A relay station used in a communication network that has a tree-structured architecture including a number of hierarchical levels, the communication network including a base station of the highest hierarchical level, one or more relay stations and one or more subscriber stations, wherein a relay station has two radio modules, a first radio module being designed to communicate with stations of lower hierarchical level and a second radio module being designed to communicate with stations of higher hierarchical level, the two radio modules being synchronized in their MAC layer and the relay station including at least one antennas connected to the MAC layer of the radio modules.