Bringing sensor networks underwater with low-power acoustic communications

Sensor networks are changing how data is collected inmany applications on earth today. However, today’s sen-sornets do not address the 71% of the earth’s surface thatis covered by water. Just as sensornets beneflt environmen-tal monitoring and industrial control on land, environmentalmonitoring in oceans and lakes, and control of underwaterindustrial processes can beneflt from sensor networks [4, 2].While underwater sensornets can exploit the same compu-tation and storage approaches of terrestrial sensornets, radionetworks are simply not viable underwater because waterabsorptions most radio frequencies. Acoustic modems are aviable alternative, but most commercial acoustic modemstoday target long-distance, point-to-point communicationwith high-power consumption and high costs. While matchedfor some vertical applications that are flelded today, thesemodems are the antithesis of a sensornet, which calls forshort-range, low-power, many-to-many communications, andsmall, inexpensive platforms.We are developing a new underwater acoustic modem tar-geted at the needs of sensor networks [7]. Our design tar-gets low cost (