Research On Collaborative Deployment And Wireless Resource Allocation Strategies In Heterogeneous Emergency Networks

In public emergencies such as natural disaster handling,accident disaster rescue,and social security prevention and control,establishing emergency networks to achieve rapid communication recovery and enhance service quality is the key link to support efficient information management,reliable data transmission,and rapid command and decisionmaking.Meanwhile,with the development of wireless communications and information technologies,emergency communications need to realize the integrated transmission of multimedia,such as voices,data,pictures,and videos,to meet the communication requirements of different emergency services.Due to the strong suddenness of emergency scenarios and limited deployable resources,it is of great significance to solve the contradiction between limited resources and rigid demands of various services for the development of emergency communication networks.A heterogeneous emergency network refers to the emergency network structure composed of network elements such as unmanned aerial vehicles(UAV),emergency vehicles,rescue workers,and different types of spectrum resources.It has heterogeneous characteristics in terms of network topology,spectrum resources,communication technologies,and service requirements.Aiming at the three major challenges of inflexible deployment,insufficient spectrum,and unreliable transmission,this dissertation conducts in-depth research on the theories and technologies related to collaborative deployment and wireless resource allocation in heterogeneous emergency networks.Firstly,in response to the challenge of inflexible deployment challenges,from the perspectives of UAV deployment and ground station deployment,the UAV multi-objective emergency network deployment for air-to-ground coordination and the ground station deployment and multi-service resource adaptation for chain networking are studied respectively,to improve deployment flexibility and resource utilization.Then,in response to the challenge of the insufficient spectrum,the heterogeneous spectrum based emergency network throughput improvement and resource scheduling is studied to improve network throughput and spectrum efficiency.Finally,in response to the challenge of unreliable transmission,the coded caching based reliable wireless transmission and cross-domain resource scheduling is studied to enhance transmission reliability by jointly optimizing communication and caching resources.The main work and research results of this dissertation are as follows:1.Multi-service UAV Emergency Network Deployment for Air-toGround Coordination:UAV networks can be quickly deployed in emergency networks without relying on existing infrastructure to meet service requirements such as communication coverage,cooperative navigating,and sensing enhancement.Considering the coexistence of communication,navigating,and sensing users in emergency scenarios,this dissertation proposes an emergency UAV network low-energyconsumption deployment for the integrated communications,navigating,and sensing(ICNS),which reduces deployment energy consumption while meeting the requirements of communications,navigating,and sensing services and improving deployment flexibility and stability.This dissertation first quantifies the demand for the number of UAVs,the signalto-interference-plus-noise-ratio of communication,and the location of UAVs in different tasks.Then,based on the UAV’s propulsion energy consumption,hovering energy consumption,and service energy consumption,the UAV energy consumption model of different services is established,and the energy consumption minimization problem is modeled under the constraints of service requirements and limited resources.Finally,an iterative algorithm combining convex optimization,hierarchical matching,and particle swarm algorithm is proposed to jointly optimize the association between UAVs and users,multi-role UAV communication resources,and UAV locations.Simulation results verify that the proposed scheme has higher stability and robustness than the nonICNS scheme,and reduces the deployment energy consumption by 37.15%and 19.22%respectively compared with the ICNS scheme based on the greedy algorithm and the nonICNS scheme based on the proposed low-energyconsumption deployment algorithm.2.Ground Station Deployment and Multi-service Resource Adaptation for Chain Networking:In the case of ground road damage and power interruption,to achieve end-to-end communication coverage,multiple ground stations can be deployed to form a chain network to support multiple types of services such as voices,data,pictures,and videos.For the requirements of end-to-end communication coverage and multiservice transmissions in emergency scenarios,this dissertation proposes a low-energy-consumption chain ground station deployment strategy and a high-spectrum-efficiency multi-service resource adaptation scheme.Through the joint optimization of the number of stations,communication bandwidth,and transmission power,the energy efficiency and the spectrum efficiency are both improved.For the low-energy-consumption chain ground station deployment,the relationship between the number of ground stations,reusing interference,transmission power,and the coverage of ground stations is first established,and then the influence of ground station storage room on transmission reliability is analyzed.A low-complexity optimization algorithm is proposed to jointly optimize the number of ground stations,storage room,and transmission power.Simulation results verify that the proposed algorithm reduces the decision time by more than 90%compared with the brute-force algorithm.For the high-spectrumefficiency multi-seirvice resource adaptation scheme,first,under the constraints of communication requirements and power constraints,a threedimensional matching problem with the optimization of user cooperation and transmission power is established,and then the original mixed-integer programming problem is transformed into a hypergraph matching problem.Finally,the conflict graph and the local search algorithm are used to achieve a low-complexity solution.Simulation results verify that the proposed scheme improves the throughput by 2.3%and reduces the computational complexity compared with the iterative Hungarian algorithm.3.Heterogeneous Spectrum Based Network Throughput Improvement and Resource Scheduling:In the emergency scenario of a local traffic surge caused by large-scale user requests,the limited licensed spectrum resources become the bottleneck to limit the improvement of network throughput.Aiming at the heterogeneous spectrum scenario with the coexistence of licensed and unlicensed spectrum,this dissertation proposes a joint optimization scheme for access mode selection and communication resource allocation,to meet the spectrum access needs of different users and improve network throughput.This dissertation first defines three spectrum access modes:licensed spectrum allocation,unlicensed spectrum competition,and licensed spectrum reusing based on the user’s priority and data size.Then,the collision avoidance-based carrier sensing mechanism in the unlicensed spectrum competition mode is analyzed,and the communication performance of unlicensed users and emergency users is quantified.Next,the graph theory is used to analyze the spectrum reusing between licensed spectrum users and emergency users in the licensed spectrum reusing mode.Finally,the network throughput maximization problem is modeled,and a three-stage resource management scheme is proposed to jointly optimize the licensed spectrum,unlicensed spectrum,and transmission power,in which the interior point method and the bipartite matching are respectively used to optimize the transmission power and the spectrum reusing relationship.Simulation results verify that the proposed scheme improves the total throughput by about 3.5 times compared with the IEEE 802.11p EDCA protocol based access mechanism,and reduces the computation time by about 99.3%compared with the exhaustive search algorithm with a performance loss of about 0.85%.4.Coded Caching Based Reliable Wireless Transmission and Cross-domain Resource Scheduling:Realizing timely and reliable data transmission is very important to support rapid emergency decisionmaking and precise emergency command.Oriented to the scenario of multiple types of users coexisting and multi-scale files concurrent in emergency scenarios,this dissertation proposes a wireless transmission scheme that couples coded caching and communication technologies to improve transmission reliability.This dissertation considers three cooperation modes of the ground station,emergency vehicle,and rescue workers as content helpers.Firstly,the hit ratio of users is quantified by combining user mobility,channel fading model,and other factors under different cooperation modes.Then,a hierarchical coded caching scheme is proposed for the transmission requirements of multi-scale files,and the problem of maximizing the averaged hit ratio is formulated under the joint constraints of communication-caching resources and user requirements.Finally,a matching theory based optimization scheme of user collaboration and resource allocation is proposed to realize the joint optimization of communication resources,user collaboration,and coding parameters.Simulation results verify that the proposed scheme improves the averaged hit ratio by about 7.59%compared with the non-coded caching transmission scheme,and improves the averaged hit ratio by about 4.67%and 4.35%compared with the transmission scheme based on the greedynext-largest-difference algorithm and the transmission scheme based on uniform-channel-gain-difference pairing algorithm,respectively.