Transmission Of Compressed Video Signals Through A Spread Spectrum Channel
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This research studies the feasibility of devising a compression scheme for video sequences that is robust to fading errors in a spread spectrum environment. Schemes like subband coding and pyramid coding are inherently well suited for SS-CDMA environment and thus, pyramid coding is the chosen spatial decomposition scheme. Interframe coding using the two tap short symmetric filters reduces the complexity of motion adaptation techniques used in the MPEG standards. The various temporal low bands are vector quantized using the frequency sensitive competitive learning algorithm. For the temporal high bands, a simple method of geometric vector quantization is implemented. The coded bands are tested for robustness over a multi-path-fading channel at a vehicle speed of 65 mph. The simulation of channel is done according to the specifications of North American Digital Cellular Standard IS-95. The reconstruction of the coded bands results in image frames with average PSNR of 26 dB and average bit rate of 0.25 bpp. The subjective quality of these images is found to be satisfactory.