A systems and method of channel estimation can be used in wireless environments. The systems and method can: (a) determine, by a transmitter, a number of receivers with which to communicate wirelessly, the number of receivers being at least one and corresponding to at least a first receiver; and (b) generate, by the transmitter, a frame to transmit to the first receiver, the frame generated based on a total number of receivers that is higher than the determined number of receivers.