A Research On Preamble Detection Technology Of TD-lLTE Random Access

Through the random accessing of wireless channel,mobile terminals can be connected to the network to configure the communication resources.The performance of random access could directly affect the efficiency and user experience of the communication system.At present,the random access preamble detection algorithm that widely used in the LTE(Long Term Evolution)system is a frequency domain detection algorithm.This algorithm reduces the computational complexity of the receiver successfully by using the over sampling technique and the principle of frequency domain dot multiplication equivalent to time domain convolution,and improves the accuracy of the uplink synchronization by adjusting the detection threshold based on the estimated noise power.The detection performance,however,remains to be improved.This thesis first introduces the key concepts of the LTE and its physical layer,including the division of each channel in the physical layer,the format of the data frame,and the mapping of the time and frequency resources.Then the LTE random access technology is discussed in which different LTE random access technologies are discussed,and the structure of the LTE random access channel is deeply analyzed,including the preamble symbol,the preamble format,the preamble generation sequence,the frequency domain and the resource configuration mode.Furthermore,the effects of preamble sequence detection caused by the signal frequency shift at receivers are analyzed as well.According to the above analysis,this thesis proposes a preamble detection scheme for TD-LTE random access for users in low/medium speed movement scenarios.The proposed scheme adds the compensation of the Doppler shift caused by the user movement at the receiver,and optimizes the progress of the whole preamble detection.The proposed scheme is simulated in MATLAB and comparing to the traditional random access detection algorithm in LTE system.The simulation result shows that the proposed scheme has a better performance of preamble detection in low/medium speed movement scenarios..