Communications: radio wave antennas – Antennas – With coupling network or impedance in the leadin
Reexamination Certificate
2003-06-13
2004-10-19
Nguyen, Hoang V. (Department: 2821)
Communications: radio wave antennas
Antennas
With coupling network or impedance in the leadin
C455S067700, C455S561000, C455S562100
Reexamination Certificate
active
06806844
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a calibration system of an array antenna receiving apparatus. More particularly, the present invention relates to a calibration system for correcting the change in phase (delay) and amplitude information between antenna radio receiving units in an array antenna receiving apparatus for adaptive antenna control.
BACKGROUND ART
Conventional cellular mobile communication systems require the high speed and the high quality of signals and the increase in subscriber capacity. For example, a method for reducing reception gain against the interference from another user and the interference due to delay waves is examined by using an array antenna receiving apparatus comprising a plurality of antenna devices having the high correlation. As a result, a reception directive pattern is formed so that the reception gain is increased in the incoming direction of a desired signal.
The array antenna receiving apparatus comprises the plurality of antenna radio receiving units. In general, in the above-mentioned array antenna receiving apparatus, the amplitudes and phases in the antenna radio receiving units connected to the antenna devices are individually varied every moment. The formatting of the reception directive pattern requires the correction of the variation of the amplitudes and phases. The above operation is called calibration.
For example, Japanese Unexamined Patent Publication (JP-A) No. 11-46180 discloses a conventional calibration system of the above-mentioned array antenna receiving apparatus. Japanese Unexamined Patent Publication No. 11-46180 prepares a technology in which a well-known signal is inputted to antenna radio receiving units connected to antenna devices and a result of demodulating a calibration signal is used. In this preparation, the change in phases (delays) and amplitudes of the antenna radio receiving units, as the demodulating results, which are individually varied every moment, are corrected.
FIG. 1
is a block diagram showing a calibration system of a conventional array antenna receiving apparatus.
The array antenna receiving apparatus comprises an array antenna
1001
, multiplexing circuits
1003
-
1
to
1003
-N corresponding to N antenna devices
1002
-
1
to
1002
-N, antenna radio receiving units
1004
-
1
to
1004
-N corresponding to the N antenna devices
1002
-
1
to
1002
-N, user signal processing units
1005
-
1
to
1005
-M corresponding to M users, a calibration signal transmitting unit
1010
, and a calibration signal processing unit
1011
.
The array antenna
1001
comprises N antenna devices
1002
-
1
to
1002
-N. The N antenna devices
1002
-
1
to
1002
-N are closely arranged so that reception signals from the antenna devices have a correlation, and receive signal obtained by multiplexing a desired signal and a plurality of interference signals.
One multiplexing circuit
1003
-
i
in the N multiplexing circuits multiplexes a calibration signal as an output from the calibration signal transmitting unit
1010
and a reception signal as an output from the antenna device
1002
-
i
. The multiplexing circuit
1003
-
i
multiplexes an input signal at a radio band and outputs the multiplexing signal to the antenna radio receiving unit
1004
-
i
. A multiplexing method is not particularly limited and a code multiplex is used as an example.
The antenna radio receiving unit
1004
-
i
comprises devices such as a low-noise amplifier, a band limiting filter, a mixer, a local transmitter, an AGC (Auto Gain Controller), an orthogonal detector, a low-pass filter, and an analog/digital converter (ADC). The antenna radio receiving unit
1004
-
i
subjects the signal inputted from the multiplexing circuit
1003
-
i
to amplification, frequency conversion from the radio band to a base band, orthogonal detection, analog/digital conversion, and so on. The antenna radio receiving unit
1004
-
i
further outputs the processed signal to the user signal processing unit
1005
-
i
and the calibration signal processing unit
1011
. Normally, an AGC amplifier is used for keeping of a power level of the output signal constant independently of the power level of the input signal every antenna radio receiving unit.
The calibration signal processing unit
1011
receives signals from the antenna radio receiving units
1004
-
1
to
1004
-N, extracts the calibration signal from the signals, detects phase/amplitude information of the antenna radio receiving units
1004
-
1
to
1004
-N, and outputs the detected information to the user signal processing units
1005
-
1
to
1005
-M. Herein, the calibration signal multiplexed to the input signal can be extracted.
A user signal processing unit
1005
-
j
corresponding to a user j inputs outputs from the antenna radio receiving units
1004
-
1
to
1004
-N and the phase/amplitude information of the antenna radio receiving units
1004
-
1
to
1004
-N as outputs from the calibration signal processing unit
1011
. The user signal processing unit
1005
-
j
corrects the inputs from the antenna radio receiving units
1004
-
1
to
1004
-N by using the phase/amplitude information of the antenna radio receiving units
1004
-
1
to
1004
-N as the outputs from the calibration signal transmitting unit
1010
, and increases the reception gain against the incoming direction of the signal to the target user j. On the other hand, the user signal processing unit
1005
-
j
forms a reception directive pattern so that the reception gain is reduced against the interference from another user and the interference due to the delay waves, and outputs a user demodulating signal j which is received by the reception directive pattern.
The calibration signal transmitting unit
1010
generates a calibration signal at the base band and subjects the generated signal to digital/analog conversion and frequency conversion from the base band to the radio band. Thereafter, the calibration signal transmitting unit
1010
forms the calibration signal having the same frequency band as that of reception signals of the antenna devices
1002
-
1
to
1002
-N, and outputs the formed signal to the multiplexing circuits
1003
-
1
to
1003
-N at arbitrary power levels. In this case, the calibration signal processing unit
1011
detects the phase/amplitude information of the antenna radio receiving units
1004
-
1
to
1004
-N every reception power by changing the calibration signals to have a plurality of power levels.
The signals received by each of the N antenna devices
1002
-
1
to
1002
-N include a users desired signal component, an interference signal component, and thermal noise. Further, the desired signal component and the interference signal component include multi-path components, respectively. Generally, the signal components comes in different directions.
The conventional array antenna receiving apparatus shown in
FIG. 1
identifies the signal components in different incoming directions and forms the reception directive pattern by using the phase/amplitude information of the signals received by the N antenna devices
1002
-
1
to
1002
-N.
In this case, the antenna radio receiving units
1004
-
1
to
1004
-N generate the change in phase/amplitude therein. Then, information different from the phase/amplitude information of the signals received by each of the original antenna devices
1002
-
1
to
1002
-N is given to the user signal processing units
1005
-
1
to
1005
-M. Thus, the signal components are not accurately identified and an ideal reception directive pattern is not formed.
The calibration signals having the same frequency band as those of the reception signals from the antenna devices
1002
-
1
to
1002
-N are multiplexed thereto. The calibration signal processing unit
1011
detects the phaselamplitude information of the calibration signals extracted from the outputs from the antenna radio receiving units
1004
-
1
to
1004
-N, thereby correcting the phase/amplitude information given to the user signal processing units
1005
-
1
to
1005
-M.
The multiplex of the calibration signals enable
NEC Corporation
Nguyen Hoang V.
Sughrue & Mion, PLLC
LandOfFree
Calibration system for array antenna receiving apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Calibration system for array antenna receiving apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Calibration system for array antenna receiving apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3268580