In a method for transmitting a data unit in a wireless communication network, a physical layer (PHY) preamble and a media access control layer (MAC) header are generated. In generating the MAC header, a first address field to include a first address and a second address field to include a second address are generated. The first, not globally unique, address indicates a communication device for which the data unit is intended or a communication device that is transmitting the data unit. The second address field indicates the other one of a communication device for which the data unit is intended or a communication device that is transmitting the data unit. The first address field and the second address field are included in the MAC header. The MAC header omits a globally unique address corresponding to the first address of the first address field.