Base station apparatus and user terminal

• US 8,787,281 B2
• Filed: 04/21/2011
• Issued: 07/22/2014
• Est. Priority Date: 04/30/2010
• 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, Miki, Nobuhiko
• Primary Examiner(s): Lai, Andrew
• Assistant Examiner(s): Andrews, Hoyet H
• Application Number:
  US13/261,493
• Publication Number:
  US 20130058286A1
• Time in Patent Office: 1,188 Days
• US Class Current: 370/329
• CPC Class Codes: H04J 11/0069 Cell search, i.e. determining cell identity [cell-ID] design of multiplexing codes H04J13/00; processing access restriction or access information H04W48/16; discovery of network devices for network data management H04W8/005; sounding signals for channel estimation H04L25/0226; structure of reference signals in multicarrier modulation systems H04L27/2613; frame, time or carrier synchronisation in multicarrier modulation systems H04L27/2655
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A base station apparatus having a control information generation section that generates, per fundamental frequency block, a downlink control information piece for demodulating a data channel that is transmitted for each of a plurality of fundamental frequency blocks assigned to a user terminal, a determining section that determines, per fundamental frequency block, a search space which is a candidate area where the downlink control information piece is arranged, and a transmission section that transmits a downlink control channel in which the search space containing the downlink control information piece is arranged is disclosed. The control information generation section arranges respective downlink control information pieces corresponding to the fundamental frequency blocks in a downlink control channel of a specific fundamental frequency block among the fundamental frequency blocks, and the determining section distributes positions of search spaces such that the search spaces are separate between fundamental frequency blocks and between user terminals.

Claims

1. A base station apparatus comprising:

a control information generation section configured to generate, per fundamental frequency block, a downlink control information piece for demodulating a data channel that is transmitted on each of a plurality of fundamental frequency blocks assigned to a user terminal;

a determining section configured to determine, per fundamental frequency block, a search space which is a candidate area where the downlink control information piece is arranged; and

a transmission section configured to transmit a downlink control channel in which the search space containing the downlink control information piece is arranged, wherein;

the control information generation section arranges respective downlink control information pieces corresponding to the fundamental frequency blocks in the downlink control channel of a specific fundamental frequency block among the fundamental frequency blocks; and

using at least a fundamental frequency block-specific offset value out of the fundamental frequency block-specific offset value and a user terminal-specific offset value, the determining section distributes positions of search spaces such that the search spaces are separate between the fundamental frequency blocks and between user terminals.

2. The base station apparatus as defined in claim 1, wherein the determining section determines a starting position of the search space using a following equation:

S_k^(L)=L{(Y_k+m+f(n_CC,n_RNTI))mod└

N_CCE,k/L┘

}+i

where Y_k=(A·

Y<sub>k−

1</sub>)mod D;

f(n_CC, n_RNTI) is an offset value that is calculated using a fundamental frequency block-specific index value n_CC and a user terminal-specific index value n_RNTI;

L is an aggregation level to show the number of control channel elements, where a control channel element is a basic unit upon rate matching of downlink control information and is a minimum unit to form the search space;

i=0, . . . , L−

1, m=0, . . . M^(L)−

1;

M^(L) is the number of downlink control channel candidates at each aggregation level;

N_CCE,k is a total number of control channel elements (CCEs) in subframe k in a fundamental frequency block;

Y<sub>−

1</sub>=n_RNTI≠

0; and

A is a constant and D is a constant.

3. The base station apparatus as defined in claim 1, wherein the determining section determines a starting position of the search space using a following equation:

S_k^(L)=L{(Y_k+m))mod└

N_CCE,k/L┘

}+i

where Y_k=(A(Y<sub>k−

1</sub>+f(n_CC,n_RNTI)))mod D,

f(n_CC, n_RNTI) is an offset value that is calculated using a fundamental frequency block-specific index value n_CC and a user terminal-specific index value n_RNTI;

L is an aggregation level to show the number of control channel elements, where a control channel element is a basic unit upon rate matching of downlink control information and is a minimum unit to form the search space;

i=0, . . . , L−

1, m=0, . . . M^(L)−

1;

M^(L) is the number of downlink control channel candidates at each aggregation level;

N_CCE,k is a total number of control channel elements (CCEs) in subframe k in a fundamental frequency block;

Y<sub>−

1</sub>=n_RNTI≠

0; and

A is a constant and D is a constant.

4. The base station apparatus as defined in claim 2, wherein the offset value f(n_CC, n_RNTI) that is calculated using the fundamental frequency block-specific index value n_CC and the user terminal-specific index value n_RNTI is determined by a following equation:

f(n_CC,n_RNTI)=n_CC+Kn_RNTI or n_CC·

n_RNTI

where K is a constant.

5. The base station apparatus as defined in claim 4, wherein, when the aggregation level is equal to or lower than a predetermined value, K=0 is assumed and the starting position of the search space is determined without using the user terminal-specific offset value, and, when the aggregation level is equal to or greater than the predetermined value, K≠

0 is assumed the starting position of the search space is determined using the user terminal-specific offset value.

6. The base station apparatus as defined in claim 1, wherein, when an aggregation level to show the number of control channel elements is equal to or lower than a predetermined value, the determining section determines a starting position of the search space using a following equation 4:

S_k^(L)=L{(Y_k+m+f(n_CC,n_RNTI))mod└

N_CCE,k/L┘

}+i

where Y_k=(A·

Y<sub>k−

1</sub>)mod D; and

when the aggregation level is equal to or greater than the predetermined value, the determining section determines the starting position of the search space using a following equation;

S_k^(L)=L{(Y_k+m))mod└

N_CCE,k/L┘

}+i

where Y_k=(A(Y<sub>k−

1</sub>+f(n_CC,n_RNTI)))mod D;

f(n_CC, n_RNTI) is an offset value that is calculated using a fundamental frequency block-specific index value n_CC and a user terminal-specific index value n_RNTI;

L is an aggregation level to show the number of control channel elements, where a control channel element is a basic unit upon rate matching of downlink control information and is a minimum unit to form the search space;

i=0, . . . , L−

1, m=0, . . . M^(L)−

1;

M^(L) is the number of downlink control channel candidates at each aggregation level;

N_CCE,k is a total number of control channel elements (CCEs) in subframe k in a fundamental frequency block;

Y<sub>−

1</sub>=n_RNTI≠

0; and

A is a constant and D is a constant.

7. The base station apparatus as defined in claim 6, wherein the offset value f(n_CC, n_RNTI) that is calculated using the fundamental frequency block-specific index value n_CC and the user terminal-specific index value n_RNTI is determined by a following equation:

f(n_CC,n_RNTI)=n_CC+Kn_RNTI, or n_CC·

n_RNTI

where K is a constant.

8. The base station apparatus as defined in claim 1, wherein, using a time offset value as the fundamental frequency block-specific offset value, the determining section distributes the positions of the search spaces such that the search spaces are separate between the fundamental frequency blocks.

9. The base station apparatus as defined in claim 8, wherein the determining section determines a starting position of the search space using a following equation:

S_k,nCC^(L)=L·

{(Y_{k+x(nCC,nRNTI)}+m)mod└

N_CCE,k/L┘

}+i

where Y_{k+x(nCC,nRNTI)}=(A·

Y<sub>k+x(nCC,nRNTI)−

1</sub>)mod D;

x(n_CC, n_RNTI) is a fundamental frequency block-specific time offset value calculated using a fundamental frequency block-specific index value n_CC and a user terminal-specific index value n_RNTI;

L is an aggregation level to show the number of control channel elements, where a control channel element is a basic unit upon rate matching of downlink control information and is a minimum unit to form the search space;

i=0, . . . , L−

1, m=0, . . . M^(L)−

1;

M^(L) is the number of downlink control channel candidates at each aggregation level;

N_CCE,k is a total number of control channel elements (CCEs) in subframe k in a fundamental frequency block;

Y<sub>−

1</sub>=n_RNTI≠

0; and

A is a constant and D is a constant.

14. The base station apparatus as defined in claim 3, wherein the offset value f(n_CC, n_RNTI) that is calculated using the fundamental frequency block-specific index value n_CC and the user terminal-specific index value n_RNTI is determined by a following equation:

f(n_CC,n_RNTI)=n_CC+Kn_RNTI or n_CC·

n_RNTI

where K is a constant.

10. A user terminal comprising:

a receiving section configured to receive data channels that are transmitted individually on a plurality of fundamental frequency blocks constituting a system band, and downlink control information pieces for demodulating the respective data channels, the downlink control information pieces being arranged in a downlink control channel of a specific fundamental frequency block among the fundamental frequency blocks;

a control information demodulation section configured to demodulate the downlink control information pieces for the fundamental frequency blocks by determining, per fundamental frequency block, a search space which is a candidate area where the downlink control information is arranged and performing blind decoding; and

a data demodulation section configured to, using the downlink control information pieces of the fundamental frequency blocks demodulated in the control information demodulation section, demodulate the data channels of the fundamental frequency blocks,

where the control information demodulation section determines a position of the search space using a fundamental frequency block-specific offset value and a user terminal-specific offset value.

11. The user terminal as defined in claim 10, wherein a constant K, which is used to calculate the user terminal-specific offset value, is stored as a fixed value.

12. The user terminal as defined in claim 10, wherein a constant K, which is used to calculate the user terminal-specific offset value, is reported using a higher control signal.

13. A communication control method comprising the steps of:

generating, per fundamental frequency block, a downlink control information piece for demodulating a data channel that is transmitted on each of a plurality of fundamental frequency blocks assigned to a user terminal;

arranging respective downlink control information pieces corresponding to the fundamental frequency blocks in a downlink control channel of a specific fundamental frequency block among the fundamental frequency blocks; and

determining, per fundamental frequency block, a search space which is a candidate area where the downlink control information piece of each of the fundamental frequency blocks is arranged, in the downlink control channel of the specific fundamental frequency block,

wherein, using a fundamental frequency block-specific offset value and a user terminal-specific offset value, search spaces are arranged such that the search spaces are separate between fundamental frequency blocks and between user terminals.