In the mobile communication cell network

base station is used to coverage a large area and repeater is used to coverage small area as supplement.Repeater raises up the GSM base noise

increases system interference

effects the network quality.In some suitable condition

passive relay system can solve the problem of weak signals coverage without effects the network quality.The article demonstrates that passive relay system is feasible in theory and by experiment

educes the idea of using it in the GSM network.basing on the analysis of the application example

the technical request and the application location of passive relay system are given.