A method includes receiving, at a wireless device, a frame via a sub-1 gigahertz (GHz) wireless network. The frame includes a signal (SIG) unit including a length field and an aggregation field. The length field may be interpreted as a number of bytes or as a number of symbols based on a value of the aggregation field and based on whether the frame is associated with a 1 megahertz (MHz) bandwidth mode, based on whether the frame includes either a short format preamble or a long format preamble, or based on whether the frame is determined to be a single user (SU) frame or a multi user (MU) frame.