Radio base station, user terminal and radio communication method

Patent metadata

Field	Value
Publication number	US-2017195889-A1
Application number	US-201515325359-A
Country	US
Kind code	A1
Filing date	Jun 24, 2015
Priority date	Jul 11, 2014
Publication date	Jul 6, 2017
Grant date	—

Abstract

The present invention is designed to prevent the deterioration of communication quality even when LBT is used in a radio communication system that runs LTE/LTE-A and/or the like in an unlicensed band. A radio base station communicates with a user terminal that can use a licensed band and an unlicensed band, and has a transmission section that transmits a plurality of DL signals in the unlicensed band, and a control section that controls the transmissions of the DL signals in the unlicensed band based on the results of LBT (Listen Before Talk), and the control section control section controls the transmission of part of the DL signals among the plurality of DL signals without applying LBT. To be more specific, the control section configures the transmission cycle of a DL signal that is transmitted without applying LBT longer than the transmission cycle that is applied in an existing system.

First claim

1 . A radio base station that communicates with a user terminal that is capable of using a licensed band and an unlicensed band, the radio base station comprising:
a transmission section that transmits a plurality of DL signals in the unlicensed band; and a control section that controls transmission of the DL signals in the unlicensed band based on results of LBT (Listen Before Talk), wherein the control section controls transmission of part of the DL signals among the plurality of DL signals without applying LBT.

2 . The radio base station according to claim 1 , wherein the control section configures a transmission cycle of a DL signal that is transmitted without applying LBT longer than a transmission cycle that is applied to the DL signal in an existing system.

3 . The radio base station according to claim 1 , wherein the control section configures an allocation density of a DL signal that is transmitted without applying LBT in a time direction lower than an allocation density that is applied in an existing system.

4 . The radio base station according to claim 3 , wherein the transmission section transmits information about the transmission cycle of the DL signal that is transmitted without applying LBT and/or the allocation density in the time direction to the user terminal.

5 . The radio base station according to claim 1 , wherein the control section controls a plurality of DL signals that are transmitted without applying LBT to be allocated to predetermined subframes.

6 . The radio base station according to claim 5 , wherein the control section controls all DL signals that are allocated to the predetermined subframes to be transmitted without applying LBT.

7 . The radio base station according to claim 1 , wherein the DL signals that are transmitted without applying LBT include at least one of a synchronization signal, a broadcast signal, a cell-specific reference signal and a channel measurement reference signal.

8 . The radio base station according to claim 1 , wherein, when there are DL signals of a same type, the control section configures a subframe that is transmitted by using LBT and a subframe that is transmitted without using LBT.

9 . A user terminal that is capable of communicating with a radio base station by using a licensed band and an unlicensed band, the user terminal comprising:
a transmission section that transmits a plurality of UL signals in the unlicensed band; and a transmission control section that controls transmission of the UL signal in the unlicensed band based on results of LBT (Listen Before Talk), wherein the transmission control section controls transmission of part of the UL signals among the plurality of UL signals regardless of the results of LBT.

10 . A radio communication method for a radio base station that connects with a user terminal by using a licensed band and an unlicensed band, the radio communication method comprising, in the radio base station, the steps of:
transmitting a plurality of DL signals in the unlicensed band; and controlling transmission of the DL signals in the unlicensed band by using LBT (Listen Before Talk), wherein part of the DL signals among the plurality of DL signals are transmitted without applying LBT.

11 . The radio base station according to claim 2 , wherein the DL signals that are transmitted without applying LBT include at least one of a synchronization signal, a broadcast signal, a cell-specific reference signal and a channel measurement reference signal.

12 . The radio base station according to claim 3 , wherein the DL signals that are transmitted without applying LBT include at least one of a synchronization signal, a broadcast signal, a cell-specific reference signal and a channel measurement reference signal.

13 . The radio base station according to claim 4 , wherein the DL signals that are transmitted without applying LBT include at least one of a synchronization signal, a broadcast signal, a cell-specific reference signal and a channel measurement reference signal.

14 . The radio base station according to claim 5 , wherein the DL signals that are transmitted without applying LBT include at least one of a synchronization signal, a broadcast signal, a cell-specific reference signal and a channel measurement reference signal.

15 . The radio base station according to claim 6 , wherein the DL signals that are transmitted without applying LBT include at least one of a synchronization signal, a broadcast signal, a cell-specific reference signal and a channel measurement reference signal.

16 . The radio base station according to claim 2 , wherein the control section configures an allocation density of a DL signal that is transmitted without applying LBT in a time direction lower than an allocation density that is applied in an existing system.

Assignees

• Ntt Docomo Inc

Inventors

• Takeda Kazuki
• Harada Hiroki
• Nagata Satoshi
• Wang Jing
• Liu Liu
• Jiang Huiling

Classifications

• H04W16/14 Primary

  Spectrum sharing arrangements {between different networks} · CPC title

• H04W72/0446

  Resources in time domain, e.g. slots or frames · CPC title

• H04W74/0808

  using carrier sensing, e.g. carrier sense multiple access [CSMA] · CPC title

• H04W88/10

  adapted for operation in multiple networks, e.g. multi-mode access points · CPC title