Improved method for grouping messages in TDMA communication; Associated computer program system and product.

Abstract

Improved method for grouping messages in TDMA communication; associated computer system and program product. This method, implemented in a computer system (10) comprising, between red and black domains, a red message source application and a black TDMA transmit interface, as well as a red message receiver application and a black TDMA receive interface, consists of: timestamping a message with its generation date; placing the message on a red stack (62); destroying each message on the red stack that has been present for a time such that it has already been transmitted; transmitting, in a group, the messages from the red stack to the black domain; placing the group on a black stack (64) by overwriting some of its contents; and, upon receiving a TDMA signal, transmitting the contents of the black stack to the black TDMA transmit interface for insertion into a frame. Figure for the abstract: Figure 4

Description

Title of the invention: Improved method for grouping messages in TDMA communication; Associated computer program system and product.

[0001] The present invention has as its general technical field that of systems implementing TDMA communications (“Time Division Multiple Access” in English or “access multiple by time distribution” in French).

[0002] The present invention has as its particular technical domain that of systems in which the TDMA frame access interface is not directly accessible to the application wishing to transmit data, because of a security segregation.

[0003] In general, the TDMA technique allows the sharing of a communication channel between several entities of a system, or nodes, by allocating to each of them a time interval in the TDMA frame, the latter being repeated cyclically.

[0004] The time interval, or slot, allocated to a node allows the latter to transmit data. During this slot, the other nodes are either passive or listening to the channel to receive data.

[0005] In the case where the allocation of TDMA slots to the nodes is identical in each frame, the regular time interval between two slots allocated to a node is called the TDMA latency, denoted TDMA_L.

[0006] In this case, illustrated in [Fig.1], a TDMA frame has a header S, followed by a succession of slots, each slot being associated with a transmitting node Ni (i an integer between 1 and large N, the total number of nodes N being for example equal to 9 in the example of [Fig.1]).

[0007] We are particularly interested, for example, in the 6th node of the system, N6. It includes an application 12 and a TDMA interface 14.

[0008] Application 12 generates data in the form of messages Mj (j integer). A message Mj is generated at a time tj.

[0009] The application 12 thus generates the message M1 at time t1, the message M2 at time t2 and the message M3 at time t3.

[0010] Application 12 places a message generated on a transmission stack in the memory of node N6.

[0011] In general, the TDMA interface 14 directly informs the application 12 at time TCk (k integer) of the arrival of an available slot for the node it equips by means of an adapted TDMA signaling, such as the message "N6 slot" on the [Fig.1].

[0012] The TDMA interface 14 thus generates signals at TCI, TC2, TC3, and TC4 times, on the arrival of a slot allocated to node N6 in each TDMA frame.

[0013] Application 12 responds by transmitting the message at the bottom of its transmission stack. For simplicity, we assume that the transmission of a message is instantaneous upon receipt of a slot announcement.

[0014] Thus, at time TC2, application 12 transmits message M1 (removing it from the stack) and TDMA interface 14 incorporates it into the slot reserved for node N6 of the TDMA frame. At time TC3, application 12 transmits message M2 (removing it from the stack) and TDMA interface 14 incorporates it into the slot reserved for node N6 of the TDMA frame. At time TC4, application 12 transmits message M3 (removing it from the stack) and TDMA interface 14 incorporates it into the slot reserved for node N6 of the TDMA frame.

[0015] The delay between the generation of a message to be transmitted by a client application of a node and its insertion into the first slot allocated to that node which is available is called the TDMA access latency, denoted TDMA_AL.

[0016] In a system that transmits only one message per time slot, it is observed that the TDMA access latency can be greater than the TDMA latency. This is the case, for example, for message M3 where the interval between t3 and TC4 is greater than TDMA_L.

[0017] More optimal use of the TDMA capacity offered to a node, in terms of latency or throughput, can be obtained by grouping several messages into a single slot when the capacity of the latter allows it.

[0018] For example, in [Fig.2], application 12 generates message M1 at time t1, message M2 at time t2 and message M3 at time t3.

[0019] When the TDMA interface 14 informs application 12, at time TC2, of the arrival of a time slot, the client application 12 then transmits to it the entire contents of its transmission stack in a message group, G2, consisting of messages M1, M2, and M3 (i.e., all the messages generated between TCI and TC2). The TDMA interface inserts the message group G2 into the time slot reserved for node N6 of the TDMA frame.

[0020] This grouping implies that application 12 must not generate an amount of data during a period equal to TDMA_L greater than what a slot can contain.

[0021] However, in certain configurations, the application cannot receive TDMA signaling enabling it to know on which time interval to group the messages.

[0022] This is typically the case in systems, such as secure systems, exhibiting security segregation between two domains, or zones, associated with different security rules: the client application is located in one domain The domain designated as "red" has a high security level, while the TDMA frame access interface is located in a domain designated as "black" with a low security level. Security rules may prohibit any data traversal from the black domain to the red domain, specifically the transmission of TDMA signaling generated in the black domain by interface 14 to the red domain where application 12 resides.

[0023] Since the timing of the TDMA frame and the TDMA signaling are no longer directly visible to the application, the application cannot detect the arrival of a slot and cannot implement the message grouping mechanism described above.

[0024] Fig. 3 illustrates a possible solution to allow grouping of messages in a configuration exhibiting red / black segregation.

[0025] The delimitation between the black domain and the red domain is, for example, made at the crossing of an encryption means 16, interposed between the application 12 and the TDMA interface 14 of a node (N6). This encryption means is configured to block TDMA signaling from the TDMA interface for cybersecurity purposes.

[0026] This solution consists of implementing a transmission stack in the red domain associated with the client application 12 and a transmission stack in the black domain associated with the encryption means 16.

[0027] Application 12 periodically transmits the entire contents of its stack to the encryption means 16. The transmission period of application 12 is equal to the TDMA latency, but the TC'k transmission times cannot be synchronized with the TCk arrival times of the TDMA frame slots allocated to node N6.

[0028] This is the encryption means 16, which, upon receiving the TDMA signaling, transmits in response to the TDMA interface 14 the contents of its stack.

[0029] According to this solution, the application in the red domain somehow tries to align the timing of its group message sendings with the TDMA frame.

[0030] For example, at time tl, application 12 generates an ML message

[0031] At time TC' 1, it transmits it by means of encryption 16.

[0032] The latter is adapted to encrypt messages received from application 12 and place the corresponding packet P (represented by the message(s) and an adapted IP header) in the black transmit stack.

[0033] The encryption method 16 places the packet PI on the black stack, which corresponds to the encryption of the message ML

[0034] While message Ml was generated at time tl, prior to the TCI arrival time of a slot, packet PI cannot be included in that slot, since time TC'1 is later than TCI. Therefore, it is necessary to wait for the following slot, at time TC2, for packet PI to be included in the TDMA frame by the TDMA interface 14.

[0035] For example, application 12 generates a message M2 at time t2 and a message M3 at time t3.

[0036] At time TC'2, application 12 transmits the message group G2 consisting of messages M2 and M3 by means of encryption 16, which places the corresponding packet P2 in the black stack.

[0037] Thus, at time TC3, the TDMA interface signals the arrival of a time slot using encryption 16. The latter responds by transmitting packet P2 so that it can be integrated into the TDMA frame.

[0038] With this solution, the clock of the red domain triggering the sending of the queue of pending messages is not synchronized with the TDMA frame (and the arrival of slots allocated to the node in question) because of the segregation between red and black domains.

[0039] If there is no grouping of messages, there is an access latency to the TDMA frame which can systematically be greater than the TDMA latency.

[0040] If there is grouping of messages, it is observed that some slots will not be filled, while data are waiting in the red domain, while other slots will be more filled.

[0041] In addition, among the grouped messages, the TDMA access latency, TDMA_AL, of some messages will be reduced compared to a solution without message grouping, while that of other messages will be increased.

[0042] Thus, by acting independently of the actual timing of the TDMA frame, the application's data transfer mechanisms prove to be underperforming, or even penalizing for communication performance in terms of latency (messages may take longer to cross the communication system than if they were not grouped) and also in terms of throughput (some slots of the TDMA frame may remain unused).

[0043] The aim of the invention is therefore to propose a method to avoid these disadvantages by offering each application message a transit time no more than that which it would have encountered without grouping, while optimizing the filling of TDMA slots.

[0044] To this end, the invention relates to a method, implemented in a computer system segregated to include so-called "red" and "black" domains, the system comprising: a transmitting node hosting a source application generating messages, said source application belonging to the red domain, and a transmitting TDMA interface belonging to the black domain, the source application being unable to receive TDMA signaling from the transmitting TDMA interface; a receiving node hosting a message recipient application, the recipient application belonging to the red domain, and a receiving TDMA interface belonging to the dark domain, the TDMA transmit and receive interfaces allowing TDMA communication from one to the other, the process comprising, on the side of the transmitting node, the steps of, each time a new message is generated by the source application, in the red domain: timestamping said message with a date on which it was generated; placing said timestamped message on a red transmit stack; destroying each message from the red transmit stack that has been present in the red transmit stack for such a time that said message has already been transmitted to the dark domain; transmitting, in a group, all the remaining messages from the red transmit stack to the dark domain; in the dark domain: receiving the group; placing the group in a black transmit stack by overwriting a current content of the black transmit stack;and upon receiving a signal from the transmitting TDMA interface, transmit a packet consisting of the contents of the transmitting black stack to the transmitting TDMA interface for insertion into a TDMA frame.

[0045] According to other advantageous aspects of the invention, the method comprises one or more of the following features, taken individually or in all technically possible combinations:

[0046] - the method further comprising, on the side of the receiving node, the steps consisting to: each time a new packet is received by the receive TDMA interface, forward the received packet from the black domain to the red domain to obtain a received group; ungroup the received messages contained in the received group; and compare received messages with messages contained in a receive red stack: if a received message is not among the messages in the receive red stack, then said message is forwarded to the receiving application and placed in the receive red stack; if a received message is among the messages in the receive red stack, then said message is destroyed without being forwarded to the receiving application and is removed from the receive red stack; and if a message in the receive red stack is not among the received messages, then said message is removed from the receive red stack.

[0047] - TDMA communication is based on a communication protocol, by for example, an IP communication protocol.

[0048] The invention also relates to a computer system segregated to present so-called "red" and "black" domains, and comprising a transmitting node hosting a source application in the red domain and a transmit TDMA interface in the black domain, the source application being unable to receive TDMA signaling from the transmit TDMA interface, a receiving node hosting a destination application in the red domain and a TDMA interface of reception in the dark domain, the TDMA transmit and receive interfaces allowing TDMA communication from one to the other.

[0049] According to other advantageous aspects of the invention, the system comprises one or more of the following features, taken individually or in all technically possible combinations:

[0050] - a segregation of the transmitting node, respectively of the receiving node, is carried out by an encryption method executed by the sending node, respectively the receiving node.

[0051] - the transmitting node comprises: a red transmitting unit, located in the domain red, and associated with a red emission stack; and a black emission unit, located in the black domain, and associated with a black emission stack.

[0052] - the receiving node comprises: a red receiving unit, associated with a battery red reception.

[0053] - the red transmitting unit, the black transmitting unit and / or the red receiving unit is a type of mediation software.

[0054] - the red domain is a high-security level domain and the black domain is a low-security-level domain.

[0055] The invention finally relates to a computer program comprising software instructions which, when executed by the preceding computer system, implement the preceding process.

[0056] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0057] [Fig-1] Fig. 1 is a timing diagram of message insertion into a frame TDMA without message aggregation, in a system where the application receives TDMA signaling, according to the state of the art;

[0058] [Fig.2] Fig.2 is a timing diagram of the insertion of messages into a frame TDMA with message aggregation, in a system where the application receives TDMA signaling, according to the state of the art;

[0059] [Fig.3] The [Fig.3] is a timing diagram of the insertion of messages into a TDMA frame without and with message grouping, in a system where the application does not receive TDMA signaling, according to the prior art;

[0060] [Fig.4] Fig.4 is a schematic representation in the form of units functional aspects of a possible embodiment of a system for implementing the process according to the invention;

[0061] [Fig. 5] Fig. 5 is a schematic block representation of one possible embodiment of the process according to the invention; and,

[0062] [Fig.6] [Fig.7] The [Fig.6] is a timing diagram of the insertion of messages into a TDMA frame with message grouping, in a system where the application does not receive TDMA signaling, according to the invention.

[0063] The invention uses a mechanism for grouping messages to be transmitted, coupled with a timestamping of the messages which makes it possible to remove messages that are too old from the group of messages before sending it.

[0064] In relation to this mechanism used by a sending node, a complementary mechanism implemented by a receiving node makes it possible to detect and delete messages that would have been sent several times, as a side effect of the grouping mechanism. System

[0065] Figure 4 represents one possible embodiment of a system for putting into implementation of the process according to the invention.

[0066] The system 10 comprises at least two nodes, referenced N6 and N8 on [Fig.4], communicating via a TDMA link 19.

[0067] These two nodes are identical to each other. A node can operate alternately in sending messages and receiving messages. In what follows, node N6 will be described in more detail, but an identical description could be given for node N8.

[0068] A node, such as node N6, is a computer comprising a hardware layer 20 and a software layer 40.

[0069] The hardware layer 20 includes a computing means, such as a processor 22, storage means, such as a memory 24, and a TDMA communication means, such as a TDMA communication card 26.

[0070] The software layer 40 comprises an operating system layer 42, a mediation layer 44, and an application layer 46.

[0071] The operating system layer 42 includes in particular a TDMA communication driver 41, enabling data exchange with the card 26. The driver 41 and the card 26 together constitute an interface for accessing the TDMA frame.

[0072] The application layer 46 includes, in particular, a client application 47, such as a service application, which, on the sending node N6 side, is designed to generate messages and which, on the receiving node N8 side, is designed to receive messages. The message Mj is generated at time tj by the application 47.

[0073] The application layer 46 also includes an encryption application 49.

[0074] The encryption application 49 delimits in each node a so-called "red" domain in which the client application 47 is located and a so-called "black" domain in which the TDMA interface is located.

[0075] According to the invention, the mediation layer 44 integrates a software 50.

[0076] Software 50 comprises different units:

[0077] - a red emission unit 52;

[0078] - a black transmit / receive unit 54; and,

[0079] - a red receiving unit 56.

[0080] Each software unit 50 is associated with a battery in the memory 24. Thus, a red transmitting unit 52 is associated with a red transmitting battery 62, a black transmitting unit 54 is associated with a black transmitting battery 64, and a red receiving unit 56 is associated with a red receiving battery 66.

[0081] The black transmission stack 64 has a size equal to the maximum capacity of a TDM A transmission slot.

[0082] The red transmit stack 52 has a size that is defined in such a way that, taking into account the different data that will be added to the content of this stack during its transmission (such as an IP header, encryption data, etc.), the packet arriving in the black domain does not exceed the capacity of the black stack, i.e. of a TDMA slot.

[0083] In transmission mode, the red transmission unit 52 is adapted to receive messages Mj generated by the client application 47. It is adapted to construct message groups Gj from the received messages. It is adapted to transmit the message groups to the encryption application 49 each time a new message Mi is received.

[0084] The encryption application 49 is adapted to encrypt a group of messages Gj from the red transmitting unit 52. It is adapted to transmit the packet Pj thus obtained to the black unit 54.

[0085] The black unit 54 is adapted to receive the data packets Pj generated by the encryption application 49. It is adapted to store the last data packet received on the black transmission stack 64. It is adapted to transmit the data packet from the black transmission stack 64 to the driver 41 when the latter transmits to it an arrival signal of a TDMA slot.

[0086] On reception, the black unit 54 is adapted to receive data packets extracted from a TDMA slot by the driver 4L. It is adapted to transmit, transparently, the data packet Pj to the encryption application 49.

[0087] The encryption application 49 is adapted to decrypt a data packet Pj from the black receiving unit. It is adapted to transmit the group of messages Gj extracted from this packet to the red receiving unit 56.

[0088] The red receiving unit 56 is adapted to receive a group of messages Gj from the encryption application 49. It is adapted to filter the messages Mj from this group. It is advantageously adapted to transmit a single occurrence of each received message Mj to the client application 47.

[0089] Thus, the embodiment of [Fig.4] corresponds to an implementation in the form of a mediation software (“middleware”) offering different services to a client application.

[0090] The software 50 presents an interface, of the type application programming interface - API (“Application Programming Interface”) or protocol interface, offering message sending and receiving services.

[0091] The software 50 can also provide a signaling feature enabling the client application to obtain information in the event of destruction of its messages due to exceeding the capacity of the red transmitting stack.

[0092] Preferably, the system 10 is an IP (Internet Protocol) communication system in which a group of messages Gj is "packaged" into a first IP frame, which is then transmitted to the encryption application. Alternatively, systems implementing other communication protocols are conceivable.

[0093] The output of the encryption application is a second IP frame whose payload consists of the encryption of the first packet, and consequently of the message group.

[0094] However, the principle of the invention is compatible with other types of message communication protocols or technologies. Process

[0095] An embodiment of the process according to the invention is shown in [Fig.5] and its implementation by the timing diagram in [Fig.6].

[0096] The method 100 includes an emission phase 105 implemented on the side of the sending node, for example the N6 node, hosting a client application, such as application 47, which then operates as the source application for the messages.

[0097] At time tj, the source client application generates (step 110) a new application message Mj and transmits it to the red transmission unit 52.

[0098] It is assumed that each application message incorporates information enabling its unique identification. Thus, each message Mj is identified by a message identifier Idj. If this is not the case, this information can be generated and managed by the red transmission unit 52.

[0099] For example, as illustrated by the timing diagram in [Fig.6], message M1 is generated at time t1, message M2 is generated at time t2, message M3 is generated at time t3 and message M4 is generated at time t4 by application 47.

[0100] In step 120, the red transmitting unit 52 seeks to place the new message received Mj on top of the red transmitting stack 62.

[0101] If the red transmitting stack 62 is full, then, in a step 130, the red transmitting unit 52 destroys the message Mj and informs the client application 47 by appropriate signaling.

[0102] Otherwise, in a step 140, the message Mj is timestamped with the date tj on which it was generated and the timestamped message is placed in the red transmit stack.

[0103] For example, the initially empty stack contains at time tl the time-stamped message (Ml; tl) then, at time t2, the time-stamped messages (Ml; tl) and (M2; t2), then, at time t3, the time-stamped messages (Ml; tl), (M2; t2) and (M3; t3), and, at time t4, the time-stamped messages (Ml; tl), (M2; t2), (M3; t3) and (M4; t4).

[0104] At each instant tj when a new message Mj is added to the red transmit stack 62, the red transmit unit 52 proceeds to clean the red transmit stack 62 by traversing (step 150) its entire contents, and destroying all messages Mk whose date tk is earlier than: tj - Max_Qdelay, where Max_Qdelay is a duration parameter which is configured such that if a message has been in the red transmit stack 52 for longer than MaxjQdelay, then it has necessarily been transmitted by the TDMA communication system.

[0105] Thus, we have: Max_Delay = TDMA_L + d, where: ADMAL is the TDMA latency, that is, the time interval between the occurrence of two slots allocated to node N6; and d is a guard time, which accounts for the processing times of the different components of the transmission path. For the case of an ideal system, d is equal to 0. This is the case retained in the remainder of this description for the sake of simplicity.

[0106] For example, at time t1, the stack contains only the message M1 and no message from the stack is discarded. At time t2, the stack contains the messages M1 and M2, but since the interval between times t1 and t2 is less than Max_Delay, no message from the stack is discarded. At time t3, the stack contains the messages M1, M2, and M3, but since the interval between times t1 and t3 is less than Max_Delay, no message from the stack is discarded. At the current time t4, the stack contains the messages M1, M2, M3, and M4, and since the interval between times t1 and t4 is greater than Max_Delay, then the message M1 is considered expired and is discarded. M2 is preserved since the interval between times t2 and t4 is less than Max_Delay. This destruction of the time-stamped message (Ml; tl) is symbolized by a "trash can" on the [Fig.6].

[0107] Then, after cleaning the red transmit stack 62, in a step 160, the red transmit unit 52 transmits all the messages remaining in the red transmit stack 62 to the encryption application 49.

[0108] To do this, a single IP packet, Gj, grouping the different messages from the red transmit stack is generated and sent to the encryption application 49.

[0109] For example, at time t1, an IP packet G1 containing only message M1 is transmitted to the encryption application. Thus, at time t2, an IP packet G2 containing messages M1 and M2 is transmitted to the encryption application. Thus, at time t3, an IP packet G3 containing messages M1, M2, and M3 is transmitted to the encryption application. Thus, at time t4, an IP packet G4 containing messages M2, M3, and M4 is transmitted to the encryption application.

[0110] In step 170, the encryption application 49 encrypts the IP packet Gj to obtain an encrypted IP packet Pj. The latter is transmitted to the black unit 54.

[0111] For example, at time t1, an encrypted IP packet PI containing the single encrypted message M1 is received on the black side. Thus, at time t2, an encrypted IP packet P2 containing the encrypted messages M1 and M2 is received on the black side. At time t3, an encrypted IP packet P3 containing the encrypted messages M1, M2, and M3 is received on the black side. At time t4, an encrypted IP packet P4 containing the encrypted messages M2, M3, and M4 is received on the black side.

[0112] In step 180, upon receiving an encrypted packet Pj, the black transmit / receive unit 54 places it in the black transmit stack 64.

[0113] If this black stack 64 already contains a data packet Pj-1, the latter is destroyed, since the messages it contains are also found in the newly received encrypted packet, Pj.

[0114] For example, the black stack 64 is initially empty. At time t1, the cipher packet PI, containing the single message M1, is placed in the stack 64. At time t2, the cipher packet PI is destroyed and the cipher packet P2, grouping the messages M1 and M2, is placed in the stack 64. At time TC2, the black stack 64 is emptied so that at time t3, the cipher packet PC3, grouping the messages M1, M2 and M3, is placed in the stack 64. At time t4, the cipher packet P3 is destroyed and the cipher packet P4, grouping the messages M2, M3 and M4, is placed in the stack 64.

[0115] At step 190, when the TDMA communication pilot 41 transmits a TDMA slot arrival signal to the black unit 54, the latter responds by transmitting the contents of the black stack 64, which is consequently emptied.

[0116] For example, if a first slot arrives at a TCI time, before the tl time, since the black stack 64 is empty, no encrypted packet is transmitted in the first TDMA slot.

[0117] For example, if a second slot arrives at a time TC2, between times t2 and t3, it is the encrypted packet P2 that is transmitted in the second TDMA slot.

[0118] If a third slot arrives at a time TC3, later than time t4, it is the encrypted packet P4 that is transmitted in the third TDMA slot.

[0119] It is clear that the destruction of the message group M1, M2, M3 and its replacement by the message group M2, M3, M4 in the black stack 64 at time t4, are carried out when the message Ml has already been sent in a previous TDMA slot.

[0120] With such a mechanism, as long as the capacity requested from the TDMA communication system remains less than or equal to that which can be served by the allocated slot trains, then the maximum TDMA frame access latency is less than or equal to the TDMA latency, TDMA_L.

[0121] The method 100 includes a reception phase 205 implemented on the receiving node side of a message, for example again the N6 node, hosting a client application 47, then operating as the recipient application of the messages.

[0122] In step 210, the TDMA interface transmits to the black unit 54 the encrypted packet Pj extracted from the TDMA frame. This is transmitted directly using encryption 49 to decrypt its contents.

[0123] In phase 105 of transmission, the grouping of messages in the red domain implies that some Mj messages may be sent twice, in two successive message packets.

[0124] For example, in the particular example of [Fig.6], the message M2 is transmitted once at time TC2 and a second time at time TC3.

[0125] According to method 100, a message cannot be transmitted more than twice.

[0126] In order for the grouping of messages to be totally transparent to client applications communicating with each other, it is therefore necessary that the receiving node hosting the recipient client application implement steps for detecting and eliminating such duplicates.

[0127] To do this, the receiving node N6 maintains a red receive stack 66, storing the received messages.

[0128] When a group Gj of messages is received by the red receiving unit 56, the messages are first ungrouped in a step 220.

[0129] Then, in a step 230, for each unbundled message, a duplicate search is performed in the red receiving stack 66, using the message identifier Idj.

[0130] Three cases are conceivable: the received message is either New, or Duplicate, or Non-Duplicate.

[0131] A message is New if it is in the newly received message group Gj, but not in the red received stack 66.

[0132] Then in step 240, it is passed to the recipient application 47. It is also stored in the red receive stack.

[0133] A message is Duplicate if it is in the newly received message group Gj and in the red received stack 66 of received messages.

[0134] Then in a step 250, it is destroyed without being passed on to the receiving application and it is removed from the red receiving stack.

[0135] A message is Non-Duplicate if it is not in the newly received message group Gj, but is present in the red receive stack 66. It is then removed from the red receive stack and is no longer at risk of being received a second time. Advantages

[0136] The solution proposes a mechanism for grouping application messages operating in the red domain:

[0137] - which never penalizes the TDMA communication performance of a node;

[0138] - which reduces the transmission delay for bursts of packets sent during a period equal to the TDMA latency;

[0139] - which does not increase the TDMA access latency of messages compared to a system not implementing message grouping;

[0140] - which optimizes the use of slots allocated to a node and therefore increases the throughput transmission efficiency compared to a solution without grouping;

[0141] - which induces a TDMA access latency (TDMA_AL) less than or equal to that of a solution without message grouping and which is bounded by the TDMA latency (TDMA_L);

[0142] - which is independent of the source and destination applications, as well as the protocol of communication effectively implemented.

[0143] For applications that cannot access the timing information of an underlying TDMA communication system, the invention provides the following advantages: - by ensuring both the grouping and ungrouping of messages, the invention offers a transparent mechanism for the applications served; - The invention is compatible with any type of TDMA communication system; and, - The invention has no impact on the TDMA communication system.

[0144] The invention finds applications in any communication system based on TDMA technology, such as professional / military / industrial communication systems, featuring security segregation.

Claims

1. Demands Method (100) implemented in a computer system (10) segregated to include so-called "red" and "black" domains, the system comprising: - a transmitting node hosting a source application generating messages, said source application belonging to the red domain, and a transmitting TDMA interface belonging to the black domain, the source application not being able to receive TDMA signaling from the transmitting TDMA interface; - a receiving node hosting a message recipient application, the recipient application belonging to the red domain, and a receiving TDMA interface belonging to the black domain, TDMA transmit and receive interfaces allowing TDMA communication from one to the other, the process comprising, on the side of the emitting node, the steps consisting of each time a new message is generated by the source application, in the red zone: - timestamp the message with the date it was generated; - place said time-stamped message on a red transmit stack (62); - destroy each message from the red transmit stack (62) which has been present in the red transmit stack for such a time that said message has already been transmitted to the black domain; - transmit, in a group, all the remaining messages from the red transmit stack (62) to the black domain; in the black market: - receive the group; - place the group in a black transmit stack (64) by overwriting a current content of the black transmit stack; and, - upon receiving a signal from the TDMA transmit interface, transmit a packet consisting of the content of the black transmit stack (64) to the TDMA transmit interface for insertion into a TDMA frame.

2. A method according to claim 1, further comprising, on the receiving node side, the steps of, each time a new packet is received by the receiving TDMA interface: - forwarding the received packet from the black domain to the red domain to obtain a received group; - ungrouping the received messages contained in the received group; and, - comparing received messages with messages contained in a received red stack (66): • if a received message is not among the messages in the received red stack, then said message is forwarded to the receiving application and placed in the received red stack; • if a received message is among the messages in the received red stack, then said message is destroyed without being forwarded to the receiving application and is removed from the received red stack;and, • if a message from the red receive stack is not among the received messages, then said message is removed from the red receive stack.;

3. A method according to any one of the preceding claims, wherein the TDMA communication is based on a communication protocol, for example an IP communication protocol.

4. A computer system (10) adapted for implementing a method (100) according to any one of the preceding claims, the computer system being segregated to present so-called "red" and "black" domains, and comprising a transmitter node hosting a source application in the domain red and a transmit TDMA interface in the black domain, the source application unable to receive TDMA signaling from the transmit TDMA interface, a receiving node hosting a destination application in the red domain and a receive TDMA interface in the black domain, the transmit and receive TDMA interfaces permitting TDMA communication from one to the other.

5. System according to claim 4, wherein a segregation of the sending node, respectively of the receiving node, is achieved by an encryption means (49) executed by the sending node, respectively the receiving node.

6. System according to claim 4 or claim 5, wherein the emitting node comprises: - a red emitting unit (52), located in the red domain, and associated with a red emitting stack (62); and, - a black emitting unit (54), located in the black domain, and associated with a black emitting stack (64).

7. System according to any one of claims 4 to 6, wherein the receiving node comprises: a red receiving unit (56), associated with a red receiving stack (66).

8. System according to claim 6 or claim 7, wherein the red transmitting unit, the black transmitting unit and / or the red receiving unit is of the mediation software type.

9. System according to any one of claims 4 to 7, wherein the red domain is a high security level domain and the black domain is a low security level domain.

10. Computer program comprising software instructions which, when executed by a node, transmitter and / or receiver, of a system (10) according to any one of claims 4 to 9, implement a method (100) according to any one of claims 1 to 3.

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