Radio base station, user terminal, radio communication system and radio communication method

Patent metadata

Field	Value
Publication number	US-9832764-B2
Application number	US-201314431329-A
Country	US
Kind code	B2
Filing date	Jul 31, 2013
Priority date	Sep 28, 2012
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

The present invention is designed to make it possible to adequately form the search space candidates to be used in the blind decoding of downlink control information when the radio resource region for downlink control channels is expanded. The radio base station of the present invention is a radio base station that transmits downlink control information for a user terminal by using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, and has a configuring section that configures, for the user terminal, a plurality of resource sets that are each formed by including a plurality of resource blocks allocated to the enhanced downlink control channel, and a determining section that determines enhanced control channel elements to constitute a plurality of search space candidates such that the plurality of search space candidates of each resource set are all placed in different resource blocks.

First claim

The invention claimed is:

1. A radio base station that transmits downlink control information for a user terminal by using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, the radio base station comprising:
a processor that configures one or more resource sets for the user terminal, each of the resource sets including one or more resource blocks allocated to the enhanced downlink control channel and
that determines enhanced control channel elements to constitute a plurality of search space candidates of each of the resource sets based on a total number of enhanced control channel elements in the resource blocks constituting each of the resource sets, and a number of search space candidates at each aggregation level in each of the resource sets; and
a transmitter that transmits information indicating the resource blocks included in each of the resource sets, wherein
the enhanced control channel elements are specified by index numbers that are assigned on a per resource set basis and that are represented by a hash function, and
the hash function is represented by the following equation:

L
⁢

{

(

Y
k

+

m
⁢

⌊

N
ECCE

L
·

M
set

(
L
)

⌋

)

⁢
mod
⁢

⁢

⌊

N
ECCE

⁢

/

⁢
L

⌋

}

+
i

where:
N ECCE is the total number of the enhanced control channel elements;
M set (L) is the number of search space candidates at each aggregation level;
L is an aggregation level of the enhanced control channel elements;
m=0, . . . , M set (L) −1;
i=0, . . . , L−1; and
Y k is a predetermined parameter that varies per subframe.

2. The radio base station according to claim 1 , wherein
the processor selects a resource block from the resource blocks based on channel quality information from the user terminal, and
maps the downlink control information to at least one of the enhanced channel elements constituting a search space candidate that is placed in the selected resource block.

3. A user terminal that receives downlink control information from a radio base station by using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, the user terminal comprising:
a receiver that, when the user terminal is configured with one or more resource sets including one or more resource blocks allocated to the enhanced downlink control channel, receives information indicating the resource blocks included in each of the resource sets; and
a processor that determines enhanced control channel elements to constitute a plurality of search space candidates of each of the resource sets based on a total number of enhanced control channel elements in the resource blocks constituting each of the resource sets, and a number of search space candidates at each aggregation level in each of the resource sets, wherein
the enhanced control channel elements are specified by index numbers that are assigned on a per resource set basis and that are represented by a hash function, and
the hash function is represented by the following equation:

L
⁢

{

(

Y
k

+

⌊

m
⁢

N
ECCE

L
·

M
set

(
L
)

⌋

)

⁢
mod
⁢

⁢

⌊

N
ECCE

⁢

/

⁢
L

⌋

}

+
i

where:
N ECCE is the total number of the enhanced control channel elements;
M set (L) is the number of search space candidates at each aggregation level;
L is an aggregation level of the enhanced control channel elements;
m=0, . . . , M set (L) −1;
i=0, . . . , L−1; and
Y k is a predetermined parameter that varies per subframe.

4. A radio communication system in which a radio base station transmits downlink control information for a user terminal by using an enhanced downlink control channel that is frequency-division-multiplexed with a downlink shared data channel, wherein:
the rad

Assignees

• Ntt Docomo Inc

Inventors

• Takeda Kazuaki
• Mu Qin
• Liu Liu
• Chen Lan

Classifications

• H04W72/23 Primary

  in the downlink direction of a wireless link, i.e. towards a terminal · CPC title

• H04L27/2643

  using symbol repetition, e.g. time domain realization of distributed FDMA · CPC title

• H04W88/08

  Access point devices · CPC title

• H04L1/0046 Primary

  Code rate detection or code type detection (H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091) · CPC title

• H04W88/02

  Terminal devices · CPC title