Wireless communication system, base station, and wireless communication method

Patent metadata

Field	Value
Publication number	US-9203575-B2
Application number	US-201113882648-A
Country	US
Kind code	B2
Filing date	Oct 27, 2011
Priority date	Nov 5, 2010
Publication date	Dec 1, 2015
Grant date	Dec 1, 2015

Abstract

A base station performs an association between frequency range and combinations of a plurality of base stations including an local base station to notify a terminal of the association. According to the notified association, the terminal, for each frequency, calculates quality of communication with one base station or quality of communication with the combination of the plurality of base stations. The base station and the control station determine the base station/the plurality of base stations that communicate with the terminal, the wireless resource and the transmission scheme, based on the result. Further, the base station selects whether to notify an entirety of or a part of the association to the terminal using positional information of the terminal. Since the association information that is unnecessary for the terminal is not communicated, it is possible to further lighten the load of control.

First claim

The invention claimed is:

1. A wireless communication system comprising:
a plurality of base stations;
a terminal that wirelessly communicates with a base station based on a result of channel estimation and communication quality estimation with the base station; and
a control station that determines association information in which a first frequency range used in a cooperative transmission by the plurality of base stations and a second frequency range used in single transmission by one base station are specified, and notifies the plurality of base stations of the association information, wherein
the base station includes:
a transmission unit that performs the cooperative transmission to the terminal by the plurality of base stations and performs single transmission to the terminal from a local base station; and
an association processing unit that notifies the terminal of the association information notified from the control station,

the terminal specifies a corresponding frequency range, according to whether to perform communication with the base station by the cooperative transmission from the base station or to perform communication with the base station by single transmission from the base station, based on the association information received from the base station, and performs channel estimation and communication quality estimation in the frequency range, wherein
the control station determines whether the terminal is in a cell edge or inside a cell based on positional information of the terminal,

determines to communicate with the terminal by the cooperative transmission from the plurality of base stations, in a case where the terminal is in the cell edge, and
determines to communicate with the terminal by single transmission with any one of the base stations, in a case where the terminal is inside the cell.

2. The wireless communication system according to claim 1 , wherein
the terminal notifies the base station and/or the control station of the estimated channel information and communication quality information, and
the base station or the control station determines communication scheduling and communication scheme with the terminal using the notified result.

3. The wireless communication system according to claim 1 , wherein
the control station includes a memory which stores in advance information indicating whether position is the cell edge or inside the cell, corresponding to positional information within the cell, and
the terminal transmits the positional information of a local terminal to the control station through the base station.

4. The wireless communication system according to claim 3 , wherein the control station includes:
a data input unit that inputs positional information of the position, that is measured in any position inside an area that the base station covers, and reception strength data from each base station in the position;
an operation and maintenance unit that determines whether the position is a cell edge or a cell center based on the input reception strength data from each base station, and stores information indicating whether the position is the cell edge or inside the cell, corresponding to the input positional information, in the memory; and
an association determination unit that determines association information in which the first frequency range used in the cooperative transmission by the plurality of base stations and the second frequency range used in the single transmission by one of the base stations are specified.

5. The wireless communication system according to claim 1 , wherein the base station selects either one of notifying the terminal of all association information or notifying the terminal of a portion corresponding to the corresponding frequency range, according to whether to communicate with the terminal by the cooperative transmission or to communicate by the single transmission, in association information, and notifies the terminal of an entire or a part of the association information.

6. The wireless communication system according to claim 1 , wherein the channel estimated in the terminal is either one of an environment of a propagation channel from one associated base station or an environment of a propagation channel in a case where an associated plurality of base stations perform the cooperation communication.

7. The wireless communication system according to claim 1 , wherein
the control station transmits power profile information including an association between the first frequency range and first transmission power of the base station in the cooperative transmission and an association between the second frequency range and second transmission power of the base station in the single transmission, to the base station, and
the base station sets transmission power in each frequency range according to received power profile information,
wherein the second transmission power in the single transmission is set to be smaller than the first transmission power in the cooperative transmission.

8. The wireless communication system according to claim 7 , wherein the control station includes,
a data input unit that inputs positional information of the position, that is measured in any position inside an area that the base station covers, and strength data received from each base station in the position;
an operation and maintenance unit that reduces a second transmission power of a desired base station in a case where reception strength data of the second frequency range from the desired base station is larger than a predetermined threshold value, in a position of the cell edge, based on reception strength data that is input in the data input unit, and creates power profile information based on predetermined first transmission power and the reduced second transmission power; and
an association determination unit that determines association information in which the first frequency range used in the cooperative transmission by the plurality of base stations and the second frequency range used in the single transmission by the one base station are specified.

9. The wireless communication system according to claim 1 , wherein the association information is commonly used by all base stations within the system.

10. The wireless communication system according to claim 1 , wherein the base station transmits association information of available bandwidths at least other than a bandwidth in which allocation is completed, to the terminal.

11. The wireless communication system according to claim 1 , wherein the association information is notified in a bit map format indicating whether a value of each bit is for the cooperative transmission or for the single transmission, each bit corresponding to a frequency or a sub band.

12. The wireless communication system according to claim 1 , wherein the control station dynamically changes an allocation amount of the first frequency range used in the cooperative transmission and an allocation amount of the second frequency range used in the single transmission.

13. A base station in a wireless communication system which includes a plurality of base stations, a terminal that wirelessly communicates with a base station based on a result of channel estimation and communication quality estimation with the base station, and a control station, the base station comprising:
a transmission unit that performs a cooperative transmission to the terminal by the plurality of base stations and a single transmission from a local base station to the terminal; and
an association processing unit that receives from the control station, association information in which a fir

Assignees

• Jia Yunjian
• Fujishima Kenzaburo
• Hitachi Ltd

Inventors

• Jia Yunjian
• Fujishima Kenzaburo

Classifications

• H04W72/23

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

• H04W72/21

  in the uplink direction of a wireless link, i.e. towards the network · CPC title

• H04L5/0035 Primary

  Resource allocation in a cooperative multipoint environment · CPC title

• H04W72/0413

  Electricity · mapped topic

• H04L5/006

  Quality of the received signal, e.g. BER, SNR, water filling · CPC title