作者：
Alexandre, EPena, ASobreira, MUniv Alcala de Henares
Dept Signal Theory & Commun Dept Teor Senal & Comun Escuela Politecn Super Alcala De Henares 28805 Spain Univ Vigo
Dept Signal Theory & Commun Dept Teor Senal & Comun ETSE Telecommun Vigo 36310 Spain
This letter presents a method for estimating the quan-. tization noise introduced by a nonuniform quantizer, like those used in the family of MPEG-2/4 AAC audio coders. The method is generalized for the case of estima...
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This letter presents a method for estimating the quan-. tization noise introduced by a nonuniform quantizer, like those used in the family of MPEG-2/4 AAC audio coders. The method is generalized for the case of estimating the mean squared or the maximum value of the quantization noise. Its use will allow the bit-allocation algorithm to be adapted to different coding scenarios, depending on the available number of bits. Using the proposed method, it is possible to implement a loopless bit-allocation algorithm, without the need for using any kind of iteration loops. This helps to dramatically reduce the computational complexity of the bit-allocation algorithm, making it easier to implement in real-time applications where computational,power is limited.
Stereophonic teleconferencing provides more natural acoustic perception by virtue of its enhanced sound localization. Of paramount importance is stereo acoustic echo cancellation (SAEC) that poses a difficult challeng...
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Stereophonic teleconferencing provides more natural acoustic perception by virtue of its enhanced sound localization. Of paramount importance is stereo acoustic echo cancellation (SAEC) that poses a difficult challenge to lowcomplexity adaptive algorithms to achieve acceptable AEC due, mainly, to the strong crosscorrelation between the two-channel input signals. This paper proposes a transform domain two-channel lattice algorithm that inherently decorrelates the stereo signals. The algorithm, however, bears a high computational complexity for large filter orders, N. A lowcomplexity 0(4N) algorithm is developed based on employing the functionality of the two-channel lattice cell in the previous algorithm in a weighted subband scheme. The algorithm is capable of producing complete orthogonal subbands of the stereo signals, and also allows for a tradeoff between performance and complexity. The performance of the proposed algorithms is compared with other existing algorithms via simulations and using actual teleconferencing room impulse responses.
dThis paper presents a fast low-complexity synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems over fading channels. By utilizing the guard interval in OFDM signals, the Frame synchron...
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dThis paper presents a fast low-complexity synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems over fading channels. By utilizing the guard interval in OFDM signals, the Frame synchronization and the frequency offset estimation are considered simultaneously. The Implementation can be simplified by only using the sign bits of the in-phase and the quadrature components of the received OFDM signal for frame synchronization and frequency offset compensation. A frequency-offset independent frame synchronization algorithm is derived, and a low-complexity frequency offset estimator based on the synchronized correlator output is presented in this paper. Due to the subcarrier ambiguity in the guard-interval-based (GIB) frequency detector, the maximum correctable frequency range is limited to +/- 1/2 of the subcarrier spacing. In this paper, we also present a new frequency acquisition scheme that can solve the subcarrier ambiguity problem and extend the frequency acquisition range to nearly a half of the useful OFDM signal bandwidth.
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