A High Data Rate Wireless Communications System for Unmanned Aircraft Systems

Autor: Shen, Yung Chang, 沈永昌
Rok vydání: 2016
Druh dokumentu: 學位論文 ; thesis
Popis: 105
For the past few years, the application of unmanned aircraft vehicles (UAVs), or unmanned aircraft system (UAS) have been a rising issue. Except for the military aspect, they widely used on inspecting the highly risky fields such as volcanic eruption, agriculture with sensor detect soil, crop and water condition or conflagration for science research and firefighter res- cue. In the thesis, our goal is to design a communication system applied on the UAVs. The scenario is the unmanned aircraft vehicles equipped camera to transmit the video through the ground station. There are two cases in our scenario, first has maximum cruise speed 200km per hour, the distance from the ground station to aircraft has 150km and a data rate 45Mbps required. Another case has maximum cruise speed 0.7 Mach number (743.5km per hour) and also has 150km transmission distance. We define the aeronautical channel respectively, calcu- late the link budget, then an OFDM system based design is presented. The system parameters such as subcarrier spacing, cyclic prefix length and the pilots arrangement evaluation which is effected by the different Doppler frequency, delay spread and data rate requirement. We pro- posed an OFDM system with 256 and 2048 fast Fourier transform (FFT) size, which has large subcarrier spacing 31.25kHz and 7.63kHz with 8s cyclic prefix (CP) duration to overcome the frequency-selective fading channel. The proposed transceiver includes two transmitters and one receiver with space frequency block code and channel coding which concatenated Reed Solomon (255,239) codes and convolutional codes, both the techniques can improve 8dB and 5dB compared with the single input and single output OFDM system respectively. The timing and frequency synchronization are also discussed.
Databáze: Networked Digital Library of Theses & Dissertations
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