A method for generating a physical layer (PHY) data unit includes generating a first signal field to include multiple copies of first signal field content, wherein the first signal field content spans one sub-band of a plurality of sub-bands of the PHY data unit, and wherein the multiple copies collectively span the plurality of sub-bands of the PHY data unit; generating a second signal field to include multiple copies of second signal field content, wherein the second signal field content spans multiple ones of the plurality of sub-bands of the PHY data unit, and wherein the multiple copies of the second signal field collectively span the plurality of sub-bands of the PHY data unit; generating a preamble of the PHY data unit to include at least the first signal field and the second signal field; generating the PHY data unit to include at least the preamble.