A variation of this protocol, called SPIN-EC, adds a simple heuristic to add energy conservation
to the SPIN-PP protocol. As long as all nodes have sufficient energy, they participate
in the three-way handshake of the SPIN-PP protocol. However, once the energy of a node
approaches a specific low-energy threshold, it becomes more selective in its participation in
the protocol. That is, a node should only participate in the three-way handshake if it believes
that it can complete all stages of the protocol without falling below the energy threshold.
Therefore, a node replies to an advertisement only if it has sufficient energy to transmit the
request and receive the requested data. Similarly, a node initiates the three-way handshake
with its neighbors only if it believes that it can complete the protocol even if all neighbors
request a copy of the data.