Color Intensity Modulation for Multicolored Visible Light Communications

Abstract

This letter explains color space and signal space in visible light communications using multicolored LEDs. We propose the concept of color intensity modulation that satisfies color and dimming requirements in color space and maximizes communication capacity in signal space. The capacity values and corresponding signal constellation examples are given for orthogonal and nonorthogonal channels. Index Terms-Color matching, dimming, inverse source coding (ISC), optical wireless communication, visible light communication (VLC).

A Deep Learning Approach to Universal Binary Visible Light Communication Transceiver

“…The remaining task for the stochastic binarization is to identify the gradient ∇s b,d for training the encoding neural network parameter Θ E through the SGD algorithm in (7). However, no closed-form expression for the gradient ∇s b,d exists due to the stochastic operation (9). To handle this, we employ an unbiased estimation on the gradient as…”

“…In this section, we present an efficient training algorithm for the proposed DNN transceiver under the dimming constraint (3). The proposed training algorithm includes the optimization of the encoding network parameter Θ E along with the stochastic binarization (9) and the decoding network parameter Θ D .…”

“…Intensity modulation and direct detection (IM/DD) technique is considered a major approach to convey a message via a nonnegative real-valued optical signal [9]- [11]. In addition, the average and peak intensity restriction imposed by LED property, human physiologic effect and external preference require a careful design of binary transmission strategy when dimming control is achieved by utilizing on-off keying (OOK) [12]- [15].…”

Performance evaluation of IEEE 802.15.7 CSK physical layer

“…modulation (CIM) explained in [11] has not been considered in this paper. Equation 7 shows the overall electrical noise that is added to the transmitted chromaticities at the receiver.…”

Optimal Signal Amplitude of Orthogonal Frequency-Division Multiplexing Systems in Dimmable Visible Light Communications

“…Color-shift keying (CSK) [26,35,36] positions the signal constellation according to color and controls dimming by the signal amplitude (optical power) for multicolored VLC. Although CSK modulates the signal under the constraint of a fixed overall intensity, color-intensity modulation [37] allows the simultaneous use of colors and intensities for dimming support and outperforms CSK. In addition, multiple codeword allocation [38] was used for dimming support, and the channel coding issues for binary transmission in dimmable VLC using Reed-Muller codes [39,40] and turbo codes [41] were addressed.…”