Multiplex communications – Special services – Conferencing
Reexamination Certificate
2000-02-29
2001-11-27
Olms, Douglas (Department: 2732)
Multiplex communications
Special services
Conferencing
C379S202010
Reexamination Certificate
active
06324169
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to multimedia conferencing services and, more particularly, relates to a method for providing such services by interconnecting multiple nonguaranteed quality of service (NGQOS) local area networks (LANs) by an asynchronous transfer mode (ATM) wide area network (WAN) in which a multimedia bridging function is performed.
BACKGROUND OF THE INVENTION
Real-time multimedia conferencing services have typically been provided by connecting signals over circuit-switched networks, such as an Integrated Services Digital Network (ISDN), having guaranteed quality of service (QOS). Although circuit-switched networks provide a guarantee of QOS as they provide a communications channel for exclusive use by connected parties until the connection is released, they cannot save bandwidth through statistical multiplexing (i.e., by dynamically allocating bandwidth according to actual demand rather than on a predefined basis). Therefore, the adoption of multimedia services through the interconnection of geographically dispersed locations over circuit-switched networks is very limited because it is cost prohibitive.
Accordingly, millions of multimedia personal computers (MPCs) or workstations throughout the world are connected to packet-switched “nonguaranteed” quality of service local area networks such as Ethernet (EN), Token Ring (TN), or Fiber Distributed Data Intetface (FDDI). By definition of the protocol standards for each of EN, TN and FDDI, for example, the LANs are “nonguaranteed” in that there is no guarantee of performance in providing services through that network. Such networks are inherently unreliable as they provide no guarantee of bandwidth or quality of service parameters. Real-time multimedia conferencing services require a guarantee of bandwidth and quality of service parameters. A critical requirement for successful real-time conferencing is to ensure that there are sufficient network and bridging resources available to maintain the desired level of performance once the conference call has been accepted. However, in a conventional system the bridge has absolutely no knowledge of the state of the network and its resources.
Recently, the ATM network has emerged as the most promising networking technology for providing statistical multiplexing of real-time isochronous signals (i.e., signals repeating in time, such as 8 khz voice samples for example), such as audio and video, as well as asynchronous signals, such as data, while maintaining a guarantee of quality of service for each signal.
SUMMARY OF THE INVENTION
The present invention enables real-time conferencing services to be provided to dispersed locations interconnected by an ATM wide area network. The multimedia signals originating at the dispersed locations may be audio, video, or data signals, or any combination of such signals. The locations employ nonguaranteed quality of service packet switched local area networks which do not provide a guarantee of bandwidth or QOS parameters.
In such an environment, multimedia conferencing signals from the dispersed locations are carried to a bridge, located in the ATM network, to provide multimedia bridging. The bridged multimedia signals are then transmitted back over the ATM wide area network to the various locations. By using this method, the overall bandwidth required to transmit the multimedia signals between the dispersed locations is reduced through bridging and statistical multiplexing, especially for bursty signals.
In accordance with another aspect of the invention, architectural entities, such as a bridge service manager (BSM), quality of service manager (QOSM), multimedia bridge resource manager (BRM), and network resource information (NRI), residing within the upper layer architecture of the ATM network-based multimedia bridge (MMB), will execute a multimedia performance and resource analysis algorithm and will assess what type and quantity of resources for the ATM wide area network, the ATM network based multipoint multimedia bridge, and the local area networks, will be required to maintain the desired levels of quality of service for the multimedia conference call. The necessary properties of all network and bridge resources are examined by these architectural entities, and the absence of the required properties to satisfy the multimedia conferencing services are detected by the algorithm executed within the ATM wide area network-based bridge.
In yet another aspect of the invention, if the necessary resources are available to accept the conference call, the originating and the receiving computers of the dispersed locations are informed by the bridge, and the quality of service parameters for the conference call will be maintained after acceptance of the call. The locations are also informed that the conference call will operate in degraded mode when only the certain minimum acceptable criteria of the call are met due to unavailability of sufficient resources within the ATM network, the multimedia bridge, the local area networks, or any combination of the above. Finally, if the minimum requirement criteria of the conference call is not met, the bridge informs the calling and the called locations that the conference call cannot be accepted.
It is a feature of the present invention to send the new control signaling messages together with the H.323 standard based signaling messages, which will improve the multimedia conference call negotiating capabilities.
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AT&T Corp.
Olms Douglas
Ryan William
Vanderpuye Ken
Williams Karin L.
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