Research On The Technology Of Latency Reduction For 5G

As the two driving forces of the future 5G communication,mobile Internet and IoT are the main scenes and business demand characteristics,and the important point is to provide the user with the millisecond end-to-end delay.Latency reduction technology have a positive significance for the future 5G large-scale deployment scenarios,for example,industry,medical and other vertical industries.There are two technical routes for 5G,including new radio(NR)and 4G Evolution.4G Evolution route for the 5G scene and business requirements,under the premise of ensuring compatibility,based on the existing 4G framework(LTE/LTE-advanced technology framework),introduce new technology on the traditional mobile communication band,and then further enhance the 4G system speed,capacity,connection number,delay and other radio performance indicators.The design of new technology support a shorter transmission time interval(TTI)structure and a more streamlined signaling process to meet the requirements of millisecond end-to-end low latency.Because the 5G new radio has higher latency business requirements than the 4G evolution route,the ideas and methods for the research of key technology of 4G evolution route to reduce the time delay also apply to that of the 5G new radio which is based on the reduction of time delay target.This paper focuses on the key technologies for 5G based on short TTI architecture,including three aspects:Aiming at the transmission of uplink control information under the short TTI system architecture,a flexible design of uplink control channel based on demodulation reference signal(DMRS)sharing is proposed so as to increase the uplink throughput and improve the signal-to-interference-plus-noise ratio effectively.In order to reduce the overhead of the short physical downlink control channel(sPDCCH)and reduce the user effort of the short TTI in the carrier aggregation scenario,a signaling mechanism for activating/deactivating sPDCCH is proposed and two technical schemes are extended to choose from.In view of the situation that the short TTI and the legacy TTI need to coexist in the same frequency band or in different frequency bands,the method of resource allocation indication is proposed to avoid resource conflicts that may occur during the uplink scheduling.Through theoretical analysis and simulation,the results show that the above proposed methods can effectively improve the performance of 5G radio based on short TTI.