Research On Network And Waveform Design Based On Integrated Communication And Localization For Emergency Rescue

Regular emergency disasters have resulted in losses to the economy and personnel.Thus,China has strengthened its attention to emergency rescue and relief efforts.However,due to the destruction caused by disasters or the remote location of certain areas,the affected areas often face communication difficulties.Environments such as mountainous forests where satellite signals are often blocked can result in rescue workers having difficulty accurately locating themselves.Therefore,communication and localization in harsh environments are complex research topics in disaster relief.Unmanned aerial vehicles(UAVs)have high mobility and are adaptable.They can quickly reach a disaster-stricken area and establish an integrated communication and localization network.On the one hand,as communication relays,UAVs expand the communication range and strength in disaster areas.On the other hand,UAVs can obtain their absolute position through satellite signals and act as anchor points for ground users,achieving full coverage network positioning.Therefore,UAVs have provided convenience for emergency rescue in terms of communication and localization.However,there are still two challenges in the air-ground integrated emergency network.First,considering the discrete design of communication and localization signals in emergency scenarios leads to a more noticeable problem of wireless resources,how to utilize time-frequency resources to design the integrated signal entirely is an urgent research topic.Second,a challenging issue to consider for enhancing the effectiveness of emergency rescue is how to design the network structure of UAVs to improve ground users’ communication and localization quality.This paper focuses on these two issues,extending the research from the link to network levels.For the signal design at the link level,study the integration of communication and ranging signals and design a verification platform for signal systems in the physical layer.For the network level,research clustered routing from the network layer for UAV networking problems.This paper mainly focuses on three aspects of research,which are summarized as follows:Firstly,this paper focuses on constructing an orthogonal frequency division multiplexing(OFDM)pilot based on joint optimization for communication and ranging.Specifically,the OFDM pilot sequence is designed as the ranging code,which derives the channel estimation and interpolation process.The two-step ranging principle of solving the shift of the maximum correlation function in the time domain and calculating the carrier phase in the frequency domain is derived.Considering that users have different tolerances for bit error ratio(BER)and distance measurement error in different stages and tasks in emergency scenarios,an optimization problem for pilot pattern design adapting to varying requirements with a weighting parameter is proposed.To speed up the solving process and improve the practicality,a heuristic algorithm based on particle swarm and a pilot mapping framework based on channel feedback are presented.The proposed scheme has been validated through simulation to adapt to different channel conditions and user requirements.In the forest area SUI-5 channel model,under the same ratio of pilot resources,compared to the block and comb pilot schemes,the proposed scheme achieves a 22.38%reduction in bit error rate and a 49%improvement in distance accuracy.Secondly,this paper is conducted on the clustering mechanism of UAV networks for communication and localization enhancement.Specifically,to address the differences in roles between cluster heads and members,the ability of nodes is quantified using variables like energy and mobility,and a cluster head selection scheme based on maximizing node ability is proposed.A bipartite graph is established between UAVs and users,with channel qualities as the edge weights,to determine the matching relationship for air-ground services.Considering the different number of nodes required for communication and localization,capabilities quantification schemes of cluster networks are proposed,and a cluster member joining algorithm based on the quadratic multiple knapsack problem is presented.A wireless network is built on the NS-3 simulation platform to realize the routing and anchor point selection scheme based on the clustered structure.Simulation results demonstrate the proposed scheme’s advantages in terms of communication and localization.In the networking scenario of 50 UAVs within a 1-square-kilometer area,the proposed scheme demonstrates a significant improvement compared to OLSR and SDRTOA.It achieves a 52.19%decrease in positioning error.Finally,implementing an integrated communication and ranging system based on OFDM is considered.Specifically,two software defined radio(SDR)nodes are constructed using universal software radio peripheral(USRP)and the host computer.The modular functionality of the nodes and the system’s operating mode are designed,and the hardware frequency offset correction is achieved.The experimental results verify the effectiveness and validity of the semi-physical platform.