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- WCNC 2005
- New Orleans, LA, USA
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3
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- Problem: Achieve the synchronization of a set of geographically
separated clocks located in every node of a wireless Ad Hoc network
(single-hop or multi-hop) in a distributed manner.
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5
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9
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14
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15
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- One arguable improvement to the IEEE 802.11 TSF performance is as
follows:
- Suspend the back-off timer of any pending non-beacon transmission.
- Calculate a random delay uniformly distributed in the range between zero
and
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- Wait for the random delay before transmitting the beacon.
- Cancel the remaining random delay and the pending beacon transmission if
a beacon arrives before the random delay timer has expired and that the
received beacon shows a larger time-stamp than its own.
- Send a beacon if the random delay has expired and no beacon have arrived
during the delay period with a larger time-stamp.
- Upon reception of a beacon, a node will adjust the received timestamp to
take into account its PHY layer delay. The receiving node will set its
clock to the value of the adjusted timestamp if it is later than its
own. Therefore, all nodes will try to gradually synchronize to the
fastest clock.
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- Our numerical and analytical results show that the extended TSF
improvement is marginal relative to CSMNS, additional to the extra cost
of more overhead.
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18
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Notes