The invention relates to a realization method in which a 
Relay support cellular 
system can effectively avoid the interference of uplink and downlink, and a device thereof as well as a solution which allows the interference of the uplink and the downlink to be introduced by the 
system due to coverage expansion. The invention is realized by a 
special design of a frame structure and the 
special design comprises a 
transmission order of four 
system links in the frame structure which are a downlink 
relay link L1, a downlink access link L2, an uplink access link L3 and an uplink 
relay link L4, and a guard space of a 
transfer point of the uplink and the downlink. When the 
transmission order of the four links of the frame structure is L1, L2, L3 and L4, a multiplying adjustment is processed on the required guard space of the transfer of the uplink and the downlink simultaneously allowing for path propagation delays between BS and RS as well as between RS and UE, namely offsetting the 
propagation delay between RS and UE; when the 
transmission order of the four links of the frame structure is L1, L2, L4 and L3, the guard space of the transfer of the uplink and the downlink only allows for the 
propagation delay between BS and RS while the 
propagation delay between RS and UE can be guarded by 
idle time which is caused by a sending to BS in advance from RS.