Milica Sto­janovic says the best way to think about the need for better under­water com­mu­ni­ca­tions is to con­sider the Titanic.

After the pas­senger liner sank in April 1912, its exact where­abouts remained a mys­tery until 1985, when the Woods Hole Oceano­graphic Institution’s imaging vehicle finally located the wreckage.

When the robotic vehicle honed in on the craft, its suc­cess under­scored a greater need for better under­water com­mu­ni­ca­tions, espe­cially those that would require no cables. Wire­less com­mu­ni­ca­tions, signal pro­cessing and detec­tion under­water are the areas of spe­cialty for Sto­janovic, a newly hired elec­trical engi­neering asso­ciate pro­fessor at Northeastern.

When the Titanic sank, people knew approx­i­mately where it went down, but it wasn’t until Woods Hole designed that small robotic vehicle that we knew the truth,” Sto­janovic said. “When that robot was sent down, it was attached to a long cable con­necting it to a sur­face ship. The cables are very expen­sive and heavy, and they limit the move­ment of the robot. There are appli­ca­tions that would greatly ben­efit from the ability to com­mu­ni­cate under­water without cables.”

Future appli­ca­tions could enhance myriad indus­tries, ranging from the off­shore oil industry to aqua­cul­ture to fishing indus­tries, she noted. Addi­tion­ally, pol­lu­tion con­trol, cli­mate recording, ocean mon­i­toring (for pre­dic­tion of nat­ural dis­tur­bances) and detec­tion of objects on the ocean floor are other areas that could ben­efit from enhanced under­water communications.

Oceans cover about 70 per­cent of the Earth’s sur­face, and much of this vast resource remains to be explored,” Sto­janovic said. Unlike above-​​water com­mu­ni­ca­tions devel­op­ments, which have brought us instan­ta­neous cell phone con­ver­sa­tions, wire­less Internet and myriad other advances, under­water com­mu­ni­ca­tions lags behind.

Her research focuses on finding better ways of trans­mit­ting acoustical sig­nals in hopes of improving capacity to the point where under­water robots no longer have to be chained by a heavy, expen­sive com­mu­ni­ca­tions cable, but can instead transmit their read­ings to other robots, or to ship­board researchers.

There is a need to improve the wire­less com­mu­ni­ca­tion capacity of under­water robots. Just think about the dan­gers of land­mines. We also have under­water mines. We need robots that can find and neu­tralize the mines beneath the water” without endan­gering humans, she said. “These robots need to be able to talk to each other if they are going to per­form their task efficiently.”

Yet, water puts a damper on com­mu­ni­ca­tion capacity, slowing down the signal prop­a­ga­tion and cre­ating back­ground noise and echoes—all prob­lems she trains her ana­lyt­ical mind toward solving. Among other research areas, Sto­janovic focuses her ener­gies on cre­ating clearer sig­nals through “equal­iza­tion” to solve the echo problem.

Fur­ther research inter­ests take her into cre­ation of under­water net­works. For under­water instru­ments to com­mu­ni­cate under­water, they must mimic the com­mu­ni­ca­tion net­works on land. Yet, the slow speed at which sig­nals travel would turn an under­water con­ver­sa­tion into garble, she said. “If mul­tiple people talk at the same time, their sig­nals will col­lide,” she said. “We need pro­to­cols that will orches­trate mul­tiple conversations.”

Sto­janovic, who received her master’s and doc­torate degrees in elec­trical engi­neering from North­eastern, began her research focus while working as a post­doc­toral fellow at the Woods Hole Oceano­graphic Insti­tu­tion. She jokes that she “never sur­faced” from her ear­liest under­water com­mu­ni­ca­tions work.

Growing up in Serbia, she received her under­grad­uate degree at the Uni­ver­sity of Bel­grade, and also met her future hus­band. Together, she and Zoran Zvonar came to North­eastern to study elec­trical engineering.

Prior to joining the fac­ulty, where her courses include under­grad­uate com­mu­ni­ca­tions sys­tems and linear sys­tems, she was a prin­cipal sci­en­tist at the MIT Sea Grant Col­lege and the MIT Depart­ment of Aero­nau­tics and Astronautics.

She has pro­duced numerous pub­lished works, and most recently was a guest editor for “IEEE Com­mu­ni­ca­tions Mag­a­zine,” for the fea­ture story “Under­water Wire­less Com­mu­ni­ca­tion and Net­works,” 2009.

Reflecting on her career in undersea com­mu­ni­ca­tions, Sto­janovic said the pas­sion found her. “I’m not sure we ever decide what we want to be,” she said. “Things just happen that way.”