Method and apparatus for mapping voice activity detection to a scheduled access media

• US 6,621,812 B1
• Filed: 01/04/1999
• Issued: 09/16/2003
• Est. Priority Date: 11/10/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Chapman, John T., Khaunte, Sunil, Roeck, Guenter
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): TRAN, THIEN D
• Application Number:
  US09/225,895
• Time in Patent Office: 1,716 Days
• Field of Search: 370/428, 370/429, 370/447, 370/449, 370/451, 370/461, 370/462, 370/493, 370/494, 370/495, 370/352, 370/356, 370/346, 370/442, 370/443, 704/246, 704/231
• US Class Current: 370/346
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04M 2207/14 cable networks
• CPC Class Codes: H04M 2207/203 composed of PSTN and data network, e.g. the Internet

Abstract

Unsolicited grants are allocated a selected time interval for scheduling transmission of audio packets at a network endpoint. A network processing node switches from outputting unsolicited grants to polling for packet transmission requests when Voice Activity Detection (VAD) at the transmitting endpoint stops generating audio packets. The network processing node switches back to outputting unsolicited grants when the endpoint resumes generation of audio packets. The unsolicited grants include one or more additional grants within the selected time interval that flush out one or more audio packets that may already be queued for transmitting. These additional grants reduce the latency normally caused when Voice Activity Detection (VAD) stops and then restarts audio packet transmission.

Claims

1. A system for scheduling transmission of audio packets, comprising:

a network processing node providing unsolicited grants at a selected time interval for enabling audio packet transmissions from a packet sending device;

the network processing node switching from providing the unsolicited grants to providing polled requests for soliciting packet transmissions when the audio packets are not received from the packet sending device in response to the grants; and

the network processing node upon receiving a response to the polled requests periodically reissuing the unsolicited grants at the selected time interval to the same packet sending device and also issuing at least one additional unsolicited grant to the same packet sending device between the periodically issued grants.

2. A system according to claim 1 wherein the packet sending device includes Voice Activity Detection (VAD) that discontinues transmission of audio packets to the network processing node when received audio energy is below a predefined threshold.

3. A system according to claim 2 wherein the packet sending device is coupled to the network processing node through a cable medium.

4. A system according to claim 1 wherein the network processing node comprises a cable modem termination system.

5. A system according to claim 2 wherein the network processing nodes uses a cable modem communication protocol to communicate with the packet sending device to control VAD activation.

6. A system according to claim 5 wherein the cable modem communication protocol operates according to a Data Over Cable System Interface Specification (DOCSIS).

7. A system according to claim 6 wherein the network processing node receives a registration notice for identifying VAD capability and receives or generates a request notice for requesting VAD activation, the network processing node receiving or generating a response notice for indicating acceptance or rejection of the VAD request notice and receiving or generating an acknowledge notice for acknowledging the response notice.

8. A system according to claim 7 wherein:

the registration notice comprises a DOCSIS Registration Request;

the request notice comprises a DOCSIS Dynamic Service Change Request or a Dynamic Service Addition Request;

the response notice comprises a DOCSIS Dynamic Service Change Response or a Dynamic Service Addition Response; and

the acknowledge notice comprises a DOCSIS Dynamic Service Change Acknowledge or a Dynamic Service Addition Acknowledge.

9. A system for transmitting and receiving audio packets, comprising:

a network processing device including a packet queue buffering audio packets generated from audio signals;

the network processing device transmitting the buffered audio packets according to grants received periodically at a selected time interval and that terminate when audio packets are no longer transmitted from the packet queue; and

the network processing device generating a notification signal that restarts the periodic receiving of the grants at the selected time interval and upon sending the notification signal also receiving one or more unsolicited grants between the periodically issued grants enabling transmission of at least one additional audio packet within the selected time interval.

10. A system according to claim 9 including an encoder that stops generating audio packets for the packet queue when energy of the audio signals fall below a threshold level.

11. A system according to claim 9 wherein the network processing device is enabled to transmit multiple audio packets by receiving multiple grants within the selected time interval.

12. A system according to claim 9 including a network processing node coupled to the network processing device for outputting the grants, the network processing node switching from outputting unsolicited grants to generating a polling request when the network processing device stops transmitting the audio packets.

13. A system according to claim 9 wherein the network processing device outputs the notification signal immediately after detecting audio signals and encodes the audio signals into audio packets while waiting for the grants to restart.

14. A system according to claim 13 wherein initial encoded audio packets are loaded in the packet queue and ready for transmission before the grants are restarted.

15. A method for transmitting audio packets in a network, comprising:

allocating unsolicited grants to a same endpoint periodically at a selected time interval for scheduling transmission of audio packets;

switching from allocating unsolicited grants to providing a polled transmission request when the audio packets are not transmitted in response to the unsolicited grants;

switching back to allocating unsolicited grants to the same endpoint periodically at the selected time interval when there is a response to the polled transmission request; and

inserting one of more additional unsolicited grants to the same endpoint within the selected time interval after switching back to allocating unsolicited grants.

16. A method according to claim 15 including performing Voice Activity Detection (VAD) to stop transmitting audio packets when audio energy is below a predefined threshold.

17. A method according to claim 15 including the following:

receiving or generating a signal for identifying VAD capability;

receiving or generating a signal for requesting VAD activation;

receiving or generating a signal for indicating acceptance or rejection of the VAD request; and

receiving or generating a signal acknowledging the acceptance or rejection of the VAD request.

18. A method according to claim 17 wherein each signal is received or transmitted each signal according to a Data Over Cable System Interface Specification.

19. A method for scheduling transmission of audio packets, comprising:

encoding audio signals into audio packets;

queuing the audio packets for transmission over a network;

transmitting the queued audio packets according to unsolicited grants received periodically at a given time interval;

terminating packet transmission when no more audio packets are queued;

generating a notification signal to restart unsolicited grant allocation at the periodic time interval when new audio packets are queued for transmission;

receiving one or more additional unsolicited grants within a first one of the periodic time intervals after the unsolicited grant allocation is restarted; and

transmitting multiple audio packets during the same time interval of the reallocated grants in response to received unsolicited grants.

20. A method according to claim 19 including stopping encoding of the audio signals when an energy of the audio signals falls below a threshold level.

21. A method according to claim 19 including:

detecting audio signals above a given energy threshold;

generating the notification signal immediately after detecting the audio signals and at the same time encoding the audio signals into the audio packets; and

queuing the audio packets for transmission while waiting for a response to the notification signal thereby eliminating encoding latency.

22. An electronic storage medium containing computer executable code for transmitting audio packets in a network, the electronic storage medium comprising:

code for periodically allocating unsolicited grants at a selected time interval for enabling transmission of audio packets from an endpoint;

code for switching from allocating unsolicited grants to providing a polled transmission request when the audio packets are not transmitted in response to the unsolicited grants;

code for switching back to periodically allocating unsolicited grants at the selected time interval to the same endpoint when there is a response to the polled transmission request; and

code for inserting one or more additional unsolicited grants within one of the same selected time intervals to the same endpoint after switching back to allocating unsolicited grants.

23. An electronic storage medium according to claim 22 including code for performing Voice Activity Detection (VAD) to stop transmitting audio packets when audio energy is below a predefined threshold.

24. An electronic storage medium according to claim 22 including:

code for receiving or generating a signal for identifying VAD capability;

code for receiving or generating a signal for requesting VAD activation;

code for receiving or generating a signal for indicating acceptance or rejection of the VAD request; and

code for receiving or generating a signal acknowledging the acceptance or rejection of the VAD request.

25. An electronic storage medium according to claim 24 including code for receiving or transmitting each signal according to a Data Over Cable System Interface Specification.

26. An electronic storage medium storing computer executable code for scheduling transmission of audio packets, the electronic storage medium comprising:

code for encoding audio signals into audio packets;

code for queuing the audio packets for transmission over a network;

code for transmitting the queued audio packets according to unsolicited grants;

code for terminating packet transmission when no more audio packets are queued;

code for generating a notification signal to restart unsolicited grant allocation when new audio packets are queued for transmission; and

code for transmitting multiple audio packets during the same time interval of the reallocated grants in response to received back-to-back unsolicited grants to flush out queued audio packets that may have built up since terminating packet transmission.

27. An electronic storage medium according to claim 26 including code for stopping encoding of the audio signals when an energy of the audio signals falls below a threshold level.

28. An electronic storage medium according to claim 26 including:

code for detecting audio signals above a given energy threshold;

code for generating the notification signal immediately after detecting the audio signals and at the same time encoding the audio signals into the audio packets; and

code for queuing the audio packets for transmission while waiting for a response to the notification signal thereby eliminating encoding latency.

29. A system for transmitting audio packets in a network, comprising:

means for periodically allocating unsolicited grants at a selected time interval for enabling transmission of audio packets at an endpoint;

means for switching from allocating unsolicited grants to providing a polled transmission request when the audio packets are not transmitted in response to the unsolicited grants;

means for switching back to periodically allocating unsolicited grants at the selected time interval to the same endpoint when there is a response to the polled transmission request; and

means for inserting one or more additional unsolicited grants within one of the same selected time intervals to the same endpoint after switching back to allocating unsolicited grants.

30. A system according to claim 29 including means for performing Voice Activity Detection (VAD) to stop transmitting audio packets when audio energy is below a predefined threshold.

31. A system according to claim 29 including:

means for receiving or generating a signal for identifying VAD capability;

means for receiving or generating a signal for requesting VAD activation;

means for receiving or generating a signal for indicating acceptance or rejection of the VAD request; and

means for receiving or generating a signal acknowledging the acceptance or rejection of the VAD request.

32. A system according to claim 31 including means for receiving or transmitting each signal according to a Data Over Cable System Interface Specification.

33. A system for scheduling transmission of audio packets, comprising:

means for encoding audio signals into audio packets;

means for queuing the audio packets for transmission over a network;

means for transmitting the queued audio packets according to unsolicited grants;

means for terminating packet transmission when no more audio packets are queued;

means for generating a notification signal to restart unsolicited grant allocation when new audio packets are queued for transmission; and

means for transmitting multiple audio packets during the same time interval of the reallocated grants in response to received back-to-back unsolicited grants.

34. A system according to claim 33 including means for stopping encoding of the audio signals when an energy of the audio signals falls below a threshold level.

35. A system according to claim 33 including:

means for detecting audio signals above a given energy threshold;

means for generating the notification signal immediately after detecting the audio signals and at the same time encoding the audio signals into the audio packets; and

means for queuing the audio packets for transmission while waiting for a response to the notification signal thereby eliminating encoding latency.