Method and system for controlling speech encoding in a communication system

• US 6,049,537 A
• Filed: 09/05/1997
• Issued: 04/11/2000
• Est. Priority Date: 09/05/1997
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Ashley, James Patrick, Proctor, Lee Michael
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US08/926,074
• Time in Patent Office: 949 Days
• Field of Search: 370/252, 370/260, 370/342, 370/441, 370/468, 370/479, 370/335, 370/336, 370/320, 704/206, 704/207, 704/208, 704/221, 704/222, 704/223, 704/231
• US Class Current: 370/342
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates
• CPC Class Codes: H04J 3/1688 the demands of the users being taken into account after redundancy removal, e.g. by predictive coding, by variable sampling reducing bandwidth of signals in general H04B1/66; in PCM-systems H04B14/046; removal of redundancy in telegraph communication H03M7/30
• CPC Class Codes: H04W 28/20 Negotiating bandwidth
• CPC Class Codes: H04W 88/181 Transcoding devices; Rate adaptation devices

Abstract

A method and system for controlling speech encoding in a communication system utilizes feedback information such as packet modification control data (154) sent from a communication link output controller, such as a network arbitor (142). The network arbitor (142) sends the packet modification control data (154) to a selected vocoder (146) to change the filter states of the selected vocoder (146) when the network arbitor (142) modifies an output speech packet communicated of a communication link (20), to facilitate improved convergence of a speech encoder and a speech decoder, such as a mobile subscriber unit.

Claims

1. A method of controlling speech encoding in a communication system, the method comprising the steps of:

receiving encoded speech packets from a plurality of variable rate vocoders;

determining a required link bandwidth for transmission of encoded packets of voice based on the received encoded speech packets;

comparing the required link bandwidth with an available link bandwidth;

outputting encoded speech over the link;

generating a packet modification control signal for a selected variable rate vocoder indicating whether the output encoded speech was modified prior to output; and

controlling the selected vocoder, in response to the packet modification control signal, when output encoded speech was modified.

2. The method of claim 1 wherein the step of generating the packet modification control signal is based on a modification resulting from discarding speech packet information and/or reducing speech packet information rate.

3. The method of claim 2 wherein the step of controlling the selected vocoder includes recovering a previous speech packet that was discarded and updating filter state data for use in generating a subsequent speech packet.

4. The method of claim 3 wherein the step of controlling includes facilitating decaying of speech parameters for use in generating subsequent speech packets, in response to the packet modification control signal, when the modification resulted from discarding speech encoded information.

5. The method of claim 2 wherein the step of controlling includes varying a rate of encoding for the subsequent speech packet, in response to the packet modification control signal, when the modification resulted from reducing a speech packet output rate.

6. The method of claim 4 wherein the communication system is a CDMA system and a network arbiter generates the packet modification control signal for the selected variable rate vocoder indicating whether the output encoded speech was modified prior to output.

7. The method of claim 5 wherein the step of controlling further includes applying a packet reduction method for a subsequent packet, when the modification resulted from reducing a speech packet output rate.

8. A method of controlling speech encoding in a communication system, the method comprising the steps of:

receiving encoded speech packets from a plurality of variable rate vocoders;

determining a required link bandwidth for transmission of encoded packets of voice based on the received encoded speech packets;

comparing the required link bandwidth with an available link bandwidth;

outputting encoded speech over the link;

generating a packet modification control signal for a selected variable rate vocoder indicating whether the output encoded speech was modified prior to output by discarding speech packet information and/or reducing speech packet information rate; and

controlling the selected vocoder, in response to the packet modification control signal, when output encoded speech was modified by;

recovering a previous speech packet that was discarded and updating filter state data for use in generating a subsequent speech packet;

facilitating decaying of speech parameters for use in generating subsequent speech packets, in response to the packet modification control signal, when the modification resulted from discarding speech encoded information; and

varying a rate of encoding for the subsequent speech packet, in response to the packet modification control signal, when the modification resulted from reducing a speech packet output rate.

9. The method of claim 8 wherein the communication system is a CDMA system and a network arbiter generates the packet modification control signal for the selected variable rate vocoder indicating whether the output encoded speech was modified prior to output.

10. A system for controlling speech encoding in a communication system comprising:

means for receiving encoded speech packets from a plurality of variable rate vocoders;

means for determining a required link bandwidth for transmission of encoded packets of voice based on the received encoded speech packets;

means for comparing the required link bandwidth with an available link bandwidth;

means for outputting encoded speech over the link;

means, responsive to the output encoded speech, for generating a packet modification control signal for a selected variable rate vocoder indicating whether the output encoded speech was modified prior to output; and

means, responsive to the packet modification control signal, for controlling the selected vocoder when output encoded speech was modified.

11. The system of claim 10 wherein the means for generating the packet modification control signal generates the packet modification control signal based on a modification resulting from discarding speech packet information and/or reducing speech packet information rate.

12. The system of claim 11 wherein the means for controlling facilitates recovery of a speech packet corresponding to a speech packet that was discarded and updates filter state data for use in generating a subsequent speech packet.

13. The system of claim 12 wherein the means for controlling facilitates decaying of speech parameters for use in generating subsequent speech packets, in response to the packet modification control signal when the modification resulted from discarding speech encoded information.

14. The system of claim 11 wherein the means for controlling varies a rate of encoding for the subsequent speech packet, in response to the packet modification control signal when the modification resulted from reducing a speech packet output rate.

15. The system of claim 13 wherein the communication system is a CDMA system and a network arbiter generates the packet modification control signal for the selected variable rate vocoder indicating whether the output encoded speech was modified prior to output.

16. A system for controlling speech encoding in a communication system comprising:

a network arbiter having,

means for receiving encoded speech packets from a plurality of variable rate vocoders;

means for determining a required link bandwidth for transmission of encoded packets of voice based on the received encoded speech packets;

means for comparing the required link bandwidth with an available link bandwidth;

means for outputting encoded speech over the link; and

means for generating a packet modification control signal for a selected variable rate vocoder indicating whether the output encoded speech was modified prior to output by discarding speech packet information and/or reducing speech packet information rate; and

wherein the system further has,

means, responsive to the packet modification control signal, for controlling the selected vocoder when output encoded speech was modified wherein the means for controlling recovers a previous speech packet that was discarded and updating filter state data for use in generating a subsequent speech packet;

facilitates decaying of speech parameters for use in generating subsequent speech packets, in response to the packet modification control signal, when the modification resulted from discarding speech encoded information; and

varies a rate of encoding for the subsequent speech packet, in response to the packet modification control signal, when the modification resulted from reducing a speech packet output rate.

17. The system of claim 16 wherein the communication system is a CDMA system and a network arbiter generates the packet modification control signal for the selected variable rate vocoder indicating whether the output encoded speech was modified prior to output.