Image Processing Reference
In-Depth Information
Query flooding
Event f flooding
Rumor Routing—one possibility
Range of Rumor Routing under different conditions and parameters
Number of queries
FIGURE .
Rumor Routing compared to query flooding and event flooding. (Redrawn from Braginsky, D. and
Estrin,D.,Rumoralgorithmforsensornetworks,in
Proceedings of the First Workshop on Sensor Networks and
Applications (WSNA)
, Atlanta, GA, October .)
choice for the event. he generation probability is a parameter of the protocol, as well as the maximum
hop number for an agent. When a node generates a query, if it already has a route to the source of
the event it will use that route; otherwise it will forward the query in a random direction, until the
query reaches a node that has observed the event (and therefore has a route) or the packet reaches
the maximum number of hops allowed. With a similar approach, a query could fail to find an event.
In this case, the query could be retransmitted or can be flooded through the network. When an event
is found via random forwarding, the cost of flooding is avoided; otherwise this cost has to be added
to the cost of random forwarding. Because of random forwarding, latency in this protocol may be
high. Moreover, if random forwarding fails, the additional delay for flooding may be needed. So this
protocol is definitely not suitable for time-critical applications.
Similarly to Directed Difusion, Rumor Routing achieves energy efficiency by reducing the number
of messages exchanged and performing data aggregation along the path. However, as Directed Difu-
sion performs query flooding, when the number of queries is high Rumor Routing performs better.
Simulation results show that with an accurate selection of the protocol parameters Rumor Routing
can outperform both event flooding and query flooding, but the downside is that performance is
highly variable with varying parameters such as the number of agents and time-to-live values. As a
result, in order to achieve high performance the design space has to be analyzed through extensive
simulations, run using several possible configurations.
