On The Performance Of Space Shift Keying Modulation For Visible Light Communications

Visible light communications is an emerging technology developed in LED indoor lighting based on wireless optical communication technology, which utilizes the properties of white LED including short response time and the high modulation rate. Reducing both the energy and investment, white LED wireless communication systems can be used for both lighting and communications to show great significance and therefore is recognized as an emerging short-range wireless communications systems. Space shift keying (SSK) based on multiple input multiple output (MIMO) transmission technology is a new modulation method proposed in recent years, which can avoid inter-antenna interference. When the conventional multi-antenna systems transmit signals on all antennas, interference can be caused between antennas. Instead, SSK selects one of the antennas to transmit signal according to the information in one slot time, thus avoiding interference between different antennas. Because the information is carried by the selected antenna index instead of using the traditional modulation, the receiver determines the antenna index according to the unique characteristics of different multipath transmit antennas to obtain the transmitting information. Considering that the modulation of the visible light communication system is affected by indoor channel multipath effects seriously, we apply SSK as a modulation technique to VLC, so as not only to improve the bandwidth utilization and energy efficiency, but also take advantage of the indoor multipath channel.We investigate the space shift keying modulation system and indoor visible light communication system based on white LED in the thesis. Firstly, the modulation principle of SSK modulation system and the receiver detection method are introduced. Secondly, we analyze the VLC indoor channel to obtain a feasible mathematical model of the channel. Then SSK modulation is applied to indoor visible light communication system, which is simulated through MATLAB to show the feasibility of the application. While the simulation results exhibits that the system performance is poor when the distances between transmitter and receivers are similar. To deal with this situation, the thesis introduces the generalized space-shift keying modulation (GSSK) and adaptive control Finally, we present a simulation analysis of the system under the condition of inaccurate channel conditions.