Methods, apparatuses and systems for using at least one sub-channel of a physical channel for uplink communication, the physical channel including a set of resources within first and second channel boundaries such that the physical channel includes a plurality of sub-channels, each sub-channel comprising a subset of the resources of the physical channel and having at least one sub-channel boundary which is not coincident with the first or the second channel boundaries, are provided. One representative apparatus includes a Station (STA) including: a processor, and a transmit/receive unit configured to: transmit, via an uplink, control information including a sub-channel SIG field indicating an identity of the STA, receive a trigger frame indicating one or more sub-channels available form among a plurality of sub-channels, determine which of the one or more sub-channels to acquire, and transmit data, via the uplink, using the one or more acquired sub-channels.