WO2003103243A1 - Method and system for interworking between video communication terminals - Google Patents

Method and system for interworking between video communication terminals Download PDF

Info

Publication number
WO2003103243A1
WO2003103243A1 PCT/FI2003/000443 FI0300443W WO03103243A1 WO 2003103243 A1 WO2003103243 A1 WO 2003103243A1 FI 0300443 W FI0300443 W FI 0300443W WO 03103243 A1 WO03103243 A1 WO 03103243A1
Authority
WO
WIPO (PCT)
Prior art keywords
multimedia terminal
olc
low bit
terminal
packet based
Prior art date
Application number
PCT/FI2003/000443
Other languages
French (fr)
Inventor
Marko Hocevar
Keijo Laiho
Original Assignee
Telefonaktiebolaget L M Ericsson (Publ)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget L M Ericsson (Publ) filed Critical Telefonaktiebolaget L M Ericsson (Publ)
Priority to US10/516,812 priority Critical patent/US7623507B2/en
Priority to AU2003240892A priority patent/AU2003240892A1/en
Priority to EP03730258A priority patent/EP1510052B1/en
Publication of WO2003103243A1 publication Critical patent/WO2003103243A1/en

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/1066Session management
    • H04L65/1069Session establishment or de-establishment
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/10Architectures or entities
    • H04L65/102Gateways
    • H04L65/1023Media gateways
    • H04L65/103Media gateways in the network
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04NPICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N7/00Television systems
    • H04N7/14Systems for two-way working
    • H04N7/15Conference systems

Definitions

  • the present invention relates in general to video communication networks and more specifically to a method for in- terworking between a number of video communication termi- nals, to a video communication system, and to a video interactive gateway unit.
  • Video Interactive Gateway makes it possible for in- terworking between low bit-rate multimedia terminals (H.324) located in circuit switched telephony network and terminals in IP based multimedia systems (H.323).
  • Figure 1 illustrates an Schemantical Diagram of H.324-H.323 interworking according to prior art.
  • Figure 2 illustrates ⁇ ni-directional Logical Channel signalling procedures according to prior art.
  • Figure 3 illustrates Bi-directional Logical Channel signalling procedures according to prior art.
  • Figure 4 illustrates Interworking between Bidirectional Logical Channel signalling procedures and Unidirectional Logical Channel signalling procedures accord- ing to prior art.
  • Figure 1 illustrates an Schemantical Diagram of H.324- H.323 interworking according to prior art.
  • the circuit switched network may use the 64 kbit/s unrestricted digital bearer for the multimedia connection.
  • H.223 as multiplexing protocol different multimedia components, audio, video and data are multiplexed within the bearer. These channels are de-multiplexed by VIG to separate RTP and TCP channels in the IP network, and vice versa. VIG may perform transcoding for different multimedia components if needed to make the communication between end-terminals possible.
  • ISUP may be used in the circuit switched network as a call control protocol, which is mapped to H.225 protocol in the IP network by VIG.
  • H.245 is used as a control protocol both in the circuit switched network and in the IP network, providing end to end capability exchange, signalling of command and indications, and messages to open and describe the content of logical channels for different multimedia components.
  • VIG performs mapping of H.245 messages between circuit switched network and IP network, in order to adapt the different transport protocols and to enable transcoding of media channels.
  • the interworking capabilities can be used for enabling IP trunking, in case of H.324 to H.324 call.
  • Open Logical Channel signalling procedures are used for establishing a media channel between terminals . These procedures actually consist of two different procedures, i.e. Uni-directional Logical Channel signalling procedures and Bi-directional Logical Channel signalling procedures.
  • Uni-directional Logical Channel signalling procedures are used for opening a one-way media channel between the ter- minals.
  • the originating terminal which is going to transmit media through the channel, initiates the procedure by issuing Open Logical Channel (OLC) message to remote terminal.
  • OLC Open Logical Channel
  • the OLC contain description of the media type, the codec to be used, codec options to be used and description of the multiplex layer options to be used, for the channel being opened.
  • the remote terminal checks if it is able to comply the description of the channel as a receiver. If that is the case it responds with the Open Logical Channel Acknowledge message.
  • the originating terminal receives the message it can start to transmit the media according to the protocol negotiated in OLC signalling procedure.
  • Figure 2 illustrates Uni-directional Logical Channel signalling procedures according to prior art.
  • Bi-directional Logical Channel signalling procedures are used for opening a two-way media channel between the terminals.
  • the channel consists of two uni-directional channels, i.e. forward channel and reverse channel.
  • the originating terminal which is going to transmit and receive media through the channels, initiates the procedure by issuing Open Logical Channel (OLC) message to re- mote terminal.
  • OLC Open Logical Channel
  • the OLC contain description of the media type, the codec to be used, codec options to be used and description of the multiplex layer options to be used, for the channels being opened both for forward channel i.e. the media which the originating terminal is going to transmit, and for the reverse channel, i.e. for the media which the originating terminal is going to receive.
  • the remote terminal checks if it is able to comply the description of the channels as a receiver for the forward channel and as a sender for the reverse channel. If that is the case it responds with the Open Logical Channel Acknowledge message.
  • the originating terminal When the originating terminal receives the message it issues Open Logical Channel Confirm and can start to trans- mit the media on the forward channel according to the protocol negotiated in OLC signalling procedure.
  • the terminating terminal When the terminating terminal receives the message it can start to transmit the media on the reverse channel according to the protocol negotiated in OLC signalling procedures.
  • H.245 specifies the master slave determination procedure in order to find, which terminal will act as a master and which terminal will act as a slave during the call. This procedure happens in the beginning of the call in order to be able to solve conflicts at logical channel signalling procedure, e.g. both terminals start Bidirectional Logical Channel signalling procedures simultaneously.
  • FIG. 3 illustrates Bi-directional Logical Channel signalling procedures according to prior art.
  • H.323 specifies that Uni-directional channels are used for audio and video channels. This means that the both terminals are supposed to initiate a uni-directional logical channel signalling procedure to open a channel for the media, which they intend to transmit .
  • H.324 specifies the same for the audio channels. However, it is required that it is mandatory for H.324 terminal to support H.223 adaptation layer 3 for video channel. Since H.223 adaptation layer 3 has bi-directional behaviour, H.324 requires that bi-directional logical channel signalling procedure is used for opening the video channels.
  • H.324 terminal may support video channels by using H.223 AL2, which enables to use uni-directional channels .
  • H.246 specifies the interworking between H.323 and H.324.
  • Logical Channel Signalling it specifies: "When OpenLogicalChannel (OLC) messages (either unidirectional or bi-directional) are received from the remote endpoint (H.323 or H.324), the gateway should initiate the OLC procedure at the opposite endpoint of the gateway. The Gateway may initiate the OLC procedure before receiving OLC messages . "
  • OLC OpenLogicalChannel
  • VIG needs to map bi-directional logical channel signalling procedures used on H.324 side to the unidirectional logical channel signalling procedures used on the H.323.
  • this causes potential problems for VIG as seen in figure 4.
  • Figure 4 illustrates Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to prior art. Mapping of the procedures creates two fundamental problems.
  • VIG receives two descriptions for the channel in direction from H.323 terminal to H.324, one from H.324 terminal as reverse channel description, and another from H.323 terminal as forward channel description. Since the fundamental goal is that VIG do not make any transcoding of adaptation on media when ever possible, this situation creates a problem, when the descriptions received from the different terminals do not match with each other. Further, since different procedures are used for opening of the logical channels, there is no straightforward way to relay terminals to negotiate the used description.
  • OLC ack and OLC conf messages trigger terminals to start transmission of media. It must be guaranteed that the pro- cedures on the both side of VIG are synchronized so that when VIG receives media from a terminal it is able to transfer media forward to another terminal, in order not to loss the media, since this would be hard to recover by terminals for video channels. It has been noticed that some terminals will crash.
  • the present invention provides a method for interworking between a number of video communication terminals, a video communication system, and a video interactive gateway unit.
  • a method for interworking between a number of different video communication terminals through a Video Interactive Gateway (VIG) in a video communication system the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein the method comprises the steps of
  • the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description
  • Video Interactive Gateway unit further sending and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
  • the Video Interactive Gateway receives OLC from the packet based multimedia terminal
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
  • the method further comprises the step of - the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • the Video Interactive Gateway when setting up video communication between the terminals, - the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and - the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal.
  • the Video Interactive Gateway receives OLC ack from the packet based multimedia terminal and sends OLC conf to the low bit-rate multimedia terminal when both OLC ack from the low bit-rate multimedia terminal and OLC ack from the packet based multimedia terminal has been received.
  • the Video Interactive Gateway initiates OLC to the low bit-rate multi- media terminal by leaving forward channel description empty. More preferably, in case OLC is received from the packet based multimedia terminal later, VIG closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward chan- nel description.
  • a method for interworking between a number of different video communication terminals through a Video Interactive Gateway (VIG) in a video communication system comprising at least one Video Interactive Gateway unit, at least one low bit- rate multimedia terminal, and at least one packet based multimedia terminal
  • the method comprises the steps of - the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse chan- nel description, and
  • Video Interactive Gateway unit further sending and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
  • Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer
  • the Video Interactive Gateway receives OLC from the packet based multimedia terminal
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and
  • the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal, initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal.
  • the method further comprises the step of - the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • the Video Interactive Gateway sends OLC conf to H.324 when OLC ack from the packet based multimedia terminal is received.
  • VIG initiates OLC to the low bit-rate multimedia terminal by leaving forward channel description empty. More pref- erably, in case OLC is received from the packet based multimedia terminal later, VIG closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward channel description.
  • a method for interworking between a number of different video communication terminals through a Video Interactive Gateway (VIG) in a video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein the method comprises the steps of
  • the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
  • Video Interactive Gateway unit further sending and/or receiving messages in order to set up video commu- nication between the terminals, and wherein in setting up video communication between the terminals,
  • the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and - the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
  • the method further comprises the step of - the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer .
  • the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
  • the Video Interactive Gateway when initiating OLC by using the forward chan- nel description received from the packet based multimedia terminal as reverse channel description towards the low bit-rate multimedia terminal, the Video Interactive Gateway takes into account the request received from the low bit-rate multimedia terminal, and when initiating OLC ack towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal, the Video Interactive Gateway takes into account the request received from the low bit-rate multimedia terminal.
  • the Video Interactive Gate- way takes into account the capability description received from the low bit-rate multimedia terminal, and when initi- ating OLC ack towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal, the Video Interactive Gateway takes into account the capability description re- ceived from the low bit-rate multimedia terminal.
  • the Video Interactive Gateway receives OLC ack from the packet based multimedia terminal and sends OLC conf to the low bit-rate multimedia terminal when both OLC ack from the low bit-rate multimedia terminal and OLC ack from the packet based multimedia terminal has been received.
  • the Video Interactive Gateway initiates OLC to the packet based multimedia terminal, and as the packet based multimedia terminal acknowledges this, the Video Interactive Gateway initiates OLC to the low bit-rate multimedia ter- minal by leaving forward channel description empty. More preferably, in case OLC is received from the packet based multimedia terminal later, the Video Interactive Gateway closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward channel description.
  • the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
  • the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
  • a video communication system comprising at least one Video Inter- active Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein
  • the low bit-rate multimedia terminal sends an Open Logi- cal Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description,
  • OLC Open Logi- cal Channel
  • Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
  • the Video Interactive Gateway receives OLC from the packet based multimedia terminal
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
  • the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal.
  • a video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia termi- nal, and at least one packet based multimedia terminal, wherein
  • the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
  • Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
  • Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer
  • Video Interactive Gateway receives OLC from the packet based multimedia terminal
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal.
  • the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • a video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia termi- nal, and at least one packet based multimedia terminal, wherein
  • the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
  • Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
  • the Video Interactive Gateway receives OLC from the packet based multimedia terminal
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
  • the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer.
  • the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates
  • OLC ack towards the packet based multimedia terminal and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
  • the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
  • the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
  • a Video Interactive Gateway unit for interworking between a number of different video communica- tion terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein - the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and - the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals. and wherein in setting up video communication between the terminals, - the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
  • the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and
  • the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal.
  • a Video Interactive Gateway unit for in- terworking between a number of different video communication terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia termi- nal, wherein
  • the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel descrip- tion, and
  • the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals. and wherein in setting up video communication between the terminals, - as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer,
  • the Video Interactive Gateway receives OLC from the packet based multimedia terminal
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and that
  • the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal by using the forward channel description received from the the low bit- rate multimedia terminal .
  • the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • a Video Interactive Gateway unit for interworking between a number of different video communication terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein - the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and - the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals . and wherein in setting up video communication between the terminals,
  • OLC Open Logical Channel
  • the Video Interactive Gateway receives OLC from the packet based multimedia terminal
  • the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
  • the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
  • OLC Open Logical Channel
  • the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer.
  • the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
  • the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
  • the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal .
  • the solution according to the present invention presents a new method for interworking between a number of video com- munication terminals, a new video communication system, and a new video interactive gateway unit .
  • Figure 1 illustrates a Schemantical Diagram of H.324- H.323 interworking according to prior art.
  • Figure 2 illustrates Uni-directional Logical Channel signalling procedures according to prior art.
  • FIG. 3 illustrates Bi-directional Logical Channel signalling procedures according to prior art.
  • Figure 4 illustrates Interworking between Bi- directional Logical Channel signalling procedures and Unidirectional Logical Channel signalling procedures according to prior art.
  • Figure 5 illustrates one example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention.
  • Figure 6 illustrates another example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling pro- cedures according to the present invention.
  • Figure 7 illustrates a third example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention.
  • Figure 8 illustrates Interworking between Bidirectional Logical Channel signalling procedures and Unidirectional Logical Channel signalling procedures according to prior art.
  • FIG. 5 illustrates one example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention.
  • the figure 5 shows sequence diagram of the mapping.
  • VIG rejects the request and initiates OLC towards H.323 terminal by using the forward channel description received from the H.324 terminal.
  • VIG receives OLC from H.323 terminal. VIG initiates OLC by using the forward channel description received from H.323 terminal as forward channel description towards H.324 terminal; and by using the forward channel description received from the H.324 terminal as the reverse channel de- scription towards H.324 terminal.
  • VIG receives OLC ack from H.324. This initiates OLC ack towards H.323 terminal. From now on, H.323 may transmit media. VIG sends OLC conf to H.324 when both OLC ack from H.324 terminal and OLC ack from H.323 terminal has been received.
  • VIG initiates OLC to H.324 terminal by leaving forward channel description empty. This may happen if H.323 may not wish or is able to send video, e.g. because of lack of camera.
  • VIG closes the already opened channel to H.324 terminal and opens a new one by using the proper forward channel description.
  • VIG initiates OLC towards H.323 terminal before it receives OLC ack from H.324 terminal. This means that VIG needs to generate and map logical channel numbers in the messages between terminals.
  • Figure 6 illustrates another example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention.
  • the figure 6 shows sequence diagram of the mapping.
  • VIG receives OLC from H.323 terminal. VIG initiates OLC by using the forward channel description received from H.323 terminal as forward channel description towards H.324 ter- minal; and by using the forward channel description re- ceived from the H.324 terminal as the reverse channel description towards H.324 terminal.
  • VIG receives OLC ack from H.324. This initiates OLC ack towards H.323 terminal and this initiates OLC towards H.323 terminal by using the forward channel description received from the H.324 terminal. From now on, H.323 may transmit media.
  • VIG sends OLC conf to H.324 when OLC ack from H.323 terminal is received.
  • VIG initiates OLC to H.324 terminal by leaving forward channel description empty. This may happen if H.323 may not wish or is able to send video, e.g. because of lack of camera.
  • VIG closes the already opened channel to H.324 terminal and opens a new one by using the proper forward channel description .
  • Figure 7 illustrates a third example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention.
  • the figure 7 shows sequence diagram of the mapping.
  • the fundamental idea in the third Interworking example is to use Forward Channel Description from H.323 terminal for both channels. If OLC is received from H.324 terminal first in VIG, VIG starts a timer.
  • VIG receives OLC from H.323 terminal.
  • VIG initiates OLC by using the forward channel description received from H.323 terminal as forward and reverse channel description towards H.324 terminal.
  • VIG also rejects the original request from H.324 terminal.
  • VIG receives OLC ack from H.324. This initiates OLC ack towards H.323 terminal and this initiates OLC towards H.323 terminal by using the forward channel description received from the H.324 terminal. From now on, H.323 may transmit media.
  • VIG sends OLC conf to H.324 when OLC ack from H.323 terminal is received.
  • VIG initiates OLC to H.323 terminal.
  • H.323 acknowledges this, VIG initiates OLC to H.324 terminal by leaving forward channel description empty. This may happen if H.323 may not wish or is able to send video, e.g. because of lack of camera.
  • VIG closes the already opened channel to H.324 terminal and opens a new one by using the proper forward channel description.
  • Figure 8 illustrates a videoconference trunking over IP network according to the present invention.
  • IP network is desired to be used for trunking calls between two H.324 terminals
  • the call chain contains two VIGs as seen in the figure 8. This creates a potential problems to the solutions described above.
  • H.324 terminal A triggers the bidirectional OLC signalling first. This would be mapped to uni-directional OLC signalling by VIG A. This would trigger VIG B to initiated bi-directional OLC signalling to H.324 terminal B. If OLC is received by H.324 terminal B before it would initiate it' s own OLC procedure towards VIG B, the video channel from H.324 terminal B to H.324 terminal A would not be established. Therefore a solution to overcome this problem is needed and shown below.
  • the idea to solve the problem above is to not perform mapping between bi-directional OLC signalling procedures and uni-directional OLC procedures in case of trunking.
  • VIG uses the end-point-type information in H.323 call control signalling H.225. If that information contains information about gateway as an end-point, VIG interprets this as an indication that trunking is the case and thus VIG will pass bidirectional logical channel signalling through IP-network.
  • the present solution makes it possible to interwork between different terminals e.g. between a low bit-rate multimedia terminal and a packet based multimedia terminal.

Abstract

The present invention relates in general to video communication networks and more specifically to a method for interworking between a number of video communication terminals, to a video communication system, and to a video interactive gateway unit. The solution according to the present invention makes it possible to interwork between different terminals e.g. between a low bit-rate multimedia terminal and a packet based multimedia terminal.

Description

METHOD AND SYSTEM FOR INTERWORKING BETWEEN VIDEO COMMUNICATION
TERMINALS.
Technical field of the invention
The present invention relates in general to video communication networks and more specifically to a method for in- terworking between a number of video communication termi- nals, to a video communication system, and to a video interactive gateway unit.
Background of the invention
The background of the invention is discussed briefly in the following.
Video Interactive Gateway (VIG) makes it possible for in- terworking between low bit-rate multimedia terminals (H.324) located in circuit switched telephony network and terminals in IP based multimedia systems (H.323).
For a better understanding of the prior art relation to the present invention reference will be made to the accom- panying figures in which:
Figure 1 illustrates an Schemantical Diagram of H.324-H.323 interworking according to prior art.
Figure 2 illustrates ϋni-directional Logical Channel signalling procedures according to prior art. Figure 3 illustrates Bi-directional Logical Channel signalling procedures according to prior art.
Figure 4 illustrates Interworking between Bidirectional Logical Channel signalling procedures and Unidirectional Logical Channel signalling procedures accord- ing to prior art. Figure 1 illustrates an Schemantical Diagram of H.324- H.323 interworking according to prior art. The circuit switched network may use the 64 kbit/s unrestricted digital bearer for the multimedia connection.
Using H.223 as multiplexing protocol different multimedia components, audio, video and data are multiplexed within the bearer. These channels are de-multiplexed by VIG to separate RTP and TCP channels in the IP network, and vice versa. VIG may perform transcoding for different multimedia components if needed to make the communication between end-terminals possible.
ISUP may be used in the circuit switched network as a call control protocol, which is mapped to H.225 protocol in the IP network by VIG.
H.245 is used as a control protocol both in the circuit switched network and in the IP network, providing end to end capability exchange, signalling of command and indications, and messages to open and describe the content of logical channels for different multimedia components.
VIG performs mapping of H.245 messages between circuit switched network and IP network, in order to adapt the different transport protocols and to enable transcoding of media channels.
Further, the interworking capabilities can be used for enabling IP trunking, in case of H.324 to H.324 call. This means that the call is routed to IP-network as close to the terminals as possible. This makes it possible to utilize cheaper transmission costs in the IP network compared to the transmission costs in the ordinary circuit switched telephony network. As specified in H.245 Open Logical Channel signalling procedures are used for establishing a media channel between terminals . These procedures actually consist of two different procedures, i.e. Uni-directional Logical Channel signalling procedures and Bi-directional Logical Channel signalling procedures.
Uni-directional Logical Channel signalling procedures are used for opening a one-way media channel between the ter- minals. The originating terminal, which is going to transmit media through the channel, initiates the procedure by issuing Open Logical Channel (OLC) message to remote terminal. The OLC contain description of the media type, the codec to be used, codec options to be used and description of the multiplex layer options to be used, for the channel being opened.
The remote terminal checks if it is able to comply the description of the channel as a receiver. If that is the case it responds with the Open Logical Channel Acknowledge message. When the originating terminal receives the message it can start to transmit the media according to the protocol negotiated in OLC signalling procedure.
Figure 2 illustrates Uni-directional Logical Channel signalling procedures according to prior art. Bi-directional Logical Channel signalling procedures are used for opening a two-way media channel between the terminals. The channel consists of two uni-directional channels, i.e. forward channel and reverse channel.
The originating terminal, which is going to transmit and receive media through the channels, initiates the procedure by issuing Open Logical Channel (OLC) message to re- mote terminal. The OLC contain description of the media type, the codec to be used, codec options to be used and description of the multiplex layer options to be used, for the channels being opened both for forward channel i.e. the media which the originating terminal is going to transmit, and for the reverse channel, i.e. for the media which the originating terminal is going to receive.
The remote terminal checks if it is able to comply the description of the channels as a receiver for the forward channel and as a sender for the reverse channel. If that is the case it responds with the Open Logical Channel Acknowledge message.
When the originating terminal receives the message it issues Open Logical Channel Confirm and can start to trans- mit the media on the forward channel according to the protocol negotiated in OLC signalling procedure. When the terminating terminal receives the message it can start to transmit the media on the reverse channel according to the protocol negotiated in OLC signalling procedures.
Further, H.245 specifies the master slave determination procedure in order to find, which terminal will act as a master and which terminal will act as a slave during the call. This procedure happens in the beginning of the call in order to be able to solve conflicts at logical channel signalling procedure, e.g. both terminals start Bidirectional Logical Channel signalling procedures simultaneously.
Figure 3 illustrates Bi-directional Logical Channel signalling procedures according to prior art. H.323 specifies that Uni-directional channels are used for audio and video channels. This means that the both terminals are supposed to initiate a uni-directional logical channel signalling procedure to open a channel for the media, which they intend to transmit . H.324 specifies the same for the audio channels. However, it is required that it is mandatory for H.324 terminal to support H.223 adaptation layer 3 for video channel. Since H.223 adaptation layer 3 has bi-directional behaviour, H.324 requires that bi-directional logical channel signalling procedure is used for opening the video channels. In addition to AL3, H.324 terminal may support video channels by using H.223 AL2, which enables to use uni-directional channels .
H.246 specifies the interworking between H.323 and H.324. For Logical Channel Signalling it specifies: "When OpenLogicalChannel (OLC) messages (either unidirectional or bi-directional) are received from the remote endpoint (H.323 or H.324), the gateway should initiate the OLC procedure at the opposite endpoint of the gateway. The Gateway may initiate the OLC procedure before receiving OLC messages . "
The problems arising from the background solutions are discussed briefly in the following.
In case call is made between H.324M terminal, which does not support H.223 AL2 for video channels, to H.323 termi- nal, VIG needs to map bi-directional logical channel signalling procedures used on H.324 side to the unidirectional logical channel signalling procedures used on the H.323. However, this causes potential problems for VIG as seen in figure 4.
Figure 4 illustrates Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to prior art. Mapping of the procedures creates two fundamental problems. VIG receives two descriptions for the channel in direction from H.323 terminal to H.324, one from H.324 terminal as reverse channel description, and another from H.323 terminal as forward channel description. Since the fundamental goal is that VIG do not make any transcoding of adaptation on media when ever possible, this situation creates a problem, when the descriptions received from the different terminals do not match with each other. Further, since different procedures are used for opening of the logical channels, there is no straightforward way to relay terminals to negotiate the used description.
OLC ack and OLC conf messages trigger terminals to start transmission of media. It must be guaranteed that the pro- cedures on the both side of VIG are synchronized so that when VIG receives media from a terminal it is able to transfer media forward to another terminal, in order not to loss the media, since this would be hard to recover by terminals for video channels. It has been noticed that some terminals will crash.
There is a clear need for a solution for interworking between a number of video communication terminals that would make it possible to interwork between different terminals e.g. between a low bit-rate multimedia terminal and a packet based multimedia terminal.
Summary of the present invention
It is an object of the present invention to overcome or at least mitigate the disadvantages of the prior art. The present invention provides a method for interworking between a number of video communication terminals, a video communication system, and a video interactive gateway unit. According to a first aspect of the present invention there is provided a method for interworking between a number of different video communication terminals through a Video Interactive Gateway (VIG) in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein the method comprises the steps of
- the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive
Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sending and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
Preferably, the method further comprises the step of - the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
Further preferably, when setting up video communication between the terminals, - the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and - the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal.
Preferably, the Video Interactive Gateway receives OLC ack from the packet based multimedia terminal and sends OLC conf to the low bit-rate multimedia terminal when both OLC ack from the low bit-rate multimedia terminal and OLC ack from the packet based multimedia terminal has been received.
Preferably, in case OLC has not been received from the packet based multimedia terminal, when OLC ack is received from the packet based multimedia terminal, the Video Interactive Gateway initiates OLC to the low bit-rate multi- media terminal by leaving forward channel description empty. More preferably, in case OLC is received from the packet based multimedia terminal later, VIG closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward chan- nel description.
According to a second aspect of the present invention there is provided a method for interworking between a number of different video communication terminals through a Video Interactive Gateway (VIG) in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit- rate multimedia terminal, and at least one packet based multimedia terminal, wherein the method comprises the steps of - the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse chan- nel description, and
- the Video Interactive Gateway unit further sending and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
- as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, - the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and
- the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal, initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal.
Preferably, the method further comprises the step of - the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
Preferably, the Video Interactive Gateway sends OLC conf to H.324 when OLC ack from the packet based multimedia terminal is received. Preferably, in case OLC has not been received from the packet based multimedia terminal, when the timer expires, VIG initiates OLC to the low bit-rate multimedia terminal by leaving forward channel description empty. More pref- erably, in case OLC is received from the packet based multimedia terminal later, VIG closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward channel description.
According to a third aspect of the present invention there is provided a method for interworking between a number of different video communication terminals through a Video Interactive Gateway (VIG) in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein the method comprises the steps of
- the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sending and/or receiving messages in order to set up video commu- nication between the terminals, and wherein in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and - the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal. Preferably, the method further comprises the step of - the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
Preferably, in setting up video communication between the terminals, as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer .
Preferably, in setting up video communication between the terminals, the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
Preferably, when initiating OLC by using the forward chan- nel description received from the packet based multimedia terminal as reverse channel description towards the low bit-rate multimedia terminal, the Video Interactive Gateway takes into account the request received from the low bit-rate multimedia terminal, and when initiating OLC ack towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal, the Video Interactive Gateway takes into account the request received from the low bit-rate multimedia terminal.
Preferably, when initiating OLC by using the forward channel description received from the packet based multimedia terminal as reverse channel description towards the low bit-rate multimedia terminal, the Video Interactive Gate- way takes into account the capability description received from the low bit-rate multimedia terminal, and when initi- ating OLC ack towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal, the Video Interactive Gateway takes into account the capability description re- ceived from the low bit-rate multimedia terminal.
Preferably, the Video Interactive Gateway receives OLC ack from the packet based multimedia terminal and sends OLC conf to the low bit-rate multimedia terminal when both OLC ack from the low bit-rate multimedia terminal and OLC ack from the packet based multimedia terminal has been received.
Preferably, in case OLC has not been received from the packet based multimedia terminal, when the timer expires, the Video Interactive Gateway initiates OLC to the packet based multimedia terminal, and as the packet based multimedia terminal acknowledges this, the Video Interactive Gateway initiates OLC to the low bit-rate multimedia ter- minal by leaving forward channel description empty. More preferably, in case OLC is received from the packet based multimedia terminal later, the Video Interactive Gateway closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward channel description.
Preferably, in any interworking method, the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal. Al- ternatively, in any interworking method, the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
According to a fourth aspect of the present invention there is provided a video communication system, the video communication system comprising at least one Video Inter- active Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein
- the low bit-rate multimedia terminal sends an Open Logi- cal Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description,
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
Preferably, the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
Preferably, in setting up video communication between the terminals, - the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal. According to a fifth aspect of the present invention there is provided a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia termi- nal, and at least one packet based multimedia terminal, wherein
- the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
- as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal,
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal.
Preferably, the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal. According to a sixth aspect of the present invention there is provided a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia termi- nal, and at least one packet based multimedia terminal, wherein
- the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and wherein in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
Preferably, the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
Preferably, in setting up video communication between the terminals, as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer.
Preferably, in setting up video communication between the terminals, the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates
OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
Preferably, in any video communication system, the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal. Alternatively, in any video communication system, the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
According to a seventh aspect of the present invention there is provided a Video Interactive Gateway unit for interworking between a number of different video communica- tion terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein - the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and - the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals. and wherein in setting up video communication between the terminals, - the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
Preferably, the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
Preferably, in setting up video communication between the terminals, - the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and
- the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal.
According to a eighth aspect of the present invention there is provided a Video Interactive Gateway unit for in- terworking between a number of different video communication terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia termi- nal, wherein
- the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel descrip- tion, and
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals. and wherein in setting up video communication between the terminals, - as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, - the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and that
- the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal by using the forward channel description received from the the low bit- rate multimedia terminal .
Preferably, the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
According to a ninth aspect of the present invention there is provided a Video Interactive Gateway unit for interworking between a number of different video communication terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, wherein - the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and - the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals . and wherein in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
Preferably, the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
Preferably, in setting up video communication between the terminals, as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer.
Preferably, in setting up video communication between the terminals, the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
Preferably, in any Video Interactive Gateway unit, the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal. Alternatively, in any Video Interactive Gateway unit, the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal . Detailed description of certain embodiments
The solution according to the present invention presents a new method for interworking between a number of video com- munication terminals, a new video communication system, and a new video interactive gateway unit .
The fundamental idea behind the solution is always ignore the reverse channel description from the H.324 terminal and reject the bi-directional OLC procedure initiated by it and to use the forward channel description received from the H.323 terminal.
For a better understanding of the present invention and in order to show how the same may be carried into effect reference will now be made to the accompanying drawings, in which:
Figure 1 illustrates a Schemantical Diagram of H.324- H.323 interworking according to prior art. Figure 2 illustrates Uni-directional Logical Channel signalling procedures according to prior art.
Figure 3 illustrates Bi-directional Logical Channel signalling procedures according to prior art.
Figure 4 illustrates Interworking between Bi- directional Logical Channel signalling procedures and Unidirectional Logical Channel signalling procedures according to prior art.
Figure 5 illustrates one example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention.
Figure 6 illustrates another example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling pro- cedures according to the present invention. Figure 7 illustrates a third example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention. Figure 8 illustrates Interworking between Bidirectional Logical Channel signalling procedures and Unidirectional Logical Channel signalling procedures according to prior art.
The Figures 1 to 4 referring to the prior art have been discussed earlier. In the following, reference is made to the Figures 5-8.
Figure 5 illustrates one example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention. The figure 5 shows sequence diagram of the mapping.
If OLC is received from H.324 terminal first in VIG, VIG rejects the request and initiates OLC towards H.323 terminal by using the forward channel description received from the H.324 terminal.
VIG receives OLC from H.323 terminal. VIG initiates OLC by using the forward channel description received from H.323 terminal as forward channel description towards H.324 terminal; and by using the forward channel description received from the H.324 terminal as the reverse channel de- scription towards H.324 terminal.
VIG receives OLC ack from H.324. This initiates OLC ack towards H.323 terminal. From now on, H.323 may transmit media. VIG sends OLC conf to H.324 when both OLC ack from H.324 terminal and OLC ack from H.323 terminal has been received.
If OLC has not been received from H.323 terminal, when OLC ack is received from H.323 terminal, VIG initiates OLC to H.324 terminal by leaving forward channel description empty. This may happen if H.323 may not wish or is able to send video, e.g. because of lack of camera.
However, if OLC is received from H.323 terminal later, VIG closes the already opened channel to H.324 terminal and opens a new one by using the proper forward channel description.
In the presented solution according to the present invention, VIG initiates OLC towards H.323 terminal before it receives OLC ack from H.324 terminal. This means that VIG needs to generate and map logical channel numbers in the messages between terminals.
Figure 6 illustrates another example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention. The figure 6 shows sequence diagram of the mapping.
In this second Interworking example there is difference in timing. If OLC is received from H.324 terminal first in VIG, VIG rejects the request and starts a timer.
VIG receives OLC from H.323 terminal. VIG initiates OLC by using the forward channel description received from H.323 terminal as forward channel description towards H.324 ter- minal; and by using the forward channel description re- ceived from the H.324 terminal as the reverse channel description towards H.324 terminal.
VIG receives OLC ack from H.324. This initiates OLC ack towards H.323 terminal and this initiates OLC towards H.323 terminal by using the forward channel description received from the H.324 terminal. From now on, H.323 may transmit media.
VIG sends OLC conf to H.324 when OLC ack from H.323 terminal is received.
If OLC has not been received from H.323 terminal, when the timer expires, VIG initiates OLC to H.324 terminal by leaving forward channel description empty. This may happen if H.323 may not wish or is able to send video, e.g. because of lack of camera.
However, if OLC is received from H.323 terminal later, VIG closes the already opened channel to H.324 terminal and opens a new one by using the proper forward channel description .
In this second solution according to the present inven- tion, there is a timer, which delays the set-up a little bit in case H.323 terminal do not initiates OLC.
Figure 7 illustrates a third example of Interworking between Bi-directional Logical Channel signalling procedures and Uni-directional Logical Channel signalling procedures according to the present invention. The figure 7 shows sequence diagram of the mapping.
The fundamental idea in the third Interworking example is to use Forward Channel Description from H.323 terminal for both channels. If OLC is received from H.324 terminal first in VIG, VIG starts a timer.
VIG receives OLC from H.323 terminal. VIG initiates OLC by using the forward channel description received from H.323 terminal as forward and reverse channel description towards H.324 terminal. VIG also rejects the original request from H.324 terminal.
VIG receives OLC ack from H.324. This initiates OLC ack towards H.323 terminal and this initiates OLC towards H.323 terminal by using the forward channel description received from the H.324 terminal. From now on, H.323 may transmit media.
VIG sends OLC conf to H.324 when OLC ack from H.323 terminal is received.
If OLC has not been received from H.323 terminal, when the timer expires, VIG initiates OLC to H.323 terminal. When
H.323 acknowledges this, VIG initiates OLC to H.324 terminal by leaving forward channel description empty. This may happen if H.323 may not wish or is able to send video, e.g. because of lack of camera.
However, if OLC is received from H.323 terminal later, VIG closes the already opened channel to H.324 terminal and opens a new one by using the proper forward channel description.
In this third solution according to the present invention, it possible to use the same video channel properties, e.g. video codec options in both directions of video channels.
Figure 8 illustrates a videoconference trunking over IP network according to the present invention. When IP network is desired to be used for trunking calls between two H.324 terminals, the call chain contains two VIGs as seen in the figure 8. This creates a potential problems to the solutions described above.
It could happen that H.324 terminal A triggers the bidirectional OLC signalling first. This would be mapped to uni-directional OLC signalling by VIG A. This would trigger VIG B to initiated bi-directional OLC signalling to H.324 terminal B. If OLC is received by H.324 terminal B before it would initiate it' s own OLC procedure towards VIG B, the video channel from H.324 terminal B to H.324 terminal A would not be established. Therefore a solution to overcome this problem is needed and shown below.
The idea to solve the problem above is to not perform mapping between bi-directional OLC signalling procedures and uni-directional OLC procedures in case of trunking. In order to know that VIG is involved in trunking, it uses the end-point-type information in H.323 call control signalling H.225. If that information contains information about gateway as an end-point, VIG interprets this as an indication that trunking is the case and thus VIG will pass bidirectional logical channel signalling through IP-network.
The present solution makes it possible to interwork between different terminals e.g. between a low bit-rate multimedia terminal and a packet based multimedia terminal.
It makes it possible to inter-work between H.323 terminal and H.324 terminal by using just the mandatory parts of the respectively specifications.

Claims

Claims
1. A method for interworking between a number of different video communication terminals through a Video Interac- tive Gateway (VIG) in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, characterized in that the method comprises the steps of
- the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse chan- nel description, and
- the Video Interactive Gateway unit further sending and/or receiving messages in order to set up video communication between the terminals, and that in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
2. An interworking method according to claim 1, characterized in that the method further comprises the step of
- the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
3. An interworking method according to claim 1 or to claim 2, characterized in that in setting up video communication between the terminals,
- the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and
- the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack to- wards the packet based multimedia terminal.
4. An interworking method according to any of the claims 1-3, characterized in that the Video Interactive Gateway receives OLC ack from the packet based multimedia terminal and sends OLC conf to the low bit-rate multimedia terminal when both OLC ack from the low bit-rate multimedia terminal and OLC ack from the packet based multimedia terminal has been received.
5. An interworking method according to any of the claims 1-4, characterized in that in case OLC has not been received from the packet based multimedia terminal, when OLC ack is received from the packet based multimedia terminal, the Video Interactive Gateway initiates OLC to the low bit-rate multimedia terminal by leaving forward channel description empty.
6. An interworking method according to claim 5, characterized in that in case OLC is received from the packet based multimedia terminal later, VIG closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward channel description.
7. An interworking method according to any of the claims 1-6, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
8. An interworking method according to any of the claims 1-6, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
9. A method for interworking between a number of differ- ent video communication terminals through a Video Interactive Gateway (VIG) in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, characterized in that the method comprises the steps of
- the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message in- eluding a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sending and/or receiving messages in order to set up video communication between the terminals, and that in setting up video communication between the terminals,
- as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal,
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and
- the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal, initiates OLC ack to- wards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal.
10. An interworking method according to claim 9, characterized in that the method further comprises the step of
- the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
11. An interworking method according to claim 9 or to claim 10, characterized in that the Video Interactive Gateway sends OLC conf to H.324 when OLC ack from the packet based multimedia terminal is received.
12. An interworking method according to claim 9 or to claim 10, characterized in that in case OLC has not been received from the packet based multimedia terminal, when the timer expires, VIG initiates OLC to the low bit-rate multimedia terminal by leaving forward channel description empty .
13. An interworking method according to claim 12, characterized in that in case OLC is received from the packet based multimedia terminal later, VIG closes the already opened channel to the low bit-rate multimedia terminal and opens a new one by using the proper forward channel description.
14. An interworking method according to any of the claims 9-13, characterized in that the low bit-rate multi- media terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
15. An interworking method according to any of the claims 9-13, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
16. A method for interworking between a number of dif- ferent video communication terminals through a Video Interactive Gateway (VIG) in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multi- media terminal, characterized in that the method comprises the steps of
- the low bit-rate multimedia terminal sending an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message in- eluding a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sending and/or receiving messages in order to set up video communication between the terminals, and that in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
17. An interworking method according to claim 16, char- acterized in that the method further comprises the step of - the Video Interactive Gateway unit sending an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
18. An interworking method according to claim 16 or to claim 17, characterized in that in setting up video communication between the terminals, as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer.
19. An interworking method according to any of the claims 16-18, characterized in that in setting up video communication between the terminals, the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
20. An interworking method according to any of the claims 16-19, characterized in that
- when initiating OLC by using the forward channel description received from the packet based multimedia termi- nal as reverse channel description towards the low bit- rate multimedia terminal, the Video Interactive Gateway takes into account the request received from the low bit- rate multimedia terminal, and that
- when initiating OLC ack towards the packet based multi- media terminal by using the forward channel description received from the packet based multimedia terminal, the Video Interactive Gateway takes into account the request received from the low bit-rate multimedia terminal.
21. An interworking method according to any of the claims 16-20, characterized in that - when initiating OLC by using the forward channel description received from the packet based multimedia terminal as reverse channel description towards the low bit- rate multimedia terminal, the Video Interactive Gateway takes into account the capability description received from the low bit-rate multimedia terminal, and that
- when initiating OLC ack towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal, the Video Interactive Gateway takes into account the capability description received from the low bit-rate multimedia terminal .
22. An interworking method according to any of the claims 16-21, characterized in that the Video Interactive Gateway receives OLC ack from the packet based multimedia terminal and sends OLC conf to the low bit-rate multimedia terminal when both OLC ack from the low bit-rate multimedia terminal and OLC ack from the packet based multimedia terminal has been received.
23. An interworking method according to any of the claims 16-21, characterized in that in case OLC has not been received from the packet based multimedia terminal, when the timer expires, the Video Interactive Gateway initiates OLC to the packet based multimedia terminal, and as the packet based multimedia terminal acknowledges this, the Video Interactive Gateway initiates OLC to the low bit-rate multimedia terminal by leaving forward channel description empty.
24. An interworking method according to claim 23, characterized in that in case OLC is received from the packet based multimedia terminal later, the Video Interactive Gateway closes the already opened channel to the low bit- rate multimedia terminal and opens a new one by using the proper forward channel description.
25. An interworking method according to any of the claims 1-15, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
26. An interworking method according to any of the claims 1-15, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
27. A video communication system, the video communica- tion system comprising at least one Video Interactive
Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, characterized in that
- the low bit-rate multimedia terminal sends an Open Logi- cal Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description,
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and that in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal.
28. A video communication system according to claim 27, characterized in that the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
29. A video communication system according to claim 27 or to claim 28, characterized in that in setting up video communication between the terminals,
- the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multi- media terminal, and
- the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal.
30. A video communication system according to any of the claims 27-29, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
31. A video communication system according to any of the claims 27-29, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
32. A video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, characterized in that - the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and that in setting up video communication between the terminals,
- as the Video Interactive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal,
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and - the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal.
33. A video communication system according to claim 32, characterized in that the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
34. A video communication system according to claim 32 or to claim 33, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
35. A video communication system according to claim 32 or to claim 33, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
36. A video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, characterized in that
- the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel descrip- tion, and
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals, and that in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
37. A video communication system according to claim 36, characterized in that the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
38. A video communication system according to claim 36 or to claim 37, characterized in that in setting up video communication between the terminals, as the Video Interac- tive Gateway receives OLC first from the low bit-rate multimedia terminal, it starts a timer.
39. A video communication system according to any of the claims 36-38, characterized in that in setting up video communication between the terminals, the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
40. A video communication system according to any of the claims 36-39, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
41. A video communication system according to any of the claims 36-39, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
42. A Video Interactive Gateway unit for interworking between a number of different video communication terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, characterized in that
- the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel descrip- tion, and - the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals. and that in setting up video communication between the terminals,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal .
43. A Video Interactive Gateway unit according to claim 42, characterized in that the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
44. A Video Interactive Gateway unit according to claim 42 or to claim 43, characterized in that in setting up video communication between the terminals,
- the Video Interactive Gateway initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the low bit-rate multimedia terminal, and
- the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack to- wards the packet based multimedia terminal.
45. A Video Interactive Gateway unit according to any of the claims 42-44, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
46. A Video Interactive Gateway unit according to any of the claims 42-44, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
47. A Video Interactive Gateway unit for interworking between a number of different video communication terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia terminal, and at least one packet based multimedia terminal, characterized in that
- the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals. and that in setting up video communication between the terminals,
- as the Video Interactive Gateway receives OLC first from the the low bit-rate multimedia terminal, it starts a timer,
- the Video Interactive Gateway receives OLC from the packet based multimedia terminal,
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward channel description towards the low bit-rate multimedia terminal, and by using the forward channel description received from the low bit-rate multimedia terminal as the reverse channel description towards the low bit-rate multimedia terminal, and that - the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack to- wards the packet based multimedia terminal by using the forward channel description received from the the low bit- rate multimedia terminal.
48. A Video Interactive Gateway unit according to claim 47, characterized in that the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
49. A Video Interactive Gateway unit according to claim 47 or to claim 48, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
50. A Video Interactive Gateway unit according to claim 47 or to claim 48, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
51. A Video Interactive Gateway unit for interworking between a number of different video communication terminals in a video communication system, the video communication system comprising at least one Video Interactive Gateway unit, at least one low bit-rate multimedia termi- nal, and at least one packet based multimedia terminal, characterized in that
- the low bit-rate multimedia terminal sends an Open Logical Channel (OLC) message to the Video Interactive Gateway unit, the Open Logical Channel (OLC) message including a forward channel description and a Reverse channel description, and
- the Video Interactive Gateway unit further sends and/or receiving messages in order to set up video communication between the terminals. and that in setting up video communication between the terminals, - the Video Interactive Gateway receives OLC from the packet based multimedia terminal, and
- the Video Interactive Gateway initiates OLC by using the forward channel description received from the packet based multimedia terminal as forward and reverse channel description towards the low bit-rate multimedia terminal.
52. A Video Interactive Gateway unit according to claim 51, characterized in that the Video Interactive Gateway unit sends an Open Logical Channel (OLC) rejection message to the low bit-rate multimedia terminal.
53. A Video Interactive Gateway unit according to claim 51 or to claim 52, characterized in that in setting up video communication between the terminals, as the Video Interactive Gateway receives OLC first from the low bit- rate multimedia terminal, it starts a timer.
54. A Video Interactive Gateway unit according to any of the claims 51-53, characterized in that in setting up video communication between the terminals, the Video Interactive Gateway receives OLC ack from the low bit-rate multimedia terminal and initiates OLC ack towards the packet based multimedia terminal, and further initiates OLC towards the packet based multimedia terminal by using the forward channel description received from the packet based multimedia terminal.
55. A Video Interactive Gateway unit according to any of the claims 51-54, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a H.323 terminal.
56. A Video Interactive Gateway unit according to any of the claims 51-54, characterized in that the low bit-rate multimedia terminal is a H.324 terminal and that the packet based multimedia terminal is a SIP terminal.
PCT/FI2003/000443 2002-06-04 2003-06-04 Method and system for interworking between video communication terminals WO2003103243A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US10/516,812 US7623507B2 (en) 2002-06-04 2003-06-04 Method and system for interworking between video communication terminals
AU2003240892A AU2003240892A1 (en) 2002-06-04 2003-06-04 Method and system for interworking between video communication terminals
EP03730258A EP1510052B1 (en) 2002-06-04 2003-06-04 Method and system for interworking between video communication terminals

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20021067A FI20021067A0 (en) 2002-06-04 2002-06-04 Procedure for collaboration between multiple video communication terminals and video communication systems and video interoperability device
FI20021067 2002-06-04

Publications (1)

Publication Number Publication Date
WO2003103243A1 true WO2003103243A1 (en) 2003-12-11

Family

ID=8564076

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI2003/000443 WO2003103243A1 (en) 2002-06-04 2003-06-04 Method and system for interworking between video communication terminals

Country Status (5)

Country Link
US (1) US7623507B2 (en)
EP (1) EP1510052B1 (en)
AU (1) AU2003240892A1 (en)
FI (1) FI20021067A0 (en)
WO (1) WO2003103243A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1724981A1 (en) * 2005-03-17 2006-11-22 Huawei Technologies Co., Ltd. A multimedia call processing method and the system thereof
CN100433823C (en) * 2005-01-26 2008-11-12 华为技术有限公司 A H.323 terminal and method for video frequency communicating with H.324 terminal
CN100459739C (en) * 2005-04-26 2009-02-04 华为技术有限公司 Method for processing multimedia returns
CN101374330B (en) * 2007-08-20 2011-06-01 华为技术有限公司 Video intercommunication gateway equipment, system and method for implementing video call business
CN102291706A (en) * 2010-06-21 2011-12-21 中国移动通信集团公司 Method, system and equipment for realizing third-generation (3G) video service through terminal staying second-generation (2G)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7680143B2 (en) * 2002-12-12 2010-03-16 Rpx Corporation Methods and apparatus for combining session acceleration techniques for media oriented negotiation acceleration
US7206316B2 (en) 2002-12-12 2007-04-17 Dilithium Networks Pty Ltd. Methods and system for fast session establishment between equipment using H.324 and related telecommunications protocols
US20070129052A1 (en) * 2005-11-23 2007-06-07 Dilithium Networks Pty Ltd. Methods and system for fast session establishment for H.324 and related telecommunications terminals
US7139279B2 (en) * 2002-12-12 2006-11-21 Dilithium Networks Pty Ltd. Methods and system for fast session establishment between equipment using H.324 and related telecommunications protocols
US20070266161A1 (en) * 2002-12-12 2007-11-15 Dilithium Networks Pty Ltd. Methods and system for fast session establishment between equipment using h.324 and related telecommunications protocols
CN100440886C (en) * 2003-09-02 2008-12-03 华为技术有限公司 Method for realizing multimedia protocol passing through network address translation device
EP1872435A4 (en) * 2005-04-21 2009-01-07 Dilithium Networks Pty Ltd Fast session setup extensions to h.324
US7944862B2 (en) * 2005-11-09 2011-05-17 Onmobile Global Limited Accelerated session establishment in a multimedia gateway
US8687624B2 (en) * 2008-02-13 2014-04-01 Cisco Technology, Inc. Apparatus and method to handle dynamic payloads in a heterogeneous network
US8806529B2 (en) * 2012-04-06 2014-08-12 Time Warner Cable Enterprises Llc Variability in available levels of quality of encoded content
EP3782308A1 (en) * 2018-04-20 2021-02-24 Telefonaktiebolaget Lm Ericsson (Publ) Method and transmitting node for handling transmissions over a radio channel

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000076107A2 (en) * 1999-06-07 2000-12-14 Nortel Networks Limited Method and apparatus for interworking between internet protocol (ip) telephony protocols
EP1202522A2 (en) * 2000-10-31 2002-05-02 Fujitsu Limited Terminal and signal conversion apparatus for a Media communications system

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7043749B1 (en) * 1998-02-27 2006-05-09 Tandberg Telecom As Audio-video packet synchronization at network gateway
US6826272B1 (en) * 1998-10-01 2004-11-30 Nortel Networks Limited Method and apparatus for integrated multimedia call control
JP3701492B2 (en) * 1999-02-19 2005-09-28 富士通株式会社 Gateway device
US6937598B1 (en) * 1999-09-20 2005-08-30 Lucent Technologies Inc. Method and apparatus for transporting ATM cell traffic over IP networks
JP4250859B2 (en) * 2000-07-04 2009-04-08 沖電気工業株式会社 Communication terminal device and communication interception device
US6977911B1 (en) * 2000-07-31 2005-12-20 Cisco Technology, Inc. Scalable voice over IP system configured for dynamically switching codecs during a call
US20020061100A1 (en) * 2000-08-07 2002-05-23 Dicamillo Carmen A. Virtual telephony
US7031279B2 (en) * 2000-12-30 2006-04-18 Lg Electronics Inc. Gatekeeper supporting handoff and handoff method in IP telephony system
US7355988B1 (en) * 2001-03-08 2008-04-08 Cisco Technology, Inc. Application server having asynchronous event manager configured for terminating messaging operations and rolling back prescribed data structures
US7266611B2 (en) * 2002-03-12 2007-09-04 Dilithium Networks Pty Limited Method and system for improved transcoding of information through a telecommunication network

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000076107A2 (en) * 1999-06-07 2000-12-14 Nortel Networks Limited Method and apparatus for interworking between internet protocol (ip) telephony protocols
EP1202522A2 (en) * 2000-10-31 2002-05-02 Fujitsu Limited Terminal and signal conversion apparatus for a Media communications system

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
"H.323-H.324 interworking", ITU-T RECOMMENDATION H.246: ANNEX F, July 2001 (2001-07-01), pages 1 - 14, XP002252008 *
BOGEN M ET AL: "Desktop Video: Building Large-Scale Services with Incompatible Products", 8TH JOINT EUROPEAN NETWORKING CONFERENCE JENC8, 12 May 1907 (1907-05-12) - 15 May 1997 (1997-05-15), Edinburgh, pages 922-1 - 922-9, XP002252009 *
K. SINGH ET AL: "Interworking between SIP/SDP and H.323", IN PROCEEDINGS OF THE 1ST IP-TELEPHONY WORKSHOP (IPTEL 2000), April 2000 (2000-04-01), Berlin, pages 1 - 21, XP002252010 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100433823C (en) * 2005-01-26 2008-11-12 华为技术有限公司 A H.323 terminal and method for video frequency communicating with H.324 terminal
EP1724981A1 (en) * 2005-03-17 2006-11-22 Huawei Technologies Co., Ltd. A multimedia call processing method and the system thereof
EP1724981A4 (en) * 2005-03-17 2007-05-09 Huawei Tech Co Ltd A multimedia call processing method and the system thereof
US7719562B2 (en) 2005-03-17 2010-05-18 Huawei Technologies Co., Ltd. Method and system for handling multimedia calls
CN100459739C (en) * 2005-04-26 2009-02-04 华为技术有限公司 Method for processing multimedia returns
CN101374330B (en) * 2007-08-20 2011-06-01 华为技术有限公司 Video intercommunication gateway equipment, system and method for implementing video call business
US8560717B2 (en) 2007-08-20 2013-10-15 Huawei Technologies Co., Ltd. Method and system for implementing video call service and video interworking gateway device
CN102291706A (en) * 2010-06-21 2011-12-21 中国移动通信集团公司 Method, system and equipment for realizing third-generation (3G) video service through terminal staying second-generation (2G)

Also Published As

Publication number Publication date
AU2003240892A1 (en) 2003-12-19
US7623507B2 (en) 2009-11-24
EP1510052B1 (en) 2012-08-22
FI20021067A0 (en) 2002-06-04
US20050193420A1 (en) 2005-09-01
EP1510052A1 (en) 2005-03-02

Similar Documents

Publication Publication Date Title
US7623507B2 (en) Method and system for interworking between video communication terminals
US6771594B1 (en) Reliable/non-reliable transmission of voice using TCP/UDP based on network quality of service
US6711166B1 (en) System and method for packet network trunking
US6819678B2 (en) Interworking of dissimilar packet networks for telephony communications
JP4652646B2 (en) Method and system for exchanging information between nodes of a multimedia network
US8971344B2 (en) Terminal capabilities set exchange between heterogeneous endpoints
JP2009500983A (en) Data transfer system and method
KR20010108448A (en) Apparatus and associated method for communicating multimedia information upon a communication link
EP1872435A4 (en) Fast session setup extensions to h.324
US20030099192A1 (en) Method and system for a switched virtual circuit with virtual termination
WO2006078722A2 (en) Gateway interface control
CN100488249C (en) Method for bitrate adjustment
US6965600B2 (en) Low speed modem transmission over packet networks
CN101119292B (en) Method of negotiating data traffic transmission between gateways
EP2071771A1 (en) A method, system and gateway for negotiating about the ability of the data signal detector
US20030058807A1 (en) Method and device for echo cancellation in a telecommunication network
Subbiah et al. RTP payload multiplexing between IP telephony gateways
EP1646181A1 (en) A media gateway system
US7395309B1 (en) Modem activity detection
US20020037003A1 (en) Method to control data conversion in the transfer of a connection between a packet-switched and a line-switched communications network
US7593419B2 (en) Method for controlling a connection in a packet-oriented communication network and arrangements for implementing said method
US8054825B2 (en) Method for transferring a call between a telecommunications network and a data network
JP4385543B2 (en) Private branch exchange and its bandwidth management method
US8526447B1 (en) H.323 to SIP fax interworking
WO2009092264A1 (en) A method and device for providing support for transmitting a media stream embedded in the control stream

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NI NO NZ OM PH PL PT RO RU SC SD SE SG SK SL TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
121 Ep: the epo has been informed by wipo that ep was designated in this application
WWE Wipo information: entry into national phase

Ref document number: 2003730258

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 10516812

Country of ref document: US

WWP Wipo information: published in national office

Ref document number: 2003730258

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: JP

WWW Wipo information: withdrawn in national office

Country of ref document: JP