Underwater optical wireless sensor networks using resource allocation

Optical wireless communications is an energy efficient and cost-effective solution for high speed and high secure wireless connections. In this paper, we propose an underwater optical wireless sensor network using multiple input multiple output technique and power allocation algorithm for supporting multiple users with the impacts of underwater channel uncertainty interferences. In proposed power allocation algorithm, all the LED nodes in are coordinated and controlled by a central controller; each LED node supports all the users within its field of view. To separate users, optical code division multiple access is used; cyclic optical orthogonal code working as CDMA code is employed. At the receiver, a minimal mean squared error (MMSE) filter is uniquely designed for each user. The MMSE filters and the assigned power can be jointly optimized to improve the overall throughput and signal to noise ratio. Since the system performance may be impacted by the underwater channel uncertainty, the proposed power allocation can use the predicted channel uncertainty variance to reduce the interference of the channel uncertainty and improve the signal to noise ratio. Compared to the equal power allocation algorithm, the proposed algorithm can support longer transmission distance, higher bit rate and lower bit error rate.