New hierarchical modulation scheme using a constellation rotation method

In this paper, we propose a new hierarchical modulation scheme for DVB-NGH to improve the performance of LP (Low-Parity) signals by applying a conventional constellation-rotation method to the LP signals with virtually no loss of performance in the HP (High-Parity) signals. The improvement of the LP signals is mainly due to the increased diversity gain caused by the constellation-rotation method which barely affects the performance of the HP signals. For the new scheme, we also propose a hardware-efficient ML (Maximum-Likelihood) detection algorithm that first decodes the HP signals using a conventional HP receiver, followed by simply decoding the precoded LP signals based on the pre-detected HP signals.