Reducing correlation noise in Wyner-Ziv video coding

The research work disclosed in this publication is partially funded by the Strategic Educational Pathways Scholarship Scheme (Malta). The scholarship is part-financed by the European Union – European Social Fund. (ESF 1.25).Over the past few decades, Distributed Video Coding (DVC) has been considered as a compression paradigm suitable for applications which require simple encoding. Yet, the performance obtained with practical architectures is still far from the theoretical bound, mainly due to the inaccurate Side Information (SI) predicted at the decoder. The work presented in this paper tries to improve the correlation between the bit-planes of the SI and the corresponding bitplanes of the Wyner-Ziv (WZ) frame. The proposed algorithm uses the adjacent key frames to predict the quantization intervals for the SI and for the WZ frame. It then chooses whether the quantization module should use the floor or the ceiling operationsuch that theindices generated for the two frames differ by the smallest number of bits possible. Experimental results show that, for a given target quality, the proposed method can reduce the WZ bit-rate by up to 8.4% compared to the traditional coding schemes.peer-reviewe

Improved depth maps coding efficiency of 3D videos

The research work disclosed in this publication is partially funded by the Strategic Educational Pathways Scholarship Scheme (Malta). The scholarship is part-financed by the European Union – European Social Fund.Immersive 3D video services demand the transmission of the viewpoints' depth map together with the texture multiview video to allow arbitrary reconstruction of intermediate viewpoints required for free-view navigation and 3D depth perception. The Multi-view Video Coding (MVC) standard is generally used to encode these auxiliary depth maps and since their estimation process is highly computational intensive, the coding time increases. This paper proposes a technique that exploits the multi-view geometry together with the depth map itself to calculate more accurate initial compensation vectors for the Macro-blocks' estimation. Starting from a more accurate position allows for a smaller search area, reducing the computations required during depth map MVC. Furthermore, the SKIP mode is extended to predict also the disparity vectors from the neighborhood encoded vectors, to omit some of them from transmission. Results demonstrate that these modifications provide an average computational reduction of up-to 87% with a bitrate saving of about 8.3% while encoding an inter-view predicted viewpoint from a depth map multi-view video.peer-reviewe

A consensus approach for cooperative communications in cognitive radio networks

In this paper, we investigate a decentralized power allocation (PA) algorithm, i.e., without the need of a fusion center, for a coalition of bit-interleaved coded (BIC) OFDM-based cognitive radio (CR) devices. Taking advantages of a game theoretical description for our problem, it is shown that the reliability of the secondary cooperative link can be remarkably improved through a simple average consensus algorithm keeping the interference produced to the primary users (PUs) under a prescribed threshold. Finally, the performance gain of the proposed PA policy is highlighted comparing it with conventional power allocation algorithms. © 2012 EURASIP