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Each node keeps
cache of recently transmitted packets (FIFO,
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small)
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Each node, upon
receiving packet X from sender S, checks whether
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it received
packet X-1 from that sender
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If not,
broadcast retransmission request (NACK) to 1-hop neighbors
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Neighbors listen
to overhear other retransmission and cancels theirs
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First set of
experiments revealed that under high traffic load, too
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many NACKs were
issued, flooding the network and resulting in
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overall worse
performance (70% PDR for 10 sender scenarios)
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Added feature:
NACK throttle
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Results:
consistent improvement in PDR compared to best-effort
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version, at cost
of slightly higher packet latency (all performance
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differences
statistically significant at 99% confidence level).
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