Research On 5G Ultra Dense Network Spectrum Access And Localization Method Based On Millimeter Wave Communication

With the development of 5G technology,the contradiction between spectrum demand and business increment is becoming more and more serious.In order to improve the utilization efficiency of spectrum resources and improve the overall network performance,this paper focuses on the basic theory,methods and key technologies of 5G ultra dense network spectrum access and location method based on millimeter wave spectrum sharing scenarios.The main contents of this paper include the following three aspects.First,in this paper,we investigate the angle-domain spectrum opportunities of secondary users with directional transmission,and analyze the detection probability of spectrum holes.We also analyze the detection probability of interference allowed scenarios.By calculating the angle mean of spectrum holes,we get the mathematical statistical properties.Through the results of the numerical analysis in different scenarios,we demonstrate that when N is large enough(for example,N>10),the size of the angle δ has a dominant impact on the spectrum opportunity.Meanwhile,we prove that utilizing directional antennas and allowing interference can obtain more angle-domain spectrum opportunities and improve the spectrum utilization.Second,aiming at the performance problems of the millimeter wave spectrum sharing network,the system model of the millimeter wave spectrum sharing network and the theoretical analysis of the network performance are studied.Analysis results show that under the premise of not affecting the PUs,the SUs can choose the appropriate distribution density to improve the spectrum access ratio.An interesting note is that increasing the secondary network density significantly improves the secondary network coverage while causing a negligible impact on the primary network performance.This indicates that in mm Wave,both primary and secondary can achieve significant coverage probability by selecting appropriate values of ξ and BS densities.Third,since mmWave has the characteristics of narrow beam,fast signal attenuation and wide bandwidth,etc.,the positioning error can be reduced.In this paper,an LF positioning method with mmWave is proposed,which is named as DoA-LF.Besides received signal strength indicator(RSSI)of access points(APs),the fingerprint database contains direction of arrival(DoA)information of APs,which is obtained via DoA estimation.Then the impact of the number of APs,the interval of reference points(RPs),the channel model of mmWave and the error of DoA estimation algorithm on positioning error is analyzed with Cramer-Rao lower bound(CRLB).Finally,the proposed DoA-LF algorithm with mmWave is verified through simulations.The simulation results have proved that mmWave can reduce the positioning error due to the fact that mmWave has larger path loss exponent and smaller variance of shadow fading compared with low frequency signals.Besides,accurate DoA estimation can reduce the positioning error.Finally,we summarize this paper and present the future work.