Study On Channel Characteristics Of Millimeter Wave Restricted Space By Using Ray Tracing Method

In recent years,with the rapid development of science and technology,people have an increasing demand for high-speed data flow.Meanwhile,high-speed data flow is also growing rapidly.More importantly,in order to support the rate requirements of future high-speed wireless communication,there is an urgent need for new physical layer solutions,in which millimeter wave(28GHz-300GHz)is considered to be one of the most promising frequency bands.Compared with microwave,millimeter wave spectrum provides great potential for future fast communication because of its wide bandwidth and fast data transmission rate.Firstly,this paper simulates the indoor long corridor channel,and compares the large-scale and small-scale fading of line-of-sight(LOS)and non-line-of-sight(NLOS).Secondly,a stochastic model is derived to describe the distance dependent behavior of root-mean-square delay spread(RMS-DS)and root-mean-square circle angular spread(RMS-CAS).The results show that the millimeter wave band has large path loss and ar only suitable for short-distance transmission.Compared with LOS,the frequency components in NLOS have better correlation,but the LOS has richer circle angular spread.By increasing the transmission power and antenna position,the delay spread can be effectively reduced and the channel capacity can be improved.Secondly,the outdoor scene will also contain typical narrow and long channels,such as tunnels in the Internet of vehicles channel.According to the traffic requirements of vehicle-tovehicle(V2V),we research rectangular tunnels with different splicing angles.The path loss,RMS-DS,angle spread and K-factor in tunnel under different tangent angles are compared,and the correlation between them is given.Burr probability distribution model and a fourth-order polynomial are used to describe the variation law of path loss exponent(PLE)and RMS-DS respectively.Thirdly,in order to research the relationship between tunnel curvature and channel parameters.This paper researches the channel characteristics of tunnels with different curvature under different frequencies,and analyzes the relationship between PLE,RMS-DS,frequency and curvature.In this paper,a higher-order polynomial is proposed to describe the PLE,and a firstorder polynomial is used to fit the RMS-DS.Finally,a model is used to predict PLE and RMSDS is established by using neural network to verify the effectiveness of the above polynomials.Finally,in order to make the simulation environment closer to the reality,according to the changes in the tunnel,this paper gives three cases: empty tunnel,tunnel with more vehicles and tunnel model in NLOS.The changes of channel parameters under different models are given,and the change of Doppler frequency shift in the tunnel when the velocity changes is emphatically analyzed.The results obtained will be beneficial to the simulation and analysis of indoor and outdoor long and narrow channels in the future.