In a wireless communication system, a method and apparatus for closed loop transmission is disclosed. In accordance with the preferred embodiment of the present invention, a time frequency portion of an uplink frame is dynamically reserved as a sounding zone for uplink channel sounding. A first message is transmitted to a first subscriber station in a downlink frame assigning a time-frequency resource within the sounding zone, and a sounding waveform. Furthermore, a signal is received from the subscriber station within the assigned time-frequency resource, a partial channel response is determined from the received sounding signal, and the subsequent transmission to the subscriber station is tailored based on the at least partial channel response.