Patent Publication Number: US-2012044890-A1

Title: Method of Handling Uplink Reporting Trigger and Configuration and Related Communication Device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/375,044, filed on Aug. 19, 2010 and entitled “Method and Apparatus for uplink reporting trigger and configuration”, the contents of which are incorporated herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method used in a wireless communication system and related communication device, and more particularly, to a method of handling uplink reporting trigger and configuration in a wireless communication system and related communication device. 
     2. Description of the Prior Art 
     A long-term evolution (LTE) system, initiated by the third generation partnership project (3GPP), is now being regarded as a new radio interface and radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes a plurality of evolved Node-Bs (eNBs) for communicating with a plurality of user equipments (UEs) and communicates with a core network including a mobility management entity (MME), serving gateway, etc for NAS (Non Access Stratum) control. 
     UL control information in the LTE system includes an acknowledgement/negative acknowledgement (ACK/NACK) for downlink (DL) data, a channel quality indicator (CQI), a scheduling request (SR) and multiple-input multiple-output (MIMO) parameters of the UE. The UE may transmit the UL control information by using a dedicated resource. In this situation, the UE transmits the UL control information to an eNB on a physical uplink (UL) control channel (PUCCH) in the LTE system. Resource blocks allocated to the PUCCH in a subframe, i.e., a PUCCH region, locate on edges of a system bandwidth for a low out of band (OOB) emission and a low constraint on UL data scheduling. Besides, the resource blocks hop between slots (intra-subframe hopping) or between subframes (inter-subframe hopping) for gaining frequency diversity. On the other hand, the UE may also transmit the UL control information along with data. In this situation, the UE first multiplexes the UL control information and the data, and then transmits the multiplexed result to the eNB on a physical UL shared channel (PUSCH) in the LTE system. Please note that, the UE can only select the one of the PUCCH and the PUSCH to transmit the UL control information but not both so as to maintain a single carrier property, i.e., a low peak to average power ratio (PAPR). 
     On the other hand, DL control information in the LTE system includes downlink control information (DCI). The DCI is transmitted on a physical DL control channel (PDCCH), and indicates information of resource assignments for the UE on the UL and the DL, respectively, by using 4 different DCI formats and their variations. In the LTE system, the PDCCH is transmitted by using one or multiple control channel elements (CCEs). A CCE includes 9 resource element groups (REGs), and a REG includes 4 REs. More specifically, there are 4 PDCCH formats, e.g., PDCCH formats 0, 1, 2 and 3, and these PDCCH formats occupy 1, 2, 4 and 8 CCEs, respectively. The 4 DCI formats with their variations are transmitted on corresponding 4 PDCCH formats. 
     In the LTE system, a physical DL shared channel (PDSCH) is the main channel for the eNB to transmit data to the UEs. Besides, the PDSCH can also be used for broadcasting system information and transmitting paging to the UEs. Corresponding resources for transmitting the PDSCH are indicated to the UEs in the PDCCH. 
     A long term evolution-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system. The LTE-A system targets faster switching between power states, improves performance at the coverage edge of an eNB, and includes subjects, such as bandwidth extension, coordinated multipoint transmission/reception (CoMP), UL multiple-input multiple-output (MIMO), etc. 
     For bandwidth extension, a carrier aggregation (CA) is introduced to the LTE-A system by which two or more component carriers are aggregated to achieve a wider-band transmission. Accordingly, the LTE-A system can support a wider bandwidth up to 100 MHz by aggregating a maximum number of 5 component carriers, where bandwidth of each component carrier is 20 MHz and is backward compatible with 3GPP Rel-8. The LTE-A system supports the CA for both continuous and non-continuous component carriers with each component carrier limited to a maximum of 110 resource blocks. The CA increases bandwidth flexibility by aggregating the non-continuous component carriers. A component carrier is either used as a UL component carrier or a DL component carrier, but not both. 
     When the UE is configured with the CA, the UE is allowed to receive and transmit data on one or multiple component carriers to increase the data rate. In the LTE-A system, it is possible for the eNB to configure the UE different numbers of UL and DL component carriers which depend on UL and DL aggregation capabilities, respectively. Moreover, the component carriers configured to the UE necessarily consists of one DL primary component carrier (PCC) and one UL primary component carrier. Component carriers other than the primary component carriers are named UL or DL secondary component carriers (SCCs). The numbers of UL and DL secondary component carriers are arbitrary, and are related to the UE capability and available radio resources. The UL and DL primary component carriers are used for establishing and re-establishing the radio resource control (RRC), and transmitting and receiving the system information. 
     In the LTE system, a PUCCH ACK/NACK resource index n PUCCH   (1)  is used to derive a PUCCH region and a PUCCH resource index (e.g. acyclic shift index α(n s ,l) and/or an orthogonal sequence index n oc (n s )). Since there may be no first CCE location on the PDCCH for implication of the PUCCH ACK/NACK resource index when a semi-persistent scheduling (SPS) is configured, the PUCCH ACK/NACK resource index is configured semi-statically by a higher layer signaling. In the case of dynamically scheduled downlink data transmission on the PDSCH, the PUCCH ACK/NACK resource index is implicitly determined according to the index of the first CCE of the downlink control assignment. However, the LTE-A system supports the carrier aggregation, it is not clear which n PUCCH   (1)  to be used when transmissions associated with both SPS assignment and dynamic assignment happen on different component carriers in the same subframe while there is only one PUCCH CC and/or ACK/NACK multiplexing of all component carriers in a subframe is adopted. 
     Moreover, the search space for scheduling transmission on each downlink component carrier may need to be redesigned. One example is that the SPS is scheduled on the primary component carrier while other component carriers are cross scheduled by the PDCCH on the primary component carrier. Therefore, a new mechanism is needed. Please note that in the LTE system, simultaneous SPS and dynamic assignments should not happen in the same subframe. Otherwise, a similar mechanism is also needed. 
     On the other hand, before an operator deploys a relay with respect to a corresponding eNB, the radio link (backhaul) between the relay and the corresponding eNB is measured first such that the radio link between the relay and the corresponding eNB is normally under a good condition. For simplicity, there are also many configurations that are semi-static and fixed. Among these configurations, how to configure relay Un PUCCH resources to maintain the operation between the relay and the corresponding eNB is a topic to be discussed and addressed. 
     SUMMARY OF THE INVENTION 
     The present invention therefore provides a method and related communication device for handling uplink reporting trigger and configuration to solve the abovementioned problems. 
     A method of handling acknowledgement/negative acknowledgment (ACK/NACK) information of a mobile device in a wireless communication system is disclosed. The mobile device supports a carrier aggregation (CA), and the method comprises being configured with a downlink (DL) semi-persistent scheduling (SPS) resource for transmission on a component carrier in a subframe by a network of the wireless communication system, and receiving at least one dynamic DL assignment for at least one scheduled DL transmission on at least one component carrier in the subframe from the network, and feeding back ACK/NACK information on a physical uplink (UL) control channel (PUCCH) corresponding to the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission to the network according to a derived PUCCH ACK/NACK resource index indicating at least one of a PUCCH region and a PUCCH resource index. 
     A method of handling acknowledgement/negative acknowledgment (ACK/NACK) information of a mobile device in a wireless communication system is disclosed. The mobile device supports a carrier aggregation (CA), and the method comprises being configured with a downlink (DL) semi-persistent scheduling (SPS) resource for transmission on a component carrier in a subframe by a network of the wireless communication system, and receiving at least one dynamic DL assignment for at least one scheduled DL transmission on at least one component carrier in the subframe from the network, feeding back a first ACK/NACK for the DL semi-persistent scheduling transmission on a first PUCCH to the network according to a PUCCH ACK/NACK resource index associated with the DL semi-persistent scheduling resource, and feeding back a second ACK/NACK for the at least one scheduled DL transmission on a second PUCCH to the network according to a derived PUCCH ACK/NACK resource index associated with the at least one dynamic DL assignment. 
     A method of handling acknowledgement/negative acknowledgment (ACK/NACK) information of a mobile device in a wireless communication system is disclosed. The mobile device supports a carrier aggregation (CA), and the method comprises being configured with a downlink (DL) semi-persistent scheduling (SPS) resource for transmission on a component carrier in a first subframe by a network of the wireless communication system, and receiving at least one dynamic DL assignment for at least one scheduled DL transmission on at least one component carrier in a second subframe from the network, feeding back a first ACK/NACK for the DL semi-persistent scheduling transmission on a first PUCCH in a third subframe to the network according to a PUCCH ACK/NACK resource index associated with the DL semi-persistent scheduling resource, and feeding back a second ACK/NACK for the at least one scheduled DL transmission on a second PUCCH in a fourth subframe to the network according to a derived PUCCH ACK/NACK resource index associated with the at least one dynamic DL assignment. 
     A method of handling acknowledgement/negative acknowledgment (ACK/NACK) information and PUCCH resources of a relay node of a wireless communication system is disclosed. The method comprises receiving a dynamic backhaul relay physical downlink (DL) shared channel (R-PDSCH) assignment via a relay physical DL control channel (R-PDCCH), being semi-statically configured with at least one physical uplink (UL) control channel (PUCCH) resource index and at least one PUCCH region by a higher layer signaling for relaying UL control information signaling, and being semi-statically configured with a plurality of ACK/NACK resources. 
     A method of handling acknowledgement/negative acknowledgment (ACK/NACK) information and PUCCH resources of a relay node of a wireless communication system is disclosed. The method comprises receiving a dynamic backhaul relay physical downlink (DL) shared channel (R-PDSCH) assignment via a relay physical DL control channel (R-PDCCH), being semi-statically configured with at least one physical uplink (UL) control channel (PUCCH) resource index and at least one PUCCH region according to a carrier indication field (CIF) configuration, and being semi-statically configured with a plurality of ACK/NACK resources according to the CIF configuration. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an exemplary wireless communication system according to the present disclosure. 
         FIG. 2  is a schematic diagram of an exemplary communication device according to the present disclosure. 
         FIG. 3  is a schematic diagram of communication protocol layers for an exemplary wireless communication system. 
         FIG. 4  is a flowchart of an exemplary process according to the present disclosure. 
         FIG. 5  is a flowchart of an exemplary process according to the present disclosure. 
         FIG. 6  is a flowchart of an exemplary process according to the present disclosure. 
         FIG. 7  is a flowchart of an exemplary process according to the present disclosure. 
         FIG. 8  is a flowchart of an exemplary process according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 1 , which is a schematic diagram of a wireless communication system  10  according to an example of the present invention. The wireless communication system  10 , such as a long term evolution-advanced (LTE-A) system, is briefly composed of a network and a plurality of user equipments (UEs). In  FIG. 1 , the network and the UEs are simply utilized for illustrating the structure of the wireless communication system  10 . Practically, the network can be referred as to an E-UTRAN (evolved-UTAN) comprising a plurality of evolved Node-Bs (eNBs) and relays in the LTE-A system. The UEs can be mobile devices such as mobile phones, laptops, tablet computers, electronic books, and portable computer systems. Besides, the network and a UE can be seen as a transmitter or a receiver according to transmission direction, e.g., for an uplink (UL), the UE is the transmitter and the network is the receiver, and for a downlink (DL), the network is the transmitter and the UE is the receiver. 
     Please refer to  FIG. 2 , which is a schematic diagram of a communication device  20  according to an example of the present invention. The communication device  20  can be the UE or the network shown in  FIG. 1 , but is not limited herein. The communication device  20  may include a processor  200  such as a microprocessor or an Application Specific Integrated Circuit (ASIC), a storage unit  210  and a communication interfacing unit  220 . The storage unit  210  may be any data storage device that can store a program code  214 , accessed by the processor  200 . Examples of the storage unit  210  include but are not limited to a subscriber identity module (SIM), read-only memory (ROM), flash memory, random-access memory (RAM), CD-ROM/DVD-ROM, magnetic tape, hard disk, and optical data storage device. The communication interfacing unit  220  is preferably a radio transceiver and can exchange wireless signals with the network according to processing results of the processor  200 . 
     Please refer to  FIG. 3 , which illustrates a schematic diagram of communication protocol layers for the LTE-Advanced system. The behaviors of some of the protocol layers may be defined in the program code  214  and executed by the processing means  200 . The protocol layers from top to bottom are a radio resource control (RRC) layer  300 , a packet data convergence protocol (PDCP) layer  302 , a radio link control (RLC) layer  304 , a medium access control (MAC) layer  306  and a physical (PHY) layer  308 . The RRC layer  300  is used for performing broadcast, paging, RRC connection management, measurement reporting and control and radio bearer control responsible for generating or releasing radio bearers. The PDCP layer  302  is used for header compression, ciphering and integrity protection of transmissions, and maintaining delivery order during a handover. The RLC layer  304  is used for segmentation/concatenation of packets and maintaining delivery sequence when packet loses. The MAC layer  306  is responsible for a hybrid automatic repeat request (HARQ) process, multiplexing logical channels, a random access channel (RACH) procedure and maintaining a UL timing alignment. In each HARQ process, an acknowledgement (ACK) is reported to the network if the MAC data/control packet is received and decoded successfully. Otherwise, a negative acknowledgement (NACK) is reported to the network. The PHY layer  308  is used to provide physical channels, e.g. a physical UL control channel (PUCCH), a physical DL control channel (PDCCH), a physical DL shared channel (PDSCH) etc. 
     Please refer to  FIG. 4 , which is a flowchart of a process  40  according to an example of the present disclosure. The process  40  is utilized in a UE in the wireless communication system  10  shown in  FIG. 1 , to feed back ACK/NACK information to the network. The UE supports a carrier aggregation (e.g. one or more DL component carriers). The process  40  may be compiled into the program code  214  and includes the following steps: 
     Step  400 : Start. 
     Step  402 : Be configured with a DL semi-persistent scheduling (SPS) resource for transmission on a component carrier in a subframe by a network of the wireless communication system, and receive at least one dynamic DL assignment for at least one scheduled DL transmission on at least one component carrier in the subframe from the network. 
     Step  404 : Feed back the ACK/NACK information on a PUCCH corresponding to the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission to the network according to a derived PUCCH ACK/NACK resource index indicating at least one of a PUCCH region and a PUCCH resource index. 
     Step  406 : End. 
     According to the process  40 , after the UE is configured with the DL semi-persistent scheduling resource for transmission on the component carrier in the subframe by the network of the wireless communication system and receives the at least one dynamic DL assignment (e.g. a DL control information (DCI) format by the PDCCH) for the at least one scheduled DL transmission on the at least one component carrier in the subframe from the network, the UE then performs the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission. After that, the UE feeds back the ACK/NACK information on the PUCCH (e.g. DCI format 1a/1b) corresponding to the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission to the network according to the derived PUCCH ACK/NACK resource index (e.g. n PUCCH   (1) ) indicating the at least one of the PUCCH region and the PUCCH resource index (e.g. (cyclic shift index α(n s ,l), orthogonal sequence index n oc (n s ))). Therefore, the UE can feed back the ACK/NACK information to the network when the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission are configured and received, respectively. 
     Preferably, a PUCCH ACK/NACK resource index for the DL semi-persistent scheduling transmission on the component carrier is determined by a higher layer signaling, and each of at least one PUCCH ACK/NACK resource index for the at least one scheduled DL transmission using the at least one dynamic DL assignment (e.g. a DCI format by the PDCCH) on the at least one component carrier is respectively determined by the first control channel element (CCE) location index of each of the at least one dynamic DL assignment. In this situation, the UE selects one of the at least one PUCCH ACK/NACK resource index as the derived PUCCH ACK/NACK resource index. Further, the UE can select the one of the at least one PUCCH ACK/NACK resource index as the derived PUCCH ACK/NACK resource index according to a certain rule. For example, the certain rule may be the lowest CCE, the highest CCE, a CCE corresponding to the primary DL component carrier of the UE, or a CCE corresponding to a predefined or a configured DL component carrier of the UE. Besides, the at least one component carrier, on which the at least one scheduled DL transmission is received, comprise the component carrier on which the DL semi-persistent scheduling transmission is received, or the at least one component carrier does not comprise the component carrier. It is possible that the PUCCH is transmitted on the UL primary component carrier of the UE (e.g. assume the ACK/NACK for all component carriers in the subframe are multiplexed together in the same format). 
     Therefore, according to the above illustration and the process  40 , the UE is able to feed back the ACK/NACK information to the network for the DL semi-persistent scheduling and the at least one dynamic DL assignment. 
     Please refer to  FIG. 5 , which is a flowchart of a process  50  according to an example of the present disclosure. The process  50  is utilized in a UE in the wireless communication system  10  shown in  FIG. 1 , to feed back ACK/NACK information on respective PUCCHs to the network. The UE supports a carrier aggregation (e.g. one or more DL component carriers). The process  50  may be compiled into the program code  214  and includes the following steps: 
     Step  500 : Start. 
     Step  502 : Be configured with a DL semi-persistent scheduling resource for transmission on a component carrier in a subframe by a network of the wireless communication system, and receive at least one dynamic DL assignment for at least one scheduled DL transmission on at least one component carrier in the subframe from the network. 
     Step  504 : Feed back a first ACK/NACK for the DL semi-persistent scheduling transmission on a first PUCCH to the network according to a PUCCH ACK/NACK resource index associated with the DL semi-persistent scheduling resource. 
     Step  506 : Feed back a second ACK/NACK for the at least one scheduled DL transmission on a second PUCCH to the network according to a derived PUCCH ACK/NACK resource index associated with the at least one dynamic DL assignment. 
     Step  508 : End. 
     According to the process  50 , after the UE is configured with the DL semi-persistent scheduling resource for transmission on the component carrier in the subframe by the network of the wireless communication system and receives the at least one dynamic DL assignment (e.g. a DCI format by the PDCCH) for the at least one scheduled DL transmission on the at least one component carrier in the subframe from the network, the UE then performs the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission. After that, the UE feeds back the first ACK/NACK for the DL semi-persistent scheduling transmission on the first PUCCH (e.g. DCI format 1a/1b) to the network according to the PUCCH ACK/NACK resource index associated with the DL semi-persistent scheduling resource, and feeds back the second ACK/NACK for the at least one scheduled DL transmission on the second PUCCH (e.g. DCI format 1a/1b) to the network according to the derived PUCCH ACK/NACK resource index (e.g. n PUCCH   (1) ) associated with the at least one dynamic DL assignment. Therefore, the UE can feed back respective ACK/NACKs on corresponding PUCCHs for the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission. 
     Preferably, the PUCCH ACK/NACK resource index for the DL semi-persistent scheduling transmission on the component carrier is determined by a higher layer signaling, and the derived PUCCH ACK/NACK index is determined from at least one PUCCH ACK/NACK resource index which is for the at least one scheduled DL transmission using the at least one dynamic DL assignment (e.g. a DCI format by the PDCCH) on the at least one component carrier wherein each of the at least one PUCCH ACK/NACK resource index is respectively determined by the first CCE location index of each of the at least one dynamic DL assignment. In this situation, the UE selects one of the at least one PUCCH ACK/NACK resource index as the derived PUCCH ACK/NACK resource index for determining at least one of a PUCCH region (e.g. m) and a PUCCH resource index (e.g. (cyclic shift index α(n s ,l), orthogonal sequence index n oc (n s ))), to feed back the second ACK/NACK for the at least one scheduled DL transmission to the network. Further, the UE can select the one of the at least one PUCCH ACK/NACK resource index as the derived PUCCH ACK/NACK resource index according to a certain rule. For example, the certain rule may be the lowest CCE, the highest CCE, a CCE corresponding to the primary DL component carrier of the UE, or a CCE corresponding to a predefined or a configured DL component carrier of the UE. 
     On the other hand, the UE may also use the PUCCH ACK/NACK resource index for determining at least one of a PUCCH region (e.g. m) and a PUCCH resource index (e.g. (cyclic shift index α(n s ,l), orthogonal sequence index n oc (n s ))), to feed back the first ACK/NACK for the DL semi-persistent scheduling transmission to the network. Besides, the at least one component carrier for the at least one scheduled DL transmission comprises the component carrier for the DL semi-persistent scheduling transmission, or the at least one component carrier does not comprise the component carrier. It is possible that the first PUCCH and the second PUCCH are on the UL primary component carrier of the UE (e.g. assume the ACK/NACK for all the at least one dynamic DL assignment in the subframe are multiplexed together in the same format). 
     Therefore, according to the above illustration and the process  50 , the UE is able to feed back the respective ACK/NACKs for the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission on corresponding PUCCHs to the network. 
     Please refer to  FIG. 6 , which is a flowchart of a process  60  according to an example of the present disclosure. The process  60  is utilized in a UE in the wireless communication system  10  shown in  FIG. 1 , to feed back ACK/NACK information on respective PUCCHs and subframes. The UE supports a carrier aggregation (e.g. one or more DL component carriers). The process  60  may be compiled into the program code  214  and includes the following steps: 
     Step  600 : Start. 
     Step  602 : Be configured with a DL semi-persistent scheduling resource for transmission on a component carrier in a first subframe by a network of the wireless communication system, and receive at least one dynamic DL assignment for at least one scheduled DL transmission on at least one component carrier in a second subframe from the network. 
     Step  604 : Feed back a first ACK/NACK for the DL semi-persistent scheduling transmission on a first PUCCH in a third subframe to the network according to a PUCCH ACK/NACK resource index associated with the DL semi-persistent scheduling resource. 
     Step  606 : Feed back a second ACK/NACK for the at least one scheduled DL transmission on a second PUCCH in a fourth subframe to the network according to a derived PUCCH ACK/NACK resource index associated with the at least one dynamic DL assignment. 
     Step  608 : End. 
     According to the process  60 , after the UE is configured with the DL semi-persistent scheduling resource for transmission on the component carrier in the first subframe by the network of the wireless communication system and receives the at least one dynamic DL assignment (e.g. a DCI format by the PDCCH) for the at least one scheduled DL transmission on the at least one component carrier in the second subframe from the network, the UE then performs the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission. After that, the UE feeds back the first ACK/NACK for the DL semi-persistent scheduling transmission on the first PUCCH (e.g. DCI format 1a/1b) in the third subframe to the network according to the PUCCH ACK/NACK resource index associated with the DL semi-persistent scheduling resource, and feeds back the second ACK/NACK for the at least one scheduled DL transmission on the second PUCCH (e.g. DCI format 1a/1b) in the fourth subframe to the network according to the derived PUCCH ACK/NACK resource index (e.g. n PUCCH   (1) ) associated with the at least one dynamic DL assignment. Therefore, the UE can feedback respective ACK/NACKs on corresponding PUCCHs and subframes for the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission. 
     Preferably, the PUCCH ACK/NACK resource index for the DL semi-persistent scheduling transmission on the component carrier is determined by a higher layer signaling, and the derived PUCCH ACK/NACK index is determined from at least one PUCCH ACK/NACK resource index which is for the at least one scheduled DL transmission using the at least one dynamic DL assignment (e.g. a DCI format by the PDCCH) on the at least one component carrier wherein each of the at least one PUCCH ACK/NACK resource index is respectively determined by the first CCE location index of each of the at least one dynamic DL assignment. In this situation, the UE selects one of the at least one PUCCH ACK/NACK resource index as the derived PUCCH ACK/NACK resource index for determining at least one of a PUCCH region (e.g. m) and a PUCCH resource index (e.g. (cyclic shift index α(n s ,l), orthogonal sequence index n oc (n s ))), to feed back the second ACK/NACK for the at least one scheduled DL transmission to the network. Further, the UE can select the one of the at least one PUCCH ACK/NACK resource index as the derived PUCCH ACK/NACK resource index according to a certain rule. For example, the certain rule may be the lowest CCE, the highest CCE, a CCE corresponding to the primary DL component carrier of the UE, or a CCE corresponding to a predefined or a configured DL component carrier of the UE. 
     On the other hand, the UE may also use the PUCCH ACK/NACK resource index for determining at least one of a PUCCH region and a PUCCH resource index, to feed back the first ACK/NACK for the DL semi-persistent scheduling transmission to the network. Besides, the at least one component carrier for the at least one scheduled DL transmission comprises the component carrier for the DL semi-persistent scheduling transmission, or the at least one component carrier does not comprise the component carrier. It is possible that the first PUCCH and the second PUCCH are on the UL primary component carrier of the UE (e.g. assume the ACK/NACK for all the at least one dynamic DL assignment in the subframe are multiplexed together in the same format). 
     Therefore, according to the above illustration and the process  60 , the UE is able to feed back the respective ACK/NACKs for the DL semi-persistent scheduling transmission and the at least one scheduled DL transmission on corresponding PUCCHs and subframes to the network. 
     Please refer to  FIG. 7 , which is a flowchart of a process  70  according to an example of the present disclosure. The process  70  is utilized in a relay node of the wireless communication system  10  shown in  FIG. 1 , to handle an ACK/NACK information and PUCCH resources. The process  70  may be compiled into the program code  214  and includes the following steps: 
     Step  700 : Start. 
     Step  702 : Receive a dynamic backhaul relay-PDSCH (R-PDSCH) assignment via a relay-PDCCH (R-PDCCH). 
     Step  704 : Be semi-statically configured with at least one PUCCH resource index and at least one PUCCH region by a higher layer signaling for relaying UL control information signaling. 
     Step  706 : Be semi-statically configured with a plurality of ACK/NACK resources. 
     Step  708 : End. 
     According to the process  70 , after the relay node receive the dynamic backhaul R-PDSCH assignment via the R-PDCCH, the relay node is semi-statically configured with the at least one PUCCH resource index (e.g. a cyclic time shift index and an orthogonal spreading code index) and the at least one PUCCH region by the higher layer signaling for relaying the UL control information signaling, and is semi-statically configured with the plurality of ACK/NACK resources (e.g. on assigned ACK/NACK resource, scheduling request (SR) resource or channel quality indicator (CQI) resource). Therefore, the relay node can feedback the ACK/NACK to the network by using the plurality of ACK/NACK resources. 
     Preferably, a randomization for at least one of at least one PUCCH ACK/NACK resource index, the at least one PUCCH resource index and the at least one PUCCH region is achieved by adding a randomization function or a modulation operation (e.g. for inter-cell interference randomization), irrespective of corresponding semi-static configuration for the at least one PUCCH ACK/NACK resource index, the at least one PUCCH resource index and the at least one PUCCH region. Further, the first CCE location index of each R-PDSCH assignment is not related to each of the at least one PUCCH ACK/NACK resource index or is not used to derived each of the at least one PUCCH ACK/NACK resource index. The at least one PUCCH region is semi-statically configured while the at least one PUCCH resource index is randomized or hopped (e.g. by a length-31 Gold sequence generator). Besides, the at least one PUCCH resource index is semi-statically configured while the at least one PUCCH region is randomized or hopped (e.g. by a length-31 Gold sequence generator). It is possible that a search space design for the R-PDCCH is not related to a carrier indication field (CIF). 
     Therefore, according to the above illustration and the process  70 , the relay node is able to feed back the ACK/NACK to the network by using the plurality of ACK/NACK resources. 
     Please refer to  FIG. 8 , which is a flowchart of a process  80  according to an example of the present disclosure. The process  80  is utilized in a relay node of the wireless communication system  10  shown in  FIG. 1 , to handle an ACK/NACK and PUCCH resources. The process  80  may be compiled into the program code  214  and includes the following steps: 
     Step  800 : Start. 
     Step  802 : Receive a dynamic backhaul relay-PDSCH (R-PDSCH) assignment via a relay-PDCCH (R-PDCCH). 
     Step  804 : Be semi-statically configured with at least one PUCCH resource index and at least one PUCCH region according to a CIF configuration. 
     Step  806 : Be semi-statically configured with a plurality of ACK/NACK resources according to the CIF configuration. 
     Step  808 : End. 
     According to the process  80 , after the relay node receives the dynamic backhaul R-PDSCH assignment via the R-PDCCH, the relay node is semi-statically configured with the at least one PUCCH resource index (e.g. a cyclic time shift index and an orthogonal spreading code index) and the at least one PUCCH region according to the CIF configuration (e.g. upon configuration of the CIF), and is semi-statically configured with a plurality of ACK/NACK resources (e.g. on assigned ACK/NACK resource, SR resource or CQI resource) according to the CIF configuration (e.g. upon configuration of the CIF). Therefore, the relay node can feed back the ACK/NACK to the network by using the plurality of ACK/NACK resources. Preferably, the CIF configuration determines a component carrier-specific offset for search space determination, to determine the first control channel element (CCE) location index of the dynamic backhaul R-PDSCH assignment. Further, the first CCE location index determines a PUCCH ACK/NACK resource index for a PUCCH resource index (e.g. (cyclic shift index α(n s ,l), orthogonal sequence index n oc (n s ))) and a PUCCH region. 
     Therefore, according to the above illustration and the process  80 , the relay node is able to feed back the ACK/NACK to the network by using the plurality of ACK/NACK resources. 
     Please note that, the abovementioned steps of the processes including suggested steps can be realized by means that could be a hardware, a firmware known as a combination of a hardware device and computer instructions and data that reside as read-only software on the hardware device, or an electronic system. Examples of hardware can include analog, digital and mixed circuits known as microcircuit, microchip, or silicon chip. Examples of the electronic system can include a system on chip (SOC), system in package (SiP), a computer on module (COM), and the communication device  20 . 
     In conclusion, the present invention provides methods for UE to feed back ACK/NACK information when the UE supports carrier aggregation. Besides, methods for configuring PUCCH resource index, and ACK/NACK resources to a relay node semi-statically are also presented, to configure the relay node efficiently by considering stable link between the relay node and the corresponding eNB. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.