VHDL Modules and Circuits for Underwater Optical Wireless Communication Systems

Underwater wireless optical communication has been used for establishing a link between mobile vehicles and/or fixed nodes because light, especially in the blue/green region, allows to achieve higher data-rate than acoustical or electromagnetic waves for moderate distances. The here proposed work has the aim to pave the way for diffuse optical communication allowing to support optical communication in an Underwater Wireless Sensor Network of dense-deployed fixed nodes for specific application, such as monitoring and surveillance, for shallow, coastal and inland water in the case of moderate/limited area. In particular, taking into account already developed protocols for optical wireless communication, the focus is on the hardware implementation of different flexible modules to support both point-to-point and directional communication targeting the use of these technologies in the field of Underwater Wireless Sensor Network and the integration with current terrestrial technologies for Wireless Sensor Network. After a careful analysis of benefits and problems related to optical transmission underwater, design considerations are proposed with the description of the implemented modules. The use of light impulse for communication is motivated by the possibility of targeting high data-rate, low-cost and small dimension components. This paper describes an overall vision of the system: a HDL implementation of flexible modules for the management of optical communication (based on IEEE 802.15.4 and IEEE 802.11 standard) which target the interface with current terrestrial technology forWireless Sensor Networks; the design and implementation of circuits for underwater optical point-to-point and planar communication. The preliminary results and design consideration are reported considering also future possible developments.