Joint Uplink And Downlink Transmission Design And Performance Evaluation For URLLC Using Finite Blocklength Codes

With the upcoming 5G communications,some novel wireless applications like cloud connection and control,Internet of Things(IoT),Internet of Vehicles and autonomous driving,massive machine-type communications have come into sight.Comparing with the previous generations of cellular system that emphasize high communication rates and capacity only,5G stresses more on aspects including access user number,reliability,latency and energy efficiency,etc.These factors direct and comprehensively decide the performance of system.By shortening encoding length to satisfy the stringent requirements of ultra-reliable and low-latency communications(URLLC)under the IoT background,the change of 5G system design also contrasts with the classical information framework in theory.In 2010,Polyanskiy proposed the analytic expression of maximum coding rate in finite blocklength regime,which has significant influence on analysis and design of short package based communication systems.This paper considers the design and optimization problems for URLLC in finite blocklength regime.The research contents and innovative works include:1)propose the system model and problem formulation for URLLC downlink(including SISO two users case and MISO multiple users case)and joint uplink-downlink transmission design;(2)analyze and prove the monotonicity and convexity properties of maximum coding rate formula;(3)solve the downlink transmission design problem by using bisection method and CVX tools;(4)illustrate the concepts and principles of uplink-downlink duality and Golden-Section Search(GSS)and propose to exploit alternating optimization to deal with the joint uplink-downlink transmission design problem;(5)carry out numerical simulations of the proposed problems,analyze the convergence of proposed algorithms,discuss the dependency and tradeoff between multiple system parameters and obtain some valuable methods for practical system design.