1,720,985 research outputs found
Unicast, multicast and hybrid architecture for error resilient video streaming
No full textIn this work we discuss different architectures for error resilient video streaming. The architectures exploit a resilient video coding scheme, based on out-of-band transmission of suitable redundant information, that counteracts synchronization loss between the decoder and the bitstream due to transmission errors. We investigate unicast and multicast video streaming solutions and show a power/bandwidth efficient hybrid unicast/multicast architecture. Experimental results show the decoded video quality obtained by adopting the resilient streaming architecture in the case of H.264 coding. © 2005 IEEE
Asymptotically efficient phase recovery for QAM communication systems
No full textWe introduce a new blind phase offset estimator for general Quadrature Amplitude Modulated (QAM) signals. The estimator is based on the computation of a suitable phase distribution that we call "Signature". The Signature is defined as the phase-dependent distribution of the received signal magnitude after the application of a nonlinear transformation. The Signature of a QAM signal is constituted by a discrete number of pulses and it has good autocorrelation properties in the sense of maximum/side-lobe ratio. Since the effect of a phase offset is a cyclic shift of the Signature, the phase offset can be estimated by searching for the maximum of the cyclic cross-correlation between the zero-phase Signature of the expected constellation, and the Signature calculated on the received signal. The resulting estimator is characterized by a low computational complexity and does not need gain control. The comparison shows that the presented estimator is asymptotical efficient and outperforms existing estimators for medium to high values of SNR, especially for complex constellations. © 2006 IEEE
Error resilient video coding for wireless channels
No full textThis work describes how the introduction of redundancy by means of coding constraints known at the decoder side improves the error resilience of a video communication scheme. The decoder can exploit the a priori knowledge of the constraints to verify the integrity of the decoded bitstream. If the transmission errors cause the violation of the coding constraints, the decoder detects an error and recovers the synchronization with the bitstream. The improved detection capability results in better localization of the decoded frame areas affected by transmission errors, so allowing more accurate error concealment. The adoption of coding constraints does not require any feedback channel between the decoder and the coder since the decoder can be notified of the constraints during the initial negotiation phase. The syntax of the coder output is not affected and the coded bitstream remains standard compliant. Therefore, this technique is quite general and it is well suited to many transport schemes, either packet switched or circuit switched. Furthermore, it can be easily integrated with different error resilience tools. The improvement achievable in the decoded image quality using the coding constraints is here shown in the case of H.264 coded video
Blind equalization for correlated input symbols: a Bussgang approach
No full textThis paper addresses the problem of blind equalization in the case of correlated input symbols, and it shows how the knowledge of the symbol sequence probability distribution can be directly incorporated in a Bussgang blind equalization scheme. Numerical results pertaining to both linear and nonlinear modulation schemes show that a significant improvement in equalization performance is obtained by exploiting the symbol sequence probability distribution using the approach herein described
Multichannel blind image deconvolution using the Bussgang algorithm: spatial and multiresolution approaches
No full textNon linear estimators for multichannel blind image deconvolution using the Bussgang algorithm: a spatial and a multiresolution approach
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