A method of determining cell timing configuration comprising: transmitting, from an enhanced NodeB, an indication of an uplink/downlink, UL-DL, subframe configuration of a scheduling cell in a wireless time-division duplex, TDD, system utilizing cross-carrier scheduling; and transmitting an indication of a UL-DL subframe configuration of a scheduled cell in the wireless TDD system, wherein the UL-DL subframe configuration of the scheduling cell is different from the UL-DL subframe configuration of the scheduled cell; identifying a type of the UL-DL subframe configuration of the scheduling cell based on an uplink round trip time, RTT, of a hybrid automatic repeat request, HARQ, process utilizing the UL-DL subframe configuration of the scheduling cell; and determining a HARQ timing configuration of the scheduled cell based on the type of the UL-DL subframe configuration of the scheduling cell; wherein the UL-DL subframe configuration of the scheduled cell and the UL-DL subframe configuration of the scheduling cell correspond to respective TDD UL- DL configurations associated with a 3rd Generation Partnership Project, 3GPP, long-term evolution, LTE, advanced wireless communication standard; wherein a UL-DL subframe configuration having an uplink HARQ RTT of 10 milliseconds is designated as Type 1 configuration and an UL-DL subframe configuration having an uplink HARQ RTT not equal to 10 milliseconds is designated as Type 2 configuration; wherein, when the UL-DL subframe configuration of the scheduling cell is a Type 1 configuration, the determined HARQ timing configuration of the scheduled cell is a HARQ timing configuration of the UL-DL subframe configuration of the scheduling cell; and characterised in that, when the UL-DL subframe configuration of the scheduling cell is a Type 2 configuration, the determined HARQ timing configuration of the scheduled cell is a HARQ timing configuration of the UL-DL subframe configuration of the scheduled cell. transmitting, from an enhanced NodeB, an indication of an uplink/downlink, UL-DL, subframe configuration of a scheduling cell in a wireless time-division duplex, TDD, system utilizing cross-carrier scheduling; and transmitting an indication of a UL-DL subframe configuration of a scheduled cell in the wireless TDD system, wherein the UL-DL subframe configuration of the scheduling cell is different from the UL-DL subframe configuration of the scheduled cell; identifying a type of the UL-DL subframe configuration of the scheduling cell based on an uplink round trip time, RTT, of a hybrid automatic repeat request, HARQ, process utilizing the UL-DL subframe configuration of the scheduling cell; and determining a HARQ timing configuration of the scheduled cell based on the type of the UL-DL subframe configuration of the scheduling cell; wherein the UL-DL subframe configuration of the scheduled cell and the UL-DL subframe configuration of the scheduling cell correspond to respective TDD UL- DL configurations associated with a 3rd Generation Partnership Project, 3GPP, long-term evolution, LTE, advanced wireless communication standard; wherein a UL-DL subframe configuration having an uplink HARQ RTT of 10 milliseconds is designated as Type 1 configuration and an UL-DL subframe configuration having an uplink HARQ RTT not equal to 10 milliseconds is designated as Type 2 configuration; wherein, when the UL-DL subframe configuration of the scheduling cell is a Type 1 configuration, the determined HARQ timing configuration of the scheduled cell is a HARQ timing configuration of the UL-DL subframe configuration of the scheduling cell; and characterised in that, when the UL-DL subframe configuration of the scheduling cell is a Type 2 configuration, the determined HARQ timing configuration of the scheduled cell is a HARQ timing configuration of the UL-DL subframe configuration of the scheduled cell.