Single - Carrier Frequency Domain Equalization Using Subband Decomposition

SINGLE-CARRIER FREQUENCY DOMAIN EQUALIZATION USING SUBBAND DECOMPOSITION FOR OPTICAL WIRELESS COMMUNICATIONS by Di Mu Optical wireless communication is intended to be applied into indoor and visual distance high-rate data transmission, which is complementary to radio frequency communications. There are specific problems and requirements in optical wireless communications compared with radio frequency communications. Single-carrier frequency domain equalization (SCFDE) is a transmission scheme which has been considered as an alternative of orthogonal frequency-division multiplexing (OFDM), because it has most of the advantages of OFDM and avoids the problems of OFDM. Subband decomposition is a multi-resolution signal analysis and synthesis method, using quadrature mirror filter (QMF) bank to convert time-domain signal to frequency-domain subbands. As a time-tofrequency transform, subband decomposition technique can be employed to frequency domain equalization. Compared with the commonly used discrete Fourier transform (DFT), subband transform is more flexible and efficient to compensate the fading of frequency-selective channels. This thesis includes the theories of SCFDE, subband decomposition, subband equalization, and optical wireless transmission scheme. Also, simulations are given to demonstrate the processing of signals and the implementation of equalizers. The results show that the transmitted signal can be effectively equalized to compensate the channel fading, and the transmission scheme is appropriate for optical wireless communications. SINGLE-CARRIER FREQUENCY DOMAIN EQUALIZATION USING SUBBAND DECOMPOSITION FOR OPTICAL WIRELESS COMMUNICATIONS