Research On E-band Long Distance High Rate Wireless Communication Technology

As an important part of national defense and security,the air to ground communication network in near space is required to meet the business needs of longdistance and high-speed rate.However,due to the explosive growth of the number of communication terminals,the traditional communication frequency band becomes crowded and it is difficult to obtain large capacity bandwidth.Therefore,the millimeter wave frequency band with more sufficient bandwidth resources has become a new direction of air to ground high-speed communication technology,Especially the E-band millimeter wave band suitable for long-distance transmission.Considering that the cloud,rain and dust in the air to ground channel may affect the transmission of E-band millimeter wave,or the decline of supporting transmission rate due to the long communication distance of the system,the research on the channel characteristics and high-speed transmission scheme of the air to ground system using E-band millimeter wave transmission will help to promote the construction of air to ground communication network.Firstly,based on the air to ground environment,thesis studies the propagation channel of E-band millimeter wave in the atmosphere,focuses on the changes introduced by tropospheric meteorological factors for millimeter wave transmission,considers the existence of sunny single-layer cloud in the troposphere on the electromagnetic wave path,analyzes the random changes of electromagnetic wave parameters,and models the air to ground channel of sunny single-layer cloud.Then,the channel capacity of the proposed extended channel model is studied,focusing on the change of channel capacity of MIMO communication beyond or not beyond Rayleigh distance in the presence of sunny single layer cloud in air to ground channel.Finally,aiming at the scene of air to ground longdistance transmission using small aircraft with limited energy,the scheme to improve the energy efficiency of signal detection at the receiver is simulated and analyzed.It is found that in order to minimize the channel correlation and obtain the maximum channel capacity,the space-to-Earth E-band millimeter wave LOS MIMO system needs to place the antenna according to the Rayleigh distance criterion.However,this opportunistic maximum channel capacity is easy to maintain in the presence of singlelayer cloud,and the greater the water content and thickness of single-layer cloud,the more obvious the downward trend of channel capacity.When the transmission distance is far beyond the Rayleigh distance,the channel capacity decreases rapidly,and the MIMO system is approximately degraded to SISO.At this time,the single-layer cloud can be used to make the MIMO channel more uncorrelated and obtain a higher channel capacity than that without single-layer cloud.In addition,based on the simulation verification,the signal detection mode can be switched at the receiving end of small aircraft according to the situation of air ground single layer cloud channel,and the single layer cloud channel model established in thesis can be used to quickly determine the switching threshold of reception mode,so as to obtain higher energy efficiency in sunny single layer cloud air ground communication.