The original Waterhunter Movement problem aims at minimizing the total energy con-
sumption of the whole network during the observation period T, which is a global optimiza-
tion problem and still too hard to be solvable. To make it tractable, we have to make some
approximations to get a suboptimal solution. We assume that a B-node moves at a constant
speed in one epoch, that is, between two consecutive stops, and the maximum speed it can
take is a system-wide value speedmax. Therefore, the longest path node i can travel in one
epoch is Im=, = speedmax x (ti(j +t 1) 14(j) pausei(j)). To achieve the system-wide
goal of energy conservation, instead of moving along the straight path connecting two con-
secutive stops 1.. -- (j) and posi(j +t 1), node i may travel along a resource-aware path with
the purpose of letting the encountered P-nodes forward on behalf of it as many as possible
packets destined for other nodes. For simplicity, we assume that when moving towards
a P-node, node i always goes along the straight path connecting the destined P-node and
itself. Therefore, 1., -- (j J., -- (j +t 1) is a set of zigzag straight paths if there exist multi-
ple P-nodes. Notice that the simplified target now is to find an optimal path set for each
individual node to minimize its total energy consumption during the observation period T
instead of that of the whole network. We intend to utilize the solutions to this local op-
timization problem to approximate the ones to the original global optimization problem,
which is believed to be too complicated to be tractable.
Normally, when moving between two consecutive stops posse (j) and posse (j +t 1), node
i may have several potential P-nodes to utilize. It is, however, usually unwise for node
i to pass by each of them. The reason is that, the longer path node i takes, the faster
speed it should move at, as described in the aforementioned general mobility model. It
is well-known that a faster movement speed may cause some undesirable problems such
as the instability of routing paths and the drop of packets. Therefore, some rules should
be designed to guide each B-node in deciding which P-nodes and in what order it should
pass through between two consecutive stops. A simple rule would be to only consider as
candidates the P-nodes whose distance from the direct link between any two consecutive