Reliable Communication Strategy For Cognitive Radio Ad Hoc Networks

Cognitive radio technology can dynamically allocate and utilize spectrum and is considered to be the most promising technology to improve spectrum utilization.Cognitive wireless ad hoc networks(CRAHNs)can significantly alleviate the problem of insufficient wireless spectrum resources in ad hoc networks with the help of cognitive radio technology.CRAHNs can be dynamically constructed and effectively applied to temporary networking scenarios such as military operations and post-disaster rescue.In the ever-changing battlefield and rescue operations against time,the link reliability of cognitive ad hoc networks is crucial.Firstly,this thesis analyzes the challenges faced by cognitive users in the establishment of communication links and the maintenance of communication links,and investigates related technologies,especially the blind rendezvous and spectrum handoff.For the process of establishing a communication link for cognitive users,an enhanced frequency-hopping rendezvous algorithm based on channel grouping(ECGB)is proposed in this thesis.The ECGB algorithm has the advantages of supporting asymmetric models,having 100%rendezvous degree,guaranteeing the rendezvous in a limited time,and supporting asynchronous clock time.Through theoretical analysis,the upper bound of the maximum time to rendezvous(MTTR)of the ECGB algorithm is obtained,and the theoretical derivation of MTTR is verified by simulation.For other problems in the rendezvous process,such as spectrum sensing and slot synchronization,this thesis also analyzes and gives the design scheme.For the link maintenance of cognitive users,this thesis firstly establishes a theoretical model for the spectrum handover problem in broadband and asymmetric spectrum scenarios.Through theoretical analysis,the analytical expression of the key performance indicators of spectrum handover is obtained.Then,through extensive and detailed simulation and discussion of spectrum switching for cognitive users,it is further clarified how the channel characteristics affect the performance of spectrum switching.Finally,based on the above research,a spectrum management strategy in broadband scenarios is designed.