Abstract

A signal space code C is defined as geometrically uniform if, for any two code sequences in C, there exists an isometry that maps one sequence into the other while leaving the code C invariant. Geometrical uniformity, a strong kind of symmetry, implies such properties as a) the distance profiles from code sequences in C to all other code sequences are all the same, and b) all Voronoi regions of code sequences in C have the same shape. It is stronger than Ungerboeck Zehavi-Wolf symmetry or Calderbank-Sloane regularity. Nonetheless, most known good classes of signal space codes are shown to be generalized coset codes, and therefore geometrically uniform, including (a) lattice-type trellis codes based on lattice partitions Lambda / Lambda ' such that Z/sup N// Lambda / Lambda '/4Z/sup N/ is a lattice partition chain, and (b) phase-shift-keying (PSK)-type trellis codes based on up to four-way partitions of a 2/sup n/-PSK signal set.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Keywords

CombinatoricsMathematicsLambdaCosetGroup codeLattice (music)Discrete mathematicsBinary Golay codeIsometry (Riemannian geometry)Partition (number theory)Linear codeBlock codeAlgorithmDecoding methodsPhysicsPure mathematics

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Publication Info

Year
1991
Type
article
Volume
37
Issue
5
Pages
1241-1260
Citations
450
Access
Closed

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Cite This

G. David Forney (1991). Geometrically uniform codes. IEEE Transactions on Information Theory , 37 (5) , 1241-1260. https://doi.org/10.1109/18.133243

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DOI
10.1109/18.133243