Research On Modulation Technology In The VHF Aeronautical Cooperative Communication

With the development of aeronautical communication, transmission technologies which are adapted for aeronautical channel are arousing more and more attention. Collaborative communication, as a resistance technology for multipath fading, effectively ensure the quality of the transmission system without increasing the bandwidth and transmit power. Hence, it has become one of the key technologies of aeronautical communication. In the aeronautical communication, collaborative technologies can overcome the restriction on the volume of the mobile terminal and the power of the MIMO system. Collaborative technologies can obtain diversity gain in the single antenna case.Due to the fast moving of mobile terminals and the serious delay spread in the aeronautical channel, this paper makes in-dcpth researches on collaborative modulation technology depend on whether receiving ends accurately estimate the channel state information (CSI). The bit of error rate is analyzed by the BPSK system with known channel state information. If the CSI is unknown, the differential unitary space-time modulation (DUSTM) is still able to enlarge the transmission capacity and improve the information transmission rate. Moreover, DUSTM also can ensure the transmission reliability and improve the performance of the system. The main work of this paper is as follows:1. It analyzes the aeronautical channel models of different scenarios. Based on the Wide-Sense Stationary-Uncorrelated Scattering (WSSUS), the fading parameter of the aeronautical channel is established, and the fading conditions of different scenarios are simulated.2. When the CSI is known to the receiving end in the aeronautical channel, this paper proposes the multi-aircraft cooperative communication scheme to improve the diversity gain for the case that a direct link does or does not exist. The BPSK modulation is used to derive expressions of bit error rate of relay amplify-and-forward (AF) and decode-and-forward (DF). Simulation and comparison between AF and DF error performance in multi-relay coordination have also been studied. 3. When the CSI is unknown to the receiving end, this paper proposes a method to improve the reliability of cooperation schemes based on DUSTM by applying the Cyclic Redundancy Check (CRC) at the relay. This method is applied in collaborative communication of receiving end deploying multiple antennas. The error performance is simulated and analyzed.