A Study On MAC Scheme And Key Technology Of Underwater Cognitive Acoustic Network

Underwater Wireless Sensor Networks(UWSNs) consist of surface nodes, suspending nodes and AUV(UUV). All these nodes carrying sensors are responsible for data collection. All the collected data are transmitted among these nodes or to data center by acoustic communication. UWSNs have gained tremendous attention in recent years because of their wide civilian and military applications. However, with the application and deployment of sonar systems and UWSNs, the co-existence of manmade acoustic system and natural acoustic system faces great challenges. Therefore,in this thesis, based on the propagation feature of acoustic channel, I will study the influence of these features on UWSNs and then propose a novel structure of Underwater Cognitive Acoustic Networks(UCANs). Then I will analyse the possible challenges of these modules. Finally, a series of solution on MAC protocols, related localization and power control algorithms will be proposed, which can be applied in high propagation delay, low bandwidth and energy limit situation. The specific content and innovation of the thesis includes:1.Based on the acoustic characteristic of marine mammals, a passive hyperbola localization algorithm targeting marine mammals(PHLA) is proposed. PHLA can exploit passive received signal power to localize marine mammals based on the propagation characteristics of their signals. The proposed localization scheme is the basis of eco-friendly MAC scheme.2.In the thesis, we define a new metric to evaluate the spatial reuse e?ciency of networks named: spatial reuse index, which is much slower in UWSNs. To tackle this problem, a joint power control and rate adaptation MAC protocol named UPC-MAC is proposed. The proposed MAC protocol is an environmentally friendly MAC protocol. By applying a game theory based utility function with a set of limitations to optimize transmission power and related rate adaptation, the proposed power control algorithm allows for as many concurrent communications as possible to improve the goodput performance while avoiding interference with marine mammals by introducing a two mode transmission scheme.3.To improve the spectrum e?ciency of single channel MAC protocol, a multichannel MAC protocol named UMMAC is proposed in the thesis. UMMAC is a split phase and reservation based multi-channel MAC protocol which enables hosts to utilize multiple channels via a Channel Allocation and Power Control Algorithm(CAPC). With collected information, UMMAC allows for as many parallel transmissions as possible while avoiding using extra time slot for channel negotiation. By running CAPC algorithm,which aims at maximizing the network’s capacity, users can allocate their transmission power and channels in a distributed way.4.The existing UWSNs simulator faces great challenge of accurate simulation. To improve the simulator’s performance, an improvement of Aqua-sim simulator is proposed in the thesis. The new proposed simulator employs a more accurate channel model and a new OFDM modulation module. Furthermore, a novel versatile tested for UWSNs is also proposed in this thesis, which apply researches an accurate and a?ordable testing environment.