Research On Underwater Acoustic Communication Network MAC Protocol Based On Slot Scheduling

The 21st century is recognized as the ocean century by all countries in the world.In the marine field,the underwater acoustic communication network has broad application prospect,which makes it gradually become a hot spot for scholars from all over the world.As one of the core issues in the research of underwater acoustic communication network,the Media Access Control(MAC)protocol has a huge impact on throughput,communication delay,and service quality of the network.Underwater acoustic channel features unfavorable factors such as large propagation delay,limited communication bandwidth,serious multipath phenomenon,and complex noise characteristics,which presents difficulties for the MAC protocol design for underwater acoustic communication network.Based on the analysis and summary of common underwater acoustic communication network MAC protocol design ideas and characteristics,this paper conducts an in-depth study on the TDMA-based underwater acoustic communication network time slot scheduling MAC protocol,and takes the Super-TDMA protocol making use of the large delay characteristics of underwater acoustics as the framework.The channel access parameter calculation algorithm and scheduling algorithm of the protocol are researched and analyzed.In order to solve the capacity limitation and high computational complexity of the algorithms,an improvement plan is proposed.Finally the effectiveness of the plan is verified in the network simulation scenario built.The main work and research results of this paper are as follows:1)In order to solve the shortcomings of insufficient channel utilization and inflexible execution of the ?-Schedules calculation principle in the Super-TDMA protocol,an improved distributed ?-Schedules algorithm is proposed.The new algorithm uses the newly designed channel access parameter calculation method based on the node delay relationship and network scheduling information to realize the transmission of data messages across time slots,which further improves the network throughput;at the same time,the new algorithm uses the distributed operation mode,which shortens the execution cycle,compared with the original algorithm calculated by the central node.It increases the flexibility of node channel access,and effectively improves the node's response to position movement and link delay changes during communication and the ability to reduce the probability of data transmission conflicts.2)In order to solve the high computational complexity of the time slot scheduling algorithm in the Super-TDMA protocol,the paper adopts the research idea of simplifying the scheduling operation based on the characteristics of the specific network topology,and takes the ring topology as an example.According to the transmission and reception rules of the optimal slot table,combined with the constraints of unbalanced load on the link,the scheduling objective function is redesigned,and an algorithm for solving the optimal slot table under unbalanced load is proposed.The newly designed scheduling algorithm combines the advantages of the low time complexity of the ring topology simplification algorithm,and increases the adaptability of the scheduling calculation to the link load,effectively avoiding the waste of time slots caused by the mismatching of the scheduling arrangement.3)In order to verify the performance of the improved algorithm,a network simulation environment was built on OMNe T++,and the performance of the TS-TDMA protocol based on the new algorithm in the network was tested,and compared with the original protocol and common underwater acoustic network MAC protocol,which proves that the improved protocol has better performance in terms of throughput and network delay.The simulation results show that the new channel access parameter calculation algorithm has a 20% increase in throughput compared to the original algorithm,and the new scheduling algorithm reduces the calculation time compared to the original algorithm and the end-to-end delay of network data packets with the unbalanced network load.