Patent ID: 8902874

Claim:
A method comprising: allocating, within a single physical resource unit (PRU), a plurality of channel sounding groups, at least one of the channel sounding croups being allocated to mobile stations of a first user group of a plurality of user groups, wherein each channel sounding group includes both a frequency-time domain allocation and a code division multiplexing (CDM) allocation; wherein at least one of the channel sounding croups allocated to the first user croup for channel sounding are in an upper frequency edge and lower frequency edge of the PRU; wherein the CDM allocation contains a unique identifier code for a mobile station or for a specific antenna on one or more mobile stations assigned by the base station; monitoring a communication channel condition for one or more communication channels; conditionally broadcasting, in a downlink direction to the one or more mobile stations in a wireless network, including the mobile stations of the first user group, if the communication channel condition of one or more of the communication channels is below a threshold, a signal that causes one or more of the receiving mobile stations to transmit a channel sounding signal if channel quality, as measured by the receiving mobile station, is above a criteria; receiving at least one channel sounding signal from at least one of the one or more mobile stations of the first user group, the channel sounding signal being received in an uplink direction via one or more channel sounding groups allocated to the mobile stations of the first user group; and estimating the channel quality, of the channel used by the physical resource unit, based upon the received at least one channel sounding signal.