## Specific Controlled Flooding Schemes for DNT

Here we will study di fferent controlled flooding schemes. We are careful to
base our schemes on simple, non-chatty and elegant algorithms. This is because
in sparse and highly mobile networks, complex or chatty algorithms waste the
short time nodes have when they come within range of each other. The schemes
we introduce are the following:

1) Basic Probabilistic (BP): When talking about the willingness of a
node in the previous section, we implied that forwarder nodes have the same
willingness as the sender node. To more closely emulate reality, however, we
choose a uniform distribution probabilistic function that determines the will-
ingness of the nodes to transmit a given message. Based on the result of this
function, a forwarder may choose not to forward the message at all, forward it
at half the willingness of the sender or forward it at the same level of willingness
as the sender.

2) Time-to-Live (TTL): In this scheme, we add a time-to-live value. The
TTL here determines how many times the message is forwarded before it is
discarded. We add the TTL on top of the BP scheme since the BP scheme is a
more realistic representation of how nodes act regarding the choice of forwarding
messages.

3) Kill Time: Here, we add a time stamp to the message on top of the BP
scheme. The time stamp is the time interval after which the message should no
longer be forwarded. This is an absolute universal life-time for the message. This
could be very useful if the sender node knows how long it will be disconnected.
This is also a good way to set the maximum time a node should keep a message
in its bu er if the times-to-send (TTS) variable of that message does not reach
zero.

4) Passive Cure: The nal scheme or optimization we introduce is a Passive
Cure. The idea is that once the destination (Ultimate node) receives the message,
it generates a Passive Cure to “heal” the nodes in the network after they have
been “infected” by the message. The ultimate node “cures” the forwarder that
passed the message to it by sending a cure-ack instead of a normal ack that is
sent when a beacon is received. Now whenever that forwarder or the ultimate
destination detect any other node sending that same message, they send a cure-
ack to that node to prevent future retransmissions.