Design And Optimization Of Low-Latency、Low-Power Network Coding In High-Speed Underwater Acoustic Communication

Due to the complex and changeable underwater environment,the transmission efficiency of underwater acoustic communication networks have been limited by the long propagation delay of sound waves and very limited node energy.Since 2000,the proposal of network coding has creatively combined coding and routing,pointing out that network information flow can be processed or compressed,which can further improve network throughput.The network coding technology combined with the natural broadcasting characteristics of underwater acoustic network after it was applied to underwater communication,which not only improves the total throughput of underwater acoustic network,but also has significant advantages in transmission reliability and communication delay,improving the transmission efficiency of underwater acoustic sensor network and the energy utilization rate of underwater network nodes.After analyzing the underwater multipath transmission model based on network coding,in view of the problem of decoding failure caused by insufficient linear independent packet reception in the target node,this paper proposed a scheme to use the edge caching to improve the decoding probability of network coding,taking advantage of a little extra storage resource in exchange for a reduction in latency and energy savings.At the same time,aiming at the situation that edge nodes transmit more data and consume faster energy,a scheme based on sink node feedback is proposed to enable edge nodes to transform into appropriate states according to channel packet loss rate,so as to reduce the energy consumption of edge nodes as much as possible and prolong the life of network while ensuring transmission efficiency.And the paper demonstrates the effectiveness of the proposed scheme in both theoretical analysis and simulations.In order to further improve the transmission reliability of underwater acoustic multi-hop network,this paper analyzes and studies a variety of reliable transmission schemes based on network coding,and proposes a reliable transmission scheme based on network coding combined with a backup node retransmission and dynamic adjustment of coding redundancy.Each hop relay node must be forwarded to the next hop after successful decoding,and if the decoding conditions are not met,it prefers to retransmit from the backup node that is closer to the current node to reduce the propagation delay.If there is no backup node within the communication range or the receive node still failing to decode after retransmission from the backup node,the original transmitting node will dynamically adjust the redundancy of the encoding to adapt to the change of channel packet loss rate according to the feedback signal,aiming at reducing retransmission,and thus reducing propagation delay.When the channel is in good condition,transmitting nodes dynamically reduce the encoding redundancy to reduce additional energy consumption.The comparison of simulation results of multiple transmission schemes shows that the hybrid retransmission scheme through backup nodes proposed in this paper has good effects in terms of delay and energy consumption.