Motivated by Figure 2, we note that the intersection of x’s circular
radio range and the circle about D of radius xD (that is, of the
length of line segment xD) is empty of neighbors. We show this
region clearly in Figure 3. From node x’s perspective, we term the
shaded region without nodes avoid. x seeks to forward a packet to
destination D beyond the edge of this void. Intuitively,x seeks to
route around the void; if a path to D exists from x, it doesn’t include
nodes located within the void (or x would have forwarded to them
greedily).