In wireless communications for multi-users, an access point may generate a first frame for allocating resources to a plurality of stations. The first frame may contain an indication as to whether a station(s) is allocated at least one of a set of resource units (RUs) of a plurality of RUs, such as a center 26-tone RU. The set of resource units may be based on a channel bandwidth of the wireless communications. The indication may be contained in a common block field of signal fields, such as a common block field of high efficiency (HE) signal content channel(s) of an HE signal field. The station(s) may receive the first frame and determine whether the one of the set of RUs is allocated. The station(s) may transmit a second frame to the access point based on resource allocation information in the first frame. Other methods, apparatus, and computer-readable media are also disclosed.