Abstract
Inawirelesssensor-actornetwork,anactorusuallyhastoprovideservicesassoonastheactorreceivestheeventsignalsfromthesensors.Therefore,theperformanceofawirelesssensor-actornetworkdependsontheactordeployment.Inmanycircum-stances,actorsmayfailorgoouttodealwithevents,andthus,thesensorscoveredbythemissingactorscouldbeunreachableintime.Thisintroducesthenecessityofactorredeployment.Inthispaper,westudytheproblemsofredeployingactorstomaximizethenumberofsensorsabletobecoveredbyactorsandtomaximizethedecreaseoftheresidualdistancesofsensors,respectively.BothproblemsareshowntobeNP-complete.Additionally,weprovethatthegreedyalgorithmforeachprob-lemhasanapproximationratioof2.Simulationsshowthatthegreedyalgorithmforeachproblemperformswell.Keywords:wirelesssensor-actornetwork,coverage