On The MIMOSystemDesignforRF And Visible LightCommunication

With the increasing demand of delivering multimedia contents over wireless channels, developing advanced wireless communication systems become increasingly important. However, limited spectrum resources limit the data rate that an RF wireless system can achieve. As a result, the system design aim is: how to use the limited spectrum resources effectively and how to increase the availability of frequency spectrum. It is well known that MIMO (Multiple-Input Multiple-Output) technology can increase the potential channel capacity, when employing multiple antennas both on the transmitting and receiving sides. MIMO technologies are playing an important role in the4G, as one of the core transmission technologies.On the other hand, Visible Light Communications (VLC) has almost unlimited channel capacity and it has become one of the promising solutions for the indoor wireless communications. This thesis focuses on the indoor VLC, and LEDs array can be viewed as a natural MIMO system, when indoor environment usually using a group of LEDs for illumination.We introduce the classification of MIMO systems and the key technologies using MIMO system structure. Firstly, this thesis gives a detailed description of space-time codes, since it can improve the performance of MIMO systems. Then, we investigate the principles of Linear Dispersion Codes and analyses its performance in great detail. After that, we focus on VLC systems, especially, indoor VLC systems can be seen as an MIMO system when we have multiple LEDs. We discuss the channel characteristics of indoor VLC and give the mathematical model to analyses its characteristics. Lastly, a detailed investigation on PPM and OOK modulation methods for VLC systems is given and we compare their performance at different transmitting properties.