RADIO BASE STATION, USER TERMINAL AND RADIO COMMUNICATION METHOD

• US 20160204920A1
• Filed: 08/06/2014
• Published: 07/14/2016
• Est. Priority Date: 08/21/2013
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Benjebbour, Anass, Kishiyama, Yoshihisa
• Granted Patent: US 10,791,469 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 1/7143 Arrangements for generation of hop patterns
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

The present invention is designed to expand the coverage of reference signals in small cells that are arranged to overlap a macro cell, and, furthermore, reduce the interference between the small cells and improve the received quality of the reference signals in user terminals. The radio communication method of the present invention provides a radio communication method in a radio base station forming a small cell that is placed to overlap a macro cell, and includes the steps of generating a reference signal for measuring received quality, in a first transmission period in which beamforming is not executed, transmitting the reference signal in a narrower transmission bandwidth and with greater transmission power than in a second transmission period in which beamforming is executed, and allocating the reference signal to a band associated with information that is specific to each radio base station forming a small cell, and transmitting the reference signal.

Claims

1. A radio base station to form a small cell that is placed to overlap a macro cell, the radio base station comprising:

a generating section that generates a reference signal for measuring received quality; and

a transmission section that, in a first transmission period in which beamforming is not executed, transmits the reference signal in a narrower transmission bandwidth and with greater transmission power than in a second transmission period in which beamforming is executed,

wherein the transmission section allocates the reference signal to a band associated with information that is specific to each radio base station forming a small cell, and transmits the reference signal.

2. The radio base station according to claim 1, wherein the transmission section applies spectrum spreading to the reference signal on the basis of a predetermined random number sequence and transmits the reference signal.

3. The radio base station according to claim 2, wherein the transmission section spreads the reference signal on the basis of a predetermined spreading code sequence and transmits the reference signal.

4. The radio base station according to claim 3, wherein the spreading code sequence is changed every first transmission period.

5. The radio base station according to claim 2, wherein the transmission section applies frequency hopping to the reference signal on the basis of a predetermined hopping pattern and transmits the reference signal.

6. The radio base station according to claim 5, wherein the transmission section allocates the reference signal to a single band that varies per first transmission period on the basis of the hopping pattern, and applies frequency hopping.

7. The radio base station according to claim 5, wherein the transmission section divides the reference signal between a plurality bands that vary per first transmission period on the basis of the hopping pattern, and applies frequency hopping.

8. A radio base station to form a small cell that is placed to overlap a macro cell, the radio base station comprising:

a generating section that generates reference signal for measuring received quality; and

a transmission section that, in a first transmission period in which beamforming is not executed, transmits the reference signal in a narrower transmission bandwidth and with greater transmission power than in a second transmission period in which beamforming is executed,

wherein the transmission section allocates the reference signal to a band that is reported from a radio base station forming the macro cell, and transmits the reference signal.

9. A user terminal for use in a radio communication system where a macro cell and a small cell are placed to overlap each other, the user terminal comprising:

a receiving section that receives a reference signal for measuring received quality, the reference signal being transmitted in a first transmission period in which beamforming is not executed, in a narrower transmission bandwidth and with greater transmission power than in a second transmission period in which beamforming is executed; and

a measurement section that measures received quality of the reference signal,

wherein the measurement section receives the reference signal, which is allocated to a band associated with information that is specific to a radio base station forming the small cell and transmitted, and measures the received quality of the reference signal.

10. A radio communication method in a radio base station forming a small cell that is placed to overlap a macro cell, the radio communication method comprising the steps of:

generating a reference signal for measuring received quality;

in a first transmission period in which beamforming is not executed, transmitting the reference signal in a narrower transmission bandwidth and with greater transmission power than in a second transmission period in which beamforming is executed; and

allocating the reference signal to a band associated with information that is specific to each radio base station forming a small cell, and transmitting the reference signal.