Location-Aware Source Routing Protocol for Underwater Acoustic Networks of AUVs

Figure 3

An example of LASR's route handling, where an inaccurate route is automatically corrected. For clarity, only the overheard message at the previous transmitter is shown. In actuality, some or all of the other nodes would detect or overhear each transmission, improving the topology data in those other nodes.

(a) 𝐴 sends a message using its current topology data. These data will turn out to be stale

(b) 𝐵 has no newer topology data, so leaves the route unchanged. 𝐴 overhears, which implicitly acknowledges that 𝐵 received the message

(c) 𝐶 has newer data reflecting recent movement and updates the route. 𝐵 overhears implicity acknowledging; the explicit routing information received is also used to improve 𝐵’s topology data

(d) Messages delivered. Because 𝐹 is the destination, and so does not retransmit the message, no implicit acknowledgment is possible. Next 𝐹 will transmit an explicit acknowledgment (not shown)