A method and apparatus for exchanging messages via a wireless distribution system (WDS) between groups operating on different frequencies are disclosed. A wireless communication system includes a plurality of wireless transmit/receive units (WTRUs) and a plurality of basic service sets (BSSs). At least one WTRU belongs to each BSS. A source WTRU desiring to send a WDS packet to a destination WTRU in another BSS sends an availability notification (AN) message to WTRUs which the source WTRU is associated with to indicate that the source WTRU will not be available to receive data. The source WTRU then accesses a channel on which the destination WTRU camps and sends a packet to the destination WTRU. After transmission of the packet, or receiving an acknowledgement from the destination WTRU, the source WTRU reverts back to the original channel.