Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Link Quality Control Mechanism for Selective and Opportunistic AF
  Relaying in Cooperative ARQs: A MLSD Perspective   Incorporating relaying techniques into Automatic Repeat reQuest (ARQ)
mechanisms gives a general impression of diversity and throughput enhancements.
Allowing overhearing among multiple relays is also a known approach to increase
the number of participating relays in ARQs. However, when opportunistic
amplify-and-forward (AF) relaying is applied to cooperative ARQs, the system
design becomes nontrivial and even involved. Based on outage analysis, the
spatial and temporal diversities are first found sensitive to the received
signal qualities of relays, and a link quality control mechanism is then
developed to prescreen candidate relays in order to explore the diversity of
cooperative ARQs with a selective and opportunistic AF (SOAF) relaying method.
According to the analysis, the temporal and spatial diversities can be fully
exploited if proper thresholds are set for each hop along the relaying routes.
The SOAF relaying method is further examined from a packet delivery viewpoint.
By the principle of the maximum likelihood sequence detection (MLSD),
sufficient conditions on the link quality are established for the proposed
SOAF-relaying-based ARQ scheme to attain its potential diversity order in the
packet error rates (PERs) of MLSD. The conditions depend on the minimum
codeword distance and the average signal-to-noise ratio (SNR). Furthermore,
from a heuristic viewpoint, we also develop a threshold searching algorithm for
the proposed SOAF relaying and link quality method to exploit both the
diversity and the SNR gains in PER. The effectiveness of the proposed
thresholding mechanism is verified via simulations with trellis codes.

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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: q-bio
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: stat
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The categories of this paper are: hep-ph
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The categories of this paper are: physics