Variable Delay MAC Protocol For Underwater Acoustic Sensor Network

Accounting for the three-quarters of the earth's oceans affect all aspects of human life,where there is a very rich biological,mineral,oil and gas which is indispensable resource of human civilization development,with the increasing emphasis on exploration and research of worldwide marine and rapid development of terrestrial wireless sensor networks,the underwater acoustic sensor networks has emerged as the times require.As a major component of underwater acoustic sensor networks,MAC protocol in addressing collision problems which appear in multiple nodes transmit task on a shared channel,ensure efficient use of energy,make transmission delay as low as possible,and achieve fairness between nodes access channel plays important role. However,the sound of water MAC layer protocols which still limited to the transmission delay that is five times of the terrestrial radio and acoustic transceivers that has high energy consumption constrain the development of underwater acoustic sensor network,so it is time for us to study and design a suitable for underwater acoustic sensor networks MAC protocol.In the past few decades,underwater acoustic sensor networks are widely studied and made great progress. However, the characteristics of underwater acoustic communications,such as limited bandwidth,multipath transmission,relatively long and variable transmission delay,high bit error rate,energy restrictions, still limit the performance of underwater acoustic sensor networks. At present, most of the research are committed to overcoming the effects of the long propagation delay on MAC design,varying delay problem has not received enough attention,from the variable time delay starting,this paper analyze the effects of variable time delay on the performance of the MAC protocol by Markov Model, aim at the effect of variable delay on RTT(transmission and return time) in MAC protocol, proposed an optimization method to improve the performance of the protocol by setting up RTO(retransmission time).Including numerical methods and probabilistic methods. Finally.comparing optimization protocol with FAMA by Aqua-Sim simulation performance simulation results which include throughput,energy consumption,and end to end delay,we come to conclusion that optimization algorithm can effectively avoid duplication of packets due to underwater acoustic channel changes randomly generated delay to improve the performance of all aspects of the original protocol,which has higher throughput and lower latency and more end to end low average power consumption than FAMA.