To receive data in data field of a PHY Protocol Data Unit (PPDU), wherein the data field includes mid-ambles, a number of mid-ambles and a number of data symbols included in the data field is determined. The number of mid-ambles is determined according to information in an HE-SIG-A field of the PPDU, information in an L-SIG field of the PPDU, and one or more predetermined values prescribed by a standard. The number of data symbols may be determined using the number of the mid-ambles, and the data received according to the number of mid-ambles and the number of data symbols.