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| Overview | 
The Flash protocol enables multiple nodes to transmit concurrently in
order to eliminate neighborhood contention and reduce the latency of network
floods in wireless networks. Flash relies on the capture effect to ensure that
packets are received during concurrent transmissions, exploiting the fact that
all nodes in a flood transmit the same message so that each node can receive the
message from any of its neighbors. A key issue in the design of Flash is to
manage transmission concurrency: too much results in packet collisions while too
little leads to neighborhood contention. Flash proposes two flooding- specific
mechanisms to manage concurrency. The first, used in Flash-II for both high-
and low-duty networks, is to transmit the flooding packet twice, with CCA and
MAC delay in between. This allows the network to recover from floods that stop
prematurely due to high concurrency. This protocol can approach the theoretical
lower bound on flooding latency and sacrifices flooding throughput for
reliability. The second mechanism, used in Flash-III for low-duty cycle
networks only, is to use a large IPS and a very small CCA. The effect of this
combination is to allow some but not too much concurrency and operate on the
probability that the CCA of a node overlaps with the IPS of all nodes currently
transmitting. This protocol approaches the theoretical lower bound on flooding
latency and does not compromise reliability or power consumption. Flash is the
first network flooding protocol for wireless networks that explicitly exploits
the capture effect to optimize for latency. The implementation of Flash only
involves changes to tens of lines of code with respect to the standard CC2420
radio stack of TinyOS, which will allow this protocol to have an immediate and
practical impact.
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| Publications |
Jiakang Lu, and Kamin Whitehouse. Flash Flooding:
Exploiting the Capture Effect for Rapid Flooding in Wireless Sensor
Networks. The 28th Conference on Computer Communications (INFOCOM
2009). Rio de Janeiro, Brazil, Apr. 2009. Jiakang Lu, and Kamin Whitehouse. "Poster Abstract: Exploiting the capture effect for low-latency flooding in wireless sensor networks". The 6th ACM Conference on Embedded Networked Sensor Systems (SenSys). Raleigh, NC, Nov. 2008. | |||
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Kamin Whitehouse Computer Science Department The University of Virginia 217 Olsson Hall Charlottesville, Virginia 94720 |