In this study, the authors propose a new precoding-aided spatial modulation (SM) to improve the transmission performance over significantly high correlated indoor multi-input multi-output visible light communication (...
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In this study, the authors propose a new precoding-aided spatial modulation (SM) to improve the transmission performance over significantly high correlated indoor multi-input multi-output visible light communication (MIMO-VLC) channels. Especially, their precoder design relies on the fixed-sized light-emitting diode (LED) grouping and transmit beamforming, which plays an important role in enhancing the system performance. First, they propose an approximate discrete-input continuous-output memoryless channel capacity based precoder design, which offers better performance at the cost of high-computational complexity. As far as large-scale MIMO-VLC schemes are considered, the proposed precoder design presents to be impractical. Therefore, they develop a spatial correlation measure-based fast LED grouping algorithm to construct the precoder for large-scale MIMO-VLC systems. Their simulation results show that the proposed precoding-aided SM scheme can outperform the precoding-aided spatial multiplexing over significantly high correlated large-scale MIMO-VLC channels when the proposed fast LED grouping is performed, whereas the latter scheme can perform better than their proposed scheme for less correlated channels.
high-efficiency video coding (HEVC) is the latest video coding standard aimed to reduce the bitrate by half for the same video quality compared to H.264/AVC. This encoding performance makes HEVC more suitable for high...
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high-efficiency video coding (HEVC) is the latest video coding standard aimed to reduce the bitrate by half for the same video quality compared to H.264/AVC. This encoding performance makes HEVC more suitable for high-definition video applications. However, this performance is coupled with a high-computational complexity, which makes it hard to achieve real-time video encoding with a classic embedded processor. Multicore technology of programmable processors could be a very promising solution to overcome this computationalcomplexity. Moreover, software optimisations by proposing fast algorithms for the most complex functions could also be an efficient solution to speed up the encoding process. In this context, this study presents a fast mode decision algorithm for the intra prediction module. This algorithm aims to reduce the number of intra prediction modes to be tested instead of performing a full intra mode search. Experimental results for all-Intra configuration show that the proposed fast intra mode decision allows saving up to 46.79% of the intra prediction time in average. Encoding performance in terms of video quality and bitrate is not significantly affected.
3D videos have attracted attention from academia and industry after great success in the film industry. Multiview video plus depth (MVD) is the most popular 3D video format to provide vivid 3D feeling and has been ado...
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3D videos have attracted attention from academia and industry after great success in the film industry. Multiview video plus depth (MVD) is the most popular 3D video format to provide vivid 3D feeling and has been adopted as an international 3D video coding standard, namely 3D extension of high efficiency video coding (HEVC). MVD includes a limited number of textures and depth maps to synthesise virtual views. In MVD, depth samples describe the distance between a camera and an actual object as a grey-level image. The characteristics of depth maps are quite different from texture images. Consequently, new coding tools are designed for depth maps in 3D-HEVC to improve the coding efficiency at the expense of high-computational complexity, which faces great challenges in coding systems. Depth map coding is also an important technique in immersive media to support three degrees of freedom 3DoF+/6DoF applications such as virtual reality/augmented reality. The study starts with an overview of what has been done over the last decade in 3D-HEVC, especially depth map coding, regarding theories, methodologies, current research and state-of-the-art fast approaches. Following this, a comprehensive comparison of the reviewed techniques is presented, and an outlook on its future trends is provided.
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