Calibration method and radio apparatus

• US 20050070333A1
• Filed: 09/28/2004
• Published: 03/31/2005
• Est. Priority Date: 09/29/2003
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Doi, Yoshiharu
• Granted Patent: US 6,992,620 B2
• Time in Patent Office: Days
• US Class Current: 455/562.100
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence

Abstract

A signal processing unit carries out signal processings necessary for a receiving/transmission processing of an adaptive array antenna. The signal processing unit also carries out a signal processing necessary for determining phase errors in quadrature modulation and quadrature detection to be done by radio units, namely, for determining a rotation amount of an initial phase correction value. The radio units in a base station apparatus carry out frequency conversion processing, amplification processing, quadrature modulation processing, quadarture detection processing, A-D or D-A conversion processing and the like between the baseband signals and radio frequency signals. An initial phase correction value determining unit determines rotation amounts of initial phase correction values, based on power-measuring received signals inputted from the radio units, and outputs to the signal processing unit as initial phase correction value signals.

Claims

1. A radio apparatus, comprising:

a radio unit for reference which receives transmission signals from an antenna for measurement by an antenna for reference so as to derive a first weighting factor and which transmits, from the antenna for reference, signals weighted with the first weighting factor;

a correcting radio unit which receives transmission signals from the antenna for measurement by an antenna for correction so as to derive a second weighting factor and which transmits, from the antenna for correction, signals weighted with the second weighting factor;

a rotation unit which operates, at the time of transmitting signals, the second weighting factor while rotating a correction value against a π

/2 phase shifter for transmission for performing quadrature modulation in said correcting radio unit;

a measuring unit which receives signals transmitted from the antenna for reference and the antenna for correction by the antenna for measurement and which measures the strength of received signals according to an amount rotated by said rotation unit; and

an estimation unit which estimates, according to the measured strength of received signals, a difference of phase in the π

/2 phase shifter for transmission against a π

/2 phase shifter for receiving with which to perform quadrature detection in said correcting radio unit,

wherein said rotation unit rotates the correction value by the phase difference estimated by said estimation unit.

2. A radio apparatus according to claim 1, further comprising an antenna switching unit which sets the antenna for correction while switching a plurality of antennas, wherein said estimation unit estimates respectively phase differences for the correcting antennas to be switched among the plurality of antennas.

3. A radio apparatus according to claim 1, further comprising a communication unit which communicates with a targeted terminal apparatus by using at least the antenna for measurement, the antenna for reference and the antenna for correction.

4. A radio apparatus according to claim 1, further comprising:

a communication unit which communicates with a targeted terminal apparatus by using at least the antenna for reference and the antenna for correction; and

a transmitter which transmits signals from the antenna for measurement to respectively derive the first weighting factor and the second weighting factor.

5. A radio apparatus according to claim 1, wherein the difference of phase to be estimated by said estimation unit is either 0 or π

and wherein, if the amount rotated by said rotation unit is either 0 or π

, said measuring unit measures the strength of received signals.

6. A radio apparatus according to claim 5, wherein said rotation unit includes:

a storage unit which stores a correction value in a case when the difference of phase to be estimated by said estimation unit is 0; and

an inversion unit which inverts the correction value if the correction value is rotated to π

.

7. A radio apparatus according to claim 5, wherein said rotation unit includes:

a first storage unit which stores a first correction value in a case when the difference of phase to be estimated by said estimation unit is 0;

a second storage unit which stores a second correction value in a case when the difference of phase to be estimated by said estimation unit is π

; and

a selector which selects the first correction value or the second correction value according to the amount rotated by said rotation unit.

8. A calibration method, comprising:

deriving a first weighting factor by receiving transmission signals from an antenna for measurement by an antenna for reference and transmitting, from the antenna for reference, signals weighted with the first weighting factor;

deriving a second weighting factor by receiving transmission signals from the antenna for measurement by an antenna for correction and transmitting, from the antenna for correction, signals weighted with the second weighting factor which was operated while rotating a correction value, against a π

/2 phase shifter for transmission, for performing quadrature modulation;

receiving signals transmitted from the antenna for reference and the antenna for correction by the antenna for measurement and measuring the strength of received signals in units of a rotation amount of the correction value;

estimating, according to the measured strength, a difference of phase in the π

/2 phase shifter for transmission against a π

/2 phase shifter for receiving with which to perform quadrature detection; and

determining the rotation amount of the correction value to be the phase difference estimated by said estimating.

9. A calibration method according to claim 8, further comprising setting the antenna for correction while switching a plurality of antennas, wherein said estimating a difference of phase estimates respectively phase differences for the correcting antennas to be switched among the plurality of antennas.

10. A calibration method according to claim 8, further comprising communicating with a targeted terminal apparatus by using at least the antenna for measurement, the antenna for reference and the antenna for correction.

11. A calibration method according to claim 8, further comprising communicating with a targeted terminal apparatus by using at least the antenna for reference and the antenna for correction,

wherein said transmitting is such that signals are transmitted from the antenna for measurement to respectively derive the first weighting factor and the second weighting factor.

12. A calibration method according to claim 8, wherein the difference of phase to be estimated by said estimating a difference of phase is either 0 or π

and wherein said measuring the strength of received signals is such that the strength of received signals is measured if the rotation amount is either 0 or π

.

13. A calibration method according to claim 12, wherein said transmitting includes:

storing a correction value in a case when the difference of phase to be estimated in said estimating a difference of phase is 0; and

inverting the correction value if the correction value is rotated to π

.

14. A calibration method according to claim 12, wherein said transmitting includes:

storing a first correction value in a case when the difference of phase to be estimated in said estimating a difference is 0;

storing a second correction value in a case when the difference of phase to be estimated by said estimating a difference of phase is π

; and

selecting the first correction value or the second correction value according to the rotation amount.

15. A program executable by a computer, the program including the functions of:

deriving a first weighting factor by receiving transmission signals from an antenna for measurement by an antenna for reference, storing the first weighting factor in a memory and transmitting, from the antenna for reference, signals weighted with the first weighting factor stored in the memory;

deriving a second weighting factor by receiving transmission signals from the antenna for measurement by an antenna for correction, storing the second weighting factor in a memory and transmitting, from the antenna for correction, signals weighted with the second weighting factor which was operated while rotating a correction value on the memory, against a π

/2 phase shifter for transmission, for performing quadrature modulation;

receiving signals transmitted from the antenna for reference and the antenna for correction by the antenna for measurement and measuring the strength of received signals in units of a rotation amount of the correction value;

storing the measured strength in the memory;

estimating, according to the stored strength, a difference of phase in the π

/2 phase shifter for transmission against a π

/2 phase shifter for receiving with which to perform quadrature detection; and

determining the rotation amount of the correction value to be the phase difference estimated by said estimating.

16. A program according to claim 15, the functions thereof further comprising setting the antenna for correction while switching a plurality of antennas, wherein said estimating estimates respectively phase differences for the correcting antennas to be switched among the plurality of antennas.

17. A program according to claim 15, the functions thereof further comprising communicating with a targeted terminal apparatus by using at least the antenna for measurement, the antenna for reference and the antenna for correction.

18. A program according to claim 15, the functions thereof further comprising communicating with a targeted terminal apparatus by using at least the antenna for reference and the antenna for correction,

wherein said transmitting is such that signals are transmitted from the antenna for measurement to respectively derive the first weighting factor and the second weighting factor.

19. A program according to claim 15, wherein the difference of phase to be estimated by said estimating a difference of phase is either 0 or π

and wherein said measuring the strength of received signals is such that the strength of received signals is measured if the rotation amount is either 0 or π

.

20. A program according to claim 19, wherein said transmitting includes:

storing a correction value in a case when the difference of phase to be estimated in said estimating a difference of phase is 0; and

inverting the correction value if the correction value is rotated to π

.

21. A program according to claim 19, wherein said transmitting includes:

storing a first correction value in a case when the difference of phase to be estimated in said estimating a difference is 0;

storing a second correction value in a case when the difference of phase to be estimated by said estimating a difference of phase is π

; and

selecting the first correction value or the second correction value according to the rotation amount.