, the caller records, in the second sub-sequence nominally intended to receive the original number of the caller, a message which does not have the function of identifying the caller, the nature of said message being determined by the predefined functionalities of the called party. The called party then reads the said message before the possible opening of the link on the

transmission channel.

  Advantageously, the called party refuses to open the link on receipt of said frame after verification

of said message.

  Connection requests correspond to predefined information that cannot be read directly on said connection requests. Preferably, a concordance table is used between the requests for

  connection and the information to be transmitted.

  In the case of use in ISDN, the transmission channel is channel B and in that the signaling channel is channel D. Preferably, the

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  sub-sequence of the frame sent by the D channel and corresponding to the address or the original sub-address is linked to the information to be transmitted in the concordance table. The process which is the subject of the invention will advantageously be used in the fields requiring regular readings of the condition or periodic or non-periodic interrogations of remote sites, in particular in remote monitoring. A particularly advantageous application is found in alarm systems comprising

  a central site and at least one remote site.

  The use of the signaling channel is generally free, only when the signaling channel

  transmission is open as billing is completed.

  The invention will be better understood with the

  description of a particular achievement for networks

  ISDN, the invention being in no way limited by this particular implementation but applying to

  different techniques known to those skilled in the art.

  Channel D makes it possible to transmit information relating to the connection on the transmission channel to the communication network. The protocol used by this channel is specific to it (protocol D), and allows compatibility

  with other protocols like X25.

  Protocol D mainly makes it possible to send an establishment message carrying out a connection request, connection establishment confirmation and information transmission messages, alert messages, messages containing information on the user. , as well as connection, status and

release of the channel.

  In particular, during the establishment of a call, a certain number of information is transmitted to the network on the D channel in the establishment message. We find in this frame information like the

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  protocol discriminator, call reference, message type or bearer operating mode. There is also the number of the site called (destination address), the number of the calling site (origin address), the sub-address of the site called (destination sub-address) and the

  sub-address of the calling site (original sub-address).

  We then use the digital information constituting the original address or the original sub-address in order to transmit defined information to the recipient. When using the sub-address, the defined code is less important in number of coded elements. Different coding techniques allow one or more pieces of information to be passed simultaneously. We can, for example, predefine a table of concordance between the messages that we want to transmit and the address

origin of the call.

  In the context of the transmission of alarm information or any other simple or all-or-nothing information, a binary use can be envisaged: 8192 values correspond to the coding of 13 bits of information. The code can be defined as using 5 most significant bits defining a family of information, the 8 least significant bits indicating additional information or their combination indicating the state

  sensor activity (0 inactive, 1 active).

  When receiving the frame sent on the D channel, the called party reads the transmitted address and processes the information according to the chosen code. If necessary, he may decide to open channel B in order to perform a function

  predefined, such as viewing a particular site.

  This system has the advantage of using the paid B channel only when the need arises, which implies a significant saving for the caller,

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  and reduces the amount of information transferred

on a channel B which is congested.

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Claims (6)

  1 - Method for transmitting information over a digital network comprising at least one transmission channel and one signaling channel, said signaling channel transmitting frames comprising at least one customizable sequence comprising at least a first sub-sequence defining the nature of the service to be activated by the destination station, and at least a second sub-sequence intended to contain information intended to determine the origin of the call characterized in that, before the transmission of the frame, the caller records, in said second subsequence nominally intended to receive the original information a message which does not have the function of identifying the caller, the nature of said message being determined by the predefined functionalities of the called party, and in that the called party reads said message before   the possible opening of the link.   2 - Method for transmitting information on a digital network comprising at least one transmission channel and one signaling channel according to claim 1 characterized in that the called party refuses the opening of the link upon receipt of said frame after checking said message.   3 - Method for transmitting information over a digital network according to claim 1 or 2 characterized in that a concordance table is used between the   connection requests and the information to be transmitted.   4 - Method of transmitting information on a   digital network according to any of the claims   previous characterized in that the transmission channel is channel B and in that the signaling channel is the ISDN channel D. 7 2791836   - Method for transmitting information over a digital network according to claim 4 characterized in that the part of the frame sent by the D channel and corresponding to the address of the caller is linked to the information to be transmitted in the table of concordance. 6 - A method of transmitting information over a digital network according to claim 4 characterized in that the part of the frame sent by the D channel and corresponding to the sub address of origin is connected to   the information to be transmitted in the concordance table.   7 - Application of the process object of the   claim 1 to a remote monitoring system.   8 - Application of the method object of claim 1 to an alarm system comprising a site   central and at least one remote site.