| With the development of communication technology and ad hoc network technology,hightech and high-precision weapon equipment and intelligent command system are becoming more and more important for modern warfare.In the modern war,the integrated operation of sea,land and air not only requires the interconnection of information between various combat platforms,but also puts forward high requirements for the reliability,security,real-time and other aspects of information transmission.The emergence of data link technology has improved the cooperative work ability of various military equipment and realized the interconnection of information between various military equipment and the command platform.The Medium Access Control(MAC)protocol determines the channel access mode and resource allocation,which is the key of data link technology.Statistical Priority-based Multiple Access(SPMA)protocol supports multi-priority services.It can guarantee the transmission success rate and delay of high-priority services by restricting the transmission of low-priority services when the channel is busy.It is widely used in MAC protocol.However,the traditional backoff strategy of SPMA protocol is not suitable for multi-hop networks;Moreover,the existing calculation methods of SPMA channel occupancy and priority threshold have delays in multi-hop networks with rapidly changing node transmission rates.Therefore,this paper focuses on the backoff strategy,channel occupancy and priority threshold calculation of SPMA protocol in multi-hop networks.In view of the fact that the traditional backoff strategy is not applicable to multi-hop networks,this paper proposes a DQN-based Backoff strategy in Multi-hop Networks(DQN-BMN)for SPMA.The strategy consists of an intelligent backoff network.The intelligent backoff network calculates the backoff duration according to the channel occupancy and its historical value in the network and the number of forwarded packets in the sending queue.then guides the backoff of packets according to the calculated backoff duration.The simulation results show that the DQNBMN method can reasonably set the backoff duration according to the backoff effect of packets in multi-hop network,thereby improving the network throughput and the success rate of packet transmission,and reducing the system delay.Aiming at the problem of delay in the existing calculation methods of SPMA channel occupancy and priority threshold in multi-hop networks with rapidly changing node transmission rates,this paper proposes a method for calculating channel occupancy and priority threshold based on Exponential Weighting(EW)method.In the multi-hop network,the time window for statistics of channel occupancy is divided according to the change trend of channel occupancy.The current channel occupancy is obtained by analyzing the calculation results of channel occupancy in the divided sub-window and weighting calculation.On the basis of obtaining the channel occupancy,the priority queue of SPMA protocol is modeled using the knowledge of probability theory and queuing theory,and the calculation formula of priority threshold is deduced.The simulation results show that the channel occupancy rate calculated by the EW method is more accurate in the multi-hop network where the node transmission rate changes rapidly,and the error between the priority threshold and the theoretical priority threshold is controlled within 2%.In terms of network performance,the network throughput and system delay performance under the EW method have been significantly improved in high-priority data transmission. |
