JP3339328B2 - Digital beamforming antenna for base stations - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a base station digital beamforming antenna used as a base station antenna for mobile communication.

[0002]

2. Description of the Related Art FIG. 7 shows, for example, "Overview of Cellular C".
DMA ”(IEEE Trans. On Vehicular Tech., Vol. 40, No.
2, May 1991), a conventional CDMA (Code Divisi
FIG. 2 is a diagram of a base station antenna and a terminal station for describing a base station antenna for mobile communication using “on Multiple Access”. In the figure, 7 is a base station antenna, and 8 is a terminal station.

A conventional mobile communication base station antenna will be described below with reference to FIG. In CDMA, communication is performed with antennas of a plurality of terminal stations 8 using the same frequency. As the base station antenna, an antenna having a wide directivity and covering a certain service area (cell) 14 is used. Terminal station 8
Are used in the service area (cell) 14. To separate signals between terminal stations, a specific code is given to each signal, and the signals are separated by correlating with the code. A signal having no correlation has a noise level, but a signal having a correlation is correlated with a certain code, so that it can be received with a high SN ratio. CD
As described above, in a communication system employing MA, signal separation between terminal stations is performed by codes, and large-capacity communication is performed using the same frequency.

[0004]

In a communication system employing CDMA, as described above, signal separation between terminal stations is performed by codes. However, since the received power is inversely proportional to the square of the distance, when an omnidirectional antenna is used for the base station as shown in FIG. 7, the received power from the terminal station near the base station is large, and the distant terminal station is large. The received power of the signal from is reduced. Therefore, in the CDMA communication system in which a signal is separated by a code, it is necessary to make the received power from the terminal station constant, and for this purpose, it is necessary to precisely control the transmission power in the terminal device. This problem is known as a near-far problem of the CDMA communication system. For this reason, there has been a problem that the hardware of the terminal station is complicated and expensive.

[0005] In future communication systems, there is a concept that communication of high bit rate images and information is performed by the same base station in addition to the telephone terminal. In such a case, a terminal that performs transmission at a high bit rate is required to have a higher SN ratio, and for that purpose, the terminal station must increase the transmission output, and the received signal from another terminal is buried.
In other words, when information such as an image is received, the received power is increased, so that there has been a problem that other communication such as voice is buried.

[0006]

In order to achieve the above object, a digital beam forming antenna for a base station according to the present invention uses the following means.

A digital beamforming antenna for a base station according to the first aspect of the present invention is a CDMA for performing a correlation process using a code given to a spread signal to separate a signal.
An antenna for a base station used in a communication system adopting a (Code Division Multiple Access) system, comprising: a plurality of element antennas; an A / D converter for converting a signal of each of the element antennas into a digital signal; A multi-beamformer for giving a weight to the digital signal from the D-converter and synthesizing to form a predetermined number of plural beams required as the base station antenna; and a next stage for each beam terminal of each beam. A beam terminal switching device for switching connection to the beam terminal, a correlator for sequentially performing a correlation process for each of the beam terminals connected by the beam terminal switching device and detecting received power, and the correlation from the predetermined number of the plurality of beam terminals. Threshold value judging means for selecting a beam terminal at which the detector output has exceeded a certain level, and the beam terminal output selected by the threshold value judging means. It is obtained by a demodulator for demodulating the about.

According to a second aspect of the present invention, there is provided a digital beamforming antenna for a base station which is used in a communication system employing a CDMA system in which a spread signal is subjected to a correlation process using a given code to separate signals. A station antenna, comprising: a plurality of element antennas; an A / D converter for converting a signal for each of the element antennas into a digital signal; and a digital signal from the A / D converter for weighting and combining. A multi-beamformer for forming a predetermined number of plural beams required as the base station antenna,
A correlator for performing a correlation process for each beam terminal of each of the beams to detect a received power, and a threshold for selecting a beam terminal from which the correlator output has reached a certain level or more from the predetermined number of the plurality of beam terminals. In a digital beamforming antenna for a base station, comprising a value judging means and a demodulator for demodulating the beam terminal output selected by the threshold judging means, a digital beamforming antenna based on a digital signal from the A / D converter. A position detecting device for detecting a direction of arrival of a specific signal; and a weighting section for giving a weight to the digital signal from the A / D converter based on detection information of the position detecting device to generate a main beam in the direction of arrival of the specific signal. A pencil beamformer to be formed, a correlator for performing a correlation process on the output of the pencil beamformer and detecting received power, and an output of the correlator. A demodulator for demodulating provided and separates processing the particular signal.

According to a third aspect of the present invention, there is provided a digital beamforming antenna for a base station according to the first aspect of the present invention, wherein a specific signal arrives based on a digital signal from the A / D converter. A position detecting device for detecting a direction, and a pencil beam forming for giving a weight to the digital signal from the A / D converter based on detection information of the position detecting device to form a main beam in the direction of arrival of the specific signal A correlator for performing a correlation process on the output of the pencil beamformer to detect the received power, and a demodulator for demodulating the correlator output, and separating the specific signal. .

According to a fourth aspect of the present invention, there is provided a digital beamforming antenna for a base station which is used in a communication system employing a CDMA system in which a spread signal is subjected to a correlation process using a given code to separate a signal. A station antenna, comprising: a plurality of element antennas; an A / D converter for converting a signal for each of the element antennas into a digital signal; and a digital signal from the A / D converter for weighting and combining. A multi-beamformer for forming a predetermined number of plural beams required as the base station antenna,
A correlator for performing a correlation process for each beam terminal of each of the beams to detect a received power, and a threshold for selecting a beam terminal from which the correlator output has reached a certain level or more from the predetermined number of the plurality of beam terminals. In a digital beamforming antenna for a base station, comprising a value judging means and a demodulator for demodulating the beam terminal output selected by the threshold judging means, a digital beamforming antenna based on a digital signal from the A / D converter. A position detecting device for detecting an arrival direction of one or a plurality of specific signals; and a weighting device for giving a weight to the digital signal from the A / D converter based on detection information of the position detecting device. A plurality of pencil beamformers for forming a main beam in the direction of arrival of a specific signal, and correlation between output of the pencil beamformers and reception power detection. A correlator is provided a demodulator for demodulating for the correlator output and separates processing the one or more specific signals.

A digital beamforming antenna for a base station according to a fifth aspect of the present invention is the digital beamforming antenna for a base station according to the first aspect, wherein one or a plurality of digital beamforming antennas are provided based on the digital signal from the A / D converter. A position detecting device for detecting a direction of arrival of a specific signal; and a method for arriving the one or more specific signals by giving a weight to the digital signal from the A / D converter based on detection information of the position detecting device. A plurality of pencil beamformers for forming a main beam in the direction, a correlator for performing correlation processing on the output of the pencil beamformer to detect received power, and a demodulator for demodulating the correlator output are provided. , For separating one or a plurality of specific signals.

A digital beamforming antenna for a base station according to a sixth aspect of the present invention is the digital beamforming antenna for a base station according to any one of the first to fifth aspects, wherein a part or all of the element antennas are provided. Instead of a sub-array antenna having a plurality of element antennas.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram showing Embodiment 1 of a digital beamforming antenna for a base station according to the present invention. In the figure, 1 is an element antenna, 2 is an A / D converter, 3 is a multi-beamformer by a digital signal processor, 4 is C
A correlator for performing a correlation by using a code for DMA (Code Division Multiple Access); a threshold determining circuit for selecting only a beam terminal having a large power as a result of the correlation;
Is a demodulator. The first embodiment will be described with respect to an operation at the time of reception. The signal received by the element antenna 1 is converted into a digital signal by the A / D converter 2 after performing an appropriate frequency conversion. Therefore, the subsequent processing is performed by the digital signal processor. In the multi-beamformer 3 at the next stage, the inside of the service area (cell) is formed as many beams (aggregate of received signals at the element antennas) as the required number of beams determined from the number of lines, that is, multibeams. I do. The correlator 4 provided with the number of beams performs correlation processing according to the assigned code. In the threshold value judging circuit 5, only the beam terminal at which the power equal to or higher than a certain level is obtained by the correlation processing is connected to the demodulator 6 in the next stage. By simply controlling the beam reception level and independently evaluating each beam by the above method, interference between signals can be reduced and a desired signal can be detected.

FIG. 2 is a conceptual diagram of an antenna communication system, and is an explanatory diagram showing communication between a base station antenna and a terminal station employing the first embodiment. In FIG. 2, reference numeral 7 denotes a base station antenna, 8 denotes a terminal station, and 9 denotes a beam radiated far.
n and 10 are beams #m radiated to the vicinity. beam#
By making the directivity gains of n and beam #m the same, the distance problem, which has been a conventional problem, is solved. The adjustment of the directivity gain is performed by multiplying and synthesizing each signal by the digital signal processor for multi-beam formation in the multi-beamformer 3 in the digital beamforming antenna for the base station as described above. It is done by doing.

Embodiment 2 FIG. 3 is a configuration diagram showing Embodiment 2 of the digital beamforming antenna for a base station according to the present invention. In the first embodiment, the case where the number of correlators is used as many as the number of beams is shown. However, in the second embodiment, the number of correlators is one, and a beam terminal switch 11 is provided instead.
In the beam terminal switch 11, the outputs of the multi-beamformer 3 are sequentially switched in a time-division manner and connected to one correlator 4 to perform a correlation process. Only the beam whose output power is large is determined by the threshold value determination circuit 5, and the next-stage demodulation processing is performed. In this case, the beam terminal switch 1
Switching at 1 is performed at an appropriate timing according to the movement of the terminal station.

The second embodiment has a function equivalent to the method in which a single beam is scanned and a terminal station having a code assigned to the base station is directed to a certain position as shown in FIG. become.

Embodiment 3 FIG. 5 is a block diagram showing Embodiment 3 of a digital beamforming antenna for a base station according to the present invention. In the figure, 12 is a position detector, and 13 is a pencil beam former. A signal is received by the element antenna 1 and converted into an A / D signal.
After performing digital processing by the converter 2, the position detector 12 detects the position of the moving terminal station from the received signal of the element antenna. Then, the pencil beam former 13
Then, a complex weight given to each element antenna is calculated to direct the main beam of the pencil beam to the position of the terminal station detected by the position detector 12, and these are combined to form a beam. In this case, the position detector 12 may be based on other hardware such as a gyro or software. The pencil beam is used to correspond to a terminal station that performs high bit rate communication. In parallel with this, a normal signal is received using the multi-beamformer 3 and processed in the same manner as described in the second embodiment.

In the third embodiment, when a normal signal is used by using the multi-beamformer 3, a single beam is scanned and assigned to the base station as shown in FIG. It has a function equivalent to a system in which a terminal station having a code directs a beam to a certain position. Further, in the third embodiment, the portion receiving the normal signal using the multi-beamformer 3 may be replaced with the configuration shown in FIG. good. FIG. 5 of the third embodiment has a configuration in which one pencil beam is formed for a terminal station that performs high bit rate communication.

Embodiment 4 FIG. 6 is an explanatory diagram showing the configuration of a fourth embodiment of the base station digital beamforming antenna of the present invention. In the fourth embodiment, a plurality of portions corresponding to the high bit rate communication of FIG. 5 described in the third embodiment are provided in parallel to the configuration shown in FIG. 1 or FIG. This configuration enables pencil beam formation for each of a plurality of terminal stations that perform communication. In the configuration explanatory diagram of the fourth embodiment shown in FIG. 6, only the configuration of a portion provided with a plurality of portions corresponding to the high bit rate communication in parallel is shown, and the configuration of the same portion as FIG. 1 or FIG. The description is omitted.

A signal is received by the element antenna 1 and is
After the digital processing is performed by the / D converter 2, the position detector 12 detects the position of the moving terminal station from the received signal of the element antenna. After that, the terminal station detected by the position detector 12 is formed by a pencil beamformer 13 which forms the required number of beams in the service area (cell) by the required number of beams determined from the number of lines and the like. Calculate the complex weight given to each element antenna in order to direct the main beam of the pencil beam to the position, and combine them to form a beam. Further, the correlator 4 provided with the number of beams performs a correlation process according to the assigned code, and a demodulator 6 at the next stage demodulates the correlator output. In addition, a normal signal is handled by using the multi-beamformer 3 in parallel with this, and the same processing as described in the first or second embodiment is performed.

By simply controlling the beam reception level and independently evaluating each beam by the above method, interference between signals can be reduced and a desired signal can be detected. Also, voice communication such as telephone and communication requiring a plurality of high bit rates such as images can be provided by the same base station antenna.

Embodiment 5 In the first to fourth embodiments of the base station digital beam forming antenna, a sub array having a plurality of element antennas in place of part or all of the element antenna 1 is described.
The antennas are dispersed and arranged, and the received signal of the element antenna 1 or each arranged sub-array antenna is converted into a digital signal by the A / D converter 2. The A / D converter 2
Subsequent configurations and operations are the same as those of the first embodiment.
Same as # 4.

[0023]

According to the first aspect of the present invention, the number of correlators can be reduced, interference between signals can be reduced by simply controlling the beam reception level and independently evaluating each beam.
There is an effect that it is possible to detect a desired signal.

According to the second or third aspect of the present invention, for example, when there is a terminal station performing high bit rate communication, a pencil beam having a sharp directivity can be directed in that direction, and high transmission or reception can be achieved. There is an effect that communication with less interference can be performed even when power is present.

According to the invention of claim 4 or claim 5, there is an effect that communication with less interference can be performed even when a plurality of high transmission or reception powers exist. Further, there is an effect that the power supply system of the digital beamforming antenna for the base station can be flexibly configured.

According to the invention of claim 6, since the sub-array antennas having a plurality of element antennas are arranged in a dispersed manner, there is an effect that communication can be performed efficiently.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing Embodiment 1 of a digital beamforming antenna for a base station according to the present invention.

FIG. 2 is an explanatory diagram showing communication between a base station antenna and a terminal station employing the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing Embodiment 2 of a digital beamforming antenna for a base station according to the present invention.

FIG. 4 is an explanatory diagram showing a method of scanning a single beam and directing the beam to a position where a terminal station having a code assigned to the base station is located.

FIG. 5 is a configuration diagram showing Embodiment 3 of a digital beamforming antenna for a base station according to the present invention.

FIG. 6 is an explanatory diagram illustrating a configuration of a digital beamforming antenna for a base station according to a fourth embodiment of the present invention.

FIG. 7 is an explanatory diagram showing communication between a conventional base station antenna and a terminal station.

[Explanation of symbols]

1 element antenna, 2 A / D converter, 3 multi-beamformer, 4 correlator, 5 threshold value judgment circuit, 6 demodulator, 7 base station antenna, 8 terminal station, 9 beam #
n, 10 beam #m, 11 beam terminal switcher,
12 position detector, 13 pencil beamformer, 14
service area.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeru Makino 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (72) Inventor Yoshiyuki Chatani 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Inside Electric Co., Ltd. (72) Inventor Hideo Sumiyoshi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Co., Ltd. (56) References JP-A-2-141333 (JP, A) JP-A-8-213931 ( JP, A) WO 96/466 (WO, A1) (58) Fields studied (Int. Cl. ⁷ , DB name) H04B ^7/ 24-7/26 102 H04Q ^7/ 00-7/38

Claims (6)

(57) [Claims] A spread code is used by using a given code.
CDMA (Code) that performs correlation processing and separates signals
Division Multiple Access) communication system
A base station antenna used in a system,
Digital signals for each antenna
An A / D converter for converting the data into the data from the A / D converter.
Weighting the digital signals and combining them to make the base station
The required number of multiple beams required for
A multi-beamformer to form and a beam of each of the above beams
Beam terminal switching to switch connection to the next stage for each terminal
And the beam connected by the beam terminal switcher.
Correlation to detect received power by performing correlation processing sequentially for each system terminal
And a correlator from the predetermined number of beam terminals.
Select a beam terminal whose output exceeds a certain level.
Threshold determination means and the threshold determination means
And a demodulator for demodulating the output of the beam terminal.
Digital beamforming antenna for base stations. 2. Use of a code given a spread signal.
CDMA system that performs correlation processing and separates signals
Base station antenna used for the communication system used.
And a plurality of element antennas and signals for each of the above element antennas.
An A / D converter for converting the A / D into a digital signal;
Composite by giving weight to digital signal from D converter
A predetermined number required for the base station antenna
A multi-beamformer for forming a plurality of beams, and
Correlation processing is performed for each beam terminal of each beam to detect the received power.
Out of the correlator and the predetermined number of beam terminals
Beam end where the correlator output has exceeded a certain level
Threshold determination means for selecting a child, and the threshold determination means
A demodulator that demodulates the beam terminal output selected in the stage
Digital Beamforming for Base Stations with Modulator
At the antenna, the digital signal from the A / D converter
Position detection that detects the arrival direction of a specific signal based on the signal
A based on the detection information of the device and the position detecting device,
Give weight to digital signal from / D converter
A pencil that forms a main beam in the direction of arrival of a specific signal
The beamformer and the output of the pencil beamformer
A correlator for performing a correlation process and detecting a received power;
A demodulator for demodulating the output is provided, and the specific
Digital beamformer for base station to separate signals
Antenna. 3. The digital beam for a base station according to claim 1.
In the forming antenna, the A / D converter
The direction of arrival of a specific signal is detected based on these digital signals.
Output position detection device and the detection information of the position detection device.
Based on the digital signal from the A / D converter.
To form a main beam in the direction of arrival of the specific signal.
Pencil beam forming device and pencil beam shape
Correlator that performs correlation processing on the output of the generator and detects the received power
And a demodulator for demodulating the correlator output.
For the base station that separates and processes the above specific signals.
Beamforming antenna. 4. Use of a code given a spread signal.
CDMA system that performs correlation processing and separates signals
Base station antenna used for the communication system used.
And a plurality of element antennas and signals for each of the above element antennas.
An A / D converter for converting the A / D into a digital signal;
Composite by giving weight to digital signal from D converter
A predetermined number required for the base station antenna
A multi-beamformer for forming a plurality of beams, and
Correlation processing is performed for each beam terminal of each beam to detect the received power.
Out of the correlator and the predetermined number of beam terminals
Beam end where the correlator output has exceeded a certain level
Threshold determination means for selecting a child, and the threshold determination means
A demodulator that demodulates the beam terminal output selected in the stage
Digital Beamforming for Base Stations with Modulator
At the antenna, the digital signal from the A / D converter
The direction of arrival of one or more specific signals based on the signal
Position detecting device to be detected and detection information of the position detecting device
Based on the digital signal from the A / D converter
To give the arrival of one or more specific signals
Multiple pencil beamformers forming a main beam in different directions
And perform a correlation process on the output of the pencil beamformer.
Correlator for detecting received power and output of the correlator
And a demodulator for demodulating the one or more characteristics described above.
Digital beamformer for base station that separates fixed signals
Antenna. 5. The digital beam for a base station according to claim 1.
In beam forming antenna, or the A / D converter
One or more specific signals based on these digital signals.
Position detecting device for detecting the arrival direction of a signal, and the position detecting device
Based on the detection information of the device, the
Digital signal by weighting one or more of the above characteristics.
Multiple pencils that form the main beam in the direction of arrival of a given signal
To the output of the pencil beamformer and the pencil beamformer
A correlator that performs correlation processing and detects received power;
And a demodulator for demodulating the output of the
Or a base station digital signal that separates and processes multiple specific signals.
Tal beam forming antenna. 6. The method according to any one of claims 1 to 5, wherein
Digital beamforming antenna for base station as described
In place of part or all of the element antenna,
With a sub-array antenna having a number of element antennas
Digital beamforming antenna for base stations.