Rate adaptation for use in adaptive multi-rate vocoder

• US 8,265,220 B2
• Filed: 10/31/2007
• Issued: 09/11/2012
• Est. Priority Date: 05/15/1998
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Komaili, Jaleh, Wan, Yongbing
• Primary Examiner(s): Williams, Lawrence B
• Application Number:
  US11/932,726
• Publication Number:
  US 20080049661A1
• Time in Patent Office: 1,777 Days
• Field of Search: 375/229, 375/225, 375/242, 375/377, 375/222, 375/219, 375/240, 375/358, 370/225, 370/329, 370/468, 370232-234, 370/252, 370/277, 370/282, 370/333, 370/347, 370/442, 370/477, 370/914, 370/915, 455/422, 455/63, 455/72, 455/452.2, 455/83
• US Class Current: 375/377
• 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 method of receiving voice data from a transmitting side at a receiving side in a wireless communication system, the method comprising:

determining, at the receiving side, a quality indicator of a communication channel by measuring a channel quality metric;

determining, at the receiving side, a first vocoder rate based on the determined quality indicator, wherein the first vocoder rate is for the receiving side to request the transmitting side to use to encode voice data to be received by the receiving side via a first direction link;

transmitting, from the receiving side to the transmitting side via a second direction link, a first data frame including first rate bits indicating the first vocoder rate to request the transmitting side to use the first vocoder rate; and

receiving, at the receiving side from the transmitting side via the first direction link, a second data frame including soft-coded second rate bits to inform the receiving side of a second vocoder rate that was applied when encoding voice data presently received via the first direction link, third rate bits informing the receiving side of a third vocoder rate to be used for transmission via the second direction link, and the voice data,

wherein the receiving side is informed of the second vocoder rate that was applied when encoding the presently received voice data based on the soft-coded second rate bits even though the second vocoder rate is different from the first vocoder rate requested by the receiving side.

2. The method of claim 1, wherein determining the first vocoder rate comprises considering hysteresis.

3. The method of claim 1, wherein the transmitting side is a base station and the receiving side is a mobile station.

4. The method of claim 1, wherein the transmitting side is a mobile station and the receiving side is a base station.