Visible light communications (VLCs) using light-emitting-diodes (LEDs) as communication devices have developed rapidly with the widespread deployment of solid-state illumination. However, the modulation bandwidth of LEDs is one of the dominant issues that limit the VLC system efficiency. Although plenty of techniques have been investigated to deal with this restriction, few people pay attention to the theoretical analysis of LED illumination process. The light-conversion concept shows significant influence on the white LED transmission modeling and receiving technologies. We propose an LED response modeling approach based on the white light generation process and its spectral characteristics, as well as the corresponding signal receiving methods. A dual-pole zero-forcing equalizer (ZFE) is designed, and the analytical signal-to-noise ratios (SNRs) of the output signal with different receiving processes are derived. Simulation results show that SNR is effectively improved by adopting the proposed ZFE, and the dual-pole equalizer can effectively improve system bit error rate performance with different transmission rate. Under the practical lighting scenario, transmission rate can reach up to 70 Mbps over a 1.5 m line-of-sight link. Meanwhile, a minimum data rate of 30 Mbps can be supported within a coverage area of 3 m in diameter. |
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Light emitting diodes
Visible light communication
Signal to noise ratio
Frequency response
Tunable filters
Signal processing
Telecommunications