A communication apparatus (CA) such as a mobile node/station (MN), a base station (BS), or a radio station (RS) may support determination of HARQ timing. The CA may generate at least in part one or more generalized frames such as a frequency division duplex (FDD) frame or a time division duplex (TDD) frame. The generalized FDD and TDD frames may include support to determine the HARQ timing considering various factors, which may affect the HARQ timing. The FDD and TDD frames may include information corresponding to various factors to determine the HARQ timing considering factors such as DL/UL ratio, number of sub-frames per frame, variable transmission time interval (TTI), relay zones, legacy IEEE® 802.16e zones, and availability of ACKCH.