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1. (WO2007005444) METHOD AND SYSTEM FOR BANDWIDTH EXPANSION FOR VOICE COMMUNICATIONS
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CLAIMS

1. A method for bandwidth extension for voice communications, comprising:
receiving an unknown voice signal;
identifying the voice bandwidth of the received unknown voice signal;
establishing a region of support in view of the spectral content of the received voice signal; and
selecting a combination of mapping databases from a plurality of mapping databases, each mapping database associated with a predetermined bandwidth extension range for extending the voice bandwidth.

2. The method according to claim 1 , wherein establishing a region of support comprises:
issuing a request to an underlying object to return a list of sampling frequencies for which the object is capable of supporting;
identifying spectral limits based on the returned sampling frequency; and
determining spectral bands within the spectral limits for extending the voice bandwidth to regions that reside outside the voice bandwidth.

3. The method according to claim 1 , wherein selecting a combination of mapping databases is a sequential operation and further comprises applying a serial combination of mapped databases to collectively extend the voice bandwidth to a range corresponding to the addition of the selected bandwidth extension ranges.

4. The method according to claim 1 , further comprising:
acquiring a set of narrowband reflection coefficients that represent the spectral envelope from the voice signal; and
extending the set of narrowband reflection coefficients to a set of wideband reflection coefficients using the mapping databases for generating a wideband spectral envelope.

5. The method according to claim 1 , further comprising:
extracting a narrowband excitation signal from the voice signal using a set of wideband reflection coefficients or a set of narrowband linear prediction analysis coefficients; and
extending the narrowband excitation signal to a wideband excitation signal using modulation and filtering.

6. The method according to claim 1 , further comprising:
combining a wideband excitation signal with a wideband spectral envelope to generate a synthetic wideband voice signal;
extracting a supplemental wideband voice signal from the synthetic wideband voice signal in the region of support; and
adding the supplemental synthetic wideband voice signal with the voice signal to generate a wideband voice signal.

7. A system for artificially extending the bandwidth of voice, comprising:
an evaluation section that receives an unknown voice signal and determines an allowable extent of voice bandwidth for the unknown voice signal;
a database selector cooperatively coupled to the evaluation section, wherein the database selector chooses a combination of mapping databases according to the allowable extent of voice bandwidth; and
a bandwidth extension unit cooperatively coupled to the evaluation section and the database selector, wherein the bandwidth extension unit extends the voice bandwidth of the unknown voice signal to the allowable extent of voice bandwidth using the combination of mapping databases chosen by the database selector.

8. The system of claim 7, wherein the evaluation section comprises:
an analysis module that identifies a voice bandwidth associated with the unknown voice signal;
an inquiry module cooperatively coupled to the analysis module, wherein the inquiry module identifies supported sampling rates, wherein the supported sampling rates reveal the extent to which the voice bandwidth can be extended; and
a sampling module cooperatively coupled to the analysis module and the inquiry module, wherein the sampling module re-samples the unknown voice signal at one of the supported sampling rates identified by the inquiry module, wherein the re-sampling prepares the voice signal for bandwidth extension.

9. The system of claim 7, wherein the bandwidth extension unit comprises:
an envelope processor cooperatively coupled to the evaluation section and the database selector, wherein the envelope processor determines a narrowband spectral envelope from the voice signal and subsequently provides a set of wideband coefficients representing a wideband spectral envelope;
an excitation processor cooperatively coupled to the evaluation section and the envelope processor, wherein the excitation processor determines a narrowband excitation signal from the voice signal using a set of wideband reflection coefficients or a set of narrowband linear prediction analysis coefficients and subsequently creates a wideband excitation signal; and
a mixing processor cooperatively coupled to the evaluation section, the envelope processor and the excitation processor, wherein the mixing processor combines the voice signal together with the wideband excitation signal and the wideband spectral envelope for creating a wideband voice signal.

10. The system of claim 9, wherein the envelope processor comprises:
a feature extractor that acquires a set of linear prediction analysis coefficients that represent the spectral envelope of the voice signal;
a narrowband converter communicatively coupled to the feature extractor, wherein the narrowband converter converts the set of linear prediction analysis coefficients into a set of narrowband reflection coefficients;
an estimator communicatively coupled to the narrowband converter, wherein the estimator, in conjunction with the database selector, extends the set of narrowband reflection coefficients to a set of wideband reflection coefficients using the mapping databases; and
a wideband converter communicatively coupled to the estimator, wherein the wideband converter converts the wideband reflection coefficients into a set of wideband linear prediction analysis coefficients.