Aqua Communication using Modem

While wireless communication technology today has become part of our daily life, the idea of wireless undersea communications may still seem far-fetched. However, research has been active for over a decade on designing the methods for wireless information transmission underwater. Significant progress has been made in terrestrial sensor networks to revolutionize sensing and data collection. To bring the concept of long-lived, dense sensor networks to the underwater environment, there is a compelling need to develop low-cost and low-power acoustic modems for short-range communications. This post explains about Aqua communication using a modem and presents designing and developing such a model.

         Sensor networks are beginning to revolutionize data collection in the physical world, relatively little work has been done to explore how sensor networks apply underwater. wireless communication, dense deployments (each sensor may have eight or more neighbors), self-configuration and local processing, and maximizing the utility of any energy consumed. Our primary application is seismic monitoring, with alternative applications including assistance during underwater construction, pipeline and leak monitoring, biological data collection, or underwater robot communication. Sensor networks typically consist of many battery-powered nodes, densely deployed in an area for close observation and long-term monitoring.

The underwater acoustic channel presents strong challenges to the design of data communication networks. Besides severe multi-path reflections, there can be curved propagation paths due to uneven temperature distribution and various interference, such as bubbles and noise from man-made objects. However, a potential penalty of this approach is that individual modems become quite expensive and power-hungry, making use of hundreds of modem-equipped sensors economically infeasible. We, therefore, explore a complementary path that emphasizes simple but numerous devices that benefit from dense sensing (e.g., eight or more neighbors per node, rather than one or two) and shorter-range communication. In addition to simpler node-to-node channels due to shorter range, higher-level approaches can compensate for channel problems through approaches such as routing, link-layer retransmission, and application-layer coding.

Design Rationale

         Our overall goal in the design of our underwater modem is to bring the characteristics that are being exploited in terrestrial sensor networks underwater. Our primary goal is that the modem be inexpensive to make it feasible to purchase and deploy many sensor nodes. A corollary is that we need only short-range communication since long-range communication can be accomplished by multi-hop routing over many individual nodes. Fortunately, these choices reinforce each other, because focusing only on short range communication means we expect to avoid many of the challenges of long-range communication (for example, acoustic ducting and multi-path effects due to surface reflections and temperature gradients), greatly simplifying the modem design. Our target communication range is 50500m. The low-power operation to allow long-lived monitoring, support for higher level protocols in software, and design for expected channel characteristics. Our design uses several techniques to accomplish low power operation. To trigger the more expensive data receiver. When there is no communication activity, nodes can turn off most components, and only leave the wake-up receiver on.