Disclosed herein are system, method, and computer program product embodiments for providing an efficient way to assign resource blocks to user receiver devices in a wireless communications protocol. For example, the method can receive a frame for a wireless communications protocol. The method can also extract a unique value from a tone mapping field in a preamble of the frame. The method can also look up a resource block allocation for a portion of the tone space in a lookup table using the unique value. Further, the method can extract an assignment field from the preamble based on the determined resource block allocation. The method can also determine an assigned resource block number based on the assignment field. The method can also assign a resource block corresponding to the assigned resource block number to a user receiver device.