Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Reexamination Certificate
1999-12-16
2001-05-22
Hunter, Daniel (Department: 2684)
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
C455S423000, C455S424000, C455S561000, C455S562100, C455S278100, C342S359000, C342S360000, C342S368000
Reexamination Certificate
active
06236839
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to techniques for calibrating an adaptive antenna array system, and more particularly to a method and apparatus for calibrating a multi-carrier smart antenna array system.
2. Description of the Prior Art
Antenna arrays are commonly used in a wide variety of systems that transmit and/or receive radio frequency (RF) signals. Examples of such systems include wireless communication systems, such as cellular telephone systems, and radar systems. An antenna array, which includes a plurality of antenna elements, provides improved performance characteristics over a single element antenna. The improved characteristics include improved signal to noise ratio, improved interference rejection for received signals, reduced power requirements for transmitted signals, as well as improved directionality.
For an ideal antenna array, the signal characteristics, including attenuation and phase shift, associated with each element of the array are identical. An important goal in designing and manufacturing an antenna array is to optimize the signal characteristics of the array to be as close to ideal as possible. As a result, it is very difficult and expensive to manufacture an antenna array system. Antenna array calibration provides a means for optimizing the signal characteristics of an antenna array using a calibration vector, which is determined based on actual signal characteristics of the array, in order to compensate for performance variances of the actual signal characteristics of each element of the array.
FIG. 1
shows a schematic block diagram of a prior art beam steering antenna array calibration system at
10
. The system
10
includes a beam steering antenna array transceiver system
12
, including: an antenna array
14
having a plurality of N antenna elements
16
; a plurality of N transceivers
18
designated TRANSCEIVER
—
1 TRANSCEIVER
—
2, . . . , TRANSCEIVER_N, each of the transceivers
18
having a port
20
communicatively coupled with corresponding one of the antenna elements
16
via a corresponding coaxial cable
22
; and a calibration processing unit
24
communicatively coupled with each of the transceivers
18
as further explained below.
Each of the transceivers
18
further includes: a duplexer
30
having a port
32
communicatively coupled with the corresponding one of the antenna elements
16
via port
20
of the transceiver and via the corresponding coaxial cable
22
, a receive port
34
, and a transmit port
36
; a receive processor
38
having an input port
40
communicatively coupled with port
34
of the duplexer, and an output
42
; and a transmit processor
44
having a port
46
communicatively coupled with port
36
of the duplexer, and an input port
48
. The calibration processing unit
24
includes a plurality of transceiver ports designated TRANSCEIVER_PORT
—
1, . . . TRANSCEIVER_PORT_N, each of the transceiver ports having an input port
52
for receiving a signal from port
42
of the receive processor
38
of the corresponding one of the transceivers
18
, and an output port
54
for providing a signal to port
48
of the transmit processor
44
of the corresponding one of the transceivers.
In operation, the beam steering antenna array transceiver system
12
may be used in any of a variety of applications including a base station for a cellular telephone system. The antenna array
14
receives signals from mobile units, and the controlling processor
24
is operative to analyze the received signals and determine a position vector associated with the corresponding received signal in order to determine the position of the mobile unit. The position vector is then used to control a radiation pattern generated by the antenna array
14
wherein the beam is controlled by varying the phases of signals generated at the output ports
54
of the controlling processor
24
in order to focus the beam in the direction of the corresponding mobile unit.
Each of the antenna elements
16
is associated with a corresponding receive signal path and a corresponding transmit signal path. The receive path associated with each one of the antenna elements
16
extends from the corresponding antenna element
16
to the corresponding input port
52
of the calibration processing unit
24
traversing the corresponding antenna element
16
, the corresponding cable
22
, the duplexer
30
, and the receive processor
38
of the corresponding one of the transceivers
18
. The transmit signal path associated with each one of the antenna elements
16
extends from the associated one of the output ports
54
of the calibration processing unit
24
to the corresponding antenna element
16
traversing the corresponding transmit processor
44
, duplexer
30
, and coaxial cable
22
. In an ideal antenna array transceiver system, the signal path characteristics associated with each one of the antenna elements
16
are identical to each other, and the signal characteristics associated with each one of the receiver signal paths are also identical to each other. The signal path characteristics include attenuation, or amplitude difference, in a signal as a result of propagating through a corresponding path, and the phase shift in a signal as a result of propagating through a corresponding path. Therefore, each one of the antenna elements
16
has associated sets of transmit and receive signal characteristics including the phase shift and attenuation associated with the corresponding transmit and receive signal paths. Note that each of the antenna elements themselves may have different signal characteristics associated therewith as a result of very small variances in the dimensions of the antenna elements as well as in the material properties of the corresponding antenna elements.
In practice, an antenna array transceiver system provides less than ideal performance because the signal characteristics of the transmit paths and receive paths associated with each of the antenna elements vary. Therefore, it is necessary to determine the signal characteristics of each of the receive signal paths and each of the transmit signal paths so that calibration compensation values may be determined for each. The calibration compensation values are used to determine a calibration vector which is used to compensate for variances in the signal characteristics associated with each of the transmit signal paths and receive signal paths of the transceiver system. Antenna array calibration provides a means for implementing an antenna array as closely system which provides acceptable performance.
In accordance with conventional processes for calibrating a beam steering directional antenna array transceiver system, either a far-field calibration processor
64
or a transponder
60
may be used to determine a calibration vector for each of a plurality of beam directions determined by positional relationships between the transponder and the array
14
. The transponder
60
is responsive to signals transmitted thereto from corresponding ones of the antenna elements
16
, and is operative to transmit a return signal back to the antenna array
14
. The return signal is received by corresponding ones of the antenna elements
16
, and provided to the input ports
52
of the calibration processing unit
24
via the corresponding ones of the coaxial cables
22
and transceivers
18
. While either of the external calibration processor
64
or transponder
60
may be used to calibrate the system
12
, use of the external calibration processor
64
is complicated because the processor
64
must be controlled either via remote control or manually by a technician in the field.
The object of the calibration process is to determine a compensation vector for use in operation of the system
12
in order to adjust the transmit signals, and receive signals generated and received at ports
52
and
54
of the calibration processing unit
24
in order to compensate for differences between the signal characteristics of each of the transmit and
Gu Yucong
Li Shiping
Yang Zhang Ping
Boyce Justin
Hamrick Claude A. S.
Hunter Daniel
Oppenheimer Wolff & Donnelly LLP
UTStarcom Inc.
LandOfFree
Method and apparatus for calibrating a smart antenna array does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for calibrating a smart antenna array, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for calibrating a smart antenna array will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2470908