简介：Vehiclepositioningwiththeglobalnavigationsatellitesystem(GNSS)inurbanenvironmentsfacestwoproblemswhichareattenuationanddynamic.FortraditionalGNSSreceivershardlyabletotrackdynamicweaksignals,thecouplingbetweenallvisiblesatellitesignalsisignoredintheabsenceofnavigationstatefeedback,andthermalnoiseerroranddynamicstressthresholdarecontradictoryduetonon-coherentdiscriminators.Thevectordelay/frequencylockedloop(VDFLL)withnavigationstatefeedbackandthejointvectortrackingloop(JVTL)withcoherentdiscriminatorwhichisasynchronizationparametertrackingloopbasedonmaximumlikelihoodestimation(MLE)areproposedtoimprovethetrackingsensitivityofGNSSreceiverindynamicweaksignalenvironments.Ajointvectorpositiontrackingloop(JVPTL)directlytrackinguserpositionandvelocityisproposedtofurtherimprovetrackingsensitivity.ThecoherentnavigationparameterdiscriminatorofJVPTL,beingabletoeasethecontradictionbetweenthermalnoiseerroranddynamicstressthreshold,isbasedonMLEaccordingtothenavigationparameterbasedlinearmodelofreceivedbasebandsignals.SimulationresultsshowthatJVPTL,whichcombinestheadvantagesofbothVDFLLandJVTL,performsbetterthanbothVDFLLandJVTLindynamicweaksignalenvironments.

简介：Aseachtypeofsatellitenetworkhasdifferentlinkfeatures,itsdatatransmissionmustbedesignedbasedonitslinkfeaturestoimprovetheefficiencyofdatatransferring.Thetransmissionofnavigationintegratedservicesinformation(NISI)inaglobalnavigationsatellitesystem(GNSS)withinter-satellitelinks(ISLs)isstudiedbytakingtherealsituationofinter-satellitecommunicationlinksintoaccount.Anon-demandcomputingandbufferingcentralizedroutestrategyisproposedbasedondynamicgroupingandthetopologyevolutionlawoftheGNSSnetworkwithinwhichthesatellitenodesareoperatedinthemannerofdynamicgrouping.Dynamicgroupingisbasedonsatellitesspatialrelationshipsandthegrouproleofthesatellitenodechangesbyturnsduetoitsspatialrelationships.Theroutestrategyprovidessignificantadvantagesofhighefficiency,lowcomplexity,andflexibleconfiguration,bywhichtheestablishedGNSScanpossessthefeaturesandcapabilitiesoffeasibledeployment,efficienttransmission,convenientmanagement,structuralinvulnerabilityandflexibleexpansion.