Transmission Waveform And Wireless Coverage Technology In Millimeter Wave Communication

With the popularity of smart mobile terminals,the existing sub-6 GHz band wireless communication could not meet the rapidly growing demand of data traffic.Due to the limited spectrum resources of the radio frequency band,the millimeter-wave band has become the key band of the indoor wireless LAN and the fifth generation mobile communication(5G)owing to its large frequency band resources,which could achieve the 10Gbps throughput.Thus,the millimeter-wave communication technology has become the focus of the current study.Millimeter wave transmission has many disadvantages,such as fast fading,high path loss and easy occlusion,which brings great limitation to millimeter wave communication.But at the same time,the millimeter wave band has many advantages,such as long wave length,strong anti-interference ability,narrow beam,good directionality and secret performance,etc.which brings both opportunities and challenges for the future wireless communications.In order to further improve the development of millimeter-wave wireless communication,this paper focuses on the waveform techniques and coverage problem of it.The main work and innovations of this thesis are shown as follows.Firstly,the characteristics of millimeter-wave transmission are studied.Furthermore,the ray-based SCM model and 28 GHz-73 GHz millimeter wave channel model are compared and analyzed.The differences between the millimeter wave channel model and the existing microwave channel model are reached,and the specific modeling steps of the millimeter wave channel model are listed.In this chapter,the channel characteristic simulations and analyses are performed on the millimeter-wave MIMO channel in the 45 GHz band.This model provides a channel model basis for the preparation of subsequent properties of transmission techniques.Secondly,the paper studied the transmission waveform technologies of millimeter wave,including the scene applicability of different transmission waveform techniques in 5G and the transmission performance in millimeter-wave system with hardware impairment.Based on the 45 GHz millimeter wave channel,the simulations of SC-FDE,OFDM and new waveform techniques under the condition of hardware impairments are carried out.At the same time,the applicability of different transmission techniques in millimeter wave communication are analyzed.Simulation results indicate that the 45GHz band communication under the SC system is more conducive to hardware implementation,whose performance is better compared with OFDM considering the hardware impairments.In the millimeter-wave channel,some new waveforms,namely f-OFDM,GFDM,have similar performance of BER and PAPR and obvious advantage on aspect of spectrum leakage compared to OFDM.At last,the efficient coverage and hybrid beamforming technologies in millimeter wave have been studied in the paper.Under the basic goal of minimizing the transmission power and guaranteeing the full-sector quality of service(QoS),optimization of millimeter-wave MIMO hybrid beamforming has been conformed then the power-efficient hybrid beamforming scheme in millimeter-wave large-scale MIMO common channel finally.Based this scheme,efficient beam direction diagram as well as beamforming vector with lowest PAPR which enables the non-destructive implementation under the architecture of digital/simulated hybrid precoding.The simulation results show that this scheme can effectively reduce PAPR and ensure a higher and stable gain than the existing scheme.Meanwhile this scheme is more suitable for the millimeter-wave massive MIMO system with large but limited amount of antennas and ensures highly efficient wireless coverage.