System of transmission by packets with data compression, corresponding method and apparatus

In a system of data transmission by packets, of the type comprising a plurality of transmitter/receiver terminals, that can be associated in pairs to set up links, and at least two intermediate units,

• in which certain links use a transmission chain comprising two transmitter/receiver terminals and at least two intermediate units,
• and in which each packet is associated with the transmission of data belonging to only one link among said set-up links,
• wherein at least some of said intermediate units include means for the compression and/or decompression, in at least one direction of transmission, of the data elements contained in the data fields of the packets transmitted, according to at least one compression algorithm, a method for the transmission of data between a calling terminal and a destination terminal comprising the steps of:
• negotiating compression parameters including the steps of
• initializing a negotiation of the compression, in which a signalling field, present in at least certain packets of each link, travels through said transmission chain between the two terminals, said signalling field comprising:
• an activation token indicating the activation of the compression, for each of said directions of transmission, said activation tokens being susceptible to take two states, a first state signifying the non-activation of the compression and a second state signifying the activation of the compression, and having its value changed to said second state signifying the activation of the compression by an intermediate unit including means available for the compression, said intermediate unit reserving the corresponding means available for the compression, and
• a benefit token or token indicating the benefit of compression, for each of said directions of transmission, said benefit tokens being susceptible to take two states, a first state signifying a non-benefit of compression and a second state signifying a benefit of compression, said benefit token having its value changed to said second state signifying a benefit of compression by the intermediate units connecting each of the successive transmission lines forming said transmission chain when the characteristics of said transmission line prove such a benefit,
• validating the activation of the compression mode in the corresponding intermediate units of the transmission chain, said validation being done during the initialization journey of said activation token when, for each of said directions of transmission, the activation token has encountered at least one intermediate unit available for compression followed by at least one intermediate unit available for decompression and when the corresponding benefit token is in said second state signifying the benefit of a compression;
• and
• transmitting data between said terminals, the compression and the decompression being carried out in the corresponding intermediate units selected during said step of negotiating, if they have been validated during the step of validating.

In a system of data transmission by packets, of the type comprising a plurality of transmitter/receiver terminals, that can be associated in pairs to set up links, and at least two intermediate units,

• in which certain links use a transmission chain comprising two transmitter/receiver terminals and at least two intermediate units,
• and in which each packet is associated with the transmission of data belonging to only one link among said set-up links,
• wherein at least some of said intermediate units include means for the compression and/or decompression, in at least one direction of transmission, of the data elements contained in the data fields of the packets transmitted, according to at least one compression algorithm, a method for the transmission of data between a calling terminal and a destination terminal comprising the steps of:
• negotiating compression parameters including the steps of:
• initializing a negotiation of the compression, in which a signalling field, present in at least certain packets of each link, travels through said transmission chain between the two terminals, said signalling field comprising:
• an activation token indicating the activation of the compression, for each of said directions of transmission, said activation tokens being susceptible to take two states, a first state signifying the non-activation of the compression and a second state signifying the activation of the compression, and having its value changed to said second state signifying the activation of the compression by an intermediate unit including means available for the decompression, said intermediate unit reserving the corresponding means available for the compression, and
• an authorization token or token indicating an authorization of compression, for each of said directions of transmission, said authorization tokens being susceptible to take two states, a first state signifying a non-authorization of compression, and a second state signifying an authorization of compression, the state of said authorization tokens being changed by said terminals,
• validating the activation of the compression mode in the corresponding intermediate units of the transmission chain, said validation being done during the initialization journey of said activation token when, for each of said directions of transmission, the activation token has encountered at least one intermediate unit available for compression followed by at least one intermediate unit available for decompression and when the corresponding authorization token is in said second state signifying the authorization of a compression;
• and
• transmitting data between said terminals, the compression and the decompression being carried out in the corresponding intermediate units selected during said step of negotiating, if they have been validated during the step of validating.

In a system of data transmission by packets, of the type comprising a plurality of transmitter/receiver terminals, that can be associated in pairs to set up links, and at least two intermediate units,

• in which certain links use a transmission cain comprising two transmitter/receiver terminals and at least two intermediate units,
• and in which each packet is associated with the transmission of data belonging to only one link among said set-up links,
• wherein at least some of said intermediate units include means for the compression and/or decompression, in at least one direction of transmission, of the data elements contained in the data fields of the packets transmitted, according to at least one compression algorithm, a method for the transmission of data between a calling terminal and a destination terminal comprising the steps of:
• negotiating compression parameters including the steps of:
• initializing a negotiation of the compression, in which an activation token for each of said directions of transmission travels through said transmission chain between the two terminals, said activation token being susceptible to take two states, a first state signifying the non-activation of the compression and a second state signifying the activation of the compression, and having its value changed to said second state signifying the activation of the compression by an intermediate unit including means available for the compression, said intermediate unit reserving the corresponding means available for the compression,
• memorizing in each of said intermediate units of said transmission chain all the negotiation parameters, said parameters including at least one of the parameters belonging to the group comprising:
• said activation tokens;
• authorization tokens;
• benefit tokens;
• choice of a compression algorithm;
• choice of coding dictionaries;
• validating the activation of the compression mode in the corresponding intermediate units of the transmission chain, said validation being done during the initialization journey of said activation token when, for each of said directions of transmission, the activation token has encountered at least one intermediate unit available for compression followed by at least one intermediate unit available for decompression;
• and
• transmitting data between said terminals, the compression and the decompression being carried out in the corresponding intermediate units selected during said step of negotiating, if they have been validated during the step of validating.

In a system of data transmission by packets, of the type comprising a of plurality of transmitter/receiver terminals, that can be associated in pairs to set up links, and at least two intermediate units,

• in which certain links use a transmission chain comprising two transmitter/receiver terminals and at least two intermediate units,
• and in which each packet comprises a data field and is associated with the transmission of data belonging to only one link among said set-up links,
• wherein at least some of said intermediate units include means for the compression and/or decompression, in at least one direction of transmission, of the data elements contained in the data fields of the packets transmitted, according to at least one compression algorithm, a method for the transmission of data between a calling terminal and a destination terminal comprising the steps of:
• negotiating compression parameters including the steps of:
• initializing a negotiation of the compression, in which an activation token for each of said directions of transmission travels through said transmission chain between the two terminals, said activation token being susceptible to take two states, a first state signifying the non-activation of the compression and a second state signifying the activation of the compression, and having its value changed to said second state signifying the activation of the compression by an intermediate unit including means available for the compression, said intermediate unit including means available for the compression, said intermediate unit reserving the corresponding means available for the activation;
• validating the activation of the compression mode in the corresponding intermediate units of the transmission chain, said validation being done during the initialization journey of said activation token when, for each of said directions of transmission, the activation token has encountered at least one intermediate unit available for compression followed by at least one intermediate unit available for decompression;
• and
• transmitting data between said terminals, the compression and the decompression being carried out in the corresponding intermediate units selected during said step of negotiating, if they have been validated during the step of validating, comprising the steps of:
• compressing the data elements of the data field of each packet,
• testing the compressibility of the data elements of the data field of each packet, said data field being transmitted in compressed form if the length of the compressed information is strictly smaller than the length of the non-compressed information, and, if not, in non-compresses form,
• transmitting in at least certain packets an information element signifying the transmission takes place in compression mode or in transparent mode.