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

Algorithm 2

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

(1)  for each  msg  in  protocol-queue  do

(2)  if STATE(msg) = WAITING-FOR-ACK

    and IS-ACK-TIME-EXPIRED(msg) then

(3)    STATE(msg) ← PENDING

(4)  end if

(5)  if STATE(msg) = PENDING then

(6)   if MSG-TYPE(msg) = ROUTE-REQUEST then

     ▷Route request message contain a route ending at the local node.

(7)    dest ←local-node

(8)   else

     ▷Route reply message contain a route ending at the message’s destination.

(9)    dest ← DEST(msg)

(10)      end if

    ▷Both message type contain a route starting at message’s originator.

(11)    route ← ROUTE-SEARCH (ORIG(msg), dest)

(12)      if  route = ∅  then

       ▷A protocol message without a route is deleted.

(13)    DELETE-MESSAGE(msg)

(14)   else

      ▷Stop searching and return this message for transmission

(15)     STATE(msg) ← WAITING-FOR-ACK

(16)      return  msg

(17)   end if

(18)  end if

(19) end for

   ▷There are no protocol messages to transmit at this time.

(20) return NO-MSG