Image Transmission Over Noisy Wireless Channels Using HQAM and Median Filter

Abstract

This paper considers the use of unequal error protection and median filtering for transmission of images over poor wireless channels usually encountered over cellular mobile networks. Hierarchical Quadrature Amplitude Modulation (HQAM) that provides Unequal Error Protection (UEP) to the transmitted image data is used at the transmitter. In HQAM, non-uniform signal constellation is used to provide different degrees of protection to the significant and non-significant bits in the image data at lower channel Signal to Noise Ratio (SNR). Median filter is employed at the receiver to remove the impulsive noise present in the received image. Simulation results show that the use of HQAM and median filtering provides a gain of PSNR over the more conventional Quadrature Amplitude Modulation (QAM).