Research On Key Algorithms Of Non-ideal Receiver In 60 GHz Millimeter Wave Communication System

60 GHz millimeter wave communication technology is committed to the data communication scene with high-speed,large-capacity and low-latency.Compared with the traditional wireless communication frequency band,it has wide available spectrum,high transmission rate,better antiinterference characteristics and has good international versatility and license-free attributes.However,due to its higher frequency band and shorter wavelength,60 GHz millimeter wave signal has larger path loss and is easier to be blocked by obstacles in the process of propagation.Based on 60 GHz millimeter wave communication,this paper refers to the IEEE 802.11 ad standard to design an indoor wireless communication system based on SC-FDE.In this paper,the non-ideal characteristic-I/Q imbalance of the zero-IF receiver is studied,and the I/Q imbalance parameter estimation and compensation algorithms suitable for the communication system are designed.Firstly,the research background and related research status of this paper are introduced in the second chapter.Then the basic theory of wireless channel models is analyzed,including large-scale fading,small-scale fading and path loss.According to the characteristics of millimeter wave channels,a cluster channel model suitable for 60 GHz millimeter wave communication simulation system is established.Moreover,two 60 GHz wireless communication modulation schemes—OFDM and SCFDE are designed in this chapter with reference to the IEEE 802.11 ad standard.As the basis of this paper,the receiver structure of the millimeter wave communication system and the frame structure of the physical layer of the system are described in the second chapter in the form of block diagrams.Finally,the non-ideal characteristics present in receivers of 60 GHz millimeter wave communication system are briefly introduced.Secondly,the system model of I/Q imbalance is introduced in the third chapter,and the impact of I/Q imbalance on the performance of millimeter wave communication system is analyzed through mathematical model,including the influence of I/Q imbalance on modulation signal and channel estimation performance.Then the parameter estimation algorithm based on semi-pilot symbols and compensation algorithms based on blind estimation are introduced respectively.The principles of the two traditional algorithms are briefly analyzed,and their advantages and disadvantages are compared eventually.Next,an algorithm for estimating I/Q imbalance parameters under the condition of unknown channel state information is proposed in the fourth chapter,which utilizes the good autocorrelation and cross-correlation characteristics of the Golay complementary sequences in the data frame structure.Then,aiming at the poor applicability of the Golay complementary sequence algorithm,an algorithm based on the maximum likelihood estimation theory for complex vector is proposed to jointly estimate the I/Q imbalance parameters and channel impulse response.In addition,the traditional adaptive algorithm based on LMS is improved in this paper.A frequency domain adaptive algorithm that can compensate for I/Q imbalance in receivers of 60 GHz millimeter wave communication system is proposed from the perspective of eliminating frequency domain mirror subcarrier interference in this paper.Moreover,the optimal initial value for iteration is deduced.Simulation results show that the algorithm can maintain good compensation ability even in the case of 64 QAM modulation.Finally,the compensation algorithms for frequency selective I/Q imbalance at the receiver are studied in the fifth chapter.Firstly,the traditional parameter estimation algorithm based on pilot symbols is improved and applied to the problem of frequency selective I/Q imbalance parameter estimation.Secondly,the adaptive algorithm based on LMS is studied and used to eliminate conjugate interference in the received signal due to frequency-selective I/Q imbalance.By analyzing the steadystate error,image rejection ratio and computational complexity of the algorithm,aiming at the gradient noise amplification problem,an adaptive I/Q imbalance compensation algorithm based on NLMS is proposed,which further reduces the computational complexity,and can suppress the I/Q imbalance interference in a wide range.The performance of the algorithm meets the expectation.