JP2003060424A - Array antenna, radio communication system and pilot frequency determining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve by avoiding using a variable device, such as a variable phase shifter, a voltage-controlled oscillator, or the like, a drive circuit for control the device, and an algorithm for controlling beam direction. SOLUTION: Mixers M1 to M4 are inserted between antenna elements A1 to A4 and a distributor/combiner 44, respectively, and a mixer 45 is inserted between the distributor/combiner 44 and a signal terminal 45. A pilot signal is received through an antenna 33 and a filter 41, and is supplied directly to the mixers M3, 46, to be supplied to the mixer M1 through a series circuit of a delay line P1-P2-P3 of the same length and to the mixers M2, M3 through each connection point of the delay line, respectively. The frequency of the pilot signal is changed to control the beam direction, and the frequency deviation of a power supply signal due to the mixers M1 to M4 is connected by the mixer 46.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an array antenna for a terminal or a base station or a relay station used in a fixed wireless communication service for general homes and office buildings, and a radio using this array antenna. The present invention relates to a communication system and an array antenna beam direction control pilot frequency determination method.

[0002]

2. Description of the Related Art An array antenna is an antenna that forms a transmission or reception radio wave beam (hereinafter simply referred to as a beam) using a plurality of antenna elements, and the transmission signal or reception signal of each antenna element (hereinafter, both antennas). The beam direction can be electrically changed by manipulating the phase of the power supply signal). As typical array antennas whose beam directions can be changed, there are a feeding point switching scanning type antenna configuration using a multi-beam matrix circuit for the feeding circuit and a phase scanning type antenna configuration using a variable phase shifter. [Reference:
See Institute of Electronics and Communications, "Antenna Engineering Handbook", Chapter 5, Ohmsha].

FIG. 11 shows an example of a feed point switching scanning type array antenna using a Butler matrix circuit which is a typical multi-beam matrix circuit and a switch, in the case of beam transmission using four antenna elements A1 to A4. Is. The Butler matrix circuit 11 is a circuit that performs electrical FFT (Fast Fourier Transform) composed of a hybrid and a phase shifter, and the phase difference between a plurality of ports on the output side changes (output The phase slope on the side changes). Therefore, a switch in which the antenna elements A1 to A4 are respectively connected to the ports PA1 to PA4 on one side of the Butler matrix circuit 11 and the switching terminals SM are switched and connected to the ports S1 to S2 on the other side of the Butler matrix circuit 11 ( A beam selection switch) 12 is provided to form an array antenna. The beam direction of the antenna is controlled by connecting the signal from the terminal T to the switching terminal SM of the switch 12 and controlling the switch 12 to change the positions of the ports PS1 to PS4 for feeding power.

The switching of the power supply port of the switch 12 is performed by a beam selection switch control signal generating circuit (drive circuit) 13
Done by. However, such a feed point switching scanning array antenna has a drawback that the beam directing directions are discrete angles, and it is difficult to accurately direct the beams in a target direction. Also, a multi-beam matrix circuit (Butler matrix circuit 11)
With regard to (2), it is very difficult to manufacture a large-scale circuit because the connection in the circuit becomes complicated when the number of ports is large. Large-scale multi-beam matrix circuits are very large and expensive, or circuit errors and losses are very large, so at present, they are applied only when the array size is small. There is.

FIG. 12 shows an example of a phase scanning type array antenna which realizes a desired excitation phase of each antenna element by controlling a variable phase shifter. Similar to the case of FIG. 11, it is a case of beam transmission using four antenna elements A1 to A4. The signal from the terminal T is distributed by the distributor 14, and the respective distributed signals are variable phase shifters VP1 to VP4.
Through the antenna elements A1 to A4. This array antenna has individual antenna elements A1 to A1.
Since the phase of the signal distributed to the 4 is directly controlled by the variable phase shifters VP1 to VP4 by the control signal from the variable phase shifter control signal generation circuit (drive circuit) 15, the beam direction can be continuously changed. It is possible.

However, since a phase scanning array antenna generally requires a large number of variable phase shifters VP, it is generally expensive and is not suitable for a large-scale array antenna. Further, the antenna configuration using a large number of variable phase shifters VP has a drawback that complicated antenna control is required. For example, when a digital phase shifter is used as the variable phase shifter VP, one phase shifter requires a large number of control lines, and the entire antenna requires a very large number of control lines. Further, when an analog phase shifter is used, the amount of phase shift is generally not proportional to the control voltage, so it is necessary to individually adjust the control voltage applied to the variable phase shifter VP.

An antenna configuration using a voltage-controlled oscillator has been reported as a device for realizing a large-scale array antenna at a relatively low price [Japanese Patent Laid-Open No. Hei 7-202548].
This is proposed as a receiving antenna to be mounted on a mobile body such as an automobile in a satellite communication application where a relatively high gain is required. FIG. 13 shows a beam receiving antenna as this example. The antenna elements A1 to A4 are the mixer M1.
~ M4 is connected to the combiner 16. The mixer performs frequency mixing (multiplication) of two input signals, and the output of the oscillator 16 is normally input to one of the inputs of the mixer. The received signal input to the mixer Mi (i = 1, 2, ...) Is multiplied by the non-modulated wave signal from the oscillator 17 to be frequency-shifted by the output signal frequency of the oscillator 17 and output. Therefore, the mixer is generally widely used as a frequency converter. In the antenna configuration shown in FIG. 13, the oscillator output input to the mixers M1 to M4 connected to the antenna elements A1 to A4 is the phase shifter P1.
A constant phase difference is added by P3 and input to the mixer. In the phase shifters P1 to P3, for example, the same delay lines are connected in series, and the mixer M1 receives the outputs of the phase shifters P1 to P3, and the mixers M2 and M3 respectively shift the phase shifters P2 to P3.
The output of P3 is directly supplied to the output of the oscillator 17 to the mixer M4.

The received signals of the antenna elements A1 to A2 input to the respective mixers are each rotated in phase by an amount corresponding to the phase amount of the multiplication signal (oscillator output given a phase difference), and the antenna elements A1 to A2 are then rotated. A different phase difference is given for each A4. This array antenna uses a voltage controlled oscillator (VCO) as the oscillator 17, and the amount of phase rotation applied by the phase shifters P1 to P5 can be changed by changing the frequency of the oscillator output. Beam scanning is possible. With this array antenna configuration, even if the number of antenna elements is large, the beam direction can be controlled by controlling one or two voltage-controlled oscillators. It can be realized at a low price.

The phase shifters P1 to P3 are composed of delay lines of the same length, for example, and they constitute a means 18 for imparting a phase difference to the oscillator output as a whole. The mixer 19 multiplies the output of the oscillator 21 by the output of the combiner 16 to correct the frequency shift of the received signal based on the multiplication in the mixers M1 to M4. VCO 17 (and 21) by VCO control voltage generation circuit (drive circuit) 22
It is possible to control the receiving beam direction by controlling the oscillation frequency of. The oscillators 17 and 21 may be combined into one.

However, a problem common to these conventional array antenna configurations described above is that these array antennas must have most of the beam direction control mechanism themselves. That is, a variable phase shifter, a voltage controlled oscillator or a beam changeover switch which is a device for directly controlling the beam direction, and a drive circuit 15 or 2 for controlling these variable devices.
2, or 13, and because an algorithm for controlling the beam direction is required, the load of the antenna alone is very large, and these array antennas FWA (Fix
Even if it is applied to a terminal antenna or the like of a wireless communication service typified by ed Wireless Access), it will be very expensive.

For example, as shown in FIG. 14, beam control of these array antennas is performed by a specific base station (control station).
It is conceivable that centralized management is performed by 23, and the configuration is such that the beam control algorithm is not taken into consideration in each terminal array antenna. That is, the beam control signal transmitted from the control station 23 is received by the antenna 24 on the terminal side, and the information on the beam control is extracted and decoded (demodulation processing).
An extraction / decoding unit 25 for performing the above is provided, the variable device 26 such as the VCO described above is controlled by the decoded control signal, and a beam direction control circuit 22 such as a mixer is further provided as necessary.

However, even in this case, the terminal antenna 24 needs to obtain information for controlling the drive circuit from the control station (base station managing beam control). That is, in order for the terminal side to decode the beam control information transmitted from the control station 23, it is necessary to secure a communication gain sufficient for the demodulation process, and the control station 23 provides a high gain (or a large output). Beam) is being transmitted, or the terminal antenna 24 must first direct a beam with sufficient gain to the control station. However, in order for the control station 23 to be able to transmit a high-gain or high-power beam toward the individual terminal antennas 24 for beam control of the terminal array antenna, a large amount of capital investment is required for the antennas of the control station 23. At the same time, a high-gain or high-power beam may become a new interference factor. In addition, the direction of the control station 23 is known, and the terminal antenna 2
In order for 4 to direct a beam having a sufficient gain to the control station in advance, it is necessary to newly prepare an antenna (antenna with a large aperture diameter) 24 having a sufficient gain and correctly direct the beam to the control station 23. . Therefore, the size and installation price of the terminal increase, and at the same time, even if a new terminal station or control station is installed, it is difficult to deal with them, and the flexibility and expandability of the network are poor. Further, there is a possibility that the accuracy of beam control may be deteriorated due to environmental changes of the elements of the beam direction control circuit.

[0013]

As described above, in the array antenna of the prior art, a variable device (a phase shifter, a voltage controlled oscillator or a beam changeover switch) for directly controlling the beam direction, and a variable device for controlling these variable devices. Since the drive circuit and the algorithm for controlling the beam direction are required, there is a problem that the load on the antenna is large and it is difficult to reduce the cost. Also, even if the array antenna itself does not have an algorithm for controlling the beam direction and the beam direction is centrally controlled by other wireless stations, it does not work with the wireless station that performs beam control. Since it is necessary to secure the communication gain necessary for demodulation processing, it is necessary to newly install an antenna with sufficient gain and adjust the direction, and at the same time, there is a drawback that the network lacks flexibility and expandability. .

[0014]

According to a first aspect of the present invention, a pilot antenna is provided in addition to a plurality of antenna elements for an array, and a beam control pilot is provided from a signal received by the pilot antenna. The signal is extracted by the pilot signal extraction circuit, and the extracted pilot signal is given a phase-dependent phase difference depending on the frequency by a fixed circuit such as a delay line by the phase difference providing means with respect to the feed signal. The power feeding signals are multiplied by the multiplying means, and the extracted pilot signals are used to correct the frequency deviation of the power feeding signals based on the multiplication by the correcting means.

Two pilot signals are extracted by the pilot signal extraction circuit, a differential frequency signal between the extracted two pilot signals is generated by the differential signal generation circuit, and the obtained differential frequency signal is added to the phase difference. It may be provided to the means and used for correction by the correction means. Further, a pilot signal or a signal having a differential frequency of the pilot signal is reproduced by a reproducing circuit including an oscillator, and the reproduced signal is supplied to the supply difference providing means and used for correction by the correcting means, and the pilot signal A configuration may be provided in which a means for switching between transmission and reception depending on the presence or absence of

According to the second aspect of the present invention, the signals of the differential frequencies of the plurality of reference carrier waves output from the carrier wave regenerating circuit are given the phase difference by the signals of the differential frequency of the reference carrier wave obtained by the difference signal generating circuit. Is supplied to the means to be provided with an electrical length difference, the difference frequency signals provided with these electrical length differences and the respective feed signals of the antenna elements are multiplied by the multiplying means, and the multiplication is performed using the signal of the difference frequency. The frequency deviation of the power supply signal based on is corrected by the correction means. According to a third aspect of the present invention, the array antenna according to the first or second aspect is used as a terminal or base station antenna, and the frequency of a pilot signal or the frequency of a carrier wave received by the array antenna is changed. By doing so, the beam direction of the terminal or base station antenna can be controlled from the outside.

The array antenna of the present invention having the above configuration does not require a variable device such as a variable phase shifter or a voltage controlled oscillator for directly controlling the beam direction. Therefore, since a circuit for controlling these variable devices is not required, the cost of the antenna can be reduced. Further, since the array antenna of the present invention requires only the information on the frequency of the pilot signal emitted from the control station, it does not require a high gain antenna for beam control. That is,
Since it is not necessary to transmit and receive the information for beam control as a modulation signal, the antenna for receiving the pilot signal may be small, and since it has a wide directivity pattern, it is almost unnecessary to be aware of the direction of the control station. From this, it is possible to simplify the labor for antenna installation and adjustment, and at the same time, it is possible to perform beam control using control stations at different positions, and it is easy to deal with the addition of base stations. At the same time, it is possible to build a flexible network with multiple base stations.

For example, as shown in FIG. 1, the control station 31 transmits a pilot signal to a terminal 32, and the terminal 32 receives the pilot signal at its pilot antenna 33.
The pilot signal extraction unit 34 extracts the pilot signal,
The pilot signal is given a phase difference depending on the frequency by a fixed circuit such as a delay line, and these antenna elements A1
The beam direction control circuit 35 may multiply the feed signals of A4 to A4. The beam direction may be controlled by changing the frequency of the pilot signal transmitted by the control station 31. Therefore, the variable device (voltage-controlled oscillator) for directly controlling the beam direction is provided on the control station side, which makes it possible to minimize the circuit scale of the terminal 32 and at the same time make the network construction more flexible. Become.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to examples. Embodiment 1 FIG. 2 illustrates an embodiment according to the first aspect of the present invention, in which an array of four elements A1 to A4 and an antenna 33 for receiving a pilot signal are provided. The filter 41 connected to the pilot signal receiving antenna 33 is a unit that separates the frequency component in which the pilot signal exists and the frequency components other than the pilot signal and extracts only the pilot signal, that is, a pilot signal extraction circuit. The pilot signal extracted by the filter 41 is amplified by the amplifier 4 to a level sufficient for multiplication with the feed signal, if necessary.
After being amplified by 2, the phase difference (electrical length difference) is given by the phase difference giving means 43 for giving a phase-dependent phase difference consisting of a fixed circuit such as a delay line, and each antenna element A1 to A4. Mixers (multipliers) M1 to M connected to
4 is input. In this example, the phase difference providing means 43 is composed of the same phase shifters P1 to P3, which are delay lines, connected in series, and a pilot signal is supplied to one end of the series connection.
The output pilot signal at the other end is supplied to the mixer M1, the pilot signal from the connection point of each phase shifter is supplied to the corresponding mixer, and the pilot signal from the amplifier 42 is directly supplied to the mixer M4.

From the theory of array antennas, the phase difference given by the phase difference giving means 43 is the element spacing D _{E of the} array.
And the beam scanning angle required for the antenna. For example, assuming that the element spacing D _{E of the} array is 0.5 wavelength and the range of the beam scanning angle of the antenna is ± 90 degrees, the maximum signal path difference to be given between the antenna elements is 0.5 wavelength, The phase difference between the elements is ± 180 degrees. Here, if a band of ± 10% is secured as the frequency shift amount of the pilot signal, and it is assumed that delay lines are used as the phase shifters P1 to P4 and the inter-element phase difference is realized by the line length, The line length required to give a path difference of 0.5 wavelength by shifting the frequency of the pilot signal by ± 10% is 5 wavelengths of the reference pilot signal. That is, the frequency of the pilot signal is 10 GHz ±
If it is 1 GHz, the phase difference between the array elements is 1
It may be realized by a delay line (phase shifter) having a line length of 5 cm (Note: 1 wavelength at 10 GHz is 3 cm). In FIG. 2, a mixer 46 is inserted between the signal terminal 45 and the distributor / combiner 44 connected to the antenna elements of the mixers M1 to M4 on the opposite side, and the pilot signal is also input to the mixer 46. , The frequency deviation of the feed signal based on the multiplication of the pilot signals in the mixers M1 to M4 is corrected, and the frequency at the input / output of the array antenna is always constant regardless of the frequency of the pilot signal. The mixer 46 is this correction means.

This array antenna does not require a variable device such as a variable phase shifter or a voltage controlled oscillator for directly controlling the beam direction. Therefore, since a circuit for controlling these variable devices is not required, the cost of the antenna can be reduced. Further, since the beam direction of this array antenna is directly controlled by the frequency of the pilot signal as described above, the stability of the variable phase shifter and the voltage controlled oscillator which the antenna itself has, as in the antenna of the prior art, The beam direction of this array antenna is uniquely determined by the control station that transmits the pilot signal without having to be aware of environmental fluctuations. Further, unlike the conventional antenna, since it is not necessary to transmit and receive information for beam control as a modulated signal, the antenna 33 for receiving the pilot signal may have a low gain, and when the antenna is installed, it may be directed to the control station. There is no need to adjust to.

In the example shown in FIG. 2, the pilot signal received by the phase difference providing means 43 is distributed to the mixers M1 to M4 of each antenna element by serial feeding, and a plurality of signal branches are required. As shown by attaching the same reference numerals to the parts corresponding to those in FIG. 3 in FIG. 3, the phase difference giving means 43 firstly distributes the received pilot signals by a necessary number by the distributor 47, and then the electric length becomes a constant value. The phase shifters P1 to P3 each of which is composed of a fixed circuit such as a different delay line are used to mix the mixer M.
It is also possible to supply to each mixer 1 to M3 or directly to the mixer M4 without passing through the phase shifter, that is, input to each mixer by parallel feeding.

Further, in FIG. 2, a mixer (correction means) 46 between the distributor / combiner 44 and the signal terminal 45 makes the frequencies at the input and output of the array antenna equal. That is, the frequency of the signal at the signal terminal 45 and the antenna elements A1 to A
The signal frequencies of 2 are made equal. However, as shown in FIG. 7, the pilot signal from the distributor 47 is frequency-converted by the mixer 48 to a certain frequency by the local signal from the local oscillator 40 without directly inputting the pilot signal to the correction mixer 46. May be supplied to In this way, the signal of the signal terminal 45 (not the RF band)
It can be an IF band or baseband signal,
Moreover, it is possible to correct the frequency deviation of the power supply signal based on the multiplication of the pilot signals in the mixers M1 to M4. Second Embodiment FIG. 4 shows another embodiment of the first aspect of the present invention, in which parts corresponding to those in FIG. 2 are designated by the same reference numerals. In this embodiment, the connection diplexer 51 is connected to the pilot signal receiving antenna 33, and the diplexer 51 extracts two pilot signals from a plurality of received pilot signals,
The two extracted pilot signals are multiplied by each other by the mixer 52 to generate a signal having a difference frequency between the two extracted pilot signals, and the difference frequency signal is frequency-multiplied by the multiplier 53 as necessary, Is amplified by the amplifier 42 in accordance with
3 is supplied. That is, the difference frequency signal is shown in FIG.
Is used as a pilot signal in the embodiment. The diplexer 51 constitutes a pilot signal extraction circuit for extracting two pilot signals, and the mixer 52 constitutes a differential signal generation circuit for generating a differential frequency signal of the two pilot signals.

This antenna configuration is characterized in that the occupied band of the pilot signal can be reduced by using two kinds of pilot signals. In the first embodiment shown in FIGS. 2 and 3, the frequency of the pilot signal is directly shifted by 10% in order to shift the frequency input to the mixers M1 to M4 by 10%. Therefore, in the first embodiment, ± 10 of the pilot signal of 10 GHz is used.
It was supposed to occupy 2 GHz as a band corresponding to%. However, in the antenna configuration of the second embodiment, 2
Since the differential frequency signal of the two pilot signals is used, for example, if the reference differential frequency of the two pilot signals is 100 MHz, 100 MHz is required to shift the frequency input to the mixers M1 to M4 by 10%.
That is, a band corresponding to ± 10% of is good. That is,
If one of the two pilot signals was f _p, the other pilot signal f _p + 90MHz~f _p +11
It becomes 0 MHz, and the occupied band including the two pilot signals is 110 MHz. Embodiment 3 FIG. 5 shows still another embodiment of the first aspect of the present invention,
The parts corresponding to those in FIG. 2 are designated by the same reference numerals. In this embodiment, the received pilot signal is used as it is in the mixer M.
1 to M4, but not to each mixer M1 to M4
A signal reproduced by a reproducing circuit 55 having an oscillator is used as a signal directly input to the. In this figure, the phase-locked loop is supplied as a control signal to the VCO 56 through the loop filter 58, the pilot signal from the amplifier 42 and the output signal of the voltage controlled oscillator (VCO) 56 are supplied to the mixer 57, and the output of the mixer 57 is formed. The frequency of the VCO 56 is pulled into the frequency of the pilot signal by the reproduction circuit 55. The reproduced pilot signal, that is, the output signal of the VCO 56 is supplied to the phase difference providing means 43.

By thus reproducing the pilot signal using the VCO or the like, even if the pilot signal is temporarily interrupted, the beam direction (the frequency of the reproduced signal) is maintained, and at the same time, the environment in which the noise level is high is high. The feature is that the pilot signal can be transmitted and received. Further, in the third embodiment, transmission / reception is switched depending on the presence / absence of a pilot signal. That is, the correction mixer 46, the transmission signal terminal 45S, and the reception signal terminal 4
For example, TDD (Tim) as a transmission / reception switching means between the 5R and
e Division Duplex switch 61
And the received pilot signal from the amplifier 42 is supplied to the signal level detection circuit 62, and the signal level detection circuit 62 considers that the pilot signal is not being received when the level of the pilot signal is less than a predetermined value, and
By controlling the switch 61, the mixer 46 is transmitted to the transmission signal terminal 4
If the level of the pilot signal is higher than a predetermined value, the mixer 46 is connected to the reception signal terminal 45R.

With this structure, the transmission / reception timing of the antenna can be freely controlled by the control station (base station), and by making the packet length variable, a vertically asymmetric network or the like can be easily realized. is doing. Embodiment 4 FIG. 6 shows an embodiment according to the second aspect of the present invention. In this embodiment, the information for beam control is not received as a pilot signal but is received using the frequency of the carrier. Therefore, in this antenna configuration, the wireless station of the communication partner generally assumes the function of the control station for controlling the beam direction. The received signal from the correction mixer 46 is 2 out of the reference carrier waves reproduced by the carrier wave reproducing circuit 65.
For example, a main carrier and a subcarrier or two subcarriers are taken out, these two reference carriers taken out are input to a mixer 66, and a signal of a difference frequency between these two reference carrier frequencies is obtained from the mixer 66. The difference frequency signal is frequency-multiplied by the frequency multiplier 67 as needed and supplied to the phase difference providing means 43. That is, the differential frequency signal controls the beam direction.

In the current wireless communication, digital signals are generally transmitted and received, and a receiver of an antenna is provided with a carrier wave recovery circuit 65 for demodulating signals. In general, the carrier recovery circuit 65 extracts the frequency of the carrier and reproduces the reference carrier even in a situation where the reception level of the antenna is low and demodulation processing cannot be performed (the situation where the beam is not formed). By receiving the generated carrier wave, it becomes possible to obtain frequency information for controlling the beam direction. Further, since the frequency of the carrier wave once drawn is held for a while even if the received signal is interrupted, the beam direction is held for a certain time even when the carrier wave cannot be received. As described above, in the fourth embodiment, since the carrier regenerating circuit normally provided in the antenna is used to reduce the newly required circuit, the information for beam control can be obtained without using the pilot signal. It has a feature that an antenna for receiving a pilot signal and a frequency band are unnecessary.

In each of the embodiments shown in FIGS. 4, 5 and 6, the pilot signal (difference frequency signal) may be fed in parallel by using the phase difference providing means 43 shown in FIG. Similarly, in each of the embodiments shown in FIGS. 4 and 5, the pilot signal may be frequency-converted and supplied to the correction mixer 46 as shown in FIG.
Moreover, in each embodiment, the number of antenna elements of the array antenna is not limited to four. Embodiment 5 FIG. 7 shows an embodiment of the third aspect of the present invention. In this example, sector antennas are used as the antennas of the base stations A and B, and any of the array antennas shown in the first to third embodiments is used as the antenna of each terminal i (i = 1, 2, ...). It constitutes a communication system. In this wireless communication system, by using the array antenna of the present invention as the terminal antenna, a terminal antenna having a beam scanning function can be realized at a low price, and at the same time, a flexible network can be constructed.

A processing procedure for constructing a network when a base station is newly installed will be described with reference to FIGS. 7 and 8. When the base station x is newly installed, it is necessary to determine the frequency of the pilot signal that directs the beam of the terminal antenna within the communication area of the base station x to the base station x. In step S1, the transmission from the existing base station (or the beam control station) is performed at the same time when the terminal i transmits the beam at a constant level under the control of the existing base station (or the beam control station) (in the calibration mode). The frequency scanning of the pilot signal is performed, that is, the beam direction of the terminal i is scanned, and the scanning frequency and the information indicating the terminal i in the calibration mode are notified to the newly installed base station x. The base station x monitors the reception level of the transmission beam from the terminal i.

In step S2, it is checked whether or not the base station x can receive the signal at a desired level (a level at which communication is possible) or higher. If it can be received, the pilot signal when the reception level becomes highest in step S3. The frequency f _xi is stored as the pilot signal frequency f _xi that directs the beam of the terminal i to the base station x. When the frequency scanning of the pilot signal is completed in step S4, the transmission state (calibration mode) of the terminal i is released. In step S5, it is checked whether or not the above procedure has been carried out individually for all terminals in the area. If there is a terminal that has not been carried out, the procedure returns to step S1. If all terminals are completed, the processing ends. To do.

The base station x newly installed in this way
Are taken into the wireless network, and the base station x receives the frequency f
The beam of the terminal i can be directed to the base station x by transmitting the pilot signal of _xi . Depending on the terminal, for example, it becomes possible to communicate with both the base stations A and B in FIG. 7, and when starting communication from the base station side to the terminal,
For example, the base station with less traffic is used. Figure 9
Shows the processing procedure for network construction when a terminal is newly installed. In installing a terminal, it is necessary to determine the frequency of a pilot signal that directs a beam to a base station within a certain communication area. First, step S
In step S2, the terminal i installed in step 1 transmits a beam at a constant level, that is, the beam is transmitted, and the frequency of the pilot signal transmitted from the base station (or the beam control station) is scanned. Monitor the receive level of the transmit beam from. In step S3, it is checked whether or not the reception is performed at a desired level (a level at which communication is possible) or higher.
If the signal can be received, the pilot signal frequency f _xi when the reception level becomes the highest in step S4 is stored as the pilot signal frequency for directing the beam of the terminal i to the base station x.

In step S5, it is checked whether or not the above procedure has been carried out with all the base stations in the area. If there is a base station that has not been carried out, the process returns to step S2 and carried out for all the base stations. In this case, the transmission state (calibration mode) of the terminal i is canceled in step S5. In this way, the newly installed terminal i is introduced into the wireless network, and the base station x can direct the beam of the terminal i to the base station x by transmitting the pilot signal of the frequency f _xi . To put the terminal i into the transmission state (calibration mode), it is necessary to manually perform it when the terminal is installed, but the transmission state (calibration mode) can be released from the base station remotely (remote control). After the antenna is installed, the user side does not have to do any work until the terminal is taken into the wireless network, and the work required for installing and adjusting the antenna is greatly simplified.

In FIG. 7, the pilot signal is sent from the base station to the terminal and the antenna beam of the terminal is directed to the base station. However, the pilot signal does not necessarily have to be sent from the base station. That is, for example, as shown in FIG. 10, a pilot signal may be transmitted from a specific station (beam control station) to centrally control the beam control of the terminal by the specific station (beam control station). is there. That is, the terminal i is transmitted from the control station, the pilot signal is transmitted from the control station, and the frequency is scanned. The terminal i controls the direction of the transmission beam by this pilot signal, and the base stations A and B monitor the reception level of the transmission beam from the terminal i. Each base station notifies the reception level of the transmission beam of the terminal i to the control station, and the control station determines the pilot signal frequency for directing the antenna beam to each base station for each terminal i. The control station may notify each base station of the pilot signal frequency scanning state so that each base station can know the pilot signal frequency when the transmission beam of the terminal i is directed to the base station.

In the embodiment shown in FIG. 6, for example, a terminal equipped with this array antenna is caused to repeat transmission and reception, and a base station or a control station scans for deviation of carrier frequency.
The terminal may transmit in the beam direction set at the time of reception, the base station may receive this transmission beam, and find the pair of the carrier frequency deviation and the terminal at which the reception level becomes maximum. In the wireless communication system of the present invention thus constructed, since the beam control of the terminal is performed by the base station (or the beam control station), the direction of the base station is directed to the terminal (or the user who owns the terminal). It is possible to build a network without being conscious of the expansion of base stations and to increase the number of base stations, and it is possible to realize a flexible network such as changing the base station that communicates according to the line usage status (accessing multiple base stations). Have advantages. In addition, the array antenna of the present invention has a variable device (voltage controlled oscillator) for directly controlling the beam direction on the control station side, thereby minimizing the circuit scale and reducing the price of the terminal antenna. Is possible.

[0035]

As described above, the array antenna of the present invention does not require a variable device such as a variable phase shifter or a voltage controlled oscillator for directly controlling the beam direction. Therefore, there is no need for a circuit or the like for controlling these variable devices, and the cost of the antenna can be reduced. Also,
With the array antenna according to the present invention, since the beam direction of itself is adjusted without being aware of the direction in which the base station or the control station transmitting the pilot signal exists, the time and effort required for antenna installation and adjustment are simplified. At the same time, it is possible to perform beam control by using control stations located at different positions, and it is possible to flexibly cope with the expansion of base stations and at the same time to deal with multiple base stations. It is also possible to build an advanced network.

Further, according to the embodiment shown in FIG. 4, it is possible to reduce the required band of the pilot signal required for controlling the beam direction, and according to the embodiment shown in FIG. It is possible to control both the beam direction and the transmission / reception timing of the antenna from the base station or the control station using the signal. Furthermore, according to the embodiment shown in FIG. 6, control of the beam direction is realized without using a pilot signal for beam control.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a flow of a beam control signal when an array antenna beam according to a first aspect of the present invention is controlled by another station.

FIG. 2 is a diagram for explaining an embodiment of the first aspect of the present invention.

FIG. 3 is a diagram for explaining another embodiment of the first aspect of the present invention.

FIG. 4 is a diagram for explaining still another embodiment of the first aspect of the present invention.

FIG. 5 is a diagram illustrating still another embodiment of the first aspect of the present invention.

FIG. 6 is a diagram for explaining an embodiment of the second aspect of the present invention.

FIG. 7 is a diagram illustrating an embodiment of the third aspect of the present invention.

8 is a flowchart showing an example of a processing procedure when a base station is installed in the embodiment shown in FIG.

FIG. 9 is a flowchart for explaining an example of a processing procedure when the terminal is installed in the embodiment shown in FIG.

FIG. 10 is a diagram for explaining another embodiment of the third aspect of the present invention.

FIG. 11 is a diagram illustrating a conventional feed point switching scanning type array antenna.

FIG. 12 is a diagram illustrating a conventional phase scanning array antenna.

FIG. 13 is a diagram illustrating a low-cost receiving antenna mounted on a conventional moving body such as an automobile.

FIG. 14 is a diagram illustrating a flow of a beam control signal when a conventional array antenna is controlled by another station.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Taiji Takatori             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Tomohiro Seki             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation (72) Inventor Toshikazu Hori             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 5J021 AA05 AA06 DB03 EA04 FA00                       FA06 FA09 FA16 FA17 FA23                       FA24 FA26 FA32 GA02 HA05                 5K059 CC04 DD32 DD37

Claims (6)

[Claims] 1. An array antenna comprising a plurality of antenna elements, the antenna receiving a pilot signal emitted from an antenna other than this array antenna, a circuit for extracting the received pilot signal, and the extracted antenna. Means for imparting a frequency-dependent phase difference to the pilot signal by a fixed circuit such as a delay line; means for multiplying the pilot signal to which the phase difference has been imparted and each feed signal of each antenna element; And a means for correcting the frequency shift of the feed signal based on the multiplication by using the pilot signal thus generated. 2. An array antenna composed of a plurality of antenna elements, wherein an antenna receives a plurality of pilot signals emitted from an antenna other than the array antenna, and two of the received plurality of pilot signals are extracted. Circuit, a circuit for obtaining a signal of the extracted differential frequency of the two pilot signals, and means for imparting a frequency-dependent phase difference to the obtained signal of the differential frequency by a fixed circuit such as a delay line, A means for multiplying the signal of the difference frequency to which these phase differences are applied and the respective feed signals of the respective antenna elements, and using the signal of the obtained difference frequency, the frequency deviation of the feed signal based on the multiplication is calculated. An array antenna comprising: means for correcting. 3. The array antenna according to claim 1 or 2, further comprising a circuit for regenerating the pilot signal or a signal of a differential frequency of the pilot signal using an oscillator, and providing the phase difference. The signal supplied to the above is the reproduced signal, the signal used for correction by the means for correcting the frequency shift is the reproduced signal, and means for switching between transmission and reception depending on the presence or absence of the pilot signal is provided. An array antenna characterized in that 4. An array antenna composed of a plurality of antenna elements, a circuit for obtaining a signal of a differential frequency of a plurality of reference carriers output from a carrier recovery circuit, and a signal of a differential frequency of the obtained reference carrier. A means for applying a phase difference depending on the frequency by a fixed circuit such as a delay line, a means for multiplying the signals of the difference frequencies to which the phase difference is applied, and the respective feed signals of the antenna elements, and Using the signal of the difference frequency of the reference carrier,
An array antenna comprising means for correcting a frequency shift of the feed signal based on the multiplication. 5. The array antenna according to any one of claims 1 to 4 is used as a terminal or base station antenna, and by changing the frequency of a pilot signal or the frequency of a carrier wave received by this array antenna, A wireless communication system in which a beam direction of an antenna for a terminal or a base station is controllable from the outside. 6. A method of determining a pilot signal frequency for a terminal in a wireless communication system according to claim 5, wherein the terminal is in a transmission state, a pilot signal is transmitted from a base station or a control station, and the frequency of the pilot signal is determined. The base station x scans and receives the radio wave transmitted from the terminal to monitor the reception level thereof, and _obtains the frequency f _{xi of the} pilot signal when the reception level is equal to or higher than a predetermined level and is the maximum. A method for determining a pilot signal frequency for beam direction control, wherein the frequency f _xi is a frequency of a pilot signal for directing an antenna beam of the terminal i toward the base station x.