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 nonbinary belief propagation on associated TGs; soft-information output is naturally generated in the process...

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Vydáno v:	IEEE transactions on information theory Ročník 58; číslo 5; s. 2672 - 2688
Hlavní autoři:	Ionescu, D. M., Haidong Zhu
Médium:	Journal Article
Jazyk:	angličtina
Vydáno:	New York, NY IEEE 01.05.2012 Institute of Electrical and Electronics Engineers The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Témata:	Algorithms Applied sciences Belief propagation closest lattice point search Codes Coding Coding, codes complexity Constellation diagram Constellations Decoding Detection, estimation, filtering, equalization, prediction Exact sciences and technology Fading Gain Generators Information theory Information, signal and communications theory iterative decoder Iterative decoding Lattice theory Lattices Maximum likelihood method MIMO Searching Signal and communications theory Signal, noise soft-output sphere decoder Tanner graph Telecommunications and information theory Vectors Performance evaluation Equivalence relation complexity Iterative method Information extraction Iterative decoding Credal approach sphere decoder MIMO Fading MIMO system Interlacing Measurement sensor Tanner graph Quasi static theory Trellis code Graph theory iterative decoder Equalization Algorithm soft-output Interference suppression Posterior probability closest lattice point search Forward error correction Signal processing Error correcting code Maximum likelihood Belief propagation
ISSN:	0018-9448, 1557-9654
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Shrnutí:	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 nonbinary 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 nonorthogonal lattice D 4 ⊕ D 4 : 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 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 × 2 MIMO by Ionescu et al., then independently by Jafarkhani and Seshadri. Algorithmic complexity is log-linear in lattice dimensionality versus cubic in classic sphere decoders.
Bibliografie:	SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 14 ObjectType-Article-2 content type line 23
ISSN:	0018-9448 1557-9654
DOI:	10.1109/TIT.2011.2178130