Wireless communication apparatus and wireless communication method

• US 20080051150A1
• Filed: 08/17/2007
• Published: 02/28/2008
• Est. Priority Date: 08/23/2006
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Tsutsui, Masafumi
• Granted Patent: US 8,111,679 B2
• Time in Patent Office: Days
• US Class Current: 455/562.1
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04B 7/0673 using feedback from receiving side

Abstract

A wireless communication apparatus on the base station transmits beamformed multi-beam data to a wireless communication apparatus on the mobile station side using a multiple antennas. To obtain an expected directivity without gain reduction under the existence of phase variation in transmission circuits, the wireless communication apparatus on the base station is equipped with a code book that stores beamforming information, a precoder that reads the code book and performs processing to form a multi-beam pattern for the data, and a control unit that controls, based on feedback information, the reading of beamforming information from the code book for the compensation of phase variation.

Claims

1. A wireless communication apparatus, on a base station side, that performs beamforming and transmits data to a mobile station using a plurality of antennas, comprising:

a code book that stores beamforming information;

a precoder that reads the code book and performs processing to form a multi-beam pattern for the data; and

a control unit that, based on feedback information for a compensation of a phase variation in each transmission circuit of a plurality of transmission circuits that each respectively corresponds to a channel, controls a retrieval of the beamforming information that compensates the phase variation.

2. The wireless communication apparatus according to claim 1, wherein

the feedback information includes a matrix number and a beam number of the code book, and

the control unit retrieves the matrix number and the beam number from the code book.

3. The wireless communication apparatus according to claim 1, wherein

the transmission circuits modulate the data using a plurality of oscillators, each oscillator being respectively disposed for each channel.

4. The wireless communication apparatus according to claim 1, wherein

the transmission circuits modulate the data using a single oscillator.

5. A wireless communication apparatus, on a mobile station side, that receives a plurality of beams of data from a base station using a plurality of antennas, comprising:

a code book that stores beamforming information identical to that stored in a code book of the base station; and

a control unit that, when notified that a phase variation compensation is required by the base station, searches the beamforming information, based on a signal condition of each of the beams, for the beamforming information that enables optimal beamforming, and transmits the selected beamforming information to the base station as feedback information.

6. The wireless communication apparatus according to claim 5, wherein

the feedback information is a beam number and a matrix number thereof, the beam number corresponding to a beam that has a high signal to interference plus noise ratio or a high signal power among the received beams.

7. The wireless communication apparatus according to claim 5, wherein

the control unit performs a complete search of the code book, entirely, for a beam number and a matrix number, and transmits the beam number and the matrix number to the base station as the feedback information, and

after the complete search is performed, the control unit performs a partial search of a portion of the code book and transmits, as the feedback information, an optimal beam number in a matrix indicated by the matrix number.

8. The wireless communication apparatus according to claim 7, wherein

when a plurality of transmitting circuits disposed on the base station are configured to modulate data using a single oscillator, the control unit sets a longer cycle of the complete search corresponding to a period during which the transmitting circuits are affected by temperature shifts, the longer cycle relative to a cycle of the complete search when the transmitting circuits modulate data using a plurality of oscillators.

9. A wireless communication method, on a base station side, of performing beamforming and transmitting data to a mobile station using a plurality of antennas, comprising:

reading beamforming information stored in a code book;

forming a multi-beam pattern for the data; and

retrieving, based on feedback information for a compensation of a phase variation in each transmission circuit of a plurality of transmission circuits that each respectively correspond to a channel, the beamforming information to compensate the phase variation.

10. The wireless communication method according to claim 9, wherein

the retrieving includes retrieving, from the code book, a matrix number and a beam number as the feedback information.

11. The wireless communication method according to claim 9, further comprising:

modulating the data using a plurality of oscillators, each oscillator being respectively disposed for each channel.

12. The wireless communication method according to claim 9, further comprising:

modulating the data using a single oscillator.