Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SISO APP Searches in Lattices with Tanner Graphs   An efficient, low-complexity, soft-output detector for general lattices is
presented, based on their Tanner graph (TG) representations. Closest-point
searches in lattices can be performed as non-binary belief propagation on
associated TGs; soft-information output is naturally generated in the process;
the algorithm requires no backtrack (cf. classic sphere decoding), and extracts
extrinsic information. A lattice's coding gain enables equivalence relations
between lattice points, which can be thereby partitioned in cosets. Total and
extrinsic a posteriori probabilities at the detector's output further enable
the use of soft detection information in iterative schemes. The algorithm is
illustrated via two scenarios that transmit a 32-point, uncoded
super-orthogonal (SO) constellation for multiple-input multiple-output (MIMO)
channels, carved from an 8-dimensional non-orthogonal lattice (a direct sum of
two 4-dimensional checkerboard lattice): it achieves maximum likelihood
performance in quasistatic fading; and, performs close to interference-free
transmission, and identically to list sphere decoding, in independent fading
with coordinate interleaving and iterative equalization and detection. Latter
scenario outperforms former despite the absence of forward error correction
coding---because the inherent lattice coding gain allows for the refining of
extrinsic information. The lattice constellation is the same as the one
employed in the SO space-time trellis codes first introduced for 2-by-2 MIMO by
Ionescu et al., then independently by Jafarkhani and Seshadri. Complexity is
log-linear in lattice dimensionality, vs. cubic in sphere decoders.

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The categories of this paper are: plasm-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con
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The categories of this paper are: dg-ga
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: q-fin
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The categories of this paper are: cmp-lg
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
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The categories of this paper are: atom-ph