The Study Of OFDM Based Underwater Acoustic Sensor Network MAC Protocol

To achieve reliable and high-speed underwater acoustic communication with limited energy constraint, one of the urgent problems is to establish an effective medium access control (MAC) protocol. Orthogonal frequency division multiplexing(OFDM) technology can effectively use underwater acoustic channel and achieve high-speed underwater acoustic communication, this dissertation designs a low-power hybrid MAC protocol named DmRMP/CB, based on the cluster structure acoustic sensor networks and the characteristics of multi-carrier underwater acoustic communication technology. The protocol can take full use of the channel resources and significantly reduce the overall energy consumption of sensor network. Primarily researches of this dissertation are described as follows:Firstly, the dissertation discusses the structure and protocol stack of underwater acoustic sensor networks(UASN), introduces the research status and applications of UASN, elaborates the characteristics of multi-carrier underwater acoustic communication system, describes the basic criterions and important factors to be considered during the design of UASN MAC protocols and establishes the basic transmission model for cluster structure multicarrier UASNs.Secondly, the dissertation present a MAC protocol based on the cluster structure multicarrier UASN transmission model, which named as named DmRMP/CB. The protocol proposes a modified CSMA/CA protocol to optimize the channel competitive process and uses the artificial ant colony algorithm to achieve the verification and optimization of transmission solutions. The dissertation elaborates the detail process and algorithms of DmRMP/CB protocol in different time slots.Thirdly, based on the characteristics of UASNs applications, the dissertation established a simulation model of the multi-carrier UASNs. The performance of DmRMP/CB protocol are simulated and the results show that DmRMP/CB can effectively reduce the overall energy consumption and extend the overall life of the network under the premise of meeting network requirements.