Research And Implementation Of Broadcastinging Technologies Of Cognitive Radio Ad Hoc Networks

With the development of communication technology,the number of communication users keeps increasing,and spectrum resources become increasingly scarce,which restricts the development of wireless communication.In 1999,the proposed Cognitive Radio(CR)technology effectively alleviated the shortage of spectrum resources.Ad Hoc network has the characteristics of no center,multi-hop and dynamic topology.The entire network has no fixed infrastructure and is widely used in post-disaster reconstruction and emergency communications.Since Ad Hoc network has not been assigned a fixed working frequency band in practical applications,it will also face the problem of insufficient spectrum resources.Therefore,the Ad Hoc network based on cognitive radio technology deserves further study.Cognitive Radio Ad Hoc Networks(CRAHNs)can effectively alleviate the shortage of spectrum resources by increasing the utilization of spectrum through dynamic spectrum access to unused resources of authorized users.Broadcasting is an important form of communication in Ad Hoc networks.Routing queries,time synchronization and so on all depend on broadcasting communication.In CRAHNs,different unauthorized users(Secondary User,SU)can use different spectrum resources,that is,have different available channel sets.This disunity of available channels brings special challenges to broadcasting in CRAHNs.In this paper,the broadcasting problem in CRAHNs is analyzed and studied theoretically.The main work and innovation of this paper are as follows:Firstly,a fully distributed broadcast protocol without a common control channel is designed for CRAHNs.Each secondary user constructs SBCS by reasonably choosing channels from its available channel set,carries out selective broadcasting and improves channel utilization.The simulation results show that the proposed broadcasting scheme outperforms other comparative broadcasting schemes in terms of broadcast success rate and average broadcast delay.Secondly,a distributed broadcast algorithm based on neighborhood complex is proposed for multi-channel multi-radio CRAHNs.By constructing Minimum Overlapping Connected Neighborhood Subcomplex(MOCNS),low redundancy broadcasting is realized.The simulation results show that the proposed broadcasting algorithm is superior to other comparative broadcasting schemes in Broadcasting Coverage and number of packets received.Thirdly,a software-defined radio Ad Hoc network system based on USRP platform is designed and implemented,which integrates five analog radio stations with general purpose processors in software form.Each general purpose processor uses a USRP device as the RF transceiver.The Ad Hoc network system supports the time division duplex communication mode and supports the transmission of data services.Testing the entire Ad Hoc network system shows that the system can achieve fast and accurate networking.