Research On Technologies Of UAV Data Transmission And Routing

With the rapid development of unmanned aerial vehicles(UAVs)communication technology,UAV communications have gradually become networked,emerging a new network model-UAV ad hoc networks.The networked UAV communication makes the ground control station interact with multiple UAVs at the same time,and the amout of data increase dramatically.The traditional MIMO technology can no longer meet the requirements for high-speed data transmission of UAVs.Massive MIMO technology has high spatial freedom and spectral efficiency,which can meet the high-speed data transmission requirements of UAVs.Due to the limitation of UAV spectrum and energy,the problem of large pilot overhead and channel estimation computational complexity in UAV FDD Massive MIMO communication systems becomes more prominent.The routing protocol is crucial to the stability and effectiveness of the UAV ad hoc network,so it is necessary to study the routing protocols that are applicable to the UAV ad hoc network.The UAV ad hoc network has very high requirements for routing protocols.It must have the functions of adapting to high mobility of nodes,dynamic topology,intermittent links,energy constraints,and changing link performance.Existing routing protocols cannot meet the above requirements.In order to solve the above problems,this paper deeply studies the application of Massive MIMO technology in UAV communications and the routing protocols of UAV ad hoc networks.The main contents of this paper include:(1)The theoretical basis of UAV communication.The key data transmission technologies and channel models of UAVs are described in detail,and the applicability of existing routing protocols in UAV ad hoc networks is analyzed and summarized.(2)UAV data transmission technology.In the line of sight(LOS)environment with less interference,a zero-pilot Massive MIMO communication method for UAV is proposed based on the assistance of positioning technology to reduce the pilot overhead and channel estimation computational complexity of UAV FDD Massive MIMO systems.The core idea of the communication method is that using the position information of the ground control station and the UAVs instead of the pilot to calculate the direction of arrival angle(DOA)of the UAVs,so as to achieve zero-pilot transmission of the data.The simulation verified the correctness and effectiveness of the communication method.(3)UAV ad hoc network routing protocol.Based on the OLSR routing protocol,according to the characteristics of dynamic topology,unbalanced network load and limited node energy of the UAV ad hoc network,a new routing protocol of MBREOLSR(an OLSR routing protocol based on the multidimensional equalization and residual energy)is proposed.When selecting MPR nodes,factors such as the occupancy of the MAC layer interface queue at the node,the free degree of the application layer,the connection time and connection degree of the node and the remaining energy of the node are taken into consideration.Simulations show that MBREOLSR routing protocol can effectively improve the success rate of data transmission,reduce data transmission delay,and reduce the packet loss rate of the network.