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Becauseofunderwateracousticcommunicationchannelbandwidthislow,communicationShiYanGao,signalattenuationandthemultipatheffect,theinfluenceofsuchfactorsseriouslyaffectthequalityofthecommunicationbetweenthewirelesssensornodesandMUWSNsnetworkreliability.TomakeMUWSNscangetmoreextensiveapplication,MAClayerprotocolsintheunderwateracousticcommunicationrate,inrecentyears,autonomousunderwatervehicle(AUV)andunderwaterautonomousrobotmadesomeprogress.

(1)forunderwatersignaldemodulation,originalnon-coherentmodulationtechnologybydopplerdispersionandmultipatheffectisserious,topreventinterferencebetweenpulsesaddedaperiodoftimethusreducingthecommunicationrate;Coherentmodulationtechnology,thoughnotincreaseperiod,toacertainextent,improvethecommunicationrate,butthecomplexchannelshouldalsobetakentobalancecompensationsoastoadapttothedynamicvariationofunderwatercommunicationchannel.Inrecentyears,throughthetechnologyofmultipleinputmultipleoutput(MIMO)[19]andorthogonalfrequencydivisionmultiplexing(OFDM)technology[20]research,appliedtotheunderwatersignaldemodulation,madetoimprovethecommunicationratelarger.

(2)accordingtotheOSIlayersstructuremodel[4],thedatalinklayeroftheMACsub-layerisMUWSNsnetworkcommunicationperformanceofoneofthekeylink,throughtheformulationreasonableMACprotocolsforlimitedresourcesforeffectiveuseofmultipathunderwateracousticchannel,inordertorealizethecompletedataontheunreliablecommunicationlinksofreliabletransmission.MACprotocolsforunderwatersensornetworksinrecentyears,thestudyisconcentratedandmadesomeprogress,literature[21,22]fortheend-to-endtimedelay,transmissionerrorrateandnetworkthroughputperformancemetricsoftheoriginalMAClayersuchasALOHAandCSMA/CAprotocolisimproved,maketheMUWSNsnetworkcommunicationperformancehasbeenimproved.

(3)autonomousunderwaterrobotstartinginthemid-1990-sinoceanexplorationandmilitaryfieldapplication,butduetothetechnicallevelislimited,carryandAUVinenergycosts,autonomousmobilepositioning,aswellasthedepth,therearealotoflimitations.Inrecentyears,countrieshasmadegreatbreakthroughinthefieldofdesignofAUV,theAUVdepthcanreachthousandsofmetersdeep,accordingtodifferentdepthcanprovideseveraldifferentworkmode,andcancarryonthekopandwaterbasestationcommunication,achievefullautonomy,easydeliveryanddeliverycostissmallerthanbefore.