In addition,
both of them use some sort of flooding which su?®ers many drawbacks in wireless
networks, such as excessive message redundancy, contention, collision [40],
and unreliability [41].
To reduce the energy cost in disseminating queries through all nodes, like
Directed Di?®usion, authors in [42] introduce a hierarchical data querying
method. Each registration points, leaders of data source and sensor nodes
meeting multi-resolution needs construct a hierarchy of three levels. New detections
are updated locally, while advertisements are registered to registration
points. Any requests only need to traverse down the hierarchy to find
250
0
0.2
0.4
0.6
0.8
1
13 17 21 25 29 33
transimssion radius
success rate
quorum match-making
0
0.1
0.2
0.3
0.4
13 17 21 25 29 33 37
transmission radius
forwarding rate
quorum match-making
answers. Simulation shows it outperforms the directed di?®usion by achieving
higher delivery rate with lower energy cost.
More recently, many researches concentrate on dynamic sensor collaboration
and aggregation with constrained energy. Data are aggregated to a certain
leader or root, on which full update operation is carried out. Zhao et al. [43],
[44], [45] apply information driven approaches to deal with this issue. A sensor
node/leader is selected to detect the object, and the object moves, the
responsibility of tracking will be handed o?® to another node/leader according
to some criterion measuring information gain.
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