基于局部密度预测的传输参数自适应拥塞控制策略

在车载自组织网络中，车辆节点数量的变化和信标传输参数对信道负载有直接影响，节点数量达到一定程度时，周期性信标消息会占据整个控制信道而造成信道拥塞。针对该问题，通过预测局部密度设计传输参数自适应拥塞控制策略。根据网络中车辆节点自身所接收到的数据包和碰撞包的数量预测短期内局部密度的变化，依据信道忙时比率评估当前时刻信道负载，并将其与预设阈值进行对比，结合局部密度预测值自适应调整下一周期的传输参数。仿真结果表明，该策略能够在控制信道拥塞的同时，提高数据包递送率，降低消息传输延迟。

Congestion Control Strategy with Transmission Parameter Adaptation Based on Local Density Prediction

In Vehicular Ad-hoc Network(VANET), changes in the number of vehicle nodes and beacon transmission parameters have a direct impact on the channel load.When the number of nodes reaches a certain level, periodic beacon messages can easily occupy the entire control channel and cause channel congestion.To solve this problem, a congestion control strategy with transmission parameter adaptation based on local density prediction is proposed.The short-term changes of local density are predicted based on the number of packets and collision packets received by vehicle nodes in the network.Then the current channel load is evaluated based on the channel busy ratio, which is compared with a predetermined threshold, and combined with the predicted local density to adaptively adjust the transmission parameters of the next cycle.The simulation results show that this strategy can make full use of channel resources while controlling channel congestion, improve data packet delivery rate, and reduce message transmission delay.