Electrical computers and digital processing systems: multicomput – Computer conferencing
Reexamination Certificate
2000-04-07
2003-12-09
Barot, Bharat (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer conferencing
C709S205000, C709S231000, C709S232000, C370S260000, C370S263000, C370S264000, C370S266000, C370S267000, C248S057000, C379S202010
Reexamination Certificate
active
06662211
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of telecommunications and, more specifically, to a method and apparatus for providing unified conferencing services in an expandable telecommunications switching system.
2. Background Information
A competitive telecommunications system must be capable of providing a wide variety of telecommunications services. For example, subscribers may request services such as voice processing services, call waiting, caller identification and call forwarding. In the commercial context, one of the most desirable services is that of conferencing. Conferencing refers to the ability of three or more callers, each using a separate telephone set and often located at remote locations from each other, to participate in a single telephone call simultaneously. In addition, there is an ever-expanding need for conferencing services that can accommodate large conferences of, for example, ten to seventy or more participants. Moreover, the participants are often physically distributed worldwide. This means that the pulse code modulation (PCM) format pursuant to which the voice signals are encoded may differ between callers. In other words, some of the calls might be in the well known &mgr;-law PCM format commonly used in the United States, and other calls participating in the conference may be encoded in A-law format, used typically in Japan.
A further service that is often desirable in conferencing is that of a broadcast output. There are many commercial applications in which a one-way (half-duplex) operation is desired. For example, there may be a monitoring operator, such as a supervisor, listening in on a subordinate's telephone call with a customer. Alternatively, educational courses can be provided over the telephone and participants simply listen and do not have the opportunity to speak during this type of conference. The broadcast output supplies this type of one-way connection.
Originally, separate conferencing systems had interfaced with a conventional computer-controlled digital switching matrix within a Private Branch Exchange (PBX) switch or a public switching system that provided a circuit switching function. More recently, it has been known to provide conferencing within a high-speed digital communications network that includes a plurality of switching nodes with each node including its own nodal switch. This type of system is described in commonly-owned U.S. Pat. No. 5,920,546 (Hebert et al.) for a METHOD AND APPARATUS FOR CONFERENCING IN AN EXPANDABLE TELECOMMUNICATIONS SYSTEM, which is presently incorporated herein by reference in its entirety.
In accordance with that system, at least one node in the system (e.g., a conferencing node) contains a digital signal processing (“DSP”) circuit capable of performing a conferencing operation on the voice information of the conferees. More specifically, the DSP circuitry executes a conferencing function on the voice information by operating on it using, for example, a conferencing algorithm that typically includes summing together the channels of voice information from each conferee. As is typical in the industry, after summing all of the voice data, the conference processor subtracts each conferee's data from the summed total intended for that conferee. This is done in order to minimize echo effects and improve system stability. The DSP circuit executes this conferencing function on the voice information and then outputs a different instance of conferenced voice information for each conferee. Each instance of conferenced voice information is then transmitted to the corresponding conferee.
More specifically, the DSP circuitry first places the instances of conferenced voice information on an internal bus located in the conferencing node. A data transmitter in the nodal switch that is preferably linked with the bus then receives the instances of conferenced voice information. Next, the conferencing node may formulate a packet or packets containing the instances of conferenced voice information for transmission via its data transmitter over the network. Specifically, each instance of conferenced voice data may be packetized, addressed and transmitted according to instructions from the system to the programmable switching node interfaced with the corresponding conference participants. Each programmable switching node, upon receipt of the packet or packets, then captures the instance of conferenced voice information ear marked for that participant via its own data receiver and switches the information to the participant.
This process may be repeated on a high-speed basis, however, there is a limit to the number of conferees that can be included in the conference. It can be difficult to form a very large conference with typically-employed conferencing algorithm mathematics because of the noise that is accumulated from every channel, which would then be summed and thus increased per additional participant. In addition, conference participants may tend to speak even louder and louder to overcome this noise and a limit to the loudness tolerated in the audio components of the system may be reached causing the conference output signal to be incomprehensible.
For example, the above-mentioned '546 patent generally handles conferences of up to about seven conferees. Despite its utility in forming a conference that has a high quality voice signal output, the conferencing technique described above does not fully allow for the further capacity to handle larger conferences. In addition, there is a further need for a conferencing system that can accommodate larger conferences and for such a system that is capable of operating on input signals from participants whose PCM-encoded data is in different formats. This need is particularly great with large conferences because it is even more likely that a conference of thirty or more will include participants from various parts of the world and thus, will involve PCM-encoded data which is in different formats. There also remains a need for a system for large conferences that includes the capability of providing a broadcast output.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and apparatus for providing conferencing services for a large number of participants (in full duplex or half-duplex operations) that produces a high quality output signal, while accommodating participants having voice information in different PCM-encoding formats. It is a further object of the present invention to provide a conferencing system that is compatible with a high-speed, expandable telecommunications system. It is a further object of the invention to provide a conferencing system that can implement multiple distinct conferences simultaneously.
Briefly, the invention comprises a method and apparatus for providing conferencing services in a telecommunications system. A preferred embodiment of the invention operates within a high-speed telecommunications system comprised of multiple switching nodes connected by an inter-nodal network. At least one node in the system contains digital signal processing (DSP) circuitry capable of performing conferencing functions on the voice information from conferees connected to the system. Typically, many nodes will contain multiple DSP integrated circuits (“chips”) in a DSP module. A DSP chip contains a microprocessor as well as memory storage devices. The microprocessor is programmed in accordance with the invention to provide the conferencing services. When a conference is being established, available conferencing resources are identified within a DSP chip in a node in the system, which is then the conferencing node. Pursuant to instructions from the system host, the voice information at each node interfaced with a conferee is addressed and transmitted to the conferencing node. The details of the routing of this information to the conferencing node are set forth in the previously incorporated, commonly-owned U.S. Pat. No. 5,920,546. Seve
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