Research On Gated Scheduling Mechanism Of Time Sensitive Network

With the development of Industry 4.0,traditional applications have begun to transform into intelligent applications,and more and more fields have begun to put forward new requirements for the transmission performance of information in the network.Time Sensitive Network ensures the real-time,deterministic and reliable transmission of time triggered traffic(TT flow)in the network through the defined traffic scheduling mechanism,network management and control mechanism,and high-precision time synchronization mechanism.At the same time,it is also compatible with the transmission of non-TT flows,meeting the communication needs in different fields.Therefore,it is of great significance to study the relevant mechanisms defined in Time Sensitive Network.This thesis will study the gated scheduling mechanism in the traffic scheduling mechanism.In the research on the gating scheduling mechanism,the traffic scheduling planning problem in the network is directly expressed as configuring a set of constraints and objective functions on routing variables or scheduling variables according to different performance indicators,and then calculating the distribution values of these variables.The value configures the gated list in the network to meet the real-time deterministic communication of the network.Due to the wide application fields of Time Sensitive Network,different application fields have different network performance requirements.This thesis proposes two gated scheduling schemes from two aspects: reducing the response time of TT flows and improving the available bandwidth of non-TT flows.Aiming at the current situation of reducing the response time of the TT flow without considering the data arrival time,a scheduling objective of minimizing the sum of the response time is proposed,and then a gated scheduling scheme is designed based on this scheduling objective.The scheme first designs the ITIO algorithm,which arranges time slots for each flow in turn according to the given order.If the TT flow sent at the current moment has a slot overlap on a certain link,this flow will be placed on the first link.The transmission start time is delayed by a corresponding time to ensure that a given TT flow is sent as early as possible.Further,since the scheduling result is related to the scheduling order,this thesis proposes a time slot sorting scheduling algorithm,which sorts the TT flows according to the time slots occupied by the TT flows in the network when they are transmitted in the link and the transmission path,so as to ensure that the order is obtained.Scheduling according to the ITIO algorithm can make the flow in the network reach the corresponding destination node as early as possible,thereby minimizing the sum of the response time.Finally,the performance of the algorithm is verified by simulation.For the situation that sufficient resources need to be reserved for non-TT flows in the network,analyze the reasons for the waste of non-TT flow resources.Based on the schedule table generated by the gating scheduling scheme based on the response time of TT flows,an aggregation scheduling algorithm is proposed to realize the aggregation transmission of TT flows by re-planning the scheduling table.That is,in the case of ensuring that the TT flow can arrive before the deadline,let the TT flow wait in the switch buffer,so that it can be transmitted on the next link together with the TT flow arriving later,so as to achieve the purpose of aggregated transmission.It not only the number of guard bands is reduced,but also the flows can be aggregated and transmitted in the following links,and larger continuous transmission resources are reserved for other types of flows,which significantly improves the available bandwidth of non-TT flows.Finally,the performance of the algorithm is verified by simulation.