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

Algorithm 1

The algorithm for obtaining the next user-data message from the data queue.

(1)  for  each  msg  in  data-queue  do

(2)  if  IS-PENDING-TIME-EXPIRED(msg) then

     ▷The message has been waiting too long for a route. It cannot be delivered.

(3)   DELETE-MESSAGE(msg)

(4)  else

(5)   if  STATE(msg) = WAITING-FOR-ACK

     and  IS-ACK-TIME-EXPIRED(msg) then

(6)    STATE(msg) ← PENDING

(7)   end  if

(8)   if  STATE(msg) = PENDING then

(9)    route ←  ROUTE-SEARCH (ORIG(msg), DEST(msg))

(10)       if  route = ∅  then

       ▷Enqueue a route-request message if one isn’t already outstanding according to

      the route-request table.

(11)     ROUTE-REQ-MAYBE (DEST(msg))

(12)       else

       ▷Stop searching and return this message for transmission.

(13)      STATE(msg) ← WAITING-FOR-ACK

(14)     return  msg

(15)       end if

(16)   end if

(17)  end if

(18) end for

   ▷There are no data messages to transmit at this time

(19) return NO-MSG