Communications system and method utilizing centralized signal processing

• US 7,206,404 B2
• Filed: 05/09/2005
• Issued: 04/17/2007
• Est. Priority Date: 09/12/2000
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Tandberg Telecom AS (Cisco Systems, Inc.)
• Inventors: Parry, James H., Hsiang, Peter
• Primary Examiner(s): TIEU, BINH KIEN
• Application Number:
  US11/124,772
• Publication Number:
  US 20050207567A1
• Time in Patent Office: 708 Days
• Field of Search: 379/202.01, 379/406.01, 379/406.05, 379/406.06, 379/408.08, 381/26, 381/80, 381/82, 381/93, 381/94.1, 381/94.2, 381 95- 96
• US Class Current: 379/406.01
• CPC Class Codes: H04M 9/08 Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic

Abstract

A communications system and method performs centralized signal processing on received audio signals. A plurality of terminals are coupled to a processing switch via links. The terminals can be, for example, dedicated speakerphones, desktop handsets, or personal computers with audio capabilities. The links can be wired or wireless, can carry analog or digital signals, and can be shared with other users in a network. The switch receives the audio data from the terminals, processes the data according to desired acoustical procedures, creates one or more output mixes, and provides the output mixes to the appropriate terminals. The operation of the processing switch is controlled by a communications support module (CSM) which can receive, process, and send data to/from multiple terminals simultaneously. The CSM receives audio signals from the terminals. The CSM uses stored room models holding room model information including data and/or filters representing the acoustic properties of the terminal and/or the environment surrounding the terminal to produce the audio signals. Signal processing (SP) modules provide a pool of SP power from which the CSM can draw to process audio signals received from or being sent to the terminals. The CSM uses the SP modules to perform signal processing including acoustic echo cancellation, automatic gain control, noise reduction. The CSM also uses a mixing module to perform signal mixing.

Claims

1. A method for supporting communication among a plurality of terminals, the method comprising steps of:

receiving an audio signal at a centralized switch to result in a received signal, wherein the centralized switch receives the audio signal from a terminal over a communications medium, wherein the terminal has a microphone located proximate to not more than one active speaker mechanism, wherein the terminal lacks mechanisms for removing an audio feedback portion of the audio signal, wherein the audio feedback portion is caused by the microphone reacting to sound energy from the not more than one active speaker mechanism;

processing by a signal processor the received audio signal to remove the audio feedback portion resulting in a first filtered signal;

mixing the first filtered signal with a second filtered signal to result in a mixed signal; and

transmitting the mixed signal to the terminal over the communications medium.

2. The method of claim 1, wherein the communications medium is wireless.

3. The method of claim 1 further comprising the step of:

extracting room model information from the received signal, wherein the room model information contains characteristics of the acoustic qualities surrounding the terminal.

4. The method of claim 1, wherein the signal processor performs acoustic echo cancellation on the received signal.

5. The method of claim 1, wherein the signal processor performs automatic gain control on the received signal.

6. The method of claim 1, wherein the signal processor performs noise reduction on the received signal.

7. The method of claim 1 further comprising the steps of:

extracting room data from the received signal, where in the room data contains characteristics of acoustic properties surrounding the terminal;

storing portions of the room data in a first room model.

8. The method of claim 7, wherein the room model is adaptively developed and updated while the terminal is engaged in a communications session.

9. The method of claim 7 further comprising the steps of:

identifying a second terminal engaged in a communications session to result in an identified terminal; and

retrieving a second room model for the identified terminal.

10. The method of claim 1, the method further comprising the steps of:

determining an amount of processing power available to process the received signal; and

allocating processing power to the received signal based on the availability of processing power.

11. The method of claim 10 further comprising the steps of:

determining whether each of a plurality of received signals has human voice content; and

assigning processing resources to each of the plurality of received signals based on whether each has human voice content.

12. The method of claim 11 further comprising the steps of:

determining a plurality of estimations of processing resources needed by individual terminals of the plurality of terminals, wherein the individual terminals are engaged in communications sessions,

allocating processing resources to the individual terminals based on the plurality of estimations.

13. The method of claim 1 wherein the microphone and the not more than one active speaker are proximate to each other and fixably attached to the terminal.

14. The method of claim 1, wherein the processing step comprises the step of:

performing acoustic echo cancellation on the received signal.

15. The method of claim 1, wherein the processing step comprises the step of:

performing automatic gain control on the received signal.

16. The method of claim 1, wherein the processing step comprises the step of:

performing noise reduction on the received signal.

17. The method of claim 1, wherein the transmitting step comprises the steps of:

sending a time tag, wherein the time tag includes sequencing information for the mixed signal.

18. The method of claim 1 further comprising the step of:

receiving a time tag with the audio signal, wherein the processing step aligns the audio signal responsive to the received time tag.

19. A communications system comprising:

a processing switch coupled to a plurality of terminals, wherein each of the plurality of terminals has a microphone and a speaker proximate to the microphone, wherein the processing switch receives a first audio signal from a first terminal of the plurality of terminals resulting in a first received audio signal, wherein upon receipt, the first received audio has not been processed to reduce acoustic feedback;

a communications support module (CSM) coupled to the processing switch;

a signal processing (SP) module coupled to the CSM, wherein the SP module has digital signal processing resources to reduce acoustic feedback in the first received audio signal to result in a first processed signal, wherein the SP module operates under the control of the CSM,

a room module coupled to the SP module, wherein the room module accesses a plurality of room models, wherein each room model contains acoustic information specific to one of the plurality of terminals, wherein each room model contains data related to the acoustic properties surrounding its respective terminal;

a mixing module coupled to the processing switch and directed by the CSM, wherein the mixing module mixes the first processed signal with a second processed signal to produce an output mix, wherein the output mix is associated with the first terminal; and

a module for sending the output mix to the first terminal for output on the first terminal'"'"'s speaker, wherein the first terminal has less than two speakers active simultaneously.

20. The communications system of claim 19, wherein the SP module performs acoustic echo cancellation on the first received audio signal.

21. The communications system of claim 19, wherein the SP module performs automatic gain control on the first received audio signal.

22. The communications system of claim 19, wherein the SP module performs noise reduction on the first received audio signal.

23. The communications system of claim 19 further comprising:

a decoding module for decoding the first received audio signal; and

an encoding module for encoding the output mix prior to the output mix being sent to the first terminal.

24. The communications system of claim 19, wherein the CSM determines, responsive to a load on the communications system, an amount of SP module processing resources to allocate to individual audio signals within a plurality of received audio signals.

25. The communications system of claim 19, wherein the CSM determines, responsive to characteristics of each of a plurality of received audio signals, an amount of SP processing resources to allocate to individual audio signals within a plurality of audio signals.

26. The communications system of claim 23, wherein the decoding module is adapted for decoding at least one encoded output mix to produce a decoded encoded output mix, wherein the decoded encoded output mix is used by the SP module to perform acoustic echo cancellation.

27. The communications system of claim 23, wherein the room module updates a first room model based on data extracted from the first received audio signal, wherein the data is indicative of acoustic characteristics of an area surrounding the first terminal.

28. A system for supporting a communications session among a plurality of terminals, the system comprising:

a communications support module (CSM) for determining whether a first terminal of the plurality of terminals is active, wherein responsive to determining that the first terminal is active, the CSM allocates pooled feedback-reducing resources to the first terminal, wherein responsive to determining that the first terminal is not active, the CSM deallocates pooled feedback-reducing resources from the first terminal;

a receiving module for receiving a first audio signal from the first terminal, wherein the first audio signal has a feedback component caused by the proximity of a first terminal'"'"'s speaker to a first terminal'"'"'s microphone, wherein the first terminal has less than two speakers active simultaneously;

a room module for storing a first room model associated with the first terminal, wherein the first room model contains information relates to acoustic properties influenced by the environment surrounding the first terminal'"'"'s microphone and speaker; and

a centralized signal processing (SP) module for performing SP on the first audio signal to compensate for the feedback component, wherein performing SP on the first audio signal results in a first processed signal, the wherein performing SP on the first audio signal is responsive to the first room model; and

a sending module for sending the first processed signal to the first terminal.

29. The system of claim 28, further comprising:

a mixing module for mixing the first processed signal with a second processed signal to result in a first mixed signal, wherein the sending module sends the first mixed signal to the first terminal.

30. The system of claim 28, wherein the SP module is adapted to perform acoustic echo cancellation on the first audio signal.

31. The system of claim 28, wherein the SP module is adapted to perform automatic gain control on the first audio signal.

32. The system of claim 28, wherein the SP module is adapted to perform noise reduction on the first audio signal.

33. The system of claim 29, wherein the first audio signal is encoded, the system further comprising:

an encoding/decoding module for decoding the first audio signal and for encoding the first mixed signal.

34. The system of claim 28, wherein the SP resources are allocated to the first audio signal responsive to a total number of available SP resources.

35. The system of claim 28, wherein the SP resources are allocated to the first audio signal responsive to content characteristics of the first audio signal.

36. The method of claim 28, wherein the first audio signal is sent in data packets, wherein determining whether the first terminal is active comprises the steps of:

analyzing a plurality of received data packets to determine whether the plurality of data packets originate from the first terminal.