BLIND DECODING METHOD, RADIO BASE STATION, USER TERMINAL AND RADIO COMMUNICATION SYSTEM

• US 20150117353A1
• Filed: 05/10/2013
• Published: 04/30/2015
• Est. Priority Date: 05/11/2012
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Takeda, Kazuaki, Mu, Qin, Liu, Liu, Chen, Lan
• Granted Patent: US 9,763,240 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal

Abstract

The blind decoding method disclosed herein is a blind decoding method to allow a user terminal to blind-decode downlink control information that is transmitted from a radio base station using at least one of a legacy PDCCH and an enhanced PDCCH that is frequency-division-multiplexed with a PDSCH, and includes the steps in which the radio base station reports information for configuring a number of candidates, which information is used to configure numbers of search space candidates for the legacy PDCCH and numbers of search space candidates for the enhanced PDCCH, to the user terminal, and the user terminal blind-decodes the downlink control information based on the numbers of search space candidates for the legacy PDCCH and the numbers of search space candidates for the enhanced PDCCH that are configured based on the candidate quantity configuration information.

Claims

1. A blind decoding method to allow a user terminal to blind-decode downlink control information that is transmitted from a radio base station using at least one of a downlink control channel and an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, the blind decoding method comprising the steps in which:

the radio base station reports information for configuring a number of candidates, which information is used to configure the user terminal with numbers of search space candidates for the downlink control channel and numbers of search space candidates for the enhanced downlink control channel; and

the user terminal blind-decodes the downlink control information based on the numbers of search space candidates for the downlink control channel and the numbers of search space candidates for the enhanced downlink control channel that are configured based on the information for configuring the number of candidates.

2. The blind decoding method according to claim 1, wherein the numbers of search space candidates for the downlink control channel and the numbers of search space candidates for the enhanced downlink control channel each include the number of common search space candidates, which is the number of candidates of a common search space that is common between user terminals in a cell of the radio base station, and the number of specific search space candidates, which is the number of candidates of a specific search space that is user terminal-specific.

3. The blind decoding method according to claim 2, wherein:

a first frequency resource set and a second frequency resource set, each formed to include a plurality of frequency resource units that are placed for the enhanced downlink control channel, are provided;

the number of common search space candidates for the enhanced downlink control channel includes the number of common search space candidates for the first frequency resource set; and

the number of specific search space candidates for the enhanced downlink control channel includes the number of specific search space candidates for the first frequency resource set and the number of specific search space candidates for the second frequency resource set.

4. The blind decoding method according to claim 3, wherein:

as the information for configuring the number of candidates, the number of common search space candidates for the downlink control channel, the number of specific search space candidates for the downlink control channel, and the number of specific search space candidates for the first frequency resource set are reported;

the number of common search space candidates for the first frequency resource set is configured by subtracting the number of common search space candidates for the downlink control channel from a total number of common search space candidates; and

the number of specific search space candidates for the second frequency resource set is configured by subtracting the number of specific search space candidates for the downlink control channel and the number of specific search space candidates for the first frequency resource set from the total number of specific search space candidates.

5. The blind decoding method according to claim 3, wherein:

as the information for configuring the number of candidates, a first ratio, which is a ratio of the number of common search space candidates for the downlink control channel to a total number of common search space candidates, a second ratio, which is a ratio of the number of specific search space candidates for the downlink control channel to a total number of specific search space candidates, and a third ratio, which is a ratio of the number of specific search space candidates for the first frequency resource set to the number of specific search space candidates for the enhanced downlink control channel are reported;

the numbers of common search space candidates for the downlink control channel and for the enhanced downlink control channel are each configured based on a result of multiplying the total number of common search space candidates by the first ratio;

the numbers of specific search space candidates for the downlink control channel and for the enhanced downlink control channel are configured based on a result of multiplying the total number of specific search space candidates by the second ratio; and

the numbers of specific search space candidates for the first and second frequency resource sets are configured based on a result of multiplying the number of specific search space candidates for the enhanced downlink control channel, calculated based on the second ratio, further by the third ratio.

6. The blind decoding method according to claim 3, wherein:

as the information for configuring the number of candidates, pattern information to represent combinations of numbers of common search space candidates and numbers of specific search spaces candidates for the downlink control channel, and numbers of common search space candidates and numbers of specific search space candidates for the first and second frequency resource sets, is reported; and

the numbers of common search space candidates and the numbers of specific search space candidates for the downlink control channel, and the numbers of common search space candidates and the numbers of specific search space candidates for the first and second frequency resource sets are configured in the combinations shown in the pattern information.

7. The blind decoding method according to claim 3, wherein:

as the information for configuring the number of candidates, format information of the downlink control information that is transmitted in the specific search spaces for the downlink control channel and in the specific search spaces for the first and second frequency resource sets is reported; and

the number of specific search space candidates for the downlink control channel and the numbers of specific search space candidates for the first and second frequency resource sets are configured based on the format information in accordance with a decrease of the number of formats to blind-decode.

8. The blind decoding method according to claim 3, wherein, in the first frequency resource set, the downlink control information is mapped to each of the plurality of frequency resource units in a distributed manner, while, in the second frequency resource set, the downlink control information is mapped to part of the plurality of frequency resource units in a localized manner.

9. The blind decoding method according to claim 3, wherein the number of common search space candidates and the number of specific search space candidates are configured per aggregation level of the frequency resource units.

14. The blind decoding method according to claim 4, wherein, in the first frequency resource set, the downlink control information is mapped to each of the plurality of frequency resource units in a distributed manner, while, in the second frequency resource set, the downlink control information is mapped to part of the plurality of frequency resource units in a localized manner.

15. The blind decoding method according to claim 5, wherein, in the first frequency resource set, the downlink control information is mapped to each of the plurality of frequency resource units in a distributed manner, while, in the second frequency resource set, the downlink control information is mapped to part of the plurality of frequency resource units in a localized manner.

16. The blind decoding method according to claim 6, wherein, in the first frequency resource set, the downlink control information is mapped to each of the plurality of frequency resource units in a distributed manner, while, in the second frequency resource set, the downlink control information is mapped to part of the plurality of frequency resource units in a localized manner.

17. The blind decoding method according to claim 7, wherein, in the first frequency resource set, the downlink control information is mapped to each of the plurality of frequency resource units in a distributed manner, while, in the second frequency resource set, the downlink control information is mapped to part of the plurality of frequency resource units in a localized manner.

10. A blind decoding method to allow a user terminal to blind-decode downlink control information that is transmitted from a radio base station using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, the blind decoding method comprising the steps in which:

the radio base station configures a first frequency resource set and a second frequency resource set, which are each formed to include a plurality of enhanced control channel elements allocated for the enhanced downlink control channel, for the user terminal;

the radio base station reports information for configuring a number of candidates, which information is used to configure the user terminal with numbers of search space candidates for the first frequency resource set, and index number information, which represents index numbers of enhanced control channel elements allocated to a search space for the second frequency resource set, to the user terminal;

the user terminal determines search spaces for the first frequency resource set based on the numbers of search space candidates that is configured based on the information for configuring the number of candidates, and blind-decodes the downlink control information; and

the user terminal determines the search spaces for the second frequency resource set based on the index number information, and blind-decodes the downlink control information.

11. A radio base station that transmits downlink control information for a user terminal using at least one of a downlink control channel and an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, the radio base station comprising:

a generating section configured to generate information for configuring a number of candidates that is used to configure the user terminal with numbers of search space candidates for the downlink control channel and numbers of search space candidates for the enhanced downlink control channel; and

a reporting section configured to report the information for configuring the number of candidates generated by the generating section to the user terminal.

12. A user terminal that blind-decodes downlink control information that is transmitted from a radio base station using at least one of a downlink control channel and an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, the user terminal comprising:

a receiving section configured to receive information for configuring a number of candidates that is used to configure the user terminal with numbers of search space candidates for the downlink control channel and numbers of search space candidates for the enhanced downlink control channel, from the radio base station; and

a blind decoding section configured to blind-decode the downlink control information based on the numbers of search space candidates for the downlink control channel and the numbers of search space candidates for the enhanced downlink control channel that are configured based on the information for configuring the number of candidates.

13. A radio communication system to allow a user terminal to blind-decode downlink control information that is transmitted from a radio base station using at least one of a downlink control channel and an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, wherein:

the radio base station reports information for configuring a number of candidates, which information is used to configure the user terminal with numbers of search space candidates for the downlink control channel and numbers of search space candidates for the enhanced downlink control channel, to the user terminal; and

the user terminal blind-decodes the downlink control information based on the numbers of search space candidates for the downlink control channel and the numbers of search space candidates for the enhanced downlink control channel that are configured based on the information for configuring the number of candidates.