APPARATUS AND METHOD FOR MULTI-STATION CONFERENCING

Abstract: A system and method for multi-media half-duplex conferencing in a computer network comprising a plurality of stations and a control server. The method and system include, respectively, means for and the steps of receiving a packet at the server from one station of the plurality of stations (21) including a digital representation of information of at least one information type selected from audio information and video information, identifying the station as a transmitting station (22), blocking packets transmitted from the plurality of stations at the server except from the first transmitting station (23), distributing packets from the transmitting stations (24), thereby providing audio information generated by a user of the transmitting stations to users of the other stations of the plurality of stations and repeating the steps of receiving, identifying, blocking and transmitting for a different one of the plurality of station, thereby replacing the transmitting station with a different transmitting station, thereby providing the half-duplex multi-station conference.

Description: APPARATUS AND METHOD FOR MULTI-STATION CONFERENCING FIELD OF THE INVENTION The present invention relates to a method and system for half-duplex multimedia multi-station conferencing over a network generally and more particularly to a method and system for half-duplex audio multi-station conferencing over a network. BACKGROUND OF THE INVENTION Wide Area Computer Networks (WAN), in particular the INTERNET network, allow users to communicate multimedia information therebetween. For Example, the Internet Phone, commercially available from VocalTec Communications Inc. of New Jersey, enable audio conferencing between two parties using two computer stations connected to the INTERNET and equipped with the INTERNET PHONE' " application. In another application, multi-station multi-media conferencing is provided. In multi-station conferencing, a number of users employ their computer station in order to hold a conference.Generally speaking, two types of multi-station conferencing exist, namely, full-duplex conferencing in which each user may speak and hear audio information, i.e. is able to simultaneously transmit and receive voice packets, and half-duplex conferencing in which one station is determined to be the current transmitting station at a time. Full-duplex conferencing requires a mixing mechanism by which voice packets transmitted by each station are mixed in a network server so as to avoid the need to resolve according to predetermined criteria which participant will be the active participant.Obviously, mixing mechanisms directed to full duplex conferencing are costly and difficult to implement and require in addition a supplemental mechanism for self-hearing cancellation, such as an echo canceling algorithm. Half-duplex conferencing requires a mechanism which will resolve who will be the user allowed to speak to all other at any particular time. In prior art half-duplex and conferencing, a resolving mechanism based on an arbitration procedure between voice packets, for example the procedure described in U.S. Patent No. 5,434,797 to Barris is implemented. Another drawback associated with conferencing systems in general and with multi-media multi-station conferencing in particular is that it is sometimes difficult for one participant to recognize who is the current participant. This problem is particularly difficult in multi-station network conferencing, such as in INTERNET multi-station conferences where participants which are not familiar with each other have to recognize who is the current participant. SUMMARY OF THE INVENTION An object of the present invention is to provide an improved method for half-duplex multi-media multi-station conferencing in a computer network. In a preferred embodiment the multi-station half-duplex conference is an audio conference or an audio and video conference A further object of the present invention is to display the current active participant in a multi-station conference There is thus provided, in accordance with a preferred embodiment of the present invention, a method for multi-media half-duplex conferencing in a computer network which includes a plurality of stations and a control server. The method includes the steps of receiving a packet at the server from one station of the plurality of stations including a digital representation of information of at least one information type selected from audio information and video information, identifying the station as a transmitting station, blocking packets transmitted from the plurality of stations at the server except from the first transmitting station, distributing packets from the transmitting station, thereby providing audio information generated by a user of the transmitting stations to users of the other stations of the plurality of stations, and repeating the steps of receiving, identifying, blocking and transmitting for a different one of the plurality of station, thereby replacing the transmitting station with a different transmitting station, thereby providing the half-duplex multi-station conference Further, according to a preferred embodiment of the present invention, the step of replacing includes the steps of receiving a packet indicating an end of transmission of the representation of the information and receiving a packet from a different station, thereby providing the identification of the second transmitting station. According to an alternative embodiment, the step of replacing includes the steps of not receiving packets from the transmitting station for a predetermined period of time and receiving a packet from the second station after the predetermined period of time, thereby providing the activation of the second transmitting station. In accordance to a preferred embodiment of the present invention, the method also includes the step of visually indicating to the users which user utilizing the station which is the transmitting station. Preferably, this step includes the steps of transmitting a packet including a user identification from the first station to the control server, adding the user identification to a participants list of users participating in the half-duplex conference, thereby providing a current participants list, storing the current identification list with an indication which station is the current transmitting user, providing the user identification list in the stations and displaying the identification list including the indication of the current transmitting user. Further, the step of storing preferably includes the steps of storing an update of the current participants list with an indication which station is the current transmitting user, retrieving the update in the stations and displaying the update including the indication of the current transmitting user. There is also provided, according to a preferred embodiment of the present invention, a system for multi-media half-duplex conferencing in a computer network which includes a plurality of stations and a control server which is capable of operating in accordance to the methods of the present invention. There is further provided in accordance with a preferred embodiment of the present invention, a method for visually indicating to participants of a multi-station conference, both half-duplex and full-duplex conferences, which participant is the current active participant. The method includes the steps of providing a list of participants in the multi-station conference, determining a participant as a currently active participant and indicating to other participants of the multi-station conference who is the currently active participant or participants. In a preferred embodiment the step of indicating includes the steps of providing the participants list or an updated portion thereof with an indication of the currently active participant and displaying the identification list including the indication of the current active participant or participants. Further, according to a preferred embodiment of the present invention, the steps of providing the participant list and the step of providing are independent of the step of indicating. There is also provided, according to a preferred embodiment of the present invention, a system for visually indicating to participants of a multi-station conference, both half-duplex and full-duplex, which participant is the current active participant. The system includes a human or automatic operator for providing a participant lists or an update thereof and a conference bridge server connected to first means, preferably but not limited to telephone means, for determining a currently active participant and to second means, preferably but not limited to computer network means, independent of the first means for providing the visual indication of the currently active participant to the participants of the multi-station conference. In a preferred embodiment, the conference bridge server includes a CPU for receiving the participant lists or the update thereof, a storage unit for storing the participant lists and the updates thereof and a voice activity unit connected to the first means for detecting the currently active participant. The CPU is operative to provide to the participants list or an update thereof upon with an indication of the currently active user upon detecting a currently active participant or participants by the voice activity unit. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the appended drawings in which. Fig 1 is a schematic block diagrams of a Wide Area Network for providing half-duplex multimedia multi-station conferencing, constructed and operative in accordance with a preferred embodiment of the present invention; Fig 2 is a flow chart diagram illustration of a resolving mechanism for determining the current active multimedia station of the network of Fig. 1 ; Fig 3 is a flow chart diagram illustration of a preferred method for displaying the active participants in the multimedia multi-station conference held over the network of Fig 1 , Fig. 4 is a schematic block diagrams of a system for providing multi-station conferencing, constructed and operative in accordance with a preferred embodiment of the present invention; and Fig 5 is a flow chart diagram illustration of a preferred method for operating the system of Fig. 4 DETAILED DESCRIPTION OF THE PRESENT INVENTION Reference is now made to Fig. 1 which illustrates a Wide Area Network (WAN), generally referenced 10, for providing half-duplex multi-media multi-station conferencing, constructed and operative in accordance with a preferred embodiment of the present invention In a preferred embodiment, the WAN is the INTERNET In the preferred embodiment, WAN 10 is operative to provide half-duplex multi-station audio conferencing and the present invention is described by way of a nonlimiting example with respect thereto. WAN 10 comprises a control server 12, a plurality of multimedia computers 14 of which four are shown as a non limiting example in the illustrated embodiment and referenced 14A, 14B, 14C and 14D. In a preferred embodiment server 12 and stations 14 are physically remote one from the other and are connected via the INTERNET network. Multimedia computers 14 may be any suitable multimedia computer, such as a personal computer equipped with an INTERNET connection and audio transceiving application An example of a suitable multimedia computer 14 is the PACKARD BELL of the U.S. personal computer equipped with the INTERNET PHONE'" application. The INTERNET PHONE'" gateway application, commercially available from VocalTec Communications Inc of New Jersey, U.S.A, may be implemented with any other suitable personal computer as well In the illustrated embodiment WAN 10 also comprises a telephony gateway 16 equipped with the INTERNET PHONE 1 " gateway application connected to a conventional telephone and enables it to operate as one of the WAN audio transceiving applications. Each of stations 14 and gateway 16 comprises a voice activity detection mechanism, such as the one incorporated in the INTERNET PHONE ™ which is sensitive to voice signals representing audio information generated by respective users of stations 14 and telephone 18. These transmitted voice packets are utilized to determine the current speaker in the half-duplex multi-station conference as described in detail with reference to Fig. 2 hereinbeiow. Fig. 2 illustrates a preferred method of operating the multi-station multi-media conference by server 12. First, initialization takes place (step 20). In this step, parameters such as the maximal number of participants can be determined. Participants from stations 14 and telephone 18 may now connect to the half-duplex conference. In step 21 , server 12 receives a packet or packets from a first station, say 14A of the plurality of stations 14. The packet or packets indicate the beginning of information transmission in at least one type of media. In the preferred embodiment server 12 receives audio packets indicating the beginning of a speech burst in the format provided by the INTERNET PHONE 1 ". In step 22, server 12 identifies station 14A as the current transmitting station. Therefore, as indicated in step 23, server 12 will block packets from all other stations 14 and telephony gateway 16 and will continue to receive packets from current transmitting station 14A. Each received packet is generally immediately distributed as indicated by step 24 to stations 14B - 14D and telephone 18 via gateway 16, thereby providing audio information generated by the user employing station 14A. Server 12 replaces the current transmitting station with a different one as indicated by steps 25 and 26 as follows. In one operation mode, server 12 receives an end of information packet indicating that no further packets are expected from station 14A Alternatively, or in addition thereto, server 12 detects an interruption for a time period which is longer than a predetermined time. A preferred interruption time is one second. In either case, if a packet representing an end of speech burst is received or if the predetermined time threshold is exceeded without receiving a packet, server 12 ceases the identification of station 14A as the current transmitting station and expects to receive a packet from any second station which will be set as the active station. If a packet is received from a second station, say telephone 18 via gateway 16, the user utilizing telephone 18 becomes the current speaker and telephone 18 becomes the current transmitting station. Similarly, any of stations 14 may become the current transmitting station It will be appreciated that the method of Fig. 2 is more efficient and cost effective with respect to prior art conferencing methods. Since the method of the present invention provides half-duplex conferencing, it does not require complex mixing nor an echo canceling algorithm. Furthermore, according to the method of Fig 2 each station 14 receives only a single stream of information representing the information addressed by the current active participant, therefore it requires less data handling and utilizes more efficiently existing hardware and network bandwidth. Moreover, since the method of the present invention is media insensitive, i.e. it does not require any determination of the type of media transmitted, it is applicable to any multi-media information whether visual, graphic, midi or audio as described in the preferred embodiment or any combination therebetween. Reference is now made to Fig. 3 which illustrates a method for indicating to the users of stations 12 and telephone 18 a user identification of the user utilizing the station which is the current transmitting station. At step 31 a user who has not previously participated in the multi-station conference joins the conference. Step 31 is obviously required only if a new user is joining the conference. In step 32, if a new user joins, the name is added to an identification list of the participants in the multi-station conferencing. If there are not any new users, the method starts at step 33. Step 33 includes the step of transmitting a packet including a user identification from the transmitting station, say 14A to control server 12. In step 34, the current user identification is added to the identification list of users participating is the conference stored in server 12. The updated list is then retrieved by or transmitted to each station 14 and gateway 16 in its entirety, as indicated by step 35, or only an updated version thereof, as indicated by step 36. Finally, as indicated by step 37, the updated list or the entire list of participant with the current user identification highlighted is displayed. It will be appreciated that the display in stations 14 is done on the computer display whereas similar display with respect to telephone 18 requires an internal display or a different display having independent connection to WAN 10. It will be appreciated that while the present invention is not limited by what has been described hereinabove and that numerous modifications, all of which fall within the scope of the present invention, exist. For example, while the present invention has been described with reference to half-duplex multi-station audio conferencing, the method and system of the present invention is not limited thereto and is similarly applicable to video half-duplex multi-station conferencing. Another example described with reference to Figs. 4 and 5 hereinbeiow is to display the current speaker or speakers to other participants of any multi-station conference. Fig. 4 illustrates a non limiting example of a telephony multi-telephone conference. The system comprises a conference bridge server 40 having two connection channels to each participant, a telephony channel indicated by lines 41 which includes a voice activity detection unit 42 and connected to a telephone 43 for each user, and a display channel 43 connected to display units 44 for each user. Telephony units 43 and display units 44 may be separated and operative on difference physical networks, a non limiting example being the conventional telephony network and the INTERNET, respectively or may be lumped as shown for the unit referenced 45. For the INTERNET example, displays 44 may be similar to stations 14. A preferred operation mode of the system of Fig. 4 is described now with reference to Fig. 5. In step 50, the operator 46, a human operator or an automatic telephony operator acquires the details of the participants in the conference. In step 51 , the network identification associated with each participant is transmitted as a participants list to the conference bridge server 12 which stores a current participant list at storage unit 47. It will be appreciated that steps 50 and 51 are repeated for each new participant joining the conference, i.e. the operator 46 updates the participant lists and provide same to CPU 47 of server 40 for storing in storage unit 48. The conference now begins and voice activation units 42 detect a current active user or users and provide same to CPU 47 which updates participant list stored in storage unit 48 with a current active speaker or speakers as indicated by step 52. Each participant can now connect to server 40 using its display system for retrieving the current updated list of participants with the active participant or participants, i.e. the current speaker or speakers for display on his own display 44. Alternatively, displays 44 are continuously connected to server 40 and server 40 periodically transmits an updated list of participants with the current active participants to each of displays 44. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the claims that follow:

Claims: CLAIMS 1. A method for multi-media half-duplex conferencing in a computer network comprising a plurality of stations and a control server, the method comprising the steps of: a. receiving a packet at said server from one station of said plurality of stations including a digital representation of information of at least one information type selected from audio information and video information; b. identifying said station as a transmitting station; c. blocking packets transmitted from said plurality of stations at said server except from said first transmitting station; d. distributing packets from said transmitting station, thereby providing audio information generated by a user of said transmitting stations to users of the other stations of said plurality of stations; and e. repeating said steps of receiving, identifying, blocking and transmitting for a different one of said plurality of station, thereby replacing said transmitting station with a different transmitting station, thereby providing said half-duplex multi-station conference. 2. A method according to claim 1 wherein said step of replacing comprises the steps of: a receiving a packet indicating an end of transmission of said representation of said information; and b receiving a packet from a different station, thereby providing said identification of said second transmitting station 3 A method according to claim 1 wherein said step of replacing comprises the steps of a not receiving packets from said transmitting station for a predetermined period of time, and b receiving a packet from said second station after said predetermined period of time, thereby providing said activation of said second transmitting station 4 A method according to claim 1 and further comprising the step of visually indicating to said users which user utilizing the station which is said transmitting station 5 A method according to claim 4 wherein said step of indicating comprising the steps of a transmitting a packet including a user identification from said first station to said control server, b adding said user identification to a participants list of users participating is said half-duplex conference, thereby providing a current participants list; c. storing said current identification list with an indication which station is the current transmitting user; d. providing said user identification list in said stations; and e. displaying said identification list including said indication of said current transmitting user. 6. A method according to claim 5 wherein said step of storing comprises the steps of: a. storing an update of said current participants list with an indication which station is the current transmitting user; b. retrieving said update in said stations; and c. displaying said update including said indication of said current transmitting user. 7. A method for visually indicating to participants of a multi-station conference, which participant is the current active participant, the method comprising the steps of: a. providing a list of participants in said multi-station conference; b. determining a participant as a currently active participant; and c. indicating to other participants of said multi-station conference who is the currently active participant or participants. 8. A method according to claim 7 wherein said step of indicating comprising the steps of: a. providing said participants list or an updated portion thereof with an indication of the currently active participant; and b. displaying said identification list including said indication of said current active participant or participants. A method according to claim 7 wherein said steps of providing said participant list and said step of providing are independent of said step of indicating A method according to claim 7 wherein said conference is a half-duplex multi-station conference or a full-duplex multi-station conference A system for multi-media half-duplex conferencing in a computer network comprising a plurality of stations and a control server comprising a means for receiving a packet at said server from one station of said plurality of stations including a digital representation of information of at least one information type selected from audio information and video information, b means for activating said station as a transmitting station, c means for blocking packets from said plurality of stations except from said first transmitting station, d means for distributing packets from said transmitting station, thereby providing audio information generated by a user of said transmitting stations to users of the other stations of said plurality of stations, and e means for repeating said steps of receiving, activating, blocking and transmitting for a different one of said plurality of station, thereby providing said half-duplex multi-station conference 12. A system according to claim 11 wherein said means for replacing comprises: a. means for receiving a packet indicating an end of transmission of said representation of said information; and b. means for receiving a packet from said different one of said plurality of stations, thereby providing said activation of said second transmitting station. 13. A system according to claim 11 wherein said means for replacing comprises: a. means for determining non-receipt of packets from said transmitting station for a predetermined period of time; and b. means for receiving a packet from said different one of said plurality of stations after said predetermined period of time, thereby providing said activation of said second transmitting station. 14. A system according to claim 11 and further comprising means for visually indicating to said users which user utilizing the station which is said transmitting station. 15. A system according to claim 14 wherein said step of indicating comprising the steps of: a. transmitting a packet including a user identification from said first station to said control server; b. adding said user identification to an identification list of users participating is said half-duplex conference, thereby providing a current identification list; c. storing said current identification list with an indication which station is the current transmitting user; d. retrieving said user identification list in said stations; and e. displaying said identification list including said indication of said current transmitting user. 16. A system according to claim 15 wherein said means for storing comprises: a. means for storing an update of said current identification list with an indication which station is the current transmitting user; b. means for retrieving said update in said stations; and c. means for displaying said update including said indication of said current transmitting user. 17. A system for visually indicating to participants of a multi-station conference, which participant is the current active participant comprising: a. an operator for providing a participant lists or an update thereof; and b. a conference bridge server connected to first means for determining a currently active participant and to second means independent of said first means for providing said visual indication of said currently active participant to said participants of said multi-station conference. 18 A system according to claim 17 wherein said conference bridge server comprises a a CPU for receiving said participant lists or said update thereof; b a storage unit for storing said participant lists and said updates thereof, and c a voice activity unit connected to said first means for detecting said currently active participant, d wherein said CPU is operative to provide to said participants said participants list or an update thereof upon with an indication of said currently active user upon detecting a currently active user by said voice activity unit. 19. A system according to claim 17 wherein said first means are telephony means and said second means are computer network means 20 A system according to claim 17 wherein said conference is a half-duplex multi-station conference or a full-duplex multi-station conference

Inventors: COHEN ALON, COHEN, ALON
Applicants: VOCALTEC COMMUNICATIONS LTD, VOCALTEC COMMUNICATIONS LTD.
Application year: 1997
Main classification: G06F19
IPC codes: H04L12, H04M3