Research And Simulation Of Key Technologies For 5G Ultra Reliable And Low Latency Communications

The diversification of user communications demands and the continuous emergence of new mobile services are driving the evolution of wireless networks to the fifth generation mobile communications(5G)networks.5G supports diverse communication scenarios,that are enhanced mobile broadband(eMBB),ultra reliable and low latency communications(URLLC),massive machine type communications(mMTC).Diversified communications scenarios also pose new challenges for the construct of 5G networks.In addition to providing ultra high data rate and better mobile broadband experience,the 5G needs to exploit new industries,and promote the development of URLLC services,such as industrial automation,smart home and autonomous driving.These emerging services demand ultra reliability,extremely low latency,security.According to the International Telecommunication Union(ITU),the air interface latency of URLLC traffic should less than 1 ms,the end-to-end delay should less than 10 ms,and the reliability should be maintained at the order of 99.999%.Hence it is a key and diffcult issue to design the transmission schemes,especially more reliable channel coding and the traffic multiplexing in multi-service coexisting scenarios,so as to meet the stringent requirements of URLLC service.Therefore,this thesis focuses on the key technology of URLLC.Firstly,by tracking the progress of the standardarization,the promising channel coding shcmes that are proposed for the URLLC service is studied.Specifically,the property and encoding/decoding principle of low density parity check code(LDPC)are elaborated.The performance of the LDPC in the URLLC scenario is analyzed through the MATLAB based link-level simulation in terms of the bit error rate and block error rate.In addition,this thesis studies the dynamic URLLC and eMBB multiplexing scheme based on the new frame structure proposed by 5G to facilitate the coexisting of multi-service.The low latency requirement of URLLC traffic can be satisfied by letting the URLLC data puncture part of resource which is occupied by the ongoging transmission of eMBB traffic.Considering the realiability degradation of eMIBB traffic caused by the multiplexing.This thesis further studies the two compensation approaches at the eMBB receiver,that are whether transmitting the indicator of resource that are punctured or not.The performance of these two approaches are also analyzed through link-level simulation.Finally,the rotation modulation based signal space diversity technique is introuduced into the proposed traffic multiplexing scheme,the largest diversity gain is achieve through the rotation angle selection based on the average mutual information maximization.The theoretic analysis and simulation results demonstrate that the proposed scheme can meet the latency requirement of URLLC traffic meanwhile gurantee the reliability requirement of eMBB traffic.