Cellular Underwater Wireless Optical CDMA Network: Potentials and Challenges

Farhad Akhoundi, Mohammad Vahid Jamali, Navid Bani Hassan, Hamzeh Beyranvand, Amir Minoofar, Jawad A. Salehi
2016 IEEE Access  
Underwater wireless optical communications are an emerging solution to the expanding demand for broadband links in oceans and seas. In this paper, a cellular underwater wireless optical code division multiple-access network is proposed to provide broadband links for commercial and military applications. The optical orthogonal codes are employed as signature codes of underwater mobile users. Fundamental key aspects of the network, such as its backhaul architecture, its potential applications,
more » ... its design challenges, are presented. In particular, a promising underwater localization and positioning scheme based on this cellular network is presented. Furthermore, the proposed network is used as infrastructure of centralized, decentralized and relay-assisted underwater sensor networks for high-speed real-time monitoring. Finally, probable design challenges, such as cell edge coverage, blockage avoidance, power control, and network capacity, are addressed. INDEX TERMS Underwater wireless optical communications, optical CDMA networks, underwater sensor networks, relay-assisted transmission, undersea localization and positioning, power control. I. INTRODUCTION Rapidly growing commercial and military applications for underwater communication demands for a reliable, flexible and practical multi-access network. Recent studies have shown that there are two major solutions to this demand: acoustic and optical transmission. Due to the limited bandwidth of acoustic systems, their maximum achievable rates are restricted to 10∼100 kbps. Furthermore, the low speed of acoustic waves in undersea media (≈1500 m/s) which results in a high latency in long range communications causes problems for synchronization and multiple access techniques. Alternatively, in comparison with the traditional acoustic approach, wireless optical communication has three main advantages: higher bandwidth, higher security and lower time latency [1], [2] . Despite their promising advantages, limited attainable communication range of underwater wireless optical communication (UWOC) systems, i.e., less than 100 meters with realistic average transmit powers, hampers their widespread usage. The general reason is that optical beam propagation through water suffers from three main disturbing effects: absorption, scattering and turbulence. In recent years, various studies have been carried out in order to investigate how these three impairing effects can be modeled for different water types and also some intelligent techniques have been proposed to mitigate these effects and hence to improve the performance of UWOC systems and extend their viable communication range. In [3] , Mobley has accomplished an in-depth study of light interaction in water to characterize absorption and scattering effects of different water types based on theoretical analysis and experimental evidence reported in [4] . Consequently, variety of worthwhile researches have been carried out to better model the UWOC channel behavior with respect to the absorption and scattering effects. For example, in [5] Jaruwatanadilok presented mathematical modeling of an UWOC channel and its performance evaluation using radiative transfer theory. Moreover, Dong et al. succeeded to present a closed-form expression of double Gamma function to model the channel impulse response in the presence of absorption and scattering effects [6] . They also proposed a weighted Gamma function polynomial to model the 4254 2169-3536
doi:10.1109/access.2016.2593398 fatcat:6wocpv5r5bgfjntweztbccxtyu