Research On 2D-CAP Based Indoor Optical Wireless Transmission Technology

Visible Light Communication (VLC) systems provide attractive and competitive solutions for indoor high-speed data transmissions. However, the rather narrow bandwidth of LEDs could potentially greatly limits the throughput of VLC systems. Therefore, CAP (Carrierless Amplitude and Phase) modulation is employed in order to meet the needs of high data rates of VLC systems.Based on the concept of CAP modulations, this thesis carried an thorough study of the system performance of 2D-CAP system in radio frequency and indoor VLC environments. This thesis firstly introduced the system model of 2D-CAP and analysised the principle of 2D-CAP based on orthogonal bandpsss filters. The 2D-CAP is based on Hilbert transform, furthermore Additive White Gaussian Noise (AWGN) channel is assumed to analysis both QAM and 2D-CAP modulations. Furthermore, the thesis studied the Line-Of-Sight (LOS) and Non-Line-Of-Sight (NLOS) visible light channels. Next, the thesis introduced the methods of single-polarizing for 2D-CAP symbols, including DC biased 2D-CAP and polarity reversal in single polarity flip 2D-CAP. Hence, the theorectical performance of DC biased 2D-CAP was obtained. Afterwards, this thesis analyzed the BER performance of 2D-CAP modulation under indoor visible LOS channels. In order to further improve the bandwidth efficiency of 2D-CAP technology in the environment for indoor visible light, considering that indoor lighting equipment will install a plurality in order to ensure sufficient illumination, this thesis investisated for VLC in indoor multiple input multiple output (MIMO) environments. The thesis also proposed a 2D-CAP-SM system, which is the amalgamation of 2D-CAP technology and Spatial Modulation (SM) technology. The BER theoretical bound of 2D-CAP-SM was eventually obtained and confirmed its accuracy by simulation. And optical 2D-CAP-SM system was realized by changing the number or position parameters of the transmitter and receiver in the LOS transmission system. Finally, in order to enhance the transmission capacity of the CAP system, the conventional 2D-CAP was extended to a three-dimensional scheme. The thesis found the filter banks suitable for 2D-/3D-CAP system by solving the minimax optimization problem. The SER analytical solutions of 3D-8CAP in AWGN channel and LOS channel were eventually obtained and confirmed their accuracy by simulation.Research work and experimental results of this thesis provided a theoretical basis for the applications of CAP technology in indoor VLC field.