  This letter minimizes outage probability in a single decode-and-forward (DF)
relay-assisted underwater acoustic network (UAN) without direct
source-to-destination link availability. Specifically, a joint global-optimal
design for relay positioning and allocating power to source and relay is
proposed. For analytical insights, a novel low-complexity tight approximation
method is also presented. Selected numerical results validate the analysis and
quantify the comparative gains achieved using optimal power allocation (PA) and
relay placement (RP) strategies.
