| A new communication technology millimeter wave provides reliable technical support for short distance and high speed data transmission with the rapid development of wireless communication technology in recent years.Wireless communication technology is becoming more and more closely around us in our daily life,such as our mobile phone and a variety of high-speed mobile phone APP, digital TV, video on demand, etc. In order to achieve high bandwidth wireless access, we only to develop the high frequency wireless spectrum resources. Wireless communication technology is the most cutting-edge technology belongs to the millimeter wave communication, Compared with other electromagnetic wave, millimeter wave is characterized by high frequency, millimeter wave and wave length, large bandwidth, high security and so on. Millimeter wave can only be transmitted in a short distance, air, environment, obstacles and other factors also will have an impact on millimeter wave wireless communications, so that millimeter wave transmission environment becomes complex. Therefore, How to describe the short distance transmission of electromagnetic wave is very important for the key parameters of millimeter wave wireless communication channel. The analysis of short distance transmission characteristics of millimeter wave plays an important role in the link loss.This work is mainly in the following aspects: First, an overview of short distance wireless communication system, this paper introduces the diversity and multiplexing of transmit signals by using the spatial arrangement of transmitting antenna and receiving antenna, and analyzes the relationship between the short distance wireless channel transmission and the antenna array, and makes the channel modeling of the wireless channel in the array model. The results show that the angle of arrival and the height of arrival will affect the link. And the uniform rectangular array is more advantageous than uniform linear array and uniform circular array.Secondly, we further study and discuss the link loss of millimeter wave signal in short distance wireless communication in indoor environment, and compare the link loss model between ULA and URA in the outdoor space.Derived in a uniform linear array and a uniform rectangular array in the 3D spatial fading correlation expression, comparison of millimeter wave in different polarization mode fit. The results show that under the same polarization mode, the dielectric loss of the material with low dielectric constant is small, and the dielectric loss is large. Compared with the vertical polarization mode and horizontal polarization mode, it is concluded that the vertical polarization mode causes the fading and the error is smaller than the horizontal polarization mode.Then, the short distance wireless channel in indoor environment is analyzed, and the short distance wireless channel transmission model is proposed for 60GHz. Is derived based on the reflection coefficient of the transmitter and receiver ends from the reflection surface spacing and path loss based on correlation function expression of the transmitter receiver distance,accuracy of path loss model validation working group released the IEEE. The results show that, under the existing model. The error caused by reflection coefficient "R=-1" can't be ignored.Finally, theoretical study on the effect of 60GHz millimeter wave transmission in the indoor environment by the moving human body, put a 60GHz in the indoor environment caused by shadow fading mobile human expansion path calculation of three section model. Compared the results and experimental results in the frequency domain and time domain calculation.The results show that the proposed model is not in good agreement with the calculated results, and the computational model of the performance evaluation is needed. |
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