Design And Implementation On Anti-Interference And Reconfigurable MAC Protocol In Ad Hoc Network

At present,Ad Hoc Network has become more and more popular,which is suitable for multi-hop,self-organizing,decentralized scenarios.But it is also hard to ignore the increasing number of interference attacks on networks.These attacks often lead to the loss of data in the process of node communication or the long-term occupation of channel,resulting in the network performance degradation.In the face of increasingly intelligent and diversified means of interference and attack,the traditional MAC technology needs to be strengthened in effect and time variability.Based on this,the paper focuses on the MAC layer interference in Ad Hoc network,studies the design of anti-interference MAC protocol and a reconfigurable MAC protocol system to deal with the complex random interference,protocol-level interference and time-varying transmission environment in the network.The main research content and work of this paper are as followed.For random interference with variable interference intensity,an anti-interference MAC protocol Spi-MAC based on rateless coding is designed and implemented.The whole idea is to send the payload of frame with rateless coding as well as the head of frame with convolutional coding at the sender.When the end receives the shard,it first checks the frame head,and if it fails,it passes the NAK to deny the frame retransmission.If it succeeds,it will continue to decode the payload.With a certain number of shards accumulated,the original data can be recovered,and an ACK will be sent to request to stop sending the shards of this data frame,which represents the successful transmission of this data frame and prepares to send the next frame.This method does not need to estimate the channel quality in advance,even if the packet is lost due to the interference attack,the originator will continue to send shard until the receiver successfully decodes,which avoids the accuracy error and extra cost brought by the channel estimation.On GNU Radio,the overall framework including MAC layer modules,coding and decoding modules of the physical layer is built,and the realization of USRP X310 peripheral is connected.After testing the system connectivity,the Spi-MAC performance was tested under the constant change of interference intensity,and the system throughput of the shred transmission mechanism of different interference intensity and the direct transmission of original data were compared,which verified the anti-interference performance of Spi-MAC.A reconfigurable MAC protocol system(SC-MAC)based on Q-Learning was designed for the complex time-varying environments in Ad Hoc networks.The system integrates the MAC protocol based on competition/scheduling,and makes use of reinforcement learning to determine the appropriate indicators according to the current environment(whether there is external interference,whether there is competition between nodes),and selects the matching MAC protocol and the corresponding physical layer modules.In the Q-Learning model,there are many super hyperparameters that need to be set in advance.To get the most suitable hyperparameter,the system will set regret value as the index to calculate the combination of various parameters.Eventually,best combination of hyperparameter such as learning rate,conversion factor,temperature T and the constant is get.Two network scenarios were designed: external interference,internal node competition and external non-interference,node non-competition.The performance of SC-MAC and a single MAC protocol based on competition/scheduling in different transport environments was compared,and the SC-MAC system performance was verified to be superior.Finally,in the case of external interference,the optimal matching parameters within the Spi-MAC protocol are studied when the interference changes,so that the protocol parameters can be reconstructed to avoid additional overhead caused by protocol-level interference(such as ACK interference).