Research On Transmission Technique For Wideband Ground-air Communication SC-FDE System

With the development of airborne plateform, the real-time informationtransmission and transmission rate requirements for wideband ground-aircommunication have become increasingly higher. It is an urgent and importanttask for communication operators to build a series ground-air communicationsystems to satisfy the requirement of ground-air communication. Under thecondition of long-distance ground-air communication and ground station antennawith low elevation, the multipath effect, resulted from the reflection andscattering of ground obstacles, appears to be serious, multipath time delay israther large, and the Doppler effect is remarkable,because of the high speed ofairborne plateform, the channel is fast time-varying fading state. How toeliminate the interference and achieve anti-multipath fading transmission in thiscase have been the focus research.For the sake of anti-multipath fading transmission in wideband ground-aircommunication, this dissertation proposes an appropriate ground-air fadingchannel model based on the characteristics of low elevation ground-air channel, anew transmission scheme is proposed, where the SC-FDE is employed inwideband ground-air communication system. On the basis of SC-FDE traditionallinear frequency domain equalization algorithm, this dissertation in-depth studiesnonlinear frequency domain equalization optimized algorithm.Firstly, this dissertation analyzes the fading characteristics and modelingmethods of ground-air channel with long-distance and low elevation, proposes aground-air fading channel with low elevation, simulation verification has madefor the channel model.Secondly, this dissertation describes the transmission mechanism andprinciple of ground-air communication SC-FDE system, analyzes the frameformat for data transmission. Then analyzes the error performance of frequencydomain linear equalization algorithm and hybrid decision feedback equalizationalgorithm. To analysis the performance of ground-air communication SC-FDEsystem, this dissertation discusses the ISI after frequency domain linearequalization, and compares the PAPR and channel capacity.Finally, this dissertation in-depth studies several nonlinear frequencydomain equalization algorithms in ground-air communication SC-FDE system,including noise prediction with decision feedback equalization algorithm anditerative block with decision feedback equalization algorithm. The BERperformance of these algorithms are analyzed. Based on the study of time domain noise prediction equalizer and bidirectional decision feedback equalizer,this dissertation proposes bi-directional noise prediction with decision feedbackequalization algorithm. Simulation results show that this algorithm has a superiorBER performance than noise prediction with decision feedback equalizationalgorithm. Based on the study of the iterative block equalizer, a filter coefficientsoptimized algorithm named simplified iterative block with decision feedbackequalization has been proposed. Simulation results show that under the premiseof favourable BER performance, simplified iterative block with decisionfeedback equalization algorithm reduces the computational complexity of filtercoefficients significantly, and parameters of the algorithm robust performancetest results show that the algorithm is not sensitive to the value of predefinedparameters.