As an emerging wireless communication technique, visible light communication is experiencing a boom in the global communication field, and the dream of accessing to the Internet with light is fast becoming a reality. The objective of this study was to put forward an efficient and theoretical scheme that is based on generalized spatial modulation to reduce the bit error ratio in indoor short-distance visible light communication. The scheme was implemented while using two steps in parallel: (1) The multi-pulse amplitude and the position modulation signal were generated by combining multi-pulse amplitude modulation with multi-pulse position modulation using transmitted information, and (2) certain light-emitting diodes were activated by employing the idea of generalized spatial modulation to convey the generated multi-pulse amplitude and position modulation optical signals. Furthermore, pulse width modulation was introduced to achieve dimming control in order to improve anti-interference ability to the ambient light of the system. The two steps above involved the information theory of communication. An embedded hardware system, which was based on the C8051F330 microcomputer and included a transmitter and a receiver, was designed to verify the performance of this new scheme. Subsequently, the verifiability experiment was carried out. The results of this experiment demonstrated that the proposed theoretical scheme of transmission was feasible and could lower the bit error ratio (BER) in indoor short-distance visible light communication while guaranteeing indoor light quality.

We propose a data transmission scheme based on the dimming coding and quasi-orthogonal space-time block coding (QOSTBC) to improve the performance of indoor multiple-input multiple-output visible-light communication (MIMO-VLC) systems. After channel coding, the dimming coding was first applied to encode the input information bits into dimming bits. Then these encoded dimming bits were mapped to different symbols by head pulse position modulation. Finally, the symbol matrix was constructed on the basis of QOSTBC; then the light-emitting diodes would be activated to transmit the optical signals carrying the information according to the symbol matrix. The Monte Carlo simulations demonstrated the superiority of the proposed scheme in channel capacity and bit error ratio (BER). The channel capacity was a good approximation to the actual one, even though the full diversity gain could not be completely achieved. The BER could achieve 0.4 × 10 − 6 when the number of photodetectors was two.

As an emerging technique of wireless communication, visible light communication is experiencing a boom in the global communications field, and the dream of accessing the Internet with light is fast becoming a reality. Multiple input multiple output, which is a key technique in radio frequency communication, can multiply channel capacity. However, it suffers the trouble of too large channel correlation when directly applied to visible light communication. The aims of this paper were to investigate spatial modulation and cooperative communication, then put forward a cooperative strategy based on space–time labeling diversity for indoor visible light communication systems to achieve high reliability. This scheme was conceived in two steps: (1) a cooperative indoor visible light communication system with a source luminaire, a relay luminaire, and a destination receiver was set up by employing the idea of cooperative transmission. Relative to the destination receiver, these two luminaires can be symmetric or asymmetric in geographical distribution. (2) Space–time labeling diversity of the constellations at the source luminaire was re-adjusted at the relay luminaire to enlarge the product of the distance of corresponding points on both constellations and was introduced on the basis of spatial modulation. Furthermore, total bit error ratio of the proposed cooperative indoor visible light communication system was derived. This scheme was implemented through Monte Carlo simulation. Evaluations of performance demonstrated the superiority of the cooperative strategy based on space–time labeling diversity over conventional optical transmission schemes. The presented approach in this paper could be of some value and interest to those who are working on visible light communication devices.

As a new green solid-state light source, semiconductor light-emitting diodes (LEDs) have the advantages of low power consumption, small size, long life, short response time, and good modulation performance. At the same time, the frequency band to which LED light sources belong does not require regulatory registration, thus alleviating the current problem of spectrum scarcity for wireless communications. However, white LED-based visible light communication (VLC) systems suffer from limited bandwidth and low energy efficiency. Therefore, an ARM-based indoor RGB-LED VLC system is proposed. Firstly, the three RGB colours are mixed into white light, thus obtaining a larger modulation bandwidth than normal white LEDs while illuminating normally. Secondly, the S3C6410 processor is used to modulate and demodulate the RGB-LEDs with biased light OFDM, thus obtaining a high spectrum utilisation while ensuring system transmission stability. Then, according to the characteristics of the light source of the VLC system, the leading and window functions used in the optical network transceiver module are designed to improve the communication energy efficiency of the system. Finally, functional tests were carried out on an ARM development board. The experimental results show that with a single RGB-LED light source, the maximum transmission distance is 5cm, the maximum average delay is 68ms, the maximum throughput is 25Mbps, and the BER is controlled below 3.2×10⁻³, which meets the basic communication requirements.