A wireless transmit/receive unit (WTRU) may receive a PDCCH transmission comprising a CCE that is mapped to one or more REGs based on a CCE-to-REG mapping. The WTRU may receive the CCE-to-REG mapping that indicates a REG bundle corresponding to the CCE and use the CCE-to-REG mapping to identify the REGs for the SWTRU. Depending on whether the CCE-to-REG mapping is interleaving or noninterleaving, the CCE-to-REG mapping may be based on different parameters. If the CCE-to-REG mapping is interleaving, the CCE-to-REG mapping may be based on an index associated with the CCE and a number of REGs in the REG bundle. If the CCE-to-REG mapping is noninterleaving, the CCE-to-REG mapping may be based on the index of the CCE.