Low-Complexity Rotated QAM Demapper for the Iterative Receiver Targeting DVB-T2 Standard

Gray mapping and signal space diversity (SSD) are adopted in DVB-T2 to achieve better performance and system robustness. However, the traditional maximum a posteriori demapping for Gray mapped SSD signal is complicated for higher order modulation and it is not practical to be used in the iterative receiver structure. In this work, simplified demappers are proposed by approximating the 2-dimensional detection with 1-dimensional detection and compensating the loss due to the correlation between the I and Q components. Simulation results show that the proposed simplified demappers can approach the optimal demapper performance with a much lower complexity.