A method for generating signals to be transmitted within a basic service set (BSS) channel, where a set of component channels is collectively coextensive with the BSS channel, includes determining that a first duplicate, in frequency, of a low bandwidth mode data unit will be located at an edge of the BSS channel. Each duplicate includes orthogonal frequency division multiplexing (OFDM) tones and has a bandwidth less than the narrowest channel of the component channels. The OFDM tones in each duplicate include one or more data tones, one or more pilot tones, and one or more guard tones. The method also includes generating a transmission signal comprising the duplicates, at least in part by scaling down at least one data tone, and/or zeroing out at least one data tone, of the first duplicate in response to determining that the first duplicate will be located at an edge of the BSS channel.