Wavelet Domain Diversity Method For Transmission Of Images Over Wireless Sytems Using Hybrid (OFDM-CDMA-SFH) Concept And Its Real Time Implementation In TMS320C6713 DSP Development Board
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In this thesis a new OFDM based wavelet domain diversity combining method is proposed to combat errors during image transmission on wireless channels. A novel concept of utilizing OFDM sub-carriers to attain diversity is designed and analyzed. For images represented in the wavelet domain, diversity is used to obtain multiple data streams using OFDM symbols corresponding to the transmitted image at the receiver. These individual image data streams are combined to form a composite image with higher perceptual quality. Both uncompressed and compressed images are considered. The SPIHT algorithm is used for image compression. Diversity combining methods for both uncompressed and compressed images exploit the characteristics of the wavelet transform. For compressed images, COFDM is used providing unequal error protection in conjunction with diversity combining. A new method of HYBRID OFDM system (OFDM-CDMA-SFH) is thoroughly investigated and simulation results are used to show that a new level of Quality of Service can be provided for multimedia communication for the mobile network. Performance of this scheme over Rayleigh fading channels is evaluated in this paper. Real time implementation of OFDM system is done in TMS320C6713 DSP developmental board. MATLAB-RTDX protocols are used for data transfer between PC and the DSP board. A considerable improvement in the quality of the image with the diversity combining rule is shown in the results.