Research On Doppler Diversity Technique And Spatial Diversity Technique Of Aeronautical Communication

As the communication businesses in command,control,detection and monitoring are increasing,the communication security among air and ground has come to sound,data,image or other businesses which are expected to be more flexible and efficient besides simplex sound business and low-speed data sending business before.All of these have posed much challenge to the wireless communication among air and ground.While in aeronautical channel,due to the high velo of both sender and receiver,doppler frequency shift is more distinct and traditional estimation & compensation arithmatics are usually unideal.While doppler diversity technique takes use of different frequency-shift components to increase total energy,which can efficiently ease doppler shift in fast time-variant channel.On the other hand,study on spatial diversity is meaningful in addition to interleaving and error correction to decrease fading.Its advantage is improving capacity with no extra sending power or signal bandwidth.This article aimed at aeronautical communication,mainly studying doppler diverstiy technique and spatial diversity technique.The main contents and fingdings of this article are as follows:Firstly,for the receiver Doppler diversity technique in OFDM system,this article has conducted some research,and has derived the formula of branches' parameters choosing based on relativity of interference signal.In addition,this article also proposed a simplified diversity frame based on classic scheme.Simulation results show that the simplified frame has decreased complexity and figuration.It's more real-time for channel estimation,thus more suitable for fast time-variant scene of aeronautical communication.Then,for the poor quality and reliability of transmission caused by high mobility of aeronautical platform,the space diversty technic of aeronautical channel has been studied,taking Alamouti code for example to analyse DSTBC and RDSTBC schemes.Then the spatial diversity algorithm based on SC-FDE has been studied,analysis and simulation show that when the channel's multipath amount and SNR are small,it's more suitable to use the STBC algorithm combined with SC-FDE,otherwise it's more suitable to use the STBC-SC-FDE scheme based on interference cancellation.In the end,this article has combined cooperative communication and space time coding technics and waveforms like OFDM/SC-FDE to design coding schemes with cooperative character.Among these schemes,“one aircraft & multiple station” occasion is more suitable to adapt OFDM combined with STBC,while the occasion “one station & multiple aircaft” is more suitable to adapt DSTBC scheme based on SC-FDE.Simulations show that,adapting Alamouti space-time coding & orthogonal space-time coding & Q-OSTBC together with waveforms like OFDM and SC-FDE can improve performance in certain ocassions at different degree.