Method of indicating physical uplink control channel resource in enhanced multiple-input multiple-output technology and related communication device

A method of indicating a physical uplink control channel (PUCCH) resource for a user equipment (UE) of a wireless communication system includes receiving a resource index denoting PUCCH format 2 resources and PUCCH format 3 resources, instead of merely denoting PUCCH format 2 resources, from a network of the wireless communication system; and determining resources for a transmission of control information over PUCCH format 2 or PUCCH format 3 based on an operation of the received resource index.

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 indicating physical uplink control channel (PUCCH) resources for a transmission of control information in a wireless communication system and related communication device.

2. Description of the Prior Art

A long-term evolution (LTE) system supporting the 3GPP Rel-8 standard and/or the 3GPP Rel-9 standard has been developed by the 3rd Generation Partnership Project (3GPP) as a successor of a universal mobile telecommunications system (UMTS), for further enhancing performance of the UMTS to satisfy increasing needs of users. The LTE system includes a new radio interface and a new 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 multiple evolved Node-Bs (eNBs) for communicating with multiple user equipments (UEs), and communicates with a core network including a mobility management entity (MME), a serving gateway, etc., for Non Access Stratum (NAS) control.

An LTE-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 advanced techniques, such as carrier aggregation (CA), coordinated multipoint (COMP) transmission/reception, uplink (UL) multiple-input multiple-output (MIMO), etc. For a user equipment and an eNB to communicate with each other in the LTE-A system, the user equipment and the eNB must support standards developed for the LTE-A system, such as the 3GPP Rel-10 standard or later versions.

The 3GPP spec has defined the physical uplink control channel (PUCCH) with several formats, as shown in Table 1, for transmissions of certain control information.

In the prior art such as the 3GPP Rel-11 or before, a resource index nPUCCH(2,{tilde over (p)})identifies resources used for transmission of hybrid automatic repeat request (HARQ) feedbacks and channel state information (CSI) reports over PUCCH formats 2/2a/2b in a wireless communication system supporting a MIMO technology. From the resource index nPUCCH(2,{tilde over (p)})all resources including frequency band (i.e. resource block) and cyclic shift for transmissions over PUCCH format 2 can be derived. The range of the resource index nPUCCH(2,{tilde over (p)})is indicated in 3GPP TS 36.331 Rel-11 as follows:

In such a situation, the range of the resource index nPUCCH(2,{tilde over (p)})is from 0 to 1184.

However, for an enhanced MIMO technology which features finer spatial and frequency granularity, additional channel state information (CSI) reports providing sub-band channel quality indicator (CQI), sub-band precoding matrix indicator (PMI), etc. are required. In such a situation, the UE needs to transmit more bits for the CSI reports. Thus, utilizing PUCCH format 2 for transmission of HARQ feedbacks and CSI reports may be insufficient.

On the other hand, a resource index nPUCCH(3,{tilde over (p)})identifies resources used for transmission of HARQ feedbacks over PUCCH format 3 for a wireless communication system supporting a CA technology, where the UE is configured multiple cells. The range of the resource index nPUCCH(3,{tilde over (p)})is indicated in 3GPP TS 36.331 Rel-11 as follows:

In such a situation, the range of the resource index nPUCCH(3,{tilde over (p)})is from 0 to 549.

However, if the UE is configured one cell, PUCCH format 3 is not used for transmission, and thus no signalling for PUCCH format 3 is received from the serving base station.

Therefore, how to indicate PUCCH resources for a UE of a wireless communication system supporting an enhanced MIMO technology without changing the 3GPP spec too much is a topic to be addressed and discussed in the industry.

SUMMARY OF THE INVENTION

The present invention aims to provide a method of indicating physical uplink control channel (PUCCH) resources for transmission over PUCCH format 3 when the UE is configured one cell. The method and related communication device of the present invention enable transmitting more bits of CSI reports on PUCCH resources, so as to accommodate a wireless communication system featuring finer spatial and frequency granularity such as an enhanced MIMO system.

The present invention discloses a method of indicating physical uplink control channel (PUCCH) resources for a user equipment (UE) of a wireless communication system, wherein the UE is configured one cell. The method includes receiving a resource index denoting PUCCH format 2 resources and PUCCH format 3 resources, instead of merely denoting PUCCH format 2 resources, from a network of the wireless communication system; and determining resources for a transmission of control information over PUCCH format 2 or PUCCH format 3 based on an operation of the received resource index.

The present invention further discloses a method of indicating physical uplink control channel (PUCCH) resources for a user equipment (UE) of a wireless communication system, wherein the UE is configured one cell. The method includes receiving a resource index denoting PUCCH format 3 resources from a network of the wireless communication system when the UE is configured one cell.

The present invention further discloses a communication device of indicating physical uplink control channel (PUCCH) resources in a wireless communication system, wherein the communication device is configured one cell. The communication device includes a processing means; a storage unit; and a program code stored in the storage unit, wherein the program code instructs the processing unit to execute the steps of receiving a resource index denoting PUCCH format 2 resources and PUCCH format 3 resources, instead of merely denoting PUCCH format 2 resources, from a network of the wireless communication system; and determining resources for a transmission of control information over PUCCH format 2 or PUCCH format 3 based on an operation of the received resource index.

The present invention further discloses a communication device of indicating physical uplink control channel (PUCCH) resources in a wireless communication system, wherein the communication device is configured one cell. The communication device includes a processing means; a storage unit; and a program code stored in the storage unit, wherein the program code instructs the processing unit to execute the steps of receiving a resource index denoting PUCCH format 3 resources from a network of the wireless communication system when the communication device is configured one cell.

DETAILED DESCRIPTION

Please refer toFIG. 1, which illustrates a schematic diagram of a wireless communication system10according to an example of the present disclosure. The wireless communication system10, such as a long term evolution-advanced (LTE-A) system or other mobile communication systems, is briefly composed of a network and a plurality of user equipments (UEs). InFIG. 1, the network and the UEs are simply utilized for illustrating the structure of the wireless communication system10. 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 the UE can be regarded as a transmitter or receiver depending on the 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.

In an example, the wireless communication system may support an enhanced Multiple-Input Multiple-Output (MIMO) technology, which features finer spatial and frequency granularity. As shown inFIG. 2, the UE200has a radio connection with the serving cell202of the network in the wireless communication system20. The UE200and the serving cell202have multiple antennas A01-A0n, A11-A1n, respectively, to enhance the data capacity between the UE200and the serving cell202.

Please refer toFIG. 3, which is a schematic diagram of a communication device30according to an example of the present invention. The communication device30can be the UE shown inFIGS. 1 and 2. The communication device30may include a processing means300such as a microprocessor or an Application Specific Integrated Circuit (ASIC), a storage unit310and a communication interfacing unit320. The storage unit310may be any data storage device that can store a program code314, accessed by the processing means300. Examples of the storage unit310include 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 unit320is preferably a radio transceiver that can transmit and receive signals (e.g., messages or packets) according to processing results of the processing means300.

Please refer toFIG. 4, which is a flowchart of a process40according to an example of the present invention. The process40is utilized for a user equipment to indicate physical uplink control channel (PUCCH) resources for transmission of control information over PUCCH format 3 when the user equipment is configured one cell, such as the serving cell202shown inFIG. 2. The user equipment could be the UE in the wireless communication system10or the UE200in the wireless communication system20, but is not limited herein. The process40may be implemented by the communication device30and compiled into the program code314to instruct the processing means300to execute the following steps:

Step402: Receive a resource index denoting PUCCH format 2 resources and PUCCH format 3 resources, instead of merely denoting PUCCH format 2 resources, from a network of the wireless communication system.

Step404: Determine resources for a transmission of control information over PUCCH format 2 or PUCCH format 3 based on an operation of the received resource index.

According to the process40, when the UE is configured one cell (i.e., only one frequency band), the UE receives a resource index (45) nPUCCH(23,{tilde over (p)}), which denotes PUCCH format 2 resources and PUCCH format 3 resources, from the network to replace a resource index used for denoting PUCCH format 2 only. The resource index nPUCCH(23,{tilde over (p)})may be received via a radio resource control (RRC) signalling. Then, the UE determines whether the received resource index nPUCCH(23,{tilde over (p)})denotes resources for PUCCH format 2 or PUCCH format 3 by an operation of the received resource index. As a result, resources for PUCCH format 3 can be indicated or identified by the resource index nPUCCH(23,{tilde over (p)})without changing the specifications currently in effect (i.e. 3GPP Rel-11 or before) too much. In addition, since more number of bits per subframe can be included on PUCCH format 3 resources, the control information transmitted over PUCCH format 3 may comprise more hybrid automatic repeat request (HARQ) feedbacks and/or channel state information (CSI) reports including a precoding matrix indicator (PMI), a channel quality indicator (CQI) or a rank indicator (RI).

The resource index nPUCCH(23,{tilde over (p)})may be defined in various ways to denote PUCCH format 2 resources and PUCCH format 3 resources. In an example, the UE may calculate a derived resource index nPUCCH(2,{tilde over (p)})′ for PUCCH format 2 and utilize PUCCH format 2 for a transmission of control information if a specific criteria is satisfied; otherwise, the UE may calculate a derived resource index nPUCCH(3,{tilde over (p)})′ for PUCCH format 3 and utilize PUCCH format 3 for the transmission of control information. The specific criteria may be satisfied when the received resource index less than a predefined value.

Considering that the range of the resource index nPUCCH(2,{tilde over (p)})in Rel. 11 is 0≦nPUCCH(2,{tilde over (p)})≦M−1 and the range of the resource index nPUCCH(3,{tilde over (p)})in Rel. 11 is 0≦nPUCCH(3,{tilde over (p)})≦N−1, the range of the resource index nPUCCH(23,{tilde over (p)})may be defined as 0≦nPUCCH(23,{tilde over (p)})≦M+N−1. Under this condition, the UE may determine resources for a transmission of control information over PUCCH format 2 or PUCCH format 3 by the following operation:

{nPUCCH(2,p~)⁢′=nPUCCH(23,p~)if⁢⁢nPUCCH(23,p~)≤M-1nPUCCH(3,p~)⁢′=nPUCCH(23,p~)-Motherwise
where nPUCCH(23,{tilde over (p)})is the received resource index, nPUCCH(2,{tilde over (p)})′ is the derived resource index for PUCCH format 2, nPUCCH(3,{tilde over (p)})′ is the another derived resource index for PUCCH format 3, and M is the predefined value.

More specifically, the following shows an example where M=1185, N=550, and thus M+N−1 is 1735. The parameter “CQI-ReportConfig-r12” which includes the parameter “cqi-ReportPeriodic-r12” is set as follows:

In this example, both the parameters “cqi-PUCCH-ResourceIndex-r12” and “cqi-PUCCH-ResourceIndexP1-r12” are defined to replace the parameters “cqi-PUCCH-ResourceIndex-r10” and “cqi-PUCCH-ResourceIndexP1-r10”, respectively. However, if the parameters “cqi-PUCCH-ResourceIndex-r12” and “cqi-PUCCH-ResourceIndexP1-r12” are not set (or are absent), the parameters “cqi-PUCCH-ResourceIndex-r10”, “cqi-PUCCH-ResourceIndexP1-r10” are used instead. Moreover, the resource index nPUCCH(23,{tilde over (p)}), which corresponds to the parameters “cqi-PUCCH-ResourceIndex-r12” and “cqi-PUCCH-ResourceIndexP1-r12”, is set such that the derived resource index nPUCCH(2,{tilde over (p)})′ and nPUCCH(3,{tilde over (p)})′ can be calculated as follows:

Noticeably, the process30is an example of the present invention. Those skilled in the art should readily make combinations, modifications and/or alterations on the abovementioned description and examples. For example, the resource index nPUCCH(23,{tilde over (p)})denoting PUCCH format 2 resources and PUCCH format 3 resources may be defined in a reverse order such that the derived resource index nPUCCH(2,{tilde over (p)})′ or nPUCCH(3,{tilde over (p)})′ is calculated as follows:

The resource index nPUCCH(23,{tilde over (p)})denoting PUCCH format 2 resources and PUCCH format 3 resources may be defined in various manners, such as concatenation, interleaved, addition, multiplication, etc. Therefore, the UE may calculate the derived resource indexes nPUCCH(2,{tilde over (p)})′ and nPUCCH(3,{tilde over (p)})′ for PUCCH format 2 and format 3 by using various kinds of operations, for example, a separating operation, a multiplying operation, a dividing operation, a modulo operation, or a permutation operation.

Please refer toFIG. 5, which is a flowchart of a process50according to an example of the present invention. The process50is utilized for a user equipment to indicate physical uplink control channel (PUCCH) resources for transmission of control information over PUCCH format 3 when the user equipment is configured one cell, such as the serving cell202shown inFIG. 2. The user equipment could be the UE in the wireless communication system10or the UE200in the wireless communication system20, but is not limited herein. The process50may be implemented by the communication device30and compiled into the program code314to instruct the processing means300to execute the following steps:

Step502: Receive a resource index denoting PUCCH format 3 resources from a network of the wireless communication system when the UE is configured one cell.

According to the process50, when the UE is configured one cell (i.e., only one frequency band), the UE receives a resource index nPUCCH(3,{tilde over (p)}), which denotes PUCCH format 3 resources, from the network. The resource index nPUCCH(3,{tilde over (p)})may be received via a radio resource control (RRC) signalling. In contrast to the prior art where the PUCCH format 3 is used only when the UE is configured multiple cells, in the present invention, a resource index nPUCCH(3,{tilde over (p)})is introduced into RRC signaling when the UE is configured only one cell to determine the resources used for PUCCH format 3. Since more number of bits per subframe can be included on PUCCH format 3 resources, the control information transmitted over PUCCH format 3 may comprise more hybrid automatic repeat request (HARQ) feedbacks and/or channel state information (CSI) reports including a precoding matrix indicator (PMI), a channel quality indicator (CQI) or a rank indicator (RI).

To determine the resource index nPUCCH(3,{tilde over (p)}), an additional parameter “CQI-ReportConfig-r12” is set as follows:

Note that the above examples for the processes40and50apply to the wireless communication system10or20in which both the transmitter and the receiver (i.e. the UE and the serving cell) employ two antennas. If the UE and the serving cell employ different amount of antennas to communicate with each other, appropriate modifications to the parameters are required.

The abovementioned steps of the processes40and50including suggested steps may be realized by means of hardware, software, firmware, or an electronic system. Examples of hardware may include analog, digital and mixed circuits known as microcircuit, microchip, or silicon chip. Examples of the electronic system may include a system on chip (SOC), system in package (SiP), a computer on module (COM), and the communication device30.

In the prior art, the PUCCH format 3 is used only when the UE is configured multiple cells (i.e. multiple frequency bands). When the UE is configured one cell, the UE does not receive any signalling for PUCCH format 3 resources. By contrast, the present invention utilizes PUCCH format 3 for CSI reports and/or HARQ feedbacks transmission when the UE is configured one cell. In this way, the UE can transmit more bits of CSI reports on resources, so as to support the requirement of wireless communication system featuring finer spatial and frequency granularity such as an enhanced MIMO system.