Design And Development Of Medium Access Control Protocol For Data-collection-oriented Underwater Acoustic Sensor Networks

Underwater acoustic sensor network(UWASN)has broad application prospects in the current marine research and development field,and the medium access control(MAC)protocol can solve the channel sharing problem in the network,so several nodes can share network resources more fairly and effectively.Therefore,the MAC protocol is the key networking technology to guarantee underwater sensor nodes to complete data collection tasks.Unlike terrestrial wireless sensor network,UWASN adopts the acoustic signal as the propagation medium,which has many specific characteristics,such as long propagation delay,limited energy,high bit error rate,complex and changeable network topology,and so on.Therefore,it is of great significance to design and develop MAC protocols in UWASN.In the existing fixed UWASN,the data of the sensor node usually arrives at the sink node through multi-hop transmission.However,due to poor conditions of the underwater channel,it is prone to cause packet loss and data retransmission,leading to greater energy consumption as well as lower network throughput and higher network overhead.In recent years,underwater mobile nodes have been widely used in UWASN,thus it is of great application value to design and develop MAC protocols in the scenario,where the mobile node collects data from fixed underwater sensor nodes to improve channel utilization.Considering the problem of inefficient data collection in the fixed UWASN,a scheduling-based MAC(SCHeduling-based Mobile MAC,SCHM-MAC)protocol is proposed.In the SCHM-MAC protocol,the mobile node acts as a sink node,collecting data from fixed underwater sensor nodes during the movement.During the movement,the sink node periodically broadcasts a control packet to discover fixed sensor nodes within the data collection range,and uniformly schedules the data transmission of nodes according to the propagation delay with each node,in order to avoid data transmission collision.Taking the mobile node as the sink node can solve the packet loss problem caused by multi-hop data transmission in the fixed UWASN better.Theoretical analysis and simulation results show that the SCHM-MAC protocol achieves a higher network throughput,a lower end-to-end delay and energy consumption,and a higher fairness of sensor nodes.In order to verify the practicability of the proposed SCHM-MAC protocol,the experimental is carried out by underwater acoustic nodes.Experimental results show that the SCHM-MAC protocol has a better performance in terms of successful transmission rate and average transmission delay.