Implementation and performance analysis of DVB-T2 rotated constellation demappers on a GPU

Abstract

The DVB-T2 standard for digital terrestrial broadcasting supports the use of quadrature amplitude modulation constellations where the constellation points are rotated in the I-Q plane. This combined with a cyclic delay of the Q component provides improved performance in some fading channels. The complexity of the optimal demapping process for rotated constellations is however significantly higher than for non-rotated constellations. This makes the DVB-T2 demapper one of the most computationally complex parts of a receiver. In this article, we examine possible simplifications of the demapping process suitable for implementation on a general purpose computer containing a modern graphics processing unit (GPU). Furthermore, we measure the performance in terms of throughput, as well as accuracy, of the implemented algorithms. The implementations are designed to interface efficiently to a previously implemented real-time capable GPU-based low-density parity-check channel decoder.

Enhanced NOMA System Using Adaptive Coding and Modulation Based on LSTM Neural Network Channel Estimation

“…The pilot sequences, x p , were modulated by QPSK or 64-QAM. The resulting constellation was rotated by an angle of 0.506 rad for QPSK and 0.150 rad for 64-QAM [32], followed by induction of the cyclic Q-delay. The modulated signals were then superimposed using Equation (1).…”

“…Finally, an adaptive modulation scheme based on constellation rotation and cyclic Q-delay is proposed to overcome channel fading and hence restore the transmitted sequences with fewer errors. The adaptive modulation scheme was previously implemented in digital video broadcasting (DVB) systems [30][31][32]. The proposed algorithms are discussed with respect to the conventional uplink PD-NOMA system.…”