# US 9,437,203 B2 · Error concealment for speech decoder > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,203 B2 - Document ID: US9437203B2 - Status: Granted - Kind: B2 - Application number: 14/193,606 - Filed: 2014-02-28 - Published: 2014-09-11 - Granted: 2016-09-06 - Earliest claimed: 2013-03-07 - Assignees: Qosound, Inc. - Applicants: Huan-Yu Su - Inventors: Huan-Yu Su - Web page: https://patentgrep.com/patent/US9437203B2 ## CPC - G10L 19/0208: {Subband vocoders} - G10L 19/005: Correction of errors induced by the transmission channel, if related to the coding algorithm - H04L 1/203: {Details of error rate determination, e.g. BER, FER or WER} - H04L 1/0036: {arrangements specific to the receiver} - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Provided is a system, method, and computer program product for improving the quality of speech reproduction in wireless applications where the received speech frames are subject to transmission and packet losses. The speech decoding process is dynamically delayed by at least one frame period in order to perform additional error correction and concealment techniques during times when the wireless link quality if below a predetermined threshold. The wireless link is monitored and if the link quality falls below a predetermined threshold, the decoding process is delayed by at least one frame period so that one or more error correcting techniques can be performed to increase the quality of the reconstructed speech. ## Claims ### Claim 1 A method for improving the quality of a voice call transmitted over a cellular network through a cellular wireless link to a communication device having a voice decoder for generating reconstructed speech, the method comprising the steps of: monitoring the cellular wireless link to determine a link quality; receiving a voice packet from the cellular wireless link at the decoder; determining if the voice decoder is a normal speech decoder or a delayed speech decoder; if the voice decoder is said delayed speech decoder and said link quality is above a predetermined threshold, dynamically decreasing the latency of the voice call to generate a low-latency voice call by adjusting the voice decoder to said normal speech decoder during silence or background noise periods, and thereafter decoding the voice packet immediately; and if the voice decoder is said normal speech decoder and said link quality is below said predetermined threshold, dynamically increasing the latency of the voice call to generate a high-latency voice call by adjusting the voice decoder to said delayed speech decoder during silence or background noise periods, and thereafter delaying the decoding process to perform at least one error correcting technique using newer information contained in speech packets received after a missing frame for increasing the quality of the reconstructed speech. ### Claim 2 (depends on 1) The method of claim 1, wherein said error correcting technique comprises reconstructing a missing speech frame using at least one prior correctly received speech packet. ### Claim 3 (depends on 1) The method of claim 1, wherein said error correcting technique comprises an interpolation technique for filling in a missing speech frame. ### Claim 4 (depends on 1) The method of claim 1, wherein the error correcting technique uses information from speech packets received both prior to and after a missing speech packet. ### Claim 5 (depends on 1) The method of claim 1, wherein the monitoring step comprises taking quality measurements based on a calculation of a packet loss rate over a period of time. ### Claim 6 (depends on 1) The method of claim 1, wherein the monitoring step comprises taking quality measurements by measuring the radio signal strength. ### Claim 7 (depends on 1) The method of claim 1, wherein the monitoring step comprises taking quality measurements by using channel decoder hard link quality metrics. ### Claim 8 (depends on 1) The method of claim 1, wherein the monitoring step comprises taking quality measurements by using channel decoder soft link quality metrics. ### Claim 9 A system for improving the quality of a voice call transmitted over a cellular network through a cellular wireless link to a communication device having a voice decoder for generating reconstructed speech, the system comprising: a link monitor for monitoring the cellular wireless link to determine a link quality; a receiver for receiving a voice packet from the cellular wireless link; a determination module coupled to the voice decoder for determining if the voice decoder is a normal speech decoder or a delayed speech decoder; and an adjustment module, coupled to the voice decoder for: dynamically decreasing the latency of the voice call to generate a low-latency voice call by adjusting the voice decoder to said normal speech decoder during silence or background noise periods and thereafter decoding the voice packet immediately, if the voice decoder is said delayed speech decoder and said link quality is above a predetermined threshold; and dynamically increasing the latency of the voice call to generate a high-latency voice call by adjusting the voice coder to said delayed speech decoder during silence or background noise periods and thereafter delaying the decoding process to perform at least one error correcting technique using newer information contained in speech packets received after a missing frame, if the voice decoder is said normal speech decoder and said link quality is below said predetermined threshold. ### Claim 10 (depends on 9) The system of claim 9, wherein said error correcting technique comprises reconstructing a missing speech frame using at least one prior correctly received speech packet and another speech packet. ### Claim 11 (depends on 9) The system of claim 9, wherein said error correcting technique comprises an interpolation technique for filling in a missing speech frame. ### Claim 12 (depends on 9) The system of claim 9, wherein the link monitor takes quality measurements based on a calculation of a packet loss rate over a period of time. ### Claim 13 (depends on 9) The system of claim 9, wherein the link monitor takes quality measurements by measuring the radio signal strength. ### Claim 14 (depends on 9) The system of claim 9, wherein the link monitor takes quality measurements by channel decoder hard link quality metrics. ### Claim 15 (depends on 9) The system of claim 9, wherein the link monitor takes quality measurements by channel decoder soft link quality metrics. ### Claim 16 A non-transitory computer program product comprising a computer useable medium having computer program logic stored therein, said computer program logic for enabling a computer processing device to improve the quality of a voice call transmitted over a cellular network through a cellular wireless link to a communication device having a voice decoder for generating reconstructed speech, the computer program product comprising: code for monitoring the cellular wireless link to determine a link quality; code for receiving a voice packet from the cellular wireless link at the decoder; code for determining if the voice decoder is a normal speech decoder or a delayed speech decoder; code for dynamically decreasing the latency of the voice call to generate a low-latency voice call by adjusting the voice decoder to said normal speech decoder during silence or background noise periods and thereafter decoding the voice packet immediately, if the voice decoder is said delayed speech decoder and said link quality is above a predetermined threshold; and code for dynamically increasing the latency of the voice call to generate a high-latency voice call by adjusting the voice decoder to said delayed speech decoder during silence or background noise periods and thereafter performing at least one error correcting technique using newer information contained in speech packets received after a missing frame for increasing the quality of the reconstructed speech, if the voice decoder is said normal speech decoder and said link quality is below said predetermined threshold. ### Claim 17 (depends on 16) The non-transitory computer program product of claim 16, wherein said error correcting technique comprises reconstructing a missing speech frame using at least one prior correctly received speech packet. ### Claim 18 (depends on 16) The non-transitory computer program product of claim 16, wherein said error correcting technique comprises an interpolation technique for filling in a missing speech frame. ### Claim 19 (depends on 16) The non-transitory computer program product of claim 16, wherein said monitoring code comprises code for taking quality measurements based on a calculation of a packet loss rate over a period of time. ### Claim 20 (depends on 16) The non-transitory computer program product of claim 16, wherein said monitoring code comprises taking quality measurements by measuring the radio signal strength. ### Claim 21 (depends on 16) The non-transitory computer program product of claim 16, wherein said monitoring code comprises code for taking quality measurements by channel decoder hard link quality metrics. ### Claim 22 (depends on 16) The non-transitory computer program product of claim 16, wherein said monitoring code comprises code for taking quality measurements by channel decoder soft link quality metrics.