A method of processing wireless signals, including: receiving a wireless signal carrying a transmission frame having a physical layer header including a data rate index; decoding the physical layer header including the data rate index; filtering out the transmission frame for no further processing if a measured physical layer header energy is below an energy threshold corresponding to the decoded data rate index; decode a sample portion of data codewords of the transmission frame if the transmission frame is not filtered out, wherein the sample portion of data codewords is less than all of the data codewords of the transmission frame; and filtering out the transmission frame for no further processing if the decoding of the sample portion of data codewords fails, and otherwise decode a remainder of the transmission frame.