Development and Performance Evaluation of Hierarchical Quadrature Amplitude Modulation (HQAM) for Image Transmission over Wireless Channels

Asymmetric modulation techniques like Quadrature Amplitude Modulation system is one of the key techniques in building a broadband mobile communication network because of increasing shortage of wireless communication channels. It provides alternative means of Equal Error Protection (EEP) to the transmitted bits without increasing the bandwidth. Hierarchical Quadrature Amplitude Modulation (HQAM), a modification of QAM, provides Unequal Error Protection (UEP) to the transmitted bits for increasing the protection to the sensitive and non-sensitive bits and is also efficient in power and bandwidth. This paper presents an analysis and simulation of HQAM in order to bring out its merits over QAM. The simulation is carried out using MATLAB & Simulink for different values of modulation parameter. A Simulink-based simulation system is designed for the transmission of gray image as test image over AWGN wireless channel. Keywords-Wireless Channels, HQAM, Error Protection