Research On High Speed Scatter Communication Technology Based On MIMO-OFDM

In modern life,whether in urban or rural areas,wireless cellular networks can already meet communication needs in most scenarios,especially after the rise of 5G technology,people can enjoy higher-quality communication services in their daily lives.But on the other hand,in some special scenarios,such as forest fires,earthquakes,and even wars,stable communication cannot be achieved using traditional wireless cellular networks.At this time,other communication methods are very important.Tropospheric scatter communication is a reliable over-the-horizon communication method.In many cases,it can replace satellite communication and reduce the pressure of satellite communication,and it has proved its application value in practice.Aiming at the transmission characteristics of the scattering channel,the paper designs a high-speed tropospheric scattering communication scheme based on MIMO-OFDM,with a transmission rate of up to 100 Mbps.On this basis,the focus is on the time-frequency synchronization technology,channel estimation and equalization technology in the scattering communication system,etc.,and a set of time-frequency synchronization scheme and channel estimation and equalization scheme suitable for the scattering channel environment are proposed.For the time-frequency synchronization technology,the thesis first studies the coarse symbol timing synchronization method and the fine symbol timing synchronization method,and proposes a timing position adjustment scheme for the statistical characteristics of the scattering channel;secondly,the thesis studies the fractional frequency offset estimation method and Integer frequency offset estimation method,in order to adapt to the environment of low signal-to-noise ratio,a pilot-based fractional frequency offset estimation method is adopted,and then a set of time-frequency synchronization scheme based on MIMO-OFDM scatter communication system is given.The simulation of this scheme shows that using this scheme can achieve the synchronization accuracy required by the system within the range of the system's normal working signal-to-noise ratio.For channel estimation and equalization technology,the thesis first studies the pilot-based least squares estimation method and the DFT-based interpolation filtering method,and optimizes the time-domain denoising method,thereby giving a set of scattered communication system channel estimation Scheme;Secondly,the paper studies and analyzes two methods of zero-forcing equalization and minimum mean square error equalization,and gives a set of zero-forcing equalization scheme based on the weighting of channel state information.The simulation of the above scheme shows that using this channel estimation scheme can effectively remove noise and accurately estimate the channel;the zero-forcing equalization scheme weighted by the channel state information is ultimately better than the minimum mean square error equalization scheme.Finally,the paper carried out a system simulation of the proposed scheme,and the results showed that the scheme can work normally in a low signal-to-noise ratio scattering channel environment,which meets the requirements of a scattering communication system.