Transmitting apparatus employing online calibration

• US 7,409,191 B2
• Filed: 06/08/2005
• Issued: 08/05/2008
• Est. Priority Date: 06/16/2004
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Azuma, Tomohiro
• Primary Examiner(s): Urban; Edward
• Assistant Examiner(s): CHOW, CHARLES CHIANG
• Application Number:
  US11/147,443
• Publication Number:
  US 20050282506A1
• Time in Patent Office: 1,154 Days
• Field of Search: 455/91, 455/95, 455/102, 455/103, 455/126, 455/129, 455/424, 455/425, 455/456.5, 455/456.6, 455/13.3, 455/13.4, 455/17, 455/522, 455/69, 455/70, 455/67.14, 455/561, 455/562.1, 455/115.1, 455/115.2, 455/550.1, 455/575.1, 455/67.11, 455/67.13, 455/114.2, 375/298, 375/267, 375/135, 375/146, 375/221, 375/295, 375/260, 342/174, 342/368, 342/372, 342/82, 342/165
• US Class Current: 455/103
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04B 17/102 Power radiated at antenna
• CPC Class Codes: H04B 17/12 of transmit antennas, e.g. of the amplitude or phase
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal

Abstract

A transmitting apparatus includes a plurality of antenna elements, user signal output unit, calibration signal generation unit, antenna signal processing unit, and total transmission power measuring unit. The user signal output unit weights a user signal by an antenna weight and outputs it to each antenna element. The calibration signal generation unit outputs a calibration signal to be used to detect the characteristic of a transmission path. The antenna signal processing unit provided in the transmission path executes spread modulation and multiplexing for the user signal and calibration signal and outputs a multiplexed signal. The total transmission power measuring unit measures the value of total transmission power of the multiplexed signal to be transmitted from each antenna element on the basis of the multiplexed signal input from the antenna signal processing unit. An antenna weight correction unit executes a correction operation on the basis of the total transmission power value.

Claims

1. A transmitting apparatus comprising:

a plurality of antenna elements;

user signal output means for weighting a user signal by an antenna weight and outputting the user signal to each of said antenna elements;

calibration signal generation means for outputting a calibration signal to be used to detect a characteristic of a transmission path;

antenna signal processing means, provided in the transmission path, for executing spread modulation and multiplexing for the user signal input from said user signal output means and the calibration signal input from said calibration signal generation means and outputting an obtained multiplexed signal;

total transmission power measuring means for measuring a value of total transmission power of the multiplexed signal to be transmitted from each of said antenna elements on the basis of the multiplexed signal input from said antenna signal processing means; and

antenna weight correction means that executes a correction operation on the basis of the value of the total transmission power.

2. An apparatus according to claim 1, further comprising antenna weight correction means for correcting the antenna weight in accordance with the characteristic of the transmission path from said user signal output means to each of said antenna elements.

3. An apparatus according to claim 2, further comprising calibration signal generation control means for determining at least one of an output timing of the calibration signal and a set power of the calibration signal on the basis of the value of the total transmission power input from said total transmission power measuring means and outputting the result to said calibration signal generation means.

4. An apparatus according to claim 3, further comprising

calibration signal demodulation means for demodulating the calibration signal corresponding to each transmission path from the multiplexed signal extracted from the transmission path, and

demodulation result processing means for calculating a calibration coefficient based on the characteristic of the transmission path by comparing the calibration signals corresponding to transmission paths, which are input from said calibration signal demodulation means,

wherein said antenna weight correction means corrects the antenna weight on the basis of the calibration coefficient.

5. An apparatus according to claim 4, further comprising storage means for storing the calibration coefficient input from said demodulation result processing means,

wherein said antenna weight correction means corrects the antenna weight on the basis of the calibration coefficient stored in said storage means.

6. An apparatus according to claim 3, wherein said calibration signal generation control means comprises

addition means for adding the values of the total transmission powers input from said total transmission power measuring means, and

calibration execution determination means for determining on the basis of a value of a maximum transmission power of the apparatus and a sum of the total transmission powers obtained by said addition means whether to cause said calibration signal generation means to output the calibration signal.

7. An apparatus according to claim 3, wherein said calibration signal generation control means comprises calibration execution determination means for determining on the basis of a value of a maximum transmission power transmittable from each of said antenna elements and the value of the total transmission power whether to cause said calibration signal generation means to output the calibration signal.

8. An apparatus according to claim 3, wherein said calibration signal generation control means determines a set power of the calibration signal so as to obtain a predetermined power ratio of the user signal to the calibration signal.

9. An apparatus according to claim 2, further comprising storage means for storing in advance the calibration coefficient based on the characteristic of the transmission path, which varies in accordance with the value of the total transmission power, in correspondence with the value of the total transmission power, and

total transmission power value input means for reading out, from said storage means, the calibration coefficient corresponding to the value of the total transmission power input from said total transmission power measuring means and outputting the calibration coefficient to said antenna weight correction means,

wherein said antenna weight correction means corrects the antenna weight on the basis of the calibration coefficient input from said total transmission power value input means.

10. An apparatus according to claim 9, wherein

said storage means stores in advance the calibration coefficient based on the characteristic of the transmission path, which varies in accordance with the value of the total transmission power and a value of a transmission frequency, in correspondence with the value of the total transmission power and the value of the transmission frequency, and

said total transmission power value input means reads out, from said storage means, the calibration coefficient corresponding to the value of the total transmission power and a set value of the transmission frequency, which are input from said total transmission power measuring means, and outputs the calibration coefficient to said antenna weight correction means.

11. An apparatus according to claim 1, wherein the number of antenna elements is not less than three.