It is possible to reduce overhead when dynamically establishing an air interface configuration by communicating a modification instruction along with an index associated with a predefine air interface configuration. The modification instruction identifies a modification to one or more parameters of the predefined air interface configuration associated with the index. Together, the index and the modification indication specify a modified air interface configuration that is different than any of the candidate air interface configurations predefined for the network. The modification instruction allows networks to achieve similar degrees of flexibility while using substantially fewer predefined air interface configurations, which in turn permits the index associated with the selected air interface configuration to be signaled using fewer bits.