Research And Implementation Of OLSR Routing Protocol For UAV Ad Hoc Networks With Gateway Nodes

With the gradual development and popularization of UAVs in recent years,they have a wide range of applications in military and civil fields such as border detection,remote surveillance,disaster monitoring,and remote sensing mapping.Compared with a single UAV system,a multi-UAV system has greater advantages in terms of task execution efficiency,reliability,and scalability.Correspondingly,its network complexity is also higher.Therefore,it is particularly important to design a routing protocol that conforms to the characteristics of UAV network.Therefore,according to the relevant technical characteristics of the UAV ad hoc network,this thesis introduces the gateway node to the UAV ad hoc network and implements the optimized link state routing(Optimized Link State Routing,OLSR)protocol,and then optimizes the problems that may exist in its application to the UAV ad hoc network to improve the the communication performance of man-machine network.The main research contents of this thesis are as follows:First of all,this thesis introduces the relevant research background and current research status of the OLSR routing protocol in the UAV ad hoc network,and elaborates the principle and main implementation technology of the OLSR routing protocol in detail.Secondly,in view of the frequent changes in the network topology of the UAV ad hoc network and the redundant transmission of topology information between adjacent transmission cycles,a low-overhead topology maintenance algorithm based on optimized link state routing is proposed.The topology information will be compared with the content sent in the previous sending cycle,and the topology control(Topology Control,TC)message of the current cycle will be sent using the lesser part of the decrement and invariant and the newly added quantity,which reduces the redundant sending of topology information;at the same time,the algorithm uses the minimum multipoint relay(Multipoint Relay,MPR)set selection mechanism reduces the number of MPR nodes,which reduces the number of TC messages sent and forwarded,and thereby reduces network control overhead.Aiming at the problem that the UAV gateway node periodically performs gateway discovery and causes excessive network overhead,a forwarding active gateway discovery mechanism is proposed.The HELLO and TC messages of the OLSR protocol carry the gateway information to realize the gateway discovery function.Which reduces the control overhead caused by periodically flooding gateway announcement messages.Then,the software implementation framework of the OLSR routing protocol with gateway nodes is divided into link awareness module,MPR set selection module,topology diffusion module,gateway discovery module,and routing calculation module.Each module is designed and implemented according to the function of each module.achieve.Use C language to develop and implement the OLSR routing protocol with gateway nodes under the Open WRT operating system,and then implement the low-overhead topology maintenance mechanism and the gateway discovery mechanism with forwarding.Finally,the appeal protocol and its improvement mechanism are tested on the JS9331 hardware development platform.The test results show that the function of the OLSR routing protocol with gateway nodes is normal,which is in line with the expected design.By comparing the performance test results,it can be found that the improved mechanism can effectively reduce the control overhead and the end-to-end average delay in the network,and improve the average success rate of data packet transmission and the average throughput between nodes.Finally,the research work of this thesis is summarized,and the future research direction is prospected.