Efficient soft demodulation schemes for the DVB-S2X system

Abstract

In this paper, we propose efficient soft demodulation methods for the 64, 128, and 256 amplitude and phase shift keying schemes defined in the digital video broadcasting via satellite second-generation system. We first derive hard decision threshold (HDT) lines for the constituent bits in a symbol and subsequently present compact equations to estimate the soft bit information. If the HDT line for a constituent bit is a simple continuous line, then the soft bit estimation is performed by simply calculating the distance between the detected symbol and the HDT line. High computational complexity and appreciable performance degradation may occur if HDT lines are too complex. In order to prevent this, we also propose a modified max-log demodulation method that achieves the same performance as the original max-log method but with reduced complexity. Depending on the application, a hybrid method can be utilized by combining the advantages of the HDT and modified max-log methods. The simulation results reveal that the proposed hybrid scheme produces almost the same performance as the original max-log method with greatly reduced computational complexity. Ä min S Wb i .s/D0 kr hsk 2 min S Wb i .s/D1 kr hsk 2 :Although (2) eliminates the computation of the exp. / and log. / operations, the complexity of mink k 2 is still O.2 m /. We here refer to this soft demodulation method as the conventional max method.

Iterative MMSE‐based soft MIMO detection with parallel interference cancellation

“…For PSK, pulse amplitude modulation (PAM), and the amplitude and PSK schemes, the same mapping principle that is detailed in [11, 14, 15] can be applied. By applying Method I, the complexity of the SBI‐estimation process can be reduced to a linear order, which requires one distance estimation per soft‐bit, and a performance that is the same as the conventional scheme can be maintained.…”

Low‐complexity demapping algorithm for two‐dimensional non‐uniform constellations in ATSC 3.0

“…There are three main approaches. The quadrant search reduction (QSR) method was first proposed in [11–13] for the 2D demapper in second‐generation terrestrial digital video broadcasting (DVB‐T2) [14] and was also employed in [15, 16] for ‐ary phase shift keying (PSK), uniform QAM, and digital video broadcasting via satellite second‐generation extensions (DVB‐S2X) systems. QSR method exploits the symmetric property of the constellations to collect subsets of points which provide most of the information in LLR computation.…”

On Low Complexity Detection for QAM Isomorphic Constellations

“…Several authors have proposed ad hoc solutions for a given constellation or have focused on a specific subfamily of APSKs. For example, in [12] and [13] some techniques to reduce LLRs computations for DVB-S2X constellations are proposed. However, these techniques are specific to the constellations and the given bit to symbol mapping.…”