With the increasing demands on science, business and national defense in marine environment, researches on underwater wireless sensor networks, the important underwater monitoring systems, have become active. But there are many challenges in the researches of underwater wireless sensor networks because of lack of resources and acoustic communication bandwidth. Based on the survey of underwater wireless sensor network researches, this paper focuses on the communication and range measurement among the underwater wireless sensor nodes. The paper is supported by NSFC key project ‘research on key technologies of mobile underwater sensor networks’, and the main researches are introduced form three aspects as below. Firstly, communication between underwater wireless sensor nodes is considered. A QPSK demodulation strategy based on mask window is proposed. And a FPGA-based QPSK modulation/demodulation system is designed and developed for underwater wireless sensor nodes. The experimental results show the systems can fulfill acoustic communication between the underwater sensor nodes. Secondly, range measurement methods between underwater sensor nodes are considered. The range measurement strategy based on acoustic communication is given. And a pulse laser ranging system is also designed and developed for ranging between nodes. Finally, the range measurement is considered from the view of networked system. A distributed range measurement algorithm is presented by integrating the ranging process with TDMA MAC protocol. The simulation results show that the distributed ranging mode can reduce consumption on energy and time in the ranging process compared with the point-to-point ranging mode. In sum, the researches in this paper would advance the development of low-cost efficient underwater wireless sensor node and provide supports for underwater node localization.
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