Research And Implementation Of MAC Protocol Based On CSMA For Underwater Acoustic Sensor Networks

With the increase in military applications and marine resource development activities recently. Underwater acoustic sensor networks(UASNs) is being more widely used in oceanic environment monitoring, explore and development of mineral resources, navigation aid, natural mega-disaster prevention, navy strategic defending, etc. Unlike terrestrial wireless networks, UASNs is facing the poor environment, limited bandwidth, long propagation delay, large signal attenuation, multi-path effect, Doppler shift, etc. Therefore, medium access control(MAC) protocols designed for terrestrial networks cannot be directly used in UASNs.As a major component of UASNs, media access control protocol requires taking into account throughput, end to end delay and energy consumption and other performance indicators. So far, the researchers designed a lot of different mechanisms of MAC protocol, in order to meet the networking needs of different UASNs scenarios.Focusing on the sub-network in the terminal 500 m of the UASNs, this paper discusses the practicality of the CSMA based MAC protocol, CW-MAC, in such sub-network. According to the relationship with the throughput and contention window, we propose dynamic optimal contention window search method based on Golden Section Search Algorithm. In this paper, we propose DCW-MAC, which is based on the CW-MAC. DCW-MAC differentiates contention window according to the distance between nodes and sink or nodes and their interference to optimize network performance. Simulation results show that, DCW-MAC protocol compared with the original CW-MAC protocol has higher throughput and lower end-to-end delay.This paper proposes a Round-Robin based optimization neighbor discovery method, which can reduce the packets number and total bytes need to send, thereby reducing the probability of collision and neighbor discovery time. Finally, we use the NI-USB62 ll data acquisition card, BII-5000 amplifier and Transducers as hardware to finish designing and programming the MAC protocol testbed framework and the specific DCW-MAC protocol. Then we verify the network’s connectivity among four existing nodes in the pool of our Lab.