FR2904905A1 - Data flow e.g. audio data flow, transmitting method for e.g. Internet, involves transmitting portion of data flow to base stations, where stations retransmit portion of data flow received via communication network to destination of receiver - Google Patents

Abstract

The method involves determining base stations of a communication network and selecting determined base stations based on the proximity of the base stations with respect to a transmitter in the network. A portion of data flow is transmitted to the base stations of the network, where the base stations retransmit the portion of the data flow received through the communication network to a destination of a receiver. Independent claims are also included for the following: (1) a method for receiving a data flow transmitted by a transmitter (2) a system for transmitting a data flow from a transmitter to a receiver (3) a system for receiving a data flow transmitted by a transmitter (4) a computer program stored on an information medium comprising instructions for implementing a data flow transmitting method (5) a computer program stored on an information medium comprising instructions for implementing a data flow receiving method (6) a programmable component for generating a data flow to be transmitted (7) a programmable component for processing received data flow (8) a device comprising a retransmission unit.

Description

The invention relates to a method and a system for transmitting a flow of

  data from a first device to a third device on a communication network, and a method and a system for receiving in a third device a data stream transmitted by a first server device over a communication network, the network communication device comprising second devices. The data streams concerned include audio, video or multimedia data streams to be transmitted according to a certain quality of service, especially in real time. The transmission of such data streams is carried out on a communication network 20, in particular a peer-to-peer network (P2P or peer-to-peer network) or the Internet network. Today, transmitting a multimedia type data stream over an IP (Internet Protocol) or best effort communication network according to a certain quality of service, in particular in real time, is an operation that is unlikely to be implemented. succeed, even if a low bandwidth would be used. This is because the best effort communication networks, such as the IP network, are such that they have no guarantee for the transmission of data packets. In addition, the data of the packets may be corrupted, duplicated, lost, the packet order changed (even if packet A is transmitted before packet B, packet B may arrive before packet A). 1 2904905 2 Such a lack of reliability of the best effort network is due to the reduction of the complexity of the routers present on the network. It is possible, on best effort networks, to allocate a connection with a large bandwidth. However, this connection may be inappropriate for the transmission of data streams according to a certain quality of service, especially in real time. It is known that a good quality telephone signal requires a bandwidth of about 9 kilobits, in particular in the case of GSM (Global System for Mobile Communications in English terminology).

  In an IP network, it is observed that a bandwidth of 1 megabit for performing telephony over IP is not satisfactory, while the bandwidth is more than 100 times higher than the 9 kilobits normally required. This is due to the time required for a message to make a round trip between the transmitter and the receiver and the time of issue of an acknowledgment of receipt. In theory, if the packet size could be decreased, then the number of unusable packets in an application would decrease. However, in best effort communication networks, widely spread and using well-defined communication protocols, such changes are not possible. Similarly, a solution could be to use a buffer to support a slight delay. However, this solution is not suitable for real-time data flow exchanges. The object of the present invention is to overcome at least one of the disadvantages of the aforementioned prior art techniques and processes. An object of the present invention is, in particular, a method of transmitting a data stream from a first device to a third device over a communication network, the communication network 30 comprising second devices, characterized in that that the method comprises transmitting at least a same portion of the data stream to a plurality of second devices of the communication network, at least some of said plurality of second devices reemitting said at least one portion of data across the communication network to the third device. The present invention enables the transmission of a data stream, in particular a stream of audio or video data complying with quality of service constraints, in particular of real-time transmission, on best effort communication networks in which no constraints reliability does not exist. For this, the present invention is based on a step of transmitting the same portion of the data stream to a plurality of second devices of the communication network. These second devices then re-transmit this portion of the data stream to the client device. In this way, the third device can take the data portion arrived first and ignore the receipt of the same portion arrived later. The use of different second devices makes it possible, on the one hand, to impose the use of different paths in parallel or pseudo-parallel when transmitting a portion of flow and, therefore, to perform the redundant transmission of the same portion and, secondly, to use efficient paths in the communication network. According to one characteristic, the method comprises a preliminary step of determining the second devices. According to another characteristic, the determination of the second devices is carried out by the prior transmission of a request to obtain a list of second devices existing between the first device and the third device intended for a flagship device, the flagship device containing data relating to the topology of the communication network. According to this characteristic, a particular device called a flagship device containing data representative of the topology of the network is used. In this way, the latter is able to determine, from the data, second devices between the first device and the third device. According to an alternative embodiment, the determination of the second devices is carried out by the prior exchange of messages with devices of the communication network. According to a particular characteristic, the method comprises a step of selecting the second devices determined according to their proximity with respect to the first device in the communication network. The present invention also aims to provide a method for receiving in a third device a data stream transmitted by a first device on a communication network, the communication network 10 comprising second devices, characterized in that the method comprises receiving, from a plurality of second devices, at least a same portion of the data stream, at least some of said plurality of second devices having previously retransmitted said at least a same portion of the received data stream; from the first device. As described above, the present invention makes it possible to transmit a data stream, in particular a stream of audio or video data, which complies with quality of service constraints, particularly of real-time transmission, on best effort communication networks. in which there is no reliability constraint. For this, the present invention is based on a reception step from a plurality of second devices of at least a portion of the data stream, these second devices re-transmitting portions of the data stream from the first device.

  In this way, the third device can receive the data portion arrived first and ignore the receipt of the same portion arrived later. As has been previously stated, the use of different second devices makes it possible, on the one hand, to impose the use of different paths in parallel or pseudo-parallel during the transmission of a portion of flow and, therefore, to perform redundancy in the transmission of the same portion and, secondly, to use efficient paths in the communication network. According to one characteristic, the method comprises: a step of generating a list of second device identifiers, said list comprising the identifiers of the second devices of said plurality of second devices, and a transmission step of said second devices; list to the server device. According to this feature, a subset of the plurality of second devices is determined so as to reduce the relative flooding of the network due to redundancy. According to one characteristic, the method comprises a step of transmitting the list of identifiers of second devices elaborated to at least one flagship device, the flagship device containing topology data of the communication network.

In this way, the data stored in the flagship device is updated. According to one characteristic, the method comprises, as soon as a data portion of the data stream is received, a step of transmitting an acknowledgment of said portion of data to second devices for which the first device has issued said portion of data. This feature makes it possible to avoid transmission delays of the data portions induced by the use of the second worst performing devices. Correlatively, the invention also provides a system for transmitting a data stream from a first device to a third device over a communication network, the communication network comprising second devices, characterized in that the system comprises means for transmitting at least a same portion of the data stream to a plurality of second devices of the communication network, at least some of said plurality of second devices having retransmission means adapted to re-transmit said at least one portion data through the communication network to the third device.

This device has the same advantages as the transmission method briefly described above. Another object of the present invention is to provide a system for receiving in a third device a data stream transmitted by a first device on a communication network, the communication network comprising second devices, characterized in that the system comprises means for receiving, from a plurality of second devices, at least a same portion of the data stream, at least some of said plurality of second devices having retransmitting means adapted to retransmit said at least one same portion of the previously received data stream from the first device. This device has the same advantages as the reception method briefly described above. According to another aspect, the invention is directed to a computer program stored on an information carrier, said program containing instructions for implementing the method of transmitting a data flow from a first device to a data carrier. a third device on a communication network, the communication network comprising second devices according to the invention, when this program is loaded and executed by a computer system. According to another aspect, the invention is directed to a computer program stored on an information medium, said program containing instructions for implementing the method of reception in a third device of a data stream coming from a data carrier. first device on a communication network, the communication network comprising second devices according to the invention, when this program is loaded and executed by a computer system. In yet another aspect, the invention is directed to a programmable component for generating a data stream to be transmitted from a first device to a third device on a communication network, the communication network comprising second devices, characterized in that the programmable component comprises means for implementing a method of transmitting a data stream from the first device to the third device over a communication network according to the invention. In yet another aspect, the invention provides a programmable component for processing in a third device a data stream received from a first device on a communication network, the communication network comprising second devices, characterized in that the programmable component comprises means for implementing a method of receiving in the third device a data stream from the first device on a communication network according to the invention. The invention also relates to a device comprising at least one of the following means: the means of the transmission system according to the invention, the means of the reception system according to the invention, suitable retransmission means. to re-transmit at least a portion of the previously received data stream from the first device to the third device in the transmission or reception system according to the invention. Other aspects and advantages of the present invention will appear more clearly on reading the description of the embodiments below, this description being given solely by way of nonlimiting example and with reference to the appended drawings, in which: Figure 1 schematically shows a communication network in which a transmitting device transmits a data stream to a receiving device; Figure 2 illustrates an initial data exchange algorithm for discovering the surrounding topology of a new transmitter device according to the invention; Figure 3 schematically shows an implementation of the interrogation of a flagship device for obtaining a plurality of relay devices in accordance with the invention; FIG. 4 schematically represents an implementation of steps 22 to 26 of the algorithm of FIG. 2; FIG. 5 illustrates an algorithm for transmitting a data stream in normal operating mode in accordance with the invention; Figure 6 illustrates an example of sorting IP addresses; and FIG. 7 schematically represents an implementation of steps 54 to 57 of the algorithm of FIG. 5. A detailed description of the method and system for transmitting and receiving a data stream According to an object of the invention is provided below, in conjunction with Figures 1 to 7. An object of the invention is to allow the transmission of a data stream according to a given quality of service, especially in time real, from one device to another device.

In this regard, the method and system for transmitting a data stream rely on emission redundancy mechanisms of the same data portion of the data stream. Thus, according to the invention, a first device, in particular a transmitting device, transmits at least one and the same portion of the data stream to a plurality of second devices, in particular relay devices, of the communication network, the relay devices being devices present on the communication network. In turn, these relay devices will re-transmit the portion of data stream received through the communication network to a third device, including a receiver device.

In this way, the transmitting device transmits the same portion of flow, a multitude of times, forcing each message to follow, through the network, a different path while passing through different predetermined points of the network, these points being the relay devices. The receiving device receiving several identical portions of the data stream re-transmitted by different relay devices can take the portion of the data stream that arrives first in order to respect a given quality of service.

However, it may be envisaged to require, for a portion of data, to go through a plurality of relay devices one after the other. It should be noted that the portions of data are transmitted on the communication network, in particular, after their encapsulation in packets.

According to a particular embodiment, it is observed that if a number y of the same portion of the stream has been emitted and a subset x of the same portion of the stream is statistically delayed, that is, say, received in an unacceptable time window, then it is sufficient to issue the same portion (1 + x / y) times to compensate for the loss of portions and ensure a given quality of service. Although this embodiment has the drawback of flooding the communication network with unnecessary packets, the flooding of the network is however relatively weak. It should be noted that such redundancy can be performed on the first portion of the transmitted data stream or on the first portions of the transmitted data stream. Indeed, at the end of this step, the receiver device is able to analyze the relay devices by which the transmission times of a portion of data (for example a packet) between the transmitting device and the receiving device are the following. shorter. Then, it can select a subset of the relay devices adapted to the transfer and transmission to comply with constraints imposed by a given quality of service. The list of relay devices selected by the receiving device 25 is then transmitted to the transmitting device. The latter can, in this way, restrict the transmission of the same portion of data only to the number of selected relay devices. It should be noted that the number of relay devices used during the transmission of the data stream may vary and be best adjusted throughout the transmission. In addition, a transmitting device may later behave as a relay device or a receiver device and vice versa.

Fig. 1 illustrates the topology of a communication network in which a sending device named a must transmit a data stream to a receiving device named k. The different devices present in the network are named from 5 to u. According to the invention, in order to send a data stream from the sending device a to the receiving device k while respecting a certain quality of service, for example a transmission in real time, it is necessary, in a first step, to define relay devices on 10 different possible paths of communication between the transmitter device a and the receiver device k. Different methods can be used to determine the relay devices between a transmitter device a and a receiver device k. According to one method, the determination of the relay devices can be performed from a knowledge, by the transmitting device, of the topology of the network or of at least a part of the topology of the network. This knowledge may be derived from previous exchanges, in particular during the installation of the transmitter device on the network or in a period prior to the communication between the transmitter device a and the receiver device k, for example during the establishment. communication between these two devices. According to another method, the transmitting device can obtain knowledge of the topology of the network, in particular by communicating with a main station, also called a flagship device with a maximum of 25 packets transmitted to relay devices. In this way, it is enough for him to make a topology based on the transit time of the data between the devices. It should be noted that exchanges having close transit times must be made on almost identical paths. Likewise, conventional statistical methods can be used to know this topology.

This knowledge of the topology can thus be determined at the establishment of the communication between the transmitter device a and the receiver device k. In addition, the transmitting device may interrogate one or more flagship devices to determine the identity of the potential relay devices. Flagship devices are devices whose role as a lighthouse is public. These contain data on the topology of the communication network. The use of the relay devices during the transmission of a data stream from a transmitting device to a receiving device makes it possible to borrow from the communication network paths which, potentially, would not have been authorized by the protocols routing used on routers. Indeed, a router device has routing tables that are not necessarily optimized, so that the routing is not always very effective. Referring to Figure 2, there is now described an algorithm according to the invention managing the initial exchanges to obtain a knowledge of the topology of the communication network surrounding the transmitting device.

This algorithm is particularly adapted to a transmitter device newly installed on the communication network and allows it to discover its network environment. In addition, if routing mechanisms located in the vicinity of this transmitter device are inefficient, then they will be detected upon obtaining knowledge of the network. In addition, this algorithm makes it possible to establish the list of relay devices allowing the use of paths on the network which are efficient and allow the transmission of data streams respecting quality of service constraints, in particular the transmission of a stream. real-time data.

The algorithm starts in step 21 by determining relay devices. According to one embodiment, the transmitter device interrogates a beacon device to determine at least three possible relays between the transmitter device a and the receiver device k. Figure 3 illustrates, by way of example, step 21. A sending device interrogates (31) a beacon device to obtain relay device addresses existing between the transmitting device and the receiving device. This interrogation (31) is performed in particular by means of a suitable command language agreed in advance in the system. The beacon device establishes (32) the list of relay devices and transmits this list to the transmitting device (33), the list containing, for example, a plurality of IP addresses of the relay devices. Returning to FIG. 2, step 21 is followed by step 22 of transmission by the transmitter device of at least one and the same portion to the plurality of relay devices determined during step 21 or only certain 'between them. According to the embodiment previously described, the transmitting device 15 transmits at least three messages containing the same portion of the data stream to be transmitted to the relay devices. On receiving this portion of the data stream, each relay relay device re-transmits this portion, in step 23, to the receiving device directly or indirectly, for example, via other relay devices. In step 24, the receiving device receives a same portion of the data stream, a plurality of times, from the plurality of relay devices and substantially shifted in time. The receiver device compares the different arrival times of the portion of the stream 25 from the plurality of relay devices. The receiving device then establishes, at step 25, a list of relay device identifiers such that this list comprises, among the plurality of relay devices through which the transmitting device has transmitted the same portion of data, a subset of this plurality. This subset of relay devices comprises relay devices having, for example, the shortest transmission times.

Finally, during step 26, the number of messages containing the same portion of the data stream transmitted in parallel or in pseudo-parallel is progressively reduced. To do this, the receiving device transmits to the transmitting device the list of selected relay devices. In this way, the emission redundancy decreases. In addition, this list can also be sent to the flagship device, so that the latter obtains more accurate topology data. It should be noted that the list comprises at least two identifiers of 10 relay devices. FIG. 4 illustrates, by means of an example, the steps 22 to 26 of the algorithm of FIG. 2. The transmitting device transmits to the relay devices 1, 2 and 3 the same portion of the stream (41) and each of these relay devices in turn repeats this portion towards the receiving device (42).

The receiving device then ranks (43) in accordance with steps 24 and 25 of Fig. 2 and transmits to the transmitting device and the beacon device the list of relays having the shortest transmission times (44 and 45). With reference to FIG. 5, an algorithm 20 is now described which is used during exchanges in normal operating mode between a transmitting device and a receiving device. This algorithm makes it possible to adjust the transmission of the data stream according to one-off events that may affect the transmission. The algorithm starts, in step 51, obtaining, after interrogation 25 of a flagship device, a list of relay devices present in the network between the transmitter device a and the receiver device k. An example illustrating this step is shown in Figure 3 previously described. In the next step (step 52), the transmitting device determines the topology of the existing communication network between the transmitting device and the receiving device and thereby determining potential relay devices.

In step 53, the transmitting device determines a list of relay devices from the list obtained in step 51 and the potential relay devices identified in step 52. Determining the plurality of relay devices which the transmitting device uses for the transmission of the data stream to the receiving device is done in particular by means of a CIDR (Classless Inter-Domain Routing) type algorithm. According to this algorithm, it is considered that the devices whose IP addresses are numerically close are also geographically close on the communication network. Thus, all the IP addresses of the relay devices identified in steps 51 and 52 are sorted according to their numerical value. Figure 6 illustrates an organization of the IP addresses of the relay devices.

According to this sorted address tree, if we consider the following IP address 142.68.45.8, then the following IP address 142.68.46.21 is considered to be close to the first address on the communication network. The following IP address 142.69.23.76 is more distant from the first IP address.

Finally, the next IP address 154.68.45.8 is furthest from the three previous IP addresses with respect to the first IP address. In this way, from such a tree of sorted IP addresses, the plurality of relay devices whose addresses are close to the IP address of the transmitting device is determined.

The plurality of relay devices must contain at least two relay devices. According to one embodiment, the transmitting device connects to the relay devices determined from their particular IP address and indicates, according to a suitable command language agreed in advance in the system, the address, including the IP address, of the receiving device for the portions of the data stream that the transmitting device will transmit.

Returning to FIG. 5, the algorithm continues, in step 54, by sending a portion of the data stream to the plurality of relay devices determined in step 53. In step 55, the relay devices, upon receipt of the portion of the data stream, re-transmit this portion to the receiving device. As soon as the receiving device receives the portion of the data stream, the latter transmits (step 56) a message containing an acknowledgment to the plurality of relay devices determined in step 53. This message is sent to the destination. set of devices 10 relays determined, even if they have not yet received the portion to be transmitted to the receiving device, so as not to accumulate delay in time. In step 57, the receiver device compares the arrival times of the same portion from the plurality of relay devices 15 and selects a list of relay devices from this plurality. This list includes the relay devices able to ensure the transmission times on the network among the shortest. This list includes at least two relay devices. This list is transmitted to the transmitting device and can also be transmitted to the flagship device. According to a particular embodiment, the receiving device transmits a global acknowledgment message to the plurality of relay devices. Steps 54 to 57 may be iterated as long as there are portions of the data stream not yet transmitted from the transmitting device a to the receiving device k. Such emission redundancy of the same portion allows compliance with quality of service constraints, including real-time transmission of data. It should be noted that a relay list held by a known flagship device of the transmitter device can be obtained at any time so as to discover a new relay.

FIG. 7 illustrates, by means of an example, the steps 54 to 57 of FIG. 5. The transmitting device transmits to the relay devices 1, 2 and 3 a same portion of the flow (71) and each of these relay devices. re-transmits this portion to the receiving device (72).

The receiving device, upon receiving a portion of the stream, transmits a global acknowledgment (73) to the plurality of relay devices (relays 1, 2 and 3) in accordance with step 56 of FIG. 5. In addition, the receiving device ranks (74) the relay devices based on their performance in transmitting a portion of a data stream. The receiving device transmits to the transmitting device and the flagship device the list of relays with the shortest transmission times (75 and 76). The method and transmission system and the method and reception system according to the invention can be implemented in the context of a peer to peer network. To do this, the systems forming the peer-to-peer network constitute the various systems necessary for the implementation of the invention. According to a particular embodiment, the transmitting device has previously carried out an authentication step of the receiver device k before transmitting portions of the data stream. In addition, the transmitting device and the receiving device can exchange a key for encrypting portions of the data stream to secure the transmission of the data stream. 25

Claims (17)

  A method of transmitting a data stream from a first device to a third device over a communication network, the communication network comprising second devices, characterized in that the method comprises transmitting at least one portion of the data stream to a plurality of second devices of the communication network, at least some of said plurality of second devices re-transmitting said at least one portion of data across the communication network to the third device.   2. Emission method according to claim 1, characterized in that it comprises a preliminary step of determining the second devices.   3. Transmission method according to claim 2, characterized in that the determination of the second devices is performed by the prior issue of a request to obtain a list of second devices existing between the first device and the third device. to a flagship device, the flagship device containing data relating to the topology of the communication network.   4. Transmission method according to claim 2, characterized in that the determination of the second devices is achieved by the prior exchange of messages with devices of the communication network.   5. Transmission method according to any one of claims 2 to 4, characterized in that the method comprises a step of selecting the second devices determined according to their proximity to the first device in the communication network.   6. A method of receiving in a third device a data stream transmitted by a first device over a communication network, the communication network comprising second devices, characterized in that the method comprises receiving, from a plurality of second devices, at least a same portion of the data stream, at least some of said plurality of second devices having previously retransmitted said at least a same portion of the received data stream from the first device.   7. Reception method according to claim 6, characterized in that it comprises: a step of generating a list of identifiers of second devices, said list comprising the identifiers of the second devices of said plurality of second devices; and a step of transmitting said list to the server device. 15   8. Reception method according to claim 7, characterized in that it comprises a step of transmitting the list of identifiers of second devices developed to at least one flagship device, the flagship device containing topology data of the network of communication. 20   9. Reception method according to claim 6, characterized in that it comprises, upon receipt of a data portion of the data stream, a step of transmitting an acknowledgment of said portion of data to data. second devices to which the first device has sent said portion of data. 25   10. System for transmitting a data stream from a first device to a third device on a communication network, the communication network comprising second devices, characterized in that the system comprises means for transmitting data. at least a same portion of the data stream to a plurality of second devices of the communication network, at least some of said plurality of second devices having re-transmission means adapted to re-transmit said at least one portion of data across the network communication to the third device.   11. Transmission system according to claim 10, characterized in that it comprises means for determining the second devices.   12. System for receiving in a third device a data stream transmitted by a first device on a communication network, the communication network comprising second devices, characterized in that the system comprises reception means, from a plurality of second devices, at least one and the same portion of the data stream, at least some of said plurality of second devices having retransmission means adapted to re-transmit said at least one same portion of the data stream previously received in from the first device.   13. Computer program stored on an information carrier, said program containing instructions for carrying out the method of transmitting a data stream from a first device to a third device over a communication network. , the communication network comprising second devices according to any one of claims 1 to 5, when the program is loaded and executed by a computer system. 25   14. Computer program stored on an information carrier, said program containing instructions for implementing the method of receiving in a third device a data stream from a first device on a communication network, the communication network comprising second devices according to any one of claims 6 to 9, when this program is loaded and executed by a computer system. 2904905 20   15. Programmable component for generating a data stream to be transmitted from a first device to a third device on a communication network, the communication network comprising second devices, characterized in that the programmable component comprises means for implementing implement a method of transmitting a data stream from the first device to the third device over a communication network according to any one of claims 1 to 5.   16. Programmable component for processing in a third device a data stream received from a first device on a communication network, the communication network comprising second devices, characterized in that the programmable component comprises means for implementing a method of receiving in the third device a data stream from the first device on a communication network according to any one of claims 6 to 9.   17. Device characterized in that it comprises at least one of the following means: the means of the transmission system according to claim 10 or claim 11, the means of the reception system according to claim 12, retransmission means able to re-transmit at least a portion of the previously received data stream from the first device to the third device in the system according to claim 10 or 12.