Research On Evaluation Scheme Of Measurement Performance For LTE-A Systems

With the development of mobile network,the user demand for high-speed and stable multimedia communication service keep increasing.It is important to evaluate the measurement performance precisely in the cell switching process in order to stabilize users' communication.In this thesis,we review the existing measurement methods of system measurement performance in the Long Term Evolution-Advanced(LTE-A)system and the Narrowband Internet of Things(NB-IoT)system.A variety of measurement schemes for Radio Resource Management(RRM)metrices are investigated,including Reference Signal Received Power(RSRP),Reference Signal Received Quality(RSRQ)and Reference Signal Signal-to-Interference-plus-Noise Ratio(RS-SINR).The absolute value of measurement error,Mean Squared Error(MSE)and the Cumulative Distribution Function(CDF)curve of measurement accuracy are also presented.Moreover,the simulation results could provide applicable parameters for engineering.The RSRP,which is a key parameter representing the strength of the cell communication,measures the received signal strength of the system.The existing method based on the LS channel estimation will cause serious measurement error because of the noise interference.In order to solve the problem of low accuracy of RSRP measurement,this thesis analyzes a variety of RSRP evaluation methods,including mean-based method and subset mean-based method.The closed expression of measurement error is also given.Moreover,the conjugate multiplication based method is proposed,which could achieve high accuracy with low complexity.Further,according to the characteristics of NB-IoT system,a joint RSRP measurement scheme is proposed to improve the measurement accuracy.Afterwards,the measurement bandwidth,reporting cycle and sampling interval are analyzed on the effects of measurement performance.Finally,the comparision between theoretical value and simulated value is presented.RSRQ and RS-SINR represent the relationship between the useful signal and the noise interference in different dimensions.The relationship is an important index to measure the quality of the link.In this thesis,their performance gap is analyzed,and the shortcomings of RSRQ are summarized.Thus,it is necessary to introduce RS-SINR.A variety of methods for measuring RS-SINR are analyzed,including the difference-based method,second-order and fourth-order based method and null subcarrier-based method.The closed expression of the measured value is provided.Further,the variance-based method is proposed and the improved method is given to improve the performance under high SNR.Finally,the simulation results are presented to support our theoretical analysis.