Rate adaptation for use in adaptive multi-rate vocoder

• US 20030002446A1
• Filed: 04/16/2002
• Published: 01/02/2003
• Est. Priority Date: 05/15/1998
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Komaili, Jaleh, Wan, Yongbing
• Granted Patent: US 7,164,710 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: G10L 19/24 Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
• CPC Class Codes: H04L 1/0011 applied to payload information
• CPC Class Codes: H04L 1/0014 by adapting the source coding
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 88/181 Transcoding devices; Rate adaptation devices
• CPC Class Codes: Y10S 370/914 Rate converter

Abstract

The present invention includes a time-division-multiple-access (TDMA) communication system having a base station and at least one mobile station, each transmitting and receiving an analog radio-frequency signal carrying digitally coded speech. The speech is encoded using a vocoder which samples a voice signal at variable encoding rates. During periods when the radio-frequency channel is experiencing high levels of channel interference, the encoded voice channel having a lower encoding rate is chosen. This low-rate encoded voice is combined with the high degree of channel coding necessary to ensure reliable transmission. When the radio-frequency channel is experiencing low levels of channel interference, less channel coding is necessary and the vocoder having a higher encoding rate is used. The high-rate encoded voice is combined with the lower degree of channel coding necessary to ensure reliable transmission. The appropriate levels of channel coding necessary for reliable transmission are determined by various channel metrics, such as frame erase rate and bit error rate. The determination of the appropriate vocoder rate and level of channel coding for both the uplink and downlink may be determined centrally at the base station, with the vocoder rate and level of channel coding for the uplink being relayed to the mobile station. Alternatively, the appropriate vocoder rate and level of channel coding for the downlink may be determined by the mobile station, and the appropriate vocoder rate and level of channel coding for the uplink may be determined by the base station.

Claims

1. A wireless communication system comprising:

a mobile station; and

a base station which transmits a downlink signal to the mobile station wherein the downlink signal includes a downlink rate and wherein the mobile station extracts the downlink rate from the downlink signal and decodes the downlink signal using this extracted downlink rate.

2. The wireless communication system of claim 1, wherein the downlink rate is determined by the mobile station using one or more channel quality metrics.

3. The wireless communication system of claim 2, wherein the downlink rate is communicated to the base station by the mobile station using one or more rate bits in a uplink signal.

4. The wireless communication system of claim 3, wherein the one or more rate bits are soft-coded into the uplink signal.

5. The wireless communication system of claim 2, wherein determination of the downlink rate comprises comparing one of the one or more channel quality metrics to a predefined value, and selecting a downlink rate corresponding to the predefined value.

6. The wireless communication system of claim 5, wherein the downlink rate is communicated from the base station to the mobile station using one or more rate bits in the downlink signal.

7. The wireless communication system of claim 6, wherein the one or more rate bits are soft-coded into the downlink signal.

8. The wireless communication system of claim 2, wherein the one or more channel quality metrics includes a frame erase metric.

9. The wireless communication system of claim 2, wherein the one or more channel quality metrics includes a receive quality metric.

10. The wireless communication system of claim 2, wherein the one or more channel quality metrics includes a bit-err or-rate metric.

11. The wireless communication system of claim 2, wherein the one or more channel quality metrics includes an average receive quality metric.

13. The wireless communication system of claim 12, wherein the downlink signal includes the downlink rate.

14. The wireless communication system of claim 12, wherein determination of the downlink rate comprises comparing one of the one or more channel quality metrics to a predefined value, and selecting a downlink rate corresponding to the predefined value.

15. The wireless communication system of claim 12, wherein the downlink rate is communicated from the base station to the mobile station using one or more rate bits in the downlink signal.

16. The wireless communication system of claim 15, wherein the one or more rate bits are soft-coded into the downlink signal.

17. The wireless communication system of claim 12, wherein the one or more channel quality metrics includes a frame erase metric.

18. The wireless communication system of claim 12, wherein the one or more channel quality metrics includes a receive quality metric.

19. The wireless communication system of claim 12, wherein the one or more channel quality metrics includes a bit-error-rate metric.

20. The wireless communication system of claim 12, wherein the one or more channel quality metrics includes an average receive quality metric.

12. A wireless communication system comp rising:

a mobile station which monitor s one or more downlink channel quality metrics, wherein the mobile station determines one or more quantization bits corresponding to the one or more downlink channel quality metrics; and

a base station which receives an uplink signal including the one or more quantization bits from the mobile station, and wherein the base station determines a downlink rate corresponding to the one or more quantization bits and transmits a downlink signal to the mobile station using the downlink rate.

21. A wireless communication system comprising:

a base station; and

a mobile station which transmits an uplink signal to the base station, wherein the uplink signal includes an uplink rate and wherein the base station extracts the uplink rate from the uplink signal and decodes the uplink signal using this extracted uplink rate.

22. The wireless communication system of claim 21, wherein the uplink rate is determined in the base station and communicated to the mobile station.

23. The wireless communication system of claim 21, wherein the uplink rate information is determined by the base station using one or more channel quality metrics.

24. The wireless communication system of claim 23, wherein the channel quality metrics includes a frame erase metric.

25. The wireless communication system of claim 23, wherein the channel quality metrics includes a receive quality metric.

26. The wireless communication system of claim 23, wherein the channel quality metrics includes a bit-error-rate metric.

27. The wireless communication system of claim 23, wherein the channel quality metrics includes an average receive quality metric.

28. A method of maximizing voice quality in a wireless communication system including a base station and a mobile station, the method comprising the steps of:

determining the quality of a downlink communication channel in the mobile station using one or more channel quality metrics;

determining a new downlink rate based on the channel quality metrics;

transmitting the new downlink rate from the mobile station to the base station in an uplink signal;

extracting the new downlink rate from the uplink signal;

creating a downlink signal using the new downlink rate;

encoding the new downlink rate into the downlink signal;

transmitting the downlink signal from the base station to the mobile station;

receiving the downlink signal at the mobile station;

extracting the new downlink rate from the downlink signal; and

decoding the downlink signal using the extracted new downlink rate.

29. A method of maximizing voice quality in a wireless communication system including a base station and a mobile station, the method comprising the steps of:

determining the quality of a downlink communication channel in the mobile station using one or more channel quality metrics;

selecting one or more quantization bits corresponding to the one or more channel quality metrics from a predetermined group of quantization bits;

transmitting the quantization bits from the mobile station to the base station in an uplink signal;

extracting the quantization bits from the uplink signal in the base station;

determining a downlink rate from the extracted quantization bits;

creating a downlink signal using the downlink rate;

encoding the downlink rate into the downlink signal;

transmitting the downlink signal from the base station to the mobile station;

receiving the downlink signal at the mobile station;

extracting the downlink rate from the downlink signal; and

decoding the downlink signal using the extracted downlink rate.

30. A method of maximizing voice quality in a wireless communication system including a base station and a mobile station, the method comprising the steps of:

determining the quality of an uplink communication channel in the base station using one or more channel quality metrics;

determining an uplink rate based on the channel quality metrics;

transmitting the uplink rate from the base station to the mobile station in a downlink signal;

extracting the uplink rate from the downlink signal;

creating an uplink signal using the uplink rate;

encoding the new uplink rate into the uplink signal;

transmitting the uplink signal from the mobile station to the base station;

receiving the uplink signal at the base station;

extracting the new uplink rate from the uplink signal; and

decoding the uplink signal using the extracted uplink rate.

31. A wireless communication system comprising:

means for determining the quality of a downlink communication channel in the mobile station using one or more channel quality metrics;

means for determining a new downlink rate based on the channel quality metrics;

means for transmitting the new downlink rate from the mobile station to the base station in an uplink signal;

means for extracting the new downlink rate from the uplink signal;

means for creating a downlink signal using the new downlink rate;

means for encoding the new downlink rate into the downlink signal;

means for transmitting the downlink signal from the base station to the mobile station;

means for receiving the downlink signal at the mobile station;

means for extracting the new downlink rate from the downlink signal; and

means for decoding the downlink signal using the extracted new downlink rate.

32. A wireless communication system comprising:

means for determining the quality of a downlink communication channel in the mobile station using one or more channel quality metrics;

means for selecting one or more quantization bits corresponding to the one or more channel quality metrics from a predetermined group of quantization bits;

means for transmitting the quantization bits from the mobile station to the base station in an uplink signal;

means for extracting the quantization bits from the uplink signal in the base station;

means for determining a downlink rate from the extracted quantization bits;

means for creating a downlink signal using the downlink rate;

means for encoding the downlink rate into the downlink signal;

means for transmitting the downlink signal from the base station to the mobile station;

means for receiving the downlink signal at the mobile station;

means for extracting the downlink rate from the downlink signal; and

means for decoding the downlink signal using the extracted downlink rate.

33. A wireless communication system comprising:

means for determining the quality of an uplink communication channel in the base station using one or more channel quality metrics;

means for determining an uplink rate based on the channel quality metrics;

means for transmitting the uplink rate from the base station to the mobile station in a downlink signal;

means for extracting the uplink rate from the downlink signal;

means for creating an uplink signal using the uplink rate;

means for encoding the new uplink rate into the uplink signal;

means for transmitting the uplink signal from the mobile station to the base station;

means for receiving the uplink signal at the base station;

means for extracting the new uplink rate from the uplink signal; and

means for decoding the uplink signal using the extracted uplink rate.

35. The wireless communication system of claim 34, wherein the means for determining the quality of the downlink comprises one or more channel quality metrics.

37. The wireless communication system of claim 36, wherein the means for determining the quality of the uplink comprises one or more channel quality metrics.

34. A wireless communication system, comprising:

a base station;

a mobile station which receives a downlink signal from the base station over a downlink, the downlink signal having a ratio of voice data to channel coding;

means for determining the quality of the downlink; and

means for adjusting the ratio of the voice data to channel coding of the downlink signal to improve the quality of the downlink.

36. A wireless communication system, comprising:

a mobile station;

a base station which receives an uplink signal from the mobile station over an uplink, the uplink signal having a ratio of voice data to channel coding;

means for determining the quality of the uplink; and

means for adjusting the ratio of the voice data to channel coding of the uplink signal to improve the quality of the uplink.