Abstract
Extensive attention has been given to the use of cognitive radio technology in underwater acoustic networks since the acoustic spectrum became scarce due to the proliferation of human aquatic activities. Most of the recent studies on underwater cognitive acoustic networks (UCANs) mainly focus on spectrum management or protocol design. Few efforts have addressed the quality-of-service (QoS) of UCANs. In UCANs, secondary users (SUs) have lower priority to use acoustic spectrum than primary users (PUs) with higher priority to access spectrum. As a result, the QoS of SUs is difficult to ensure in UCANs. This paper proposes an analytical model to investigate the link connectivity and the probability of coverage of SUs in UCANs. In particular, this model takes both topological connectivity and spectrum availability into account, though spectrum availability has been ignored in most recent studies. We conduct extensive simulations to evaluate the effectiveness and the accuracy of our proposed model. Simulation results show that our proposed model is quite accurate. Besides, our results also imply that the link connectivity and the probability of coverage of SUs heavily depend on both the underwater acoustic channel conditions and the activities of PUs.
Highlights
There is a growing interest in exploring the underwater environment due to a diversity of underwater applications, including ocean environment monitoring, offshore structural health monitoring, mine reconnaissance, distributed tactical surveillance, target tracking, shipping safety, and fish farm monitoring [1,2,3]
We find that the link connectivity and coverage of secondary users (SUs) depends on both the spectrum availability and the topological connectivity, while the spectrum availability has been ignored in most existing works
Our results offer an implication on optimizing the network throughput of SUs in underwater cognitive acoustic networks (UCANs)
Summary
There is a growing interest in exploring the underwater environment due to a diversity of underwater applications, including ocean environment monitoring, offshore structural health monitoring, mine reconnaissance, distributed tactical surveillance, target tracking, shipping safety, and fish farm monitoring [1,2,3]. A key technology to enable various underwater monitoring applications is underwater sensor networks (USNs), which can be deployed in various underwater environments such as reservoirs, lakes, rivers, and oceans. Due to the high attenuation of electromagnetic waves in underwater environments, acoustic communications are typically used in USNs. the underwater acoustic spectrum is becoming a scarce resource for the following reasons: (1) the high competition for acoustic spectrum between different users due to the proliferation of man-made underwater acoustic systems, including sonars, acoustic sensors, and unmanned underwater vehicles [4]; (2) the co-existence of man-made acoustic systems and natural acoustic systems (e.g., marine animals like whales, dolphins, and sea lions) [1]. It is necessary to solve the spectrum scarcity problem in an environmentally-friendly and spectrum-efficient way
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