Likelihood Generation Circuit Using 1D/2D LUTs for High-Order QAM

The patent segments the likelihood calculation process into multiple stages: first performing hard decision decoding to obtain initial bit decisions, then using these decisions to identify the quadrature of the phase plane, and finally converting likelihood information based on the identified quadrature. This segmentation reduces the computational complexity compared to calculating likelihoods for all possible signal points.

The patent performs partial action by limiting the likelihood calculation to only the necessary quadrants of the phase plane based on hard decision results. Instead of calculating likelihoods for all signal points across the entire phase plane, the system performs calculations only in the relevant quadrature regions, reducing the overall computational load while maintaining decoding performance.

The patent segments the soft decision decoding process into distinct stages: hard decision decoding to obtain preliminary bit values, quadrature detection based on these values, and likelihood conversion in the identified quadrature. This segmentation allows the system to maintain soft decision performance while reducing circuit complexity by performing calculations only in relevant quadrants rather than the entire phase plane.

The patent performs preliminary hard decision decoding before performing the full soft decision likelihood calculation. This preliminary action provides information about the likely quadrature of the received signal, which is then used to limit the scope of subsequent likelihood calculations. This preliminary step reduces the computational load of the soft decision process while maintaining its performance benefits.

The patent segments the lookup table requirements by creating separate LUTs for different quadratures of the phase plane. Each LUT stores likelihood values only for its specific quadrature region rather than storing all possible signal point likelihoods. This segmentation dramatically reduces the size of individual LUTs while collectively covering the entire phase plane through the combination of multiple smaller LUTs.

The patent uses partial action by activating and using only the LUT corresponding to the identified quadrure of the received signal. Instead of requiring all LUTs to be simultaneously active or sized to cover the entire phase plane in one large structure, the system selectively accesses only the partial LUT needed for the specific quadrature, reducing the effective LUT size required at any given time.