QoS Cross-Layer Optimization Guarantee Technology For Railway Mission-critical Data Based On 5G

With the rapid development of high-speed railways and intelligent railways,higher requirements are put forward for data transmission with large bandwidth,high speed,and low latency.The future intelligent railway communication system needs To provide high-reliability,low-latency,and high-security mission-critical data transmission guarantees for the train control system that works together between trains and ground.It also needs to meet the requirements of high-speed data transmission.The fifth generation mobile communication(5G)with ultra-reliable and low-latency communication characteristics has not yet given a solution to mission-critical data transmission.The system needs to be enhanced to meet needs of the next generation of wireless communications including railways,and the demanding requirements of Quality of Service(QoS)for mission-critical data transmission.In order to ensure the safety of railway communication and railway transportation,it is necessary to improve on the existing basis and combine the special requirements of railway broadband communication to ensure the QoS requirements of mission-critical data.In view of this,this paper conducts research on 5G-based railway mission-critical data QoS cross-layer optimization guarantee technology.The main research work is as follows:(1)The MAC layer-based priority differentiated scheduling problem and its implementation technology are studied,and a QoS weighted scheduling algorithm oriented to mission-critical data transmission requirements is proposed.The algorithm quantifies system performance indicators such as delay,reliability,and throughput,so that the system can distinguish the priority level through the calculated weight value,and realize the priority scheduling of the railway mission-critical data to ensure its QoS requirements.(2)According to the QoS requirements of mission-critical data transmission,a cross-layer optimization based technology is studied to guarantee the requirements of QoS.This paper focuses on the resource allocation and optimization technology of the physical layer and the MAC layer.Furthermore,a resource state model of the the two layers is established and a relatively complete QoS cross-layer optimization framework is proposed.In order to solve the aforementioned cross-layer optimization problem,this paper first takes maximizing the total system capacity as the optimization goal,and studies the optimal resource allocation strategy by introducing key parameters such as system capacity,delay and packet loss rate.Furthermore,in view of the non-convex form of the optimization problem and the high computational complexity of the optimal solution,this paper adopts the idea of separating power and subcarrier optimization variables to obtain the sub-optimal resource allocation strategy that satisfies the constraints.System simulation verified that the sub-optimal resource allocation strategy proposed in this paper can not only greatly reduce the computation time and computational complexity,but also ensure high accuracy.By comparing with traditional resource allocation strategies such as water injection method,the required power can be significantly reduced and system energy can be saved under the same optimization effect.(3)Aiming at the guarantee of real-time and reliability of data in traditional packet communication networks,this article attempts to introduce Time Sensitive Network(TSN)into the 5G network,and through the organic combination of 5G technology and TSN technology,it can meet System solutions for mission-critical data QoS requirements.This paper proposes a complete 5G-TSN converged network architecture and related protocol design for key interfaces.Through targeted revisions to the specific protocol standards of the TSN network,the interconnection with the 5G network is initially realized,including the proposal of 5G-TSN convergence Clock synchronization protocol and traffic processing protocol under the network architecture.