Nokia Mobile Phones Limited

Other

Nokia Corporation

Fenghua Liu

Sassan Ahmadi

Allen Gersho

Vladimir Cuperman

Ajit V Rao

Jigneshkumar P Shah

Alireza Ryan Heidari

Jan Linden

Ryan Heidari

Tung-Chiang Yang

Provided are improved systems and methods for spread spectrum communication employing hybrid Eb/No and pilot-based finger lock determination for RAKE receivers. Finger lock thresholds are periodically set using an extended time-averaged Eb/No traffic signal estimate for each finger mapped to an Ec/No pilot level, where the extended time-averaged Eb/No estimate is inversely proportional to the mapped Ec/No level, thus, decreasing the required Ec/No level when the Eb/No estimate increases and increasing the required Ec/No level when the Eb/No estimate decreases. Existing pilot-based finger lock algorithms may be used with the Ec/No threshold set using the extended time-averaged Eb/No estimate. When pilot signals are weak but traffic signals remain strong, fingers will remain locked to increase the combiner output signal-to-noise ratio.

Apparatus and method for hybrid traffic and pilot signal quality determination of finger lock status of rake receiver correlators

A variable bit rate coder, and an associated method, for encoding a frame of speech, such as frames of data generated during operation of a communication station operable in a cellular communication system. Selection of the coding rate is made responsive to indicia of actual coding performance of a coder at more than one coding rate.

Variable bit rate coder, and associated method, for a communication station operable in a communication system

A speech coder and a method for speech coding wherein the speech signal is represented by an excitation signal applied to a synthesis filter. The speech is partitioned into frames and subframes. A classifier identifies which of several categories the speech frame belongs to, and a different coding method is applied to represent the excitation for each category. For some categories, one or more windows are identified for the frame where all or most of the excitation signal samples are assigned by a coding scheme. Performance is enhanced by coding the important segments of the excitation more accurately. The window locations are determined from a linear prediction residual by identifying peaks of the smoothed residual energy contour. The method adjusts the frame and subframe boundaries so that each window is located entirely within a modified subframe or frame. This eliminates the artificial restriction incurred when coding a frame or subframe in isolation, without regard for the local behavior of the speech signal across frame or subframe boundaries.

Adaptive windows for analysis-by-synthesis CELP-type speech coding

A process for generation of codevectors in the production of synthetic speech in a communication system employing code-excited linear prediction (CELP) is implemented by dividing frames of sampled speech into sub-frames for which are generated codevectors suitable for excitation of synthesizer filters in the low-bit mode of signal transmission. Vector quantization (VQ) is employed with an algebraic representation of the CELP. A reduction of a sub-frame of 6.7 milliseconds to a vector representation of only 8 pulses results in an insufficiency of candidate codevectors, which insufficiency is overcome by a circular shifting of the codevectors at a cyclical rate equal to the pitch of the original voice signal.

Vector quantization in celp speech coder

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Fenghua Liu