Method and apparatus for reporting a channel quality in a wireless communication system

Abstract

The present invention provided a method and apparatus for reporting a channel quality in a wireless communication system. A terminal receives an uplink grant from a base station via one of a plurality of downlink component carriers (ccs). The uplink grant includes a channel quality indicator (cqi) request for instructing uplink allocation and cqi reporting. The terminal reports the cqi of the downlink cc being linked to the base station. The downlink cc being linked is one of the plurality of downlink ccs, which is linked to the uplink cc for which the uplink allocation is scheduled. A method and an apparatus for reporting channel quality are discussed. The method according to an embodiment includes receiving, by a terminal configured with a plurality of downlink component carriers (ccs), control information from a base station, the control information including an uplink allocation and a cqi request, the control information including a carrier indicator field (CIF) indicating an uplink cc in which the uplink allocation is scheduled; and transmitting, by the terminal to the base station, the cqi through an uplink cc. The cqi request indicates one of: a triggering of cqi reporting for one downlink cc linked to the uplink cc, indicated by the CIF, among the plurality of downlink ccs; and a triggering of cqi reporting for a first group of downlink ccs among the plurality of downlink ccs.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

710 701 of the DL CC #0 carries DCI for a PDSCH 702 of the same DL CC #0. A 2^nd PDCCH 711 of the DL CC #0 carries DCI for a PDSCH 712 of the DL CC #1. A 3^rd PDCCH 721 of the DL CC #0 carries DCI for a PUSCH 722 723 of the unlinked UL CC #2.

For cross-carrier scheduling, the DCI of the PDCCH may include a carrier indicator field (CIF). The CIF indicates a DL CC or a UL CC scheduled through the DCI. The CIF may include an index of a UL CC or an index of a DL CC scheduled through the DCI. For example, the 2^nd PDCCH 711 may include a CIF indicating the DL CC #1. The 3^rd PDCCH 721 may include a CIF indicating the UL CC #2.

As described above, in the conventional 3GPP LTE, a UL frequency band and a DL frequency band correspond to each other, and only one UL and one DL CC are present. Therefore, a TPC included in DCI for a DL grant is control information for a UL CC corresponding to a DL CC, and a CQI request included in DCI for a UL grant is control information for a DL CC corresponding to a scheduled UL CC.

However, an ambiguity may occur in a multi-carrier system using a plurality of CCs according to the conventional 3GPP LTE structure.

More specifically, a 3^rd PDCCH 721 transmitted through a DL CC #0 carries a UL grant for scheduling a UL CC #2. Assume that the UL CC #2 is linked to a DL CC #2. In this case, when a CQI request is included in the UL grant, whether the CQI request is a CQI for one DL CC or a CQI for a DL CC group (or all CCs)or which CC(s) is a target DL CC thereof may be ambiguous.

For example, if the CQI request is for one CC, it may be ambiguous whether the CQI request is for requesting CQI reporting for the DL CC #0 in which the 3^rd PDCCH 721 is transmitted or is for requesting CQI reporting for the DL CC #2 linked to the UL CC #2 in which the UL grant is scheduled.

FIG. 6 is a diagram for describing an operation according to an embodiment of the present invention. Although there are 5 DL CCs and 5 UL CCs, the number of CCs is not limited thereto. It is assumed that a DL CC #k (0<=k<=4) is linked to a UL CC #k according to a static CC linkage. The static CC linkage can be reported by the BS to the UE by using a part of system information (i.e., MIB or SIB).

It is assumed that a CIF consists of 3 bits, and each value is defined by Table 2 below.

TABLE 2

CIF value Description

0         UL CC index 0
1         UL CC index 1
2         UL CC index 2
3         UL CC index 3
4         UL CC index 4
5         Reserved
6         Reserved
7         UL CC index 0, dynamic CC linkage

Hereinafter, a CC index of a CIF in a UL grant is an index of a UL CC scheduled by the UL grant. However, in another example, a CC index of a CIF in a UL grant may be an index of a DL CC linked to a UL CC to be scheduled by the UL grant.

DCI of a 1^st PDCCH 801 of the DL CC #1 includes a UL grant for scheduling the UL CC #0. The UL grant includes a UL resource allocation 802, a CQI request, and a CIF.

If a value of the CQI request is 0, CQI reporting is not triggered, and if the value of the CQI request is 1, CQI reporting is triggered.

Assume that the value of the CIF included in the UL grant of the 1^st PDCCH 801 is set to 0, i.e., an index of the UL CC #0. When CQI reporting is triggered, the UE can report a CQI for the DL CC #0 linked to a UL CC having a CC index 0 (i.e., UL CC #0). That is, when CQI reporting is triggered, the UE reports a CQI of a DL CC linked to a UL CC indicated by a CIF included in the UL grant.

Assume that CQI reporting is triggered, and the CIF value is set to 7 which indicates the dynamic CC linkage. When the CIF value is 7, a UL CC in which a UL grant is scheduled can be predetermined. In this example, if the CIF value is 7, it indicates the UL CC #0. The CIF value indicating the dynamic CC linkage is for exemplary purposes only, and thus can be set to any specific value. When the CIF value indicates the dynamic CC linkage, a UL CC scheduled by a UL grant may be a UL CC defined by a higher layer message such as an RRC message, or may be a UL CC which is predetermined to transmit a control signal.

The dynamic CC linkage indicates CC mapping for CQI reporting. The dynamic CC linkage can indicate at least any one of the following four types.

(1) all available DL CCs

(2) all active DL CCs

(3) all assigned DL CCs

(4) a DL CC group (or DL CC list) including at least one DL CC

That is, if the dynamic CC linkage type (4) is used, the UE reports a CQI for DL CCs in a DL CC group.

The dynamic CC linkage may be pre-defined, or may be transmitted by the BS to the UE by using a radio resource control (RRC) message or L1/L2 signaling. The dynamic CC linkage may be UE-specific, UE group-specific, or cell-specific. The dynamic linkage may be specific for each CC or common for each CC.

Which type of dynamic CC linkage will be used can be reported by the BS to the UE by using the RRC message. If the dynamic CC linkage type (4) is used, information regarding a DL CC group for reporting a CQI can be reported by the BS to the UE by using the RRC message.

One or more dynamic CC linkages can be used. In the example of Table 2, if the CIF value is 6, it may indicate the dynamic CC linkage type (1), and if the CIF value is 7, it may indicate the dynamic CC linkage type (4). Alternatively, it is also possible to designate a plurality of dynamic CC linkage types (4) each of which can be designated by using a CIF. For example, if the CIF value is 6, it indicates DL CCs #0 and #1, and if the CIF value is 7, it indicates the DL CCs #2 to #4.

DCI of a 2^nd PDCCH 811 of a DL CC #2 includes a DL grant for a DL CC #3. The DL grant includes a DL resource allocation 812, a CIF, and a TPC. Assume that the CIF value is set to 3 which is an index of the DL CC #3. The TPC may be a TPC for a UL CC #3 linked to the DL CC #3. Alternatively, the TPC may be a TPC for the UL CC #2 linked to the DL CC #2 in which the 2^nd PDCCH 811 is transmitted.

Although it is shown in this example that the TPC is included in the DL grant, the TPC may be included in a UL grant. In this case, the TPC may be a TPC for a UL CC indicated by the CIF. Alternatively, the TPC may be a TPC for a UL CC linked to a DL CC in which the UL grant is transmitted.

The proposed invention is also applicable to not only CQI reporting and/or TPC transmission but also other control signals. A CQI request is a signal used when the BS requests the UE to set or trigger a control signal for a corresponding DL CC (or UL CC), and can be called a control setup signal or a control trigger signal.

The dynamic CC linkage is not determined by a specific CIF value, but can be predetermined by using an RRC message or the like. If the CQI request is 0, the UE may not transmit the CQI report, and if the CQI request is 1, the UE may transmit the CQI report according to a dynamic CC linkage determined by using the RRC message.

Although a case where the CQI request is 1 bit is considered in the aforementioned example, more various examples may be possible if the number of bits of the CQI request is increased. Table 3 below shows a configuration depending on each value when the CQI request is 2 bits.

TABLE 3

Value of CQI request Description

0                    No CQI reporting
1                    CQI reporting based on static CC linkage
2                    CQI reporting based on 1st dynamic CC linkage
3                    CQI reporting based on 2nd dynamic CC linkage

If the CQI request value is 1, the UE reports the CQI according to the static CC linkage. For example, upon receiving a UL grant for a UL CC #1, the UE reports a CQI for a DL CC linked to the UL CC #1. If the CQI request value is 2 or 3, the UE reports a CQI according to the pre-defined 1^st or 2^nd dynamic CC linkage. The 1^st and 2^nd dynamic CC linkages can be determined by using an RRC message.

Now, an example of CQI reporting will be described in greater detail.

FIG. 7 is a flowchart showing a CQI reporting method according to an embodiment of the present invention.

A UE receives a 1^st CC linkage from a BS (step S910). The 1^st CC linkage can be received as a part of system information, and can be called a static CC linkage.

The UE receives a 2^nd CC linkage from the BS (step S920). The 2^nd CC linkage can be received by using an RRC message, and can be called a dynamic CC linkage.

The UE receives a UL grant including a CQI request from the BS (step S930). For example, the CQI request can be configured as shown in Table 3.

When the CQI request is triggered, the UE determines a DL CC in which a CQI is reported according to the CQI request (step S940). For example, if the CQI request value is 3, the UE can determine a DL CC linked based on the 2^nd CC linkage, that is, the dynamic CC linkage. Alternatively, if the CQI request value is 2, the UE can determine a DL CC linked based on the 1^st CC linkage, that is, the static CC linkage. Determining of the DL CC according to the dynamic CC linkage and the static CC linkage is described in the embodiment of FIG. 6.

The UE reports a CQI for the determined DL CC to the BS (step S950).

FIG. 8 is a block diagram showing a wireless communication system according to an embodiment of the present invention.

A BS 50 includes a processor 51, a memory 52, and a radio frequency (RF) unit 53. The memory 52 is coupled to the processor 51, and stores a variety of information for driving the processor 51. The RF unit 53 is coupled to the processor 51, and transmits and/or receives a radio signal. The processor 51 implements the proposed functions, procedures, and/or methods. The processor 51 can implement an operation of the BS 50 according to the embodiments of FIG. 6 and FIG. 7.

A UE 60 includes a processor 61, a memory 62, and an RF unit 63. The memory 62 is coupled to the processor 61, and stores a variety of information for driving the processor 61. The RF unit 63 is coupled to the processor 61, and transmits and/or receives a radio signal. The processor 61 implements the proposed functions, procedures, and/or methods. The processor 51 can implement an operation of the UE 60 according to the embodiments of FIG. 6 and FIG. 7.

The processor may include Application-Specific Integrated Circuits (ASICs), other chip sets, logic circuits, and/or data processors. The memory may include Read-Only Memory (ROM), Random Access Memory (RAM), flash memory, memory cards, storage media and/or other storage devices. The RF unit may include a baseband circuit for processing a radio signal. When the above-described embodiment is implemented in software, the above-described scheme may be implemented using a module (process or function) which performs the above function. The module may be stored in the memory and executed by the processor. The memory may be disposed to the processor internally or externally and connected to the processor using a variety of well-known means.

In the above exemplary systems, although the methods have been described on the basis of the flowcharts using a series of the steps or blocks, the present invention is not limited to the sequence of the steps, and some of the steps may be performed at different sequences from the remaining steps or may be performed simultaneously with the remaining steps. Furthermore, those skilled in the art will understand that the steps shown in the flowcharts are not exclusive and may include other steps or one or more steps of the flowcharts may be deleted without affecting the scope of the present invention.

The above-described embodiments include various aspects of examples. Although all possible combinations for describing the various aspects may not be described, those skilled in the art may appreciate that other combinations are possible. Accordingly, the present invention should be construed to include all other replacements, modifications, and changes which fall within the scope of the claims.

Claims

1. A method for reporting channel quality by a device in a wireless communication system, the method comprising:

receiving, by the device, an uplink grant on a physical downlink control channel (PDCCH) through one of a plurality of downlink component carriers (ccs), the uplink grant including an uplink allocation and a channel quality indicator (cqi) request indicating a triggering of cqi reporting,

wherein, when a value of the cqi request is set to a first value, the cqi request indicates the triggering of cqi reporting is for one of the plurality of downlink ccs linked to an uplink cc, when the value of the cqi request is set to a second value, the cqi request indicates the triggering of cqi reporting is for a first set of downlink ccs of the plurality of downlink ccs, and when the value of the cqi request is set to a third value, the cqi request indicates the triggering of cqi reporting is for a second set of downlink ccs of the plurality of downlink ccs; and

reporting, by the device, a cqi for a downlink cc indicated by the cqi request through an uplink cc based on the uplink allocation.

2. The method of claim 1, wherein the uplink grant further includes a carrier indicator field (CIF) indicating the uplink cc in which the uplink allocation is scheduled.

3. The method of claim 1, wherein a number of bits for the cqi request is two.

4. The method of claim 1, further comprising:

receiving information on the first set of downlink ccs and the second set of downlink ccs.

5. The method of claim 1, wherein a linkage between the one of the plurality of downlink ccs linked to the uplink cc is received via system information.

6. The method of claim 1, wherein the first value is “1,” the second value is “2,” and the third value is “3.”

7. An apparatus configured for reporting channel quality in a wireless communication system, the apparatus comprising:

a radio frequency (RF) unit configured to transmit and receive a radio signal; and

a processor coupled to the RF unit and configured to:

receive an uplink grant on a physical downlink control channel (PDCCH) through one of a plurality of downlink component carriers (ccs), the uplink grant including an uplink allocation and a channel quality indicator (cqi) request indicating a triggering of cqi reporting; wherein, when a value of the cqi request is set to a first value, the cqi request indicates the triggering of cqi reporting is for one of the plurality of downlink ccs linked to an uplink cc, when the value of the cqi request is set to a second value, the cqi request indicates the triggering of cqi reporting is for a first set of downlink ccs of the plurality of downlink ccs, and when the value of the cqi request is set to a third value, the cqi request indicates the triggering of cqi reporting is for a second set of downlink ccs of the plurality of downlink ccs; and

report a cqi for a downlink cc indicated by the cqi request through an uplink cc based on the uplink allocation.

8. The apparatus of claim 7, wherein the uplink grant further includes a carrier indicator field (CIF) indicating the uplink cc in which the uplink allocation is scheduled.

9. The apparatus of claim 7, wherein a number of bits for the cqi request is two.

10. The apparatus of claim 7, wherein the processor is configured to receive information on the first set of downlink ccs and the second set of downlink ccs.

11. The apparatus of claim 7, wherein a linkage between the one of the plurality of downlink ccs linked to the uplink cc is received via system information.

12. The apparatus of claim 7, wherein the first value is “1,” the second value is “2,” and the third value is “3.”

13. A method for reporting a channel quality indicator (cqi) in a wireless communication system, the method comprising:

receiving, by a terminal configured with a plurality of downlink component carriers (ccs), control information via a physical downlink control channel (PDCCH) from a base station, the control information including an uplink allocation and a cqi request, the control information including a carrier indicator (CI) indicating an uplink cc in which the uplink allocation is scheduled; and

transmitting, by the terminal to the base station, the cqi via a physical uplink shared channel (PUSCH) of the uplink cc, based on the cqi request and the uplink allocation,

wherein the cqi request indicates one of:

a triggering of cqi reporting for one downlink cc linked to the uplink cc, indicated by the CI, among the plurality of downlink ccs; and

a triggering of cqi reporting for a first group of downlink ccs among the plurality of downlink ccs.

14. The method of claim 13, wherein:

if a value related to the cqi request is set to a first value, the cqi request indicates the triggering of cqi reporting for the one downlink cc, and

if the value related to the cqi request is set to a second value, the cqi request indicates the triggering of cqi reporting for the first group of downlink ccs among the plurality of downlink ccs.

15. The method of claim 14, wherein, if the value related to the cqi request is set to a third value, the cqi request indicates a triggering of cqi reporting for a second group of downlink ccs among the plurality of downlink ccs.

16. The method of claim 15, further comprising:

receiving information on the first group of downlink ccs and the second group of downlink ccs from the base station.

17. The method of claim 13, wherein a number of bits for the cqi request is two.

18. The method of claim 13, wherein the cqi reporting based on the cqi request corresponds to an aperiodic cqi.

19. The method of claim 13, wherein the cqi reporting for the one downlink cc is aperiodic cqi reporting, and when the cqi request indicates the triggering of the aperiodic cqi reporting for the one downlink cc, the one downlink cc is identified by a linkage with the uplink cc indicated by the CI.

20. An apparatus configured to transmit a channel quality indicator (cqi) in a wireless communication system, the apparatus comprising:

a radio frequency (RF) unit configured with a plurality of downlink component carriers (ccs) and configured to transmit and receive a radio signal; and

a processor configured to:

control the RF unit to receive control information via a physical downlink control channel (PDCCH) from a base station, the control information including an uplink allocation and a cqi request, the control information including a carrier indicator (CI) indicating an uplink cc in which the uplink allocation is scheduled, and

control the RF unit to transmit the cqi via a physical uplink shared channel (PUSCH) of the uplink cc to the base station, based on the cqi request and the uplink allocation,

wherein the cqi request indicates one of:

a triggering of cqi reporting for one downlink cc linked to the uplink cc, indicated by the CI, among the plurality of downlink ccs; and

a triggering of cqi reporting for a first group of downlink ccs among the plurality of downlink ccs.

21. The apparatus of claim 20, wherein:

if a value related to the cqi request is set to a first value, the cqi request indicates the triggering of cqi reporting for the one downlink cc, and

if the value related to the cqi request is set to a second value, the cqi request indicates the triggering of cqi reporting for the first group of downlink ccs among the plurality of downlink ccs.

22. The apparatus of claim 21, wherein, if the value related to the cqi request is set to a third value, the cqi request indicates a triggering of cqi reporting for a second group of downlink ccs among the plurality of downlink ccs.

23. The apparatus of claim 22, wherein the processor is further configured to:

receive information on the first group of downlink ccs and the second group of downlink ccs from the base station.

24. The apparatus of claim 20, wherein a number of bits for the cqi request is two.