Method for configuring PHICH carrier linkage

1. A method implemented in a wireless communication network of configuring a downlink (DL) component carrier between one or more linkage methods for PHICH (physical hybrid-ARQ (automatic repeat request) indicator channel) reception on user equipment (UE) the UE being configured for carrier aggregation, the method comprising:

(a) providing an indicator from a base station to the UE;

(b) determining, at the UE and based on a value of the indicator, whether a PHICH carrier linkage is either dynamic or cell specific; and

upon a determination from said determining step that said PHICH carrier linkage is dynamic, transmitting to the UE a PHICH on a DL component carrier used for uplink (UL) grant transmission, and

upon a determination from said determining step that said PHICH carrier linkage is cell specific, linking a DL component carrier used for PHICH reception to an UL component carrier used for PUSCH transmission in a cell-specific manner,

wherein the indicator is a single bit located in a DCI (downlink control information) format for an uplink (UL) grant.

2. The method of claim 1 , wherein if the single bit is introduced in the DCI format for the UL grant, the single bit exists in the DCI format only if a PDCCH (Physical Downlink Control Channel) carrier indicator exists.

3. The method of claim 1 , further comprising:

setting, at the base station, the PHICH carrier linkage as determined in (b).

4. A method implemented in user equipment used in a wireless communication network, of configuring a downlink (DL) component carrier between one or more linkage methods for PHICH (physical hybrid-ARQ (automatic repeat request) indicator channel) reception, the UE being configured for carrier aggregation, the method comprising:

(a) receiving an indicator from a base station; and

(b) determining whether a PHICH carrier linkage is either dynamic or cell specific, based on a value of the indicator,

wherein, upon a determination from said determining step that said PHICH carrier linkage is dynamic, a same DL component carrier as that used for transmission of an UL grant is used for PHICH transmission to the UE, and

wherein, upon a determination from said determining step that said PHICH carrier linkage is cell specific, the DL component carrier for PHICH reception is linked to an UL component carrier used for PUSCH transmission in a cell-specific manner,

wherein the indicator is a single bit located in a DCI (downlink control information) format for the uplink (UL) grant.

5. The method of claim 4 , wherein if the single bit for the indicator is introduced in the DCI format for the UL grant, the single bit exists in the DCI format only if a PDCCH (Physical Downlink Control Channel) carrier indicator exists.

6. The method of claim 4 , further comprising:

setting the PHICH carrier linkage as determined in (b).

7. A method implemented in a base station used in a wireless communication network, of configuring a downlink (DL) component carrier between one or more linkage methods for PHICH (physical hybrid-ARQ (automatic repeat request) indicator channel) reception on user equipment (UE), the UE being configured for carrier aggregation, the method comprising:

providing an indicator from the base station to the UE,

wherein the UE determines whether a PHICH carrier linkage, based on a value of the indicator, is either dynamic or cell specific,

wherein, when said PHICH carrier linkage is determined as dynamic, a same DL component carrier as that used for transmission of an UL grant is used for PHICH transmission to the UE, and

wherein, when said PHICH carrier linkage is determined as cell specific, the DL component carrier for PHICH reception is linked to an UL component carrier used for PUSCH transmission in a cell-specific manner,

wherein the indicator is a single bit located in a DCI (downlink control information) format for the uplink (UL) grant.