For use in a wireless network, a base station configured to communicate in the wireless network is provided. The base station includes a processor coupled to a transmitter and configured to generate a resource allocation message. The resource allocation message includes a plurality of fixed length fields, one or more primary variable-length fields, and a plurality of secondary variable-length fields. The one or more primary variable-length fields occupy a position in the resource allocation message preceding as many of the fixed length fields as permitted by rules that govern a structure of the resource allocation message. The one or more primary variable-length fields are positioned in the resource allocation message such that when the resource allocation message is partitioned and allocated across a sequence of basic units (BUs), every primary variable-length field appears in a smallest possible sequence of BUs starting from the first BU in the sequence.