Research And Implementation Of Physical Random Access Channel In 5G System

5th Generation mobile communication(5G)is the latest generation of cellular mobile communication technology.Its performance goals are high data rates,reduced latency,energy savings,reduced costs,increased system capacity,and large-scale device connectivity.The random access process is the first step for a terminal to access the network,so designing a fast and efficient random access process is crucial for 5G systems.With the support of the “Enhanced Mobile Broadband 5G Terminal Simulator R&D” project,this topic focuses on the analysis of related detection,detection threshold settings,and timing advance estimation(TA)in the sending and receiving process of Physical Random Access Channel(PRACH)of 5G system and gives corresponding solutions.The main work of this article are as follows:1.Combined with 3rd Generation Partnership Project(3GPP)standards,this topic completes the establishment of MATLAB link for PRACH in the process of random access.This includes the generation of baseband signals,de-modulated PRACH baseband signals,and preamble detection.In the design scheme of the receiver,this paper chooses a frequency-domain ZC sequence generation algorithm that reduces complexity by sacrificing a small amount of memory resources and a frequency-domain correlation detection algorithm with a smaller running time.2.Aiming at the problem that the threshold detection algorithm based on noise estimation affects the detection performance when the noise variance estimation is not accurate,an improved threshold detection algorithm is given.The improved algorithm mainly modifies the decision threshold variable and set a secondary threshold for detection.Simulation results show that,compared with the traditional threshold detection algorithm based on noise estimation,the improved algorithm's correct detection probability performance is improved by 1?2d B,and the false alarm probability is improved by 0.8?1d B.Therefore,the improved scheme has a certain improvement in random access performance.For the problem that propagation delay exceeding Cyclic Prefix(CP)length affects the success rate of uplink synchronization,this paper proposes a time advance estimation compensation scheme without modifying the protocol.This scheme compensates for the TA value of the new lead format 2 under different delay conditions,thus accurately estimate the TA value.Simulation results show that when the propagation delay exceeds the CP length,the maximum TA estimation error is about 0.98 us,which meets the standard requirement that the error is within 1.04 us.3.Combined with the improved threshold detection algorithm,this paper implements the Digital Signal Processing(DSP)implementation of the PRACH sending and receiving process on the TMS320C6678 chip.This paper compares the correct detection probability and false alarm probability of the preamble during MATLAB simulation and DSP implementation.The results show that the entire DSP implementation scheme can meet the requirements of the signal-to-noise ratio specified in the protocol.This paper also analyzes the feasibility of the entire scheme from the aspects of running time and occupied space,proving that it can meet the requirements of the project.