Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Distributed Space Time Codes for the Amplify-and-Forward Multiple-Access
  Relay Channel   In this work, we present a construction of a family of space-time block codes
for a Multi-Access Amplify-and- Forward Relay channel with two users and a
single half-duplex relay. It is assumed that there is no Channel Side
Information at the transmitters and that they are not allowed to cooperate
together. Using the Diversity Multiplexing Tradeoff as a tool to evaluate the
performance, we prove that the proposed scheme is optimal in some sense.
Moreover, we provide numerical results which show that the new scheme
outperforms the orthogonal transmission scheme, e. g. time sharing and offers a
significant gain.

10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
16
The categories of this paper are: stat
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
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The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess
3
The categories of this paper are: physics