Design and Development of Compressed Image Transmission System Using Asymmetric Modulation (HQAM) Over Wireless Channels

Set Partitioning in Hierarchical Trees (SPIHT) is an efficient wavelet-based progressive image-compression technique, designed to minimize the mean-squared error (MSE) between the original and decoded imagery. Since wireless channels suffer from significant bit error rates, some mechanism to protect the encoded image is required. Many error control solutions have been proposed to address the problem of transmitting images, and these algorithms add redundancy at the source level. Asymmetric modulation method, Hierarchical Quadrature Amplitude Modulation (HQAM) provides alternative means of unequal error protection without increasing the bandwidth. This paper examines the image transmission suitability of using SPIHT as an image coder and Hierarchical 16-QAM as modulation technique where non-uniform signal constellation is used to provide different degrees of protection to the significant and non-significant bits. The performance of SPIHT coded image transmission is evaluated in Simulink using gray test image for different values of the modulation parameter and bpp (bitper-pixel).