Sam Tran P.
8
II. RELATED WORK
Tree-based method • Build a hierarchy tree by using mathematic
model such as graph theory or Voronoi diagram.
• Nodes send data to the base through its ancestors.
Advantages • Can applied for a large area because of
using multi-hop communication. • Data could be aggregated at intermediate
nodes
Disadvantages • Demand heavy calculation on the nodes for
building the tree and routing. • Suffer redundancy.
Figure 6: Some methods to build hierarchy tree in the tree-based
Sam Tran P.
9
II. RELATED WORK
Cluster-based method • Build a hierarchy tree by using LEACH
algorithm:
– Nodes randomly self-elect to become cluster heads.
– The cluster head invites its neighbors to join to the group.
– Re-elect cluster heads after a period of time for energy balancing.
• Nodes send data to the base through the cluster heads.
• Cluster heads communicate to the base directly.
Advantages
• Simple.
Disadvantages
• All nodes are supposed communicate directly to the base Cannot applied to a large area and
suffer the channel limitation of the base. • Suffer redundancy.
Figure 7: A picture of cluster- based methods
Sam Tran P.
1
II. RELATED WORK
Prediction-based method • Based on tree-based or cluster-based method with added prediction
models:
– The moving objects will stay at the current speed and direction for the next few seconds.
– The object’s speed and direction for next few seconds can be deduced from the average of the object’s movement history.
– Different weights can be assigned to the different stages based on the history.
Advantages • Give more efficient results.
Disadvantages • Keep disadvantages of the base method tree or cluster.
• Prediction modes unstable results. • Demand heavy calculation for the nodes.
• Suffer redundancy.
Sam Tran P.
1 1
III. THESIS METHOD
OCO Optimized Communication and Organization includes 4 phases: position collection, processing,
tracking, and maintenance.
– In the position collection phase, the base-station collects positions of all reachable nodes in the network.
– In the processing phase, it applies image processing techniques to clean up the redundant nodes, detect border nodes, and find
the shortest path from each node to the base.
– In the tracking phase, the sensors in the network all work together to detect and track intrusion objects.
– The maintenance phase involves re-organizing the network when, for example, a change in the topology of the network occurs, or
some of the sensor nodes die i.e., running out of power.
Sam Tran P.
1 2
III. THESIS METHOD
Kategori