The calculation of the residual for every
node within a region given a set of points, as in TBF, can be computation
intensive and unnecessary.
TE-Routing attempts at finding the closest node from a set of nodes that
fall within a desirable area to a checkpoint. This diminishes the number of
nodes which are considered. The desirable area is referred as the search window.
In a best case scenario, a directional antenna would turn to face the
direction of the next checkpoint. This would force the node to only consider
neighbors within the search window and also eliminate all calculations necessary
to do so. When a directional antenna is not available, the search window
is defined as a function of the checkpoints in the shape of a triangle. The aperture
of the triangle opens in the direction of the curve and osculates along the
curve trajectory. The construction of the triangle is done as follows:
??? A line L1 connecting the current checkpoint (C1) and next checkpoint (C2)
is drawn.
??? A line L2 perpendicular to L1 which passes through C2 is drawn.
??? A line L3 parallel to L1 which passes through the current node (N1) is
drawn.
??? The intersection of L3 and L1 is defined as the midpoint M.
??? Two lines that form an angle ?µ with L3 are calculated. The intersection of
these two lines with L1 are two of the vertices for the search window, T2
and T3. N1 is the other vertex of the search window.
374
Enemy campling ground
Sensor nodes spread in the field
Points added by the expert on
Sink
Chapter 15 Information Forwarding and Tra?±c Engineering
An algorithm is needed to select the nodes which are within this search
window.
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