Design Of High Efficient Cooperative Spatial Modulation Scheme In VLC System

Visible Light Communication(VLC)technology can provide huge free spectrum resources,and has become one of the research hotspots in expanding the spectrum resources of wireless communication.Light-emitting diode(LED)provides a new revolutionary light source,which has been successfully integrated into people's daily life.Although LED is a solid-state lighting device,the LED in VLC system has dual functions of lighting and providing broadcast data.Therefore,the LED in VLC system can send data when the human eye is not aware of it.In specific scenarios,VLC can replace traditional radio frequency(RF)communication and further improve system performance through higher data transmission rate.Compared with the traditional RF wireless communication,VLC technology not only has the advantages of high cost performance,but also has the advantages of no license,anti-electromagnetic interference and high security.On the other hand,as an extension of multiple input multiple output(MIMO)technology,spatial modulation(SM)technology effectively overcomes the problems of inter-channel interference and inter-antenna synchronization in VLC,and ensures the reliability and validity of the system and effectively reduces the complexity of the system.In this paper,the efficient cooperative SM scheme in visible light communication system is studied.The efficient SM scheme based on LED grouping and the cooperative index modulation scheme based on incremental hybrid decode-amplify-forward(IHDAF)protocol are proposed.Specific research contents and innovations are summarized as follows:1)In order to improve the transmission rate of VLC system and reduce the correlation of VLC channels,an efficient SM scheme based on LED grouping is proposed.In this scheme,the visible channels are grouped based on the normalized Instantaneous Channel Correlation Matrix(NICCM),so that the groups and groups are independent of each other,and each group forms an independent SM system.Meanwhile,the symbol error rate(SER)of the system is analyzed.The pairwise error probability between symbols is expressed by the Euclidean distance matrix,and the expression of the SER of the system is obtained.Finally,the influence of elevation ansle of receiving photoelectric Detector(PD)on system performance is studied.The simulation results show that the performance of efficient SM scheme based on LED grouping is better than that of traditional SM scheme and generalized spactial modulation(GSM)scheme2)According to the modulation principle of visible light signal and the analysis of VLC channel,an efficient index SM scheme is proposed,and the upper bound representation of SER is deduced theoretically.In this scheme,spatial information and modulation information are transmitted together on the optimal visible light channel,which significantly reduces the complexity of the receiver and effectively improves the reliability of transmission in VLC system.The receiver uses maximum likelihood(ML)detection technology to analyze the SER of the system.The expression of the SER of the system is obtained by defining the Euclidean distance matrix.The simulation results show that the performance of the proposed efficient index SM scheme is better than that of the traditional SM scheme.3)According to the idea of hybrid protocol switching in cooperative communication,a cooperative SM VLC system based on IHDAF protocol is proposed.The detailed communication process and transmission scheme selection of cooperative VLC system based on IHDAF protocol are analyzed,and the power allocation algorithm under this scheme is studied.The simulation results show that the outage probability performance of cooperative SM VLC system based on IHDAF protocol is better than that of cooperative SM VLC system based on amplify forward(AF)protocol and decode forward(DF)protocol.The optimal power allocation factor of this scheme is also determined by simulation.In addition,in order to further improve the outage probability performance of cooperative VLC system based on IHDAF protocol,this paper combines efficient index SM scheme with cooperative VLC system based on IHDAF protocol,and proposes an efficient cooperative index SM scheme based on IHDAF protocol.The simulation results show that the efficient cooperative index SM scheme based on IHDAF protocol can improve the outage probability performance of the system more effectively than the traditional cooperative SM scheme and the traditional SM scheme.