Dynamic capacity operating point management for a vocoder in an access terminal

• US 20070192090A1
• Filed: 02/15/2006
• Published: 08/16/2007
• Est. Priority Date: 02/15/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Shahidi, Reza
• Granted Patent: US 8,036,242 B2
• Time in Patent Office: Days
• US Class Current: 704/221
• CPC Class Codes: H04L 1/0014 by adapting the source coding
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication

Abstract

A variable rate vocoder is configured to encode speech signals with a plurality of encoding rates and to change from a first encoding rate to a second encoding rate according to a received signal indicating reverse link load.

Claims

1. An apparatus comprising:

a variable rate vocoder configured to encode speech signals with a plurality of encoding rates, the variable rate vocoder being configured to change from a first encoding rate to a second encoding rate according to a received signal indicating reverse link load.

2. The apparatus of claim 1 further comprising a processing unit configured to receive the signal indicating reverse link load and instruct the variable rate vocoder to change from the first encoding rate to the second encoding rate.

3. The apparatus of claim 2, wherein the processing unit is configured to filter the received signal indicating reverse link load.

4. The apparatus of claim 3, wherein the processing unit comprises an infinite impulse response (IIR) filter configured to filter the received signal indicating reverse link load according to:

y(n)=(1−

1/τ

)×

y(n−

1)+(1/τ

)×

x(n)

where n denotes a time index in slots, τ

denotes a filter time constant, y denotes the IIR filter output, and x denotes the IIR filter input.

5. The apparatus of claim 3, wherein the first encoding rate is higher than the second encoding rate, the variable rate vocoder being configured to downgrade from the first encoding rate to the second encoding rate when the filtered signal indicating reverse link load is larger a first threshold value for a first period of time.

6. The apparatus of claim 5, wherein the variable rate vocoder is configured to upgrade from the second encoding rate to the first encoding rate when the filtered signal indicating reverse link load is smaller than a second threshold value for a second period of time.

7. The apparatus of claim 6, wherein the first period of time is associated with the first encoding rate, the first period of time being unequal to the second period of time associated with the second encoding rate.

8. The apparatus of claim 6, wherein the first period of time is associated with downgrading from the first encoding rate to the second encoding rate, the first period of time being shorter than a third period of time associated with downgrading from the second encoding rate.

9. The apparatus of claim 1, wherein the signal indicates a reverse link load in a wireless communication system comprising a plurality of access terminals and at least one base transceiver station, the reverse link referring to signals sent from the access terminals to the base transceiver station.

10. The apparatus of claim 1, wherein the signal indicating reverse link load comprises a reverse activity bit (RAB) in a code division multiple access (CDMA) EV-DO communication system.

11. The apparatus of claim 1 wherein each encoding rate is associated with a capacity operating point.

12. A variable rate vocoder configured to encode speech signals with a plurality of encoding rates, the variable rate vocoder being configured to change from a first encoding rate associated with a first operating point to a second encoding rate associated with a second operating point according to a filtered signal indicating reverse link load.

13. A method comprising:

receiving a signal indicating reverse link load;

processing the signal; and

based on the processed signal, changing a speech signal encoding rate from a first encoding rate to a second encoding rate.

14. The method of claim 13, wherein the signal indicates a reverse link load in a wireless communication system comprising a plurality of access terminals and at least one base transceiver station, the reverse link referring to signals sent from the access terminals to the base transceiver station.

15. The method of claim 13, wherein the processing comprises filtering the received signal indicating reverse link load with an infinite impulse response (IIR) filter according to:

y(n)=(1−

1/τ

)×

y(n−

1)+(1/τ

)×

x(n)

where n denotes a time index in slots, τ

denotes a filter time constant, y denotes the IIR filter output, and x denotes the IIR filter input.

16. The method of claim 13, wherein the first encoding rate is higher than the second encoding rate, the method comprising downgrading from the first encoding rate to the second encoding rate when the filtered signal indicating reverse link load is larger a first threshold value for a first period of time.

17. The method of claim 16, further comprising upgrading from the second encoding rate to the first encoding rate when the filtered signal indicating reverse link load is smaller than a second threshold value for a second period of time.

18. The method of claim 16, wherein the first period of time is associated with the first encoding rate, the first period of time being unequal to the second period of time associated with the second encoding rate.

19. The method of claim 16, wherein the first period of time is associated with downgrading from the first encoding rate to the second encoding rate, the first period of time being shorter than a third period of time associated with downgrading from the second encoding rate.

20. The method of claim 13, wherein the signal indicates a reverse link load in a wireless communication system comprising a plurality of access terminals and at least one base transceiver station, the reverse link referring to signals sent from the access terminals to the base transceiver station.

21. The method of claim 13, wherein the signal indicating reverse link load comprises a reverse activity bit (RAB) in a code division multiple access (CDMA) EV-DO communication system.