Screen-camera communications, using a liquid crystal display (LCD) screen and camera image sensors, have been attractive variants of visible light communications (VLC) since any external light-emitting modules and pho...
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Screen-camera communications, using a liquid crystal display (LCD) screen and camera image sensors, have been attractive variants of visible light communications (VLC) since any external light-emitting modules and photo detectors are required for recent mobile devices, which are usually equipped with display and camera. A major issue in screen-camera communications is a performance loss in transmission rate due to nonlinear channel impairments with ambient noise. To improve transmission rates, we investigate the impact of nonlinear channel equalization, nonbinary channel coding, probabilistic shaping, and nonlinear precoding for high-order modulation schemes. Experimental evaluations using an LCD screen and camera demonstrate that our proposed scheme achieves 3.8-3.3 times higher transmission rates compared to existing schemes for a communication distance of 60-160 cm.
Shannon's determination of the capacity of the linear Gaussian channel has posed a magnificent challenge to succeeding generations of researchers. This paper surveys how this challenge has been met during the past...
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Shannon's determination of the capacity of the linear Gaussian channel has posed a magnificent challenge to succeeding generations of researchers. This paper surveys how this challenge has been met during the past half century. Orthogonal minimum-bandwidth modulation techniques and channel capacity are discussed Binary coding techniques for lo low-signal-to-noise ratio (SNR) channels and nonbinary coding techniques for high-SNR channels are reviewed. Recent developments, which now allow capacity to be approached on any linear Gaussian channel, are surveyed. These new capacity-approaching techniques include turbo coding and decoding, multilevel coding, and combined coding/precoding for intersymbol-interference channels.
We consider the application of non-binary coding schemes to vector channels, in particular we apply q-ary LDPC codes to multiple-antenna transmission schemes. Based on the principle of providing a good equivalent chan...
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ISBN:
(纸本)9781424493326
We consider the application of non-binary coding schemes to vector channels, in particular we apply q-ary LDPC codes to multiple-antenna transmission schemes. Based on the principle of providing a good equivalent channel to the coding scheme, we directly map the code symbols to the transmit signal and find some suitable multi-dimensional mappings. The performance is assessed by simulations and we find that non-binary coding with direct mapping provides a significant advantage over its binary counterpart and over some space-time diversity schemes.
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