We recently did a review of the paper" Positioning of Sensors in Underwater Acoustic Networks.
by Jose Esteban Garcia, Institute of Communications Engineering, University of Hanover, Germany." It's a very good paper in the field of underwater acoustic networks which is a very promising field in the future. though i couldnot find automation companies involved in providing automation software for remote monitoring and surveillance of coastal regions i presume that they would doing so soon in the future. I can visualise a DCS system providing the location and data from sensor nodes and various details of parameters useful for monitoring the health of the sensor nodes!
The author proposes the idea of “Distributed Positioning Algorithm” for remote monitoring and surveillance of ocean regions and coastal areas. In distribution technique the sensor nodes are able to communicate only with their one hop neighbor and correspondingly find the distance with their other neighbor. While doing so the author takes into account the physical properties of water viz. salinity, temperature, and depth/pressure. This, as per the authors literature review; is not taken into account by any other previous work on Underwater Acoustic Networks. The author further states that in order to accurately determine the accurate position of sensors the physical properties of water play a vital role. He argues that in order to find the range between the sender and the receiver accurately the dependency of travel time (TDoA) on physical properties of water should be taken into account. This he proves further in his paper by performing simulation using OMNeT++ as the base platform.
The novelty lies in the development of a new distributed algorithm “Accurate position algorithm” for finding the accurate position of sensor nodes. The author successfully applies the algorithm and hence proves that considering the physical properties of water; this algorithm successfully achieves a trade off among two main parameters; namely “positioning error of all positioned sensor nodes and final number of positioned nodes”.
In section 3 of his paper the author gives the fundamentals of distributed positioning and common solutions. The author mainly cites “Ad-Hoc positioning” by Niculescu and Nath, “N-hop multilateration” by Savvides, “Robust positioning” Savarese and his own algorithm “Accurate positioning in underwater acoustic networks”. Author has done a fair amount of survey of earlier research work and later on has proposed his own algorithm based on earlier positioning algorithms. Even in the simulation software used, the author has studied the Positiff package and OMNeT++ software used in earlier simulations. He has enhanced these further and developed his own Underwater Positioning software (UWPOS) for simulation.
The current problems that might be faced in this area are mainly battery issues, we cannot replace them due to cost constraints and no self charging either due to insufficient sunlight under the water. also distributed positioning algorithm requires large number of reference nodes whose coordinates are known due to a GPS receiver. this makes it expensive if there are large number of anchor or reference nodes.
moreover we need time synchorinisation among the sensor nodes which is not so easy to achieve.Despite all these the paper definitely brings us one step closer to achieving an accurate system for underwater sensor networks.
