Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L47/00—Traffic control in data switching networks
  • H04L47/10—Flow control; Congestion control
  • H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
  • H04L47/2416—Real-time traffic
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L47/00—Traffic control in data switching networks
  • H04L47/10—Flow control; Congestion control
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
  • H04L69/22—Parsing or analysis of headers

Definitions

• the present invention relates to a method and a system for transmitting data flows between two remote stations, connected by a telecommunications network.
• the invention finds an advantageous application in the general field of telepresence, in particular tele-expertise, and more specifically in the fields involving the carrying out of remote acts such as tele-ultrasound or tele-surgery.
• Other applications can also be envisaged, such as network games, and all the fields in which remote manipulation is necessary.
• Techniques relating to tele-expertise such as tele-echography, generally use two remote stations, namely a master station, or expert station, which, in the example of tele-echography, is the one where finds the doctor or midwife, and a slave station, or patient station, which is where the pregnant woman is to be examined.
• a master station or expert station
• a slave station or patient station, which is where the pregnant woman is to be examined.
• a telecommunication network which can be an ISDN network, an IP network, or other.
• the audio data stream or sound channel, which carries in one direction and in the other the speech and the sounds coming from the stations of the expert and the patient.
• Good sound quality requires bitrate and coding adapted as well as transmitters and receivers capable of ensuring listening and expression comfort for participants where they are. This sound quality also contributes to the climate of confidence.
• the haptic data flow, or haptic channel through which pass, on the one hand, the control orders of the ultrasound probe issued by the expert station and, on the other hand, the force feedback information transmitted by the probe the expert during his remote manipulation.
• the constraints on this channel are the delays from one end to the other of the chain which, ideally, should be less than 10 ms, the jitter and the arrangement of the information. It should be noted that with an ISDN synchronous network, the arrangement is resolved, the jitter is minimized and the delays are low.
• command data flow or command control channel.
• This channel must always be available, but does not present any particular constraints. It concerns, in general, initializations, adjustments, changes of state of the videophonic (visio and audio), echographic and haptic flows.
• the expert must check on the quality of the ultrasound images the way in which his displacement orders are actually taken into account, and, possibly, adapt his orders thanks to the force feedback information that he receives on his virtual probe. regarding the pressure exerted on the actual probe.
• the patient or the staff present must be able to initialize the position of the echographic probe movement system, dialogue with the expert located on the other station, interrupt the movement of the probe and give the commands to the expert. after such an interruption, possibly move the probe manually according to the expert's voice instructions to deal with system blocking situations.
• the technical problem to be solved by the object of the present invention is to propose a method for transmitting data streams between two remote stations, connected by a telecommunications network, which would make it possible to uniformly process a set of data streams. different data while respecting the specific constraints associated with each of said flows, in particular the flow of haptic data.
• each of said data streams received from one of said stations in accordance with a single communication protocol, common to all the data streams, in which the data are organized in data packets constituted in a format comprising , at least, a flow identification field, a priority field assigned to said flow and a data field proper, and to transmit said data packets to the other of said stations through the telecommunications network according to their respective priority, - on the other hand, to process each data packet received from the other of said stations according to the priority entered in said priority field of said packet, and to provide to said station the identification of the corresponding flow, registered in said field d 'identification, as well as the data contained in said data field.
• each station is equipped with an identical communication module capable of: firstly, to process each of said data streams received from the associated station in accordance with a single communication protocol, common to all the data streams, in which the data are organized in data packets constituted in a format comprising, at least, one field identification of a flow, a priority field assigned to said flow and a data field proper, and to transmit said data packets to the communication module of the other of said stations through the telecommunications network according to their priority respectively,
• the invention achieves a certain number of objectives, in particular: - a minimum transfer delay for transmission over the haptic channel. Indeed, given the intrinsic times of a few milliseconds for switching a time interval through a public switched network, most of the transmission delays are attributable to the terminals. By minimizing the software complexity of the communication chain, while keeping a standard solution widely used on the national territory, the invention makes it possible to obtain end-to-end transfer time values approaching ten tens of milliseconds.
• the use of an ISDN network by its very nature provides guarantees in terms of data routing, in the jitter of these times and in the arrangement of information.
• - a modular architecture making the management of data flows independent of the communication medium used, and making it possible to add or delete, at will, certain flows.
• Figure 1 is a diagram showing the general architecture of the data transmission system according to the invention.
• FIG. 2 is a diagram showing the architecture of a communication module of the system of FIG. 1.
• FIG. 3 is a diagram showing a data packet format of a communication protocol used in the system of Figure 1.
• FIG. 1 shows a system for transmitting data flows between two remote stations 1, 2 connected by an ISDN, IP or other telecommunications network 3.
• stations 1, 2 are equipped so as to be able to exchange various data streams making it possible to carry out the tele-ultrasound examination under the best conditions.
• the haptic data streams (1), (1 ′) are exchanged between a virtual probe 130 manipulated by the doctor on the expert station 1 and a robot 230 carrying the echographic probe 240, both being located on the patient station 2.
• Said robot 230 reproduces the movements of the probe remotely 130 corresponding to the movements that the doctor wishes to apply to the echographic probe 240.
• the robot 230 transmits to the virtual probe 130 the pressure forces exerted by the abdomen of the patient on the probe 240 during the 'exam. This type of force feedback information is essential for the doctor because it allows him to pinpoint the place of the abdomen where the echographic probe 240 is located, and therefore to be able to move it knowingly.
• the ultrasound data streams (2), (2 ') relate to the transmission of the images supplied by the probe 240 of the patient station 2 to a TV monitor 140 of the expert station 1.
• each station 1,2 is equipped with an identical communication module 10,20 capable of processing the various data streams coming from the associated station or from the remote station, taking best account of the constraints imposed on these different flows.
• the data streams received from the associated station are processed in accordance with a single communication protocol, common to all types of streams, in which the data is organized according to a format, an example of constitution of which is given in FIG. 3 .
• - Idp which is an identifier of the transmitted stream, namely videophone, haptic or echographic.
• This field has, for example, a length of 8 bits.
• This 2-bit long field can take the values 0 for high priority, 1 for medium priority and 2 for low priority.
• - DATA which contains the data to be transmitted. Its length is the value of the Lg field.
• - CCE which is an error control code. This optional field secures the transport of data.
• the module of FIG. 2 comprises a shaping sub-module 11 which reads in real time the data of the different streams received from the associated station 1 through high-level peripherals.
• the sub-module 11 constitutes the data packets according to the format of the communication protocol of FIG. 3 and informs the identification Idp fields, the priority P field, the acknowledgment field A, the Lg length field and DATA field of data.
• the data packets are then distributed in a queuing sub-module 12 produced on the basis of queues of the FIFO type, each queue being associated with a level of the priority field P.
• a queuing sub-module 12 produced on the basis of queues of the FIFO type, each queue being associated with a level of the priority field P.
• three queues have been defined: FIFO # 0, FIFO # 1 and FIFO # 2 corresponding respectively to the high, medium and low priority levels.
• a transmission sub-module 13 reads in real time the transmission queues of the sub-module 12 and transmits the data packets on the telecommunications network in order of priority by first emptying the FIFO queue # 0 , then the FIFO # 1 queue and finally the FIFO # 2 queue. In order to avoid monopolization of the transmission channel by a single priority level, maximum values of consecutive readings are defined by type of queue. The Tsp field is completed at this time.
• a data packet When a data packet is received from the telecommunications network, it is supported by a receiving submodule 14 which reads the priority field P of the packet and deposits it in the appropriate queue of the submodule 12 on hold.
• an identification sub-module 15 reads the reception queues in real time in order of priority by successively emptying the FIFO # 0 FIFO # 1 and FIFO # 2 queues.
• maximum values of consecutive readings per type of queue are defined so as not to monopolize the transmission channel by a single priority level.
• the contents of the Idp, A and DATA fields are extracted from the packets, the data of the DATA field being supplied to the associated station for reception through high-level peripherals identified by the Idp identification field.
• the value of the acknowledgment field A is equal to 1, an acknowledgment of receipt is established and deposited in a transmission queue.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Data Exchanges In Wide-Area Networks (AREA)
• Small-Scale Networks (AREA)

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Publications (1)

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• 2001
  • 2001-03-08 FR FR0103127A patent/FR2822006B1/fr not_active Expired - Fee Related
• 2002
  • 2002-03-07 AU AU2002246205A patent/AU2002246205A1/en not_active Abandoned
  • 2002-03-07 WO PCT/FR2002/000819 patent/WO2002071676A2/fr not_active Ceased
  • 2002-03-07 US US10/471,160 patent/US20040158642A1/en not_active Abandoned
  • 2002-03-07 EP EP02714288A patent/EP1374527A2/de not_active Withdrawn

Non-Patent Citations (1)

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