Research On Channel Capacity Of The System Combining UAV Formation And Distributed MIMO

Unmanned aerial vehicle(UAV) formation has some incomparable advantages over a single UAV, it can expand the coverage, improve reconnaissance accuracy, strengthen the combat effectiveness and reduce the wind resistance by cooperating. In addition, distributed MIMO can improve the system's channel capacity and expand the coverage, so it has become an important technology for wireless communication. If distributed MIMO is applied to UAV formation, it will combine their advantages. This method will be one of research emphasises in the future.The key of the research on the system combining UAV formation with distributed MIMO is building a complete and reasonable channel model. Due to the randomness of large scale fading and the small scale fading, it is difficult to get an exact ergodic channel capacity of the system combining UAV formation with distributed MIMO. So we need to derive some approximate expressions instead of the expression about ergodic channel capacity. In addition, if the system want to have a better performance, it is necessary to make research about the impact of UAV clusters' spacing,receiving antennas' spacing and different formations. The main research of the article focuses on building a channel model, deriving some expressions approximating the expression of ergodic channel capacity and analyzing the impact of different parameters. The following major research is completed:Firstly, based on UAV formation's application scenario and principle, we build the system's three dimensional(3D) channel model considering the direct wave, reflection, scattering. This model can completely and reasonably describe the communication process.Secondly, based on the expression of ergodic channel capacity about MIMO, we derive the expression of lower bound of the sum rate, and then derive the expressions of sum rate in condition of high and low signal to noise ratio(SNR). By simulation, these expressions can approximately express ergodic channel capacity and the error is very little. Then using these approximate expressions analyzes the impact of some channel model's parameters on the system combining UAV formation and distributed MIMO.Thirdly, based on the 3D channel model, we respectively make an research about the impact of UAV clusters' spacing, receiving antennas' spacing and different formations on the system's channel capacity. The result shows that there is an optimal spacing between different UAV clusters, so does different receiving antennas. The optimal spacing can make channel capacity achieve the maximum. In addition, uniform circular formation can achieve a higher channel capacity than uniform linear formation.Finally, we verify the accuracy of the theoretical analysis by combining with Matlab simulation.