الفهرس | Only 14 pages are availabe for public view |
Abstract Optical wireless communications (OWC) has become a promising trend nowadays with the rapidly increasing demand for wireless data, while more and more crowded is the radio frequency (RF) spectrum. OWC is intended to complement conventional RF communications, especially for indoor short and medium range data transmission. Several types of single carrier modulation waveforms such as on-off keying (OOK), M-ary pulse amplitude modulation (MPAM), and M-ary quadrature amplitude modulation (M-QAM) have been applied to OWC, but they suffer from the frequency-selective OWC channel as the data rates increase. Orthogonal frequency division multiplexing (OFDM) has the ability to boost achievable data rates. Thus, it is considered for OWC. OFDM can utilize the available LED modulation and width with adaptive bit and energy loading of different frequency sub-bands. Recently, the fast growing solid-state lighting (SSL) technology has fueled the research on visible light communications (VLC), which is a sub-category of OWC, which is utilized for illumination as well as communication. VLC is a unipolar communication system, where only the real (positive) signals are used for information transmission. It may suffer from many problems associated with its traveling optical signal like multi-path fading, channel dispersion and inter-symbol interference which cause system performance degradation. OFDM can be used to mitigate and compensate for these problems. However, traditional OFDM offers complex signals with real and imaginary parts, which makes traditional OFDM not suitable for optical wireless communications. Unipolar OFDM deals with real (positive) signals, which makes it the most efficient technology for OWC. There are many different OWC-based unipolar OFDM techniques that can be used with IM/DD. This thesis presents a proposed model for indoor optical wireless communication utilizing hamming error correction coding associated with minimum mean square error (MMSE) equalizer with the evaluation comparison of performance and complexity for proposed Hamming code and LDPC code with different coding rates. |