Research On Time-sensitiveness Access Scheme For Multi-mechanism Communication In Cluster Network

A cluster system is a highly coupled,self-organizing,multi-intelligent distributed system consists of multiple mobile nodes working through distributed interconnection and collaboration.The collaboration between nodes in the system is achieved through the cluster network.Most existing cluster networks contain multiple communication mechanisms,and services under different communication mechanisms have different requirements for access latency.However,the time-sensitiveness requirements of multimechanism communication in cluster network has not been adequately considered in existing access schemes.Therefore,in cluster network scenarios,the time-sensitiveness and timeliness of high-priority service information need to be fully considered,with priority access to the most important data information.To address this problem,this thesis carries out research on the time-sensitiveness access scheme for multi-mechanism communication in cluster network.The main work and innovative contributions are as follows:Ⅰ、A Concurrent Node-Relationship-Aware Pre-Connection Algorithm(CNP)is proposed.The channel access time-sensitiveness of network nodes depends on the network topology,and the connection status between nodes is determined by node relationship awareness.Therefore,this thesis proposes the CNP algorithm to achieve channel access pre-connection based on concurrent node relationship awareness.Firstly,to address the problem of high channel duty cycle in the neighbor discovery process of the classical randomness neighbor discovery algorithm,a pre-handshake scheme is introduced to divide one control time slot into two sub-time slots,in which nodes can independently select the working state for neighbor discovery,thus improving the channel utilization efficiency.Secondly,to address the problem of information collision in concurrent communication,a collision avoidance scheme is introduced.The nodes can modify the probability of selecting the working state according to the channel collision situation,thus improving the efficiency of node relationship awareness.Then,to address the problem of low accuracy of clock synchronization brought by the high dynamics of the clustered network,relevant messages are designed to mark the active time slots of the nodes.The nodes can complete the relationship awareness of the surrounding nodes in the overlapping part of the active time slots,thus improving the robustness of the algorithm.The simulation verifies that when the number of nodes is 50,the CNP algorithm requires 29.7% fewer time slots to fully discover neighboring nodes compared to the node-relationship-aware algorithm without pre-handshake scheme.Ⅱ、 A multi-priority access strategy based on Dynamic Thresholding and Compressive Backoff(DC-SPMA)is proposed.The Statistical Priority Multiple Access(SPMA)protocol has the advantage of differentiating data priorities,but the use of fixed transmission threshold and binary exponential backoff algorithm will increase the access latency of the nodes.Therefore,this thesis proposes an access strategy including Adaptive Channel State Dynamic Threshold Adjustment Algorithm(ACSDA)and Prioritized and Adaptive Channel State Backoff(PACSB)algorithm.The ACSDA algorithm can quickly determine the initial value of the transmission threshold and adaptively adjust the transmission threshold for each priority level according to the actual channel environment.The PACSB algorithm can dynamically adjust the backoff time according to the channel occupancy,transmission threshold and data priority level.Simulation results show that DC-SPMA performs better than SPMA,with 7.4% increase in network throughput when the network load is 7Mbps,2.875% increase in the average packet success rate,0.7%increase in the transmission success rate of packets in the highest priority queue,10.4%increase in the transmission success rate of packets in the lowest priority queue,28.36%decrease in the average packet avoidance delay and the end-to-end delay was reduced by 21.42%.The time-sensitiveness access scheme for multi-mechanism communication in cluster network studied in this thesis can be applied to large-scale,distributed and highly dynamic communication scenarios,and is of practical significance and engineering value in meeting the time-sensitiveness of different communication mechanisms.