BASE STATION DEVICE, TERMINAL DEVICE, AND WIRELESS COMMUNICATION SYSTEM

• US 20100323625A1
• Filed: 02/05/2009
• Published: 12/23/2010
• Est. Priority Date: 02/05/2008
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kishigami, Takaaki, Okasaka, Shozo
• Granted Patent: US 8,620,221 B2
• Time in Patent Office: Days
• US Class Current: 455/65
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/0434 using multiple eigenmodes
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03783 Details of reference signals
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04W 72/30 Resource management for broadcast services

Abstract

A base station device (10) communicates between a first terminal device and a second terminal device over the same channel by spatial multiplexing. The base station device (10) comprises an interference cancellation coefficient extractor (30) that extracts an interference cancellation coefficient from a signal received from the first terminal device to cancel interference on a propagation channel with the first terminal device in advance, and transmits a pilot signal that contains information related to the interference cancellation coefficient to the second terminal device. In addition, the base station device (10) also comprises an interference canceller (16) that uses the interference cancellation coefficient to cancel an interference component from transmission data to be transmitted over the same channel, and transmits the transmission data from which the interference component has been canceled by the interference canceller (16) to the first terminal device and the second terminal device over the same channel. A wireless communication system is provided which, in a multi-user MIMO, suppresses superimposed interference components resulting from channel fluctuations and channel estimation errors when interference cancellation is performed in advance in a base station unit on a modulated signal to be transmitted.

Claims

1. A base station device that communicates with a first terminal device and a second terminal device over the same channel by spatial multiplexing, the base station device comprising:

an interference cancellation coefficient extractor that extracts an interference cancellation coefficient for cancelling interference on a propagation channel with the second terminal device from a signal received from the first terminal device;

a control signal transmitter that generates a control signal including a pilot signal based on the interference cancellation coefficient and transmits the control signal to the terminal devices;

an interference canceller that uses the interference cancellation coefficient to cancel an interference component from transmission data to be transmitted to the first terminal device; and

a data transmitter that transmits the transmission data, from which the interference component has been canceled by the interference canceller, with transmission data to be transmitted to the second terminal device, over the same channel.

2. The base station device according to claim 1, further comprising:

a transmission weight multiplier that weights a pilot signal used by a terminal device for estimating a propagation channel according to a value of the interference cancellation coefficient; and

a dedicated pilot signal generator that generates a dedicated pilot signal obtained at the transmission weight multiplier, wherein a signal transmitted from the control signal transmitter includes the dedicated pilot signal.

3. The base station device according to claim 1, further comprising:

a signal multiplexer that generates a signal formed by multiplexing a control signal for notifying the interference cancellation coefficient and a pilot signal for estimating a propagation channel, wherein

the control signal transmitter transmits a signal generated at the signal multiplexer.

4. The base station device according to claim 3, further comprising:

a transmission weight multiplier that weights a pilot signal used by a terminal device for estimating a propagation channel according to a value of the interference cancellation coefficient; and

a dedicated PILOT signal generator that generates a dedicated PILOT signal obtained at the transmission weight multiplier, wherein the signal multiplexer generates a signal formed by further multiplexing the dedicated PILOT signal.

5. The base station device according to claim 4, wherein the signal multiplexer generates a signal formed by multiplexing the control signal subjected to the same weighting as the dedicated pilot signal.

6. The base station device according to any one of claims 1 to 5, wherein

the interference cancellation coefficient extractor comprises an interference cancellation coefficient storage that stores the interference cancellation coefficient in association with an identifier,

the interference cancellation coefficient extractor extracts information on an identifier indicating the interference cancellation coefficient, and

the interference canceller reads out an interference cancellation coefficient corresponding to the identifier from the interference cancellation coefficient storage and uses the interference cancellation coefficient to cancel an interference component.

7. A terminal device that communicates with a base station device that performs spatial multiplexing with a plurality of terminal devices, the terminal device comprising:

a signal receiver that receives a control signal transmitted from the base station device and which includes a pilot signal generated based on an interference cancellation coefficient;

a channel estimator that uses the interference cancellation coefficient included in the control signal to estimate a propagation channel with the base station device; and

a demodulator that uses information on the propagation channel to demodulate data transmitted from the base station device.

8. A wireless communication system comprising a plurality of terminal devices and a base station device that communicates with a first terminal device and a second terminal device among the plurality of terminal devices over the same channel by spatial multiplexing, wherein

the first terminal device comprises:

an interference cancellation coefficient calculator that calculates an interference cancellation coefficient for cancelling interference on a propagation channel between the first terminal device and the base station device; and

an interference cancellation coefficient transmitter that transmits the interference cancellation coefficient to the base station device,

the base station device comprises;

an interference cancellation coefficient receiver that receives the interference cancellation coefficient from the first terminal device;

a control signal transmitter that generates a control signal including a pilot signal based on the interference cancellation coefficient and transmits the control signal to the terminal devices;

an interference canceller that uses the interference cancellation coefficient to cancel an interference component from transmission data to be transmitted to the first terminal device; and

a data transmitter that transmits the transmission data, from which the interference component has been canceled by the interference canceller, with transmission data to be transmitted to the second terminal device, over the same channel, and

the second terminal device comprises;

a signal receiver that receives the control signal transmitted from the base station device;

a channel estimator that uses the interference cancellation coefficient included in the control signal to estimate a propagation channel between the second terminal device and the base station device; and

a demodulator that uses information on the propagation channel to demodulate data transmitted from the base station device.

9. A wireless communication method used by a base station device that communicates with a first terminal device and a second terminal device over the same channel by spatial multiplexing, the wireless communication method comprising the steps of:

the base station device receiving an interference cancellation coefficient for cancelling interference on a propagation channel with the second terminal device from a signal received from the first terminal device;

the base station generating a control signal including a pilot signal based on the interference cancellation coefficient and transmitting the control signal to the terminal devices;

using the interference cancellation coefficient to cancel an interference component from transmission data to be transmitted to the first terminal device; and

transmitting the transmission data, from which the interference component has been canceled by the interference canceller, with transmission data to be transmitted to the second terminal device, over the same channel.

10. A base station device that transmits a unicast signal to be transmitted to a first terminal device and a multicast or broadcast signal to be transmitted to a plurality of groups of terminal devices by spatial multiplexing over a same channel, the base station device comprising:

an interference cancellation coefficient extractor that extracts an interference cancellation coefficient for cancelling interference on a propagation channel with the plurality of groups of terminal devices from a signal received from the first terminal device;

a control signal transmitter that generates a control signal including a pilot signal based on information related to the interference cancellation coefficient and transmits the control signal to the first terminal device and the plurality of groups of terminal devices;

an interference canceller that uses the interference cancellation coefficient to cancel an interference component from transmission data to be transmitted to the first terminal device; and

a data transmitter that transmits the transmission data, from which the interference component has been canceled by the interference canceller, with transmission data to be transmitted to the plurality of groups of terminal devices, over the same channel.

11. A wireless communication system comprising a plurality of terminal devices and a base station device that transmits a unicast signal to be transmitted to a first terminal device among the plurality of terminal devices and a multicast or broadcast signal to be transmitted to a plurality of groups of terminal devices by spatial multiplexing over a same channel, wherein

the first terminal device comprises:

an interference cancellation coefficient calculator that calculates an interference cancellation coefficient for cancelling interference on a propagation channel with the base station device; and

an interference cancellation coefficient transmitter that transmits the interference cancellation coefficient to the base station device,

the base station device comprises;

an interference cancellation coefficient receiver that receives the interference cancellation coefficient from the first terminal device;

a control signal transmitter that generates a control signal including a pilot signal based on information related to the interference cancellation coefficient and transmits the control signal to the terminal devices;

an interference canceller that uses the interference cancellation coefficient to cancel an interference component from transmission data to be transmitted to the first terminal device; and

a data transmitter that transmits the transmission data;

from which the interference component has been canceled by the interference canceller, with transmission data to be transmitted to the plurality of groups of terminal devices, over the same channel, and

the plurality of groups of terminal devices comprises;

a signal receiver that receives the control signal transmitted from the base station device;

a channel estimator that uses information related to the interference cancellation coefficient included in the control signal to estimate a propagation channel with the base station device; and

a demodulator that uses information on the propagation channel to demodulate data transmitted from the base station device.

12. A wireless communication method used by a base station device that transmits a unicast signal to be transmitted to a first terminal device and a multicast or broadcast signal to be transmitted to a plurality of groups of terminal devices by spatial multiplexing over a same channel, the wireless communication method comprising the steps of:

the base station device receiving an interference cancellation coefficient for cancelling interference on a propagation channel with the plurality of groups of terminal devices from the first terminal device;

the base station device generating a control signal including a pilot signal based on information related to the interference cancellation coefficient and transmitting the control signal to the terminal devices;

using the interference cancellation coefficient to cancel an interference component from transmission data to be transmitted to the first terminal device; and

transmitting the transmission data, from which the interference component has been canceled by the interference canceller, with transmission data to be transmitted to the plurality of groups of terminal devices, over the same channel.