Wireless communication system, wireless communication apparatus, wireless communication method, and computer program therefor

• US 20050249304A1
• Filed: 05/02/2005
• Published: 11/10/2005
• Est. Priority Date: 05/10/2004
• Status: Active Grant

• Current Assignee: Redwood Technologies, LLC (Dominion Harbor Enterprises, LLC)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Takano, Hiroaki, Kuroda, Shinichi
• Granted Patent: US 8,000,421 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0842 Weighted combining
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0631 Receiver arrangements
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Communication operation is performed with enhanced transmission efficiency by obtaining enhanced communication capacity through optimal allocation of transmission powers to individual MIMO channels obtainable by spatial multiplexing. A transmitter has a plurality of transmission antennas and a receiver has a plurality of reception antennas and perform spatial multiplex communication through transmission and reception with individual antenna weights being set. The transmitter varies the power allocation in units of a communication channel in correspondence to communication quality of the channel. The receiver uses a power allocation value of each communication channel that is estimated in accordance with a reception power of a pilot carrier included in user data after spatially separated. Thereby, the receiver returns the magnitude of the amplitude of a received signal in the signal spacing to an original magnitude, and performs an accurate demapping process.

Claims

1. A wireless communication system for performing data communication by using a plurality of spatially multiplexed communication channels between a transmitter and a receiver, wherein

in the transmitter, a transmission power is allocated to each of the communication channels, mapped in signal spacing, and spatially multiplexed, whereby data communication is performed;

and

in the receiver, power allocation information of the each communication channel is acquired, received data is spatially separated, and demapping is performed in accordance with the power allocation information.

2. A wireless communication system according to claim 1, wherein

the transmitter has a plurality of transmission antennas and the receiver has a plurality of reception antennas;

the transmitter allocates transmission data to a plurality of streams and performs weighting transmission thereof from each of the transmission antennas; and

the receiver performs weighting reception of the stream through each of the reception antennas.

3. A wireless communication system according to claim 2, wherein

the transmitter acquires optimal transmission antenna weight factors in accordance with feedback information received from the receiver.

4. A wireless communication system according to claim 1, wherein

the transmitter allocates the transmission power in correspondence to communication quality of the each communication channel.

5. A wireless communication system according to claim 1, wherein

the receiver uses a power allocation value allocated to the each communication channel and thereby returns a magnitude of an amplitude of each reception signal point in the signal spacing in the each communication channel to an original amplitude.

6. A wireless communication system according to claim 1, wherein

the receiver acquires power allocation information of the each communication channel in accordance with power information included in a reference signal transmitted from the transmitter.

7. A wireless communication system according to claim 1, wherein

the receiver estimates a power allocation of the each communication channel in accordance with a reception power of user data after spatially separated.

8. A wireless communication system according to claim 7, wherein

the receiver estimates the power allocation of the each communication channel in accordance with a reception power of a pilot carrier included in the user data after spatially separated.

9. A wireless communication system according to claim 1, wherein

the receiver estimates a power allocation of each stream in accordance with both a reception power of per-stream user data in a state after spatial separation of the reception signal and likelihood information of each stream signal.

10. A wireless communication system according to claim 1, wherein

the receiver estimates the power allocation of the each stream in accordance with both a reception power of a pilot carrier included in the per-stream user data in a state after spatial separation of the reception signal and the likelihood information of the each stream signal.

11. A wireless communication apparatus for receiving data transmitted by using a plurality of spatially multiplexed communication channels, wherein a transmission power is allocated to each of the communication channels on the side of the transmitter, the wireless communication apparatus comprising:

receiving means that receives a signal from each of the communication channel and performs spatially separation thereof;

power allocation information acquisition means that acquires power allocation information of the each communication channel; and

demodulating means that performs demapping of a reception signal in the each communication channel spatially separated in accordance with the power allocation information acquired.

12. A wireless communication apparatus according to claim 11, further comprising a plurality of reception antennas, wherein

the receiving means performs weighting reception, through each of the reception antenna, of transmission data allocated to a plurality of streams and transmitted by weighting transmission.

13. A wireless communication apparatus according to claim 11, wherein

in the transmitter, power allocation is performed in units of the communication channel in correspondence to communication quality of the each communication channel.

14. A wireless communication apparatus according to claim 11, wherein

the demodulating means uses a power allocation value allocated to the each communication channel and thereby returns a magnitude of an amplitude of each reception signal point in signal spacing in the each communication channel to an original amplitude.

15. A wireless communication apparatus according to claim 11, wherein

the power allocation information acquisition means acquires power allocation information of the each communication channel in accordance with power information included in a reference signal transmitted from the transmitter.

16. A wireless communication apparatus according to claim 11, wherein

the power allocation information acquisition means estimates a power allocation of the each communication channel in accordance with a reception power of user data after spatially separated.

17. A wireless communication apparatus according to claim 16, wherein

the power allocation information acquisition means estimates the power allocation of the each communication channel in accordance with a reception power of a pilot carrier included in the user data after spatially separated.

18. A wireless communication apparatus according to claim 11, further comprising likelihood estimation means that estimates likelihood information of each stream signal in a state after spatial separation of the reception signal,

wherein

the power allocation information acquisition means estimates the power allocation of each stream in accordance with both a reception power of per-stream user data in the state after spatial separation of the reception signal and the likelihood information of the each stream signal.

19. A wireless communication apparatus according to claim 18, wherein

the power allocation information acquisition means estimates the power allocation of the each stream in accordance with both the reception power of the per-stream user data in the state after spatial separation of the reception signal and likelihood information of the each stream signal.

20. A wireless communication apparatus according to claim 18, wherein

the power allocation information acquisition means acquires a power estimation value of the stream by performing weighting and averaging of a reception power of a pilot carrier, which is included in the per-stream user data in the state after spatial separation of the reception signal, with a likelihood amplitude of the stream signal.

21. A wireless communication apparatus according to claim 18, further comprising a plurality of reception antennas, wherein spatial multiplex data communication is performed by using a plurality of logical channels formed between the apparatus and a transmitter including a plurality of antennas,

wherein

the receiving means estimates a channel matrix of the logical channels, acquires an antenna weight matrix in accordance with the estimated channel matrix, performs a multiplication of a reception signal from each of the antennas by the antenna weight matrix thereby to perform spatial separation into a signal of each stream;

and

the likelihood estimation means estimates the likelihood information in accordance with the antenna weight matrix.

22. A wireless communication apparatus according to claim 21, wherein

the receiving means estimates the channel matrix in accordance with an MMSE (minimum mean square error) algorithm based on logic of maximizing a ratio between a signal power and a square error;

and

the likelihood estimation means estimates the likelihood information from the estimated channel matrix, an antenna reception weight matrix, and an estimated noise power.

23. A wireless communication apparatus according to claim 22, wherein

the likelihood estimation means calculates, respectively, a signal power S, an interference power I, and a noise power N in units of a stream in a state after spatial decoding from the estimated channel matrix, the antenna reception weight matrix, and the estimated noise power, and determines a likelihood amplitude made of a square root of S/(I+N) to be the likelihood information.

24. A wireless communication apparatus according to claim 23, wherein

the likelihood estimation means acquires the noise power N included in the each stream in the state after spatial decoding by the product of a square norm of an antenna weight vector of the stream multiplied by a noise power included in the signal in a state before spatial decoding.

25. A wireless communication apparatus according to claim 23, wherein

the likelihood estimation means acquires, as a true signal power estimation value S, a result of a subtraction of the noise power N performed on a power value acquired from a square norm of a scalar product of an antenna weight vector and a channel vector in the each stream in the state after spatial decoding.

26. A wireless communication apparatus according to claim 23, wherein

the likelihood estimation means acquires the interference power I of the each stream in the state after spatial decoding from a total sum of square norms of scalar products of an antenna weight vector of the stream and channel vectors of streams other than the stream.

27. A wireless communication method for receiving data transmitted by using a plurality of spatially multiplexed communication channels, wherein a transmission power is allocated to each of the communication channels on the side of the transmiteer side, the wireless communication apparatus comprising:

a receiving step that receives a signal from each of the communication channel and performs spatial separation thereof;

a power allocation information acquisition step that acquires power allocation information of the each communication channel; and

a demodulating step that performs demapping of a reception signal in the each communication channel spatially separated in accordance with the power allocation information acquired.

28. A computer program written in a computer readable format to execute a process of receiving data transmitted by using a plurality of spatially multiplexed communication channels, wherein a transmission power is allocated to each of the communication channels on the side of a transmitter, the computer program comprising:

a receiving step that receives a signal from each of the communication channel and performs spatial separation thereof;

a power allocation information acquisition step that acquires power allocation information of the each communication channel; and

a demodulating step that performs demapping of a reception signal in the each communication channel spatially separated in accordance with the power allocation information acquired.