A method switches a mobile station (MS) from a current group to a new group in a Worldwide Interoperability for Microwave Access (WiMAX) including a base station (BS). The BS operates in full duplex mode and the MS operates in half-duplex mode, such that the WiMAX network operates in semi-duplex mode. The MS receives from the BS, while the MS is in the current group, a group switching request in a downlink (DL) sub-frame. The MS also receives structural information regarding frames of the new group. The MS switches from the current group to the new group after receiving the structural information.