A novel color clustered optical RGB multiple-input multiple-output (MIMO) system is presented. As visible light can be divided into three primary regions of red, green and blue, data can be modulated and transmitted separately using these three color clusters. Each color cluster comprised of 30 RGB LEDs is modulated using on-off-keying (OOK), and selection combining is performed at the receiver, producing a diversity effect within that color cluster. The simulations demonstrate that the proposed RGB MIMO VLC system provides high performance via a relatively simple design of MIMO. Moreover, the proposed system ensures sufficient illumination from LEDs and offers extended distance if more LEDs are applied.
A 3-Gb/s high-speed indoor visible light communication system using optical diversity schemes is presented. A double optical diversity (DOD) scheme in time and frequency is employed with selection combining (SC) on the basis of red, green, and blue (RGB) light-emitting diodes (LEDs). In the proposed scheme, the original data and the delayed versions of this data are transmitted simultaneously by multiplying with orthogonal frequency in order to create diversity effect over the transmission. In addition, RGB LEDs are used for parallel transmission of data, thus resulting in an increase in the data speed. At the receiver, color filters are used to filter out for the desired signal, and SC is performed to obtain the most probable bits. Simulation results demonstrate that the proposed scheme is robust and efficient to overcome the effect of multiple reflections with a link margin of approximately 10 dB, as compared with a conventional on-off keying (OOK) modulation scheme at a bit error rate (BER) of 10 À6 . Moreover, the scheme achieves a data rate of 3 Gb/s with a BER of 10 À6 at a signal-to-noise ratio (SNR) value of 3.6 dB over most locations in an indoor visible light communication (VLC) environment.
A 2 Gbit/s visible-light communication (VLC) scheme using time-frequency color-clustered (TFCC) multiple-input multiple-output (MIMO) based on blue, cyan, yellow, and red (BCYR) light-emitting diodes (LEDs) is presented. In the proposed scheme, BCYR LEDs are employed to form four different color clusters. Data transmission using the four color clusters is performed in MIMO, so that the scheme achieves a very high speed of data transmission. Moreover, the scheme employs the TFCC strategy to yield high performance in terms of bit error rate (BER). TFCC operates in such a way that the original data and the two delayed versions of the data are multiplied by orthogonal frequencies and then transmitted using a specific color of the BCYR LED. In the receiver, color filters are employed to detect the data transmitted from the desired cluster. Selection combining (SC) is also performed to yield a diversity effect within each color cluster, to further improve the performance. Performance evaluation demonstrates that the proposed TFCC MIMO VLC offers a data rate of 2 Gbit/s and a bit error rate of 4×10 , at an Eb/No value of merely 3 dB.
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