The Effects Of Dimming Mechanism For The Transmission And Detection Of OFDM Signals In Indoor Lighting System

Nowadays, white LED becomes more and more popular due to the shortage of energy. WhiteLED will become an ideal lighting source because it has many advantages. Indoor visible lightcommunication is developed on the basis of white LED. This technology has the advantages suchas saving energy and safe, no electromagnetic interference, good safety and so on.In recent years, many researchers have done a lot research in this field. This paper discussedsystem performance and some improvements in dimming control system and system withoutdimming control, it contains the following works.Firstly, this paper analyzes the basic principle of OFDM, the indoor visible lightcommunication channel, and a system model is built. This paper analyzes two OFDMtransmission schemes which can be used in indoor lighting system, and demonstrates theirfeasibility.Secondly, this paper analyzes the performance of OFDM signal in the system withoutdimming. We study the schemes and find out which scheme is more suitable for indoor lightingsystem. In addition, different degree of clipping will appear due to the improper set of DC biasand modulation index which is the result of high PAPR. Because different sub-channels of OFDMcan use different constellation mapping methods, we study the system performance underdifferent constellation mapping methods.Finally, in the dimming control system, because OFDM signal can be transferred in the onduration only, OFDM frame is need to be coordinated well with the dimming solution to ensurethe indoor visible light communication. In this paper, we propose a new dimming control schemefor the transmission of OFDM signal in the indoor visible light communication. In this paper, weintroduce this new scheme and analysis its advantages and system performance throughsimulation.