Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Tree Search Method for Iterative Decoding of Underdetermined Multiuser
  Systems   Application of the turbo principle to multiuser decoding results in an
exchange of probability distributions between two sets of constraints. Firstly,
constraints imposed by the multiple-access channel, and secondly, individual
constraints imposed by each users' error control code. A-posteriori probability
computation for the first set of constraints is prohibitively complex for all
but a small number of users. Several lower complexity approaches have been
proposed in the literature. One class of methods is based on linear filtering
(e.g. LMMSE). A more recent approach is to compute approximations to the
posterior probabilities by marginalising over a subset of sequences (list
detection). Most of the list detection methods are restricted to non-singular
systems. In this paper, we introduce a transformation that permits application
of standard tree-search methods to underdetermined systems. We find that the
resulting tree-search based receiver outperforms existing methods.

25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: astro-ph