A 5G Low-delay Technical Solution For Automatic Driving

With the rapid development of the mobile Internet and the Internet of Things,many emerging businesses have emerged.In order to meet the new demands of new businesses,the research on the fifth generation(5G)mobile communication system begins.The 5G system has the characteristics of low delay,high transmission rate,and high reliability,which can meet the needs of many emerging businesses,such as automatic driving,virtual reality and etc.Among them,automatic driving is a typical application in low delay and high reliability scenarios.Nowadays,Long Term Evolution(LTE)system can no longer meet the requirements of end-to-end delay.It is necessary to study the low-delay technology in the 5G system to reduce the end-to-end delay and ensure the real-time information exchange between vehicles.In this thesis,firstly we define the end-to-end delay and introduce its evaluation methods.Then we study the 5G low-delay related technologies.Finally,we propose a low-delay technical scheme for automatic driving.The technical scheme is mainly designed based on the two aspects of network architecture and air interface,and an experimental platform is set up for testing and verification.The specific research contents are as follows:(1)From the perspective of network architecture,it is mainly based on the improvement of LTE network.These improvements are divided into two aspects:on the one hand,the Evolved Packet Core(EPC)is fused with the Evolved Node Base(eNB)to make the EPC function sink;On the other hand,with the Device to Device(D2D)technology,vehicle-mounted devices can discover nearby vehicles rapidly and communicate with others directly.Based on EPC function sinking and D2D technology,a new 5G network architecture is proposed to support automatic driving.(2)From the perspective of air interface,it is mainly updated through the following design:use a smaller transmission time interval(TTI)in frame framework.The subcarrier spacing is configured as 60 KHz.There are 7 consecutive symbols in each time slot;Uplink and downlink adopt synchronous and asynchronous hybrid automatic repeat request(HARQ)in the time domain respectively;The Filter Bank Multicarrier(FBMC)technology based on poly phase network is adopted;Sparse Code Multiple Access(SCMA)is used as the multiple access method.The Message Passing Algorithm(MPA)is mapped to the probability calculation as the multiple access receiving method.Through above designs,the air interface is updated and its delay is reduced.(3)A network experiment was conducted on the low-delay technical scheme in this thesis.The average end-to-end delay was 2ms.The experimental results verify the feasibility of the scheme and meet the requirement of 5G end-to-end delay proposed by the IMT-2020(5G)promotion group.Compared with the research results at home and abroad,it has certain advantages.