JPH10256969A - Radio base station equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio base station equipment based on TDD (time division) communication which improves the transmission quality of a down line with a fixed transmission power without increasing the transmission power. SOLUTION: A phase difference between branches for reception which is obtained by a phase difference detector 61 is stored in a memory 63. At the time of transmission, a code is inverted to correct the variance in phase between branches of a transmission/reception circuit by an adder 66, and a phase shifter 10 is set. The transmission signal, which has the phase controlled by the phase shifter 10 so that a reception phase of a mobile station is the same phase, is amplified by a power amplifier 11 having a fixed output and is transmitted. A gain equivalent to equal gain composite diversity is obtained on the outgoing line, and an expected value of the intensity of a reception electric field in a terminal is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio base station apparatus for communicating with a mobile terminal (mobile station).

[0002]

2. Description of the Related Art In recent years, the spread and digitization of public mobile communications represented by cellular phones and personal handy phones have been rapidly progressing. As a standard for a radio section of a mobile radio communication system that performs communication via a base station, for example, a standard relating to a personal handyphone is prescribed in the Radio Industries and Businesses Association Standard Standard RCRSTD-28. In the personal handyphone, a radio wave from the base station to the mobile station (hereinafter, referred to as “down”) and a radio wave from the mobile station to the base station (hereinafter, referred to as “up”) are communicated in the same frequency in a time division manner. Communication is performed by time division communication (TDD).

[0003] In mobile communication, fading generally occurs, and the transmission quality, that is, the bit error rate characteristic is greatly deteriorated. As a method of compensating for deterioration of transmission quality due to fading, diversity reception is generally used. However, diversity receivers that perform diversity reception are often used in base stations due to their complicated configuration, but are not preferably used in terminal devices that require small size and low power consumption.

As a method for solving this problem, there is transmission selection diversity. Transmission selection diversity is TDD
In this wireless system, transmission is performed by a diversity branch (antenna) having the best reception quality at the time of reception immediately before transmission. Therefore, if diversity reception is performed at the base station and transmission selection diversity is performed, the effect of fading can be reduced for both the upper and lower channels without performing diversity at the mobile station. Especially when the fading of the mobile station moving slowly at the walking speed is slow,
The effect of transmission selection diversity is equivalent to the effect of diversity reception by selective combining. For the public base station of the personal handy phone system, the diversity reception and transmission selection diversity should be performed at the base station as described in Ogawa / Kobayashi, edited by the Telecommunication Association, Part 3 of "Easy Personal Handy Phone". The wireless line design has been made on the premise of:

[0005] As a branch combining method in diversity reception, there are selective combining, equal gain combining, maximum ratio combining and the like, and the maximum ratio combining is the most effective. The application of this maximum ratio combining diversity to transmission is also being studied, as described in, for example, a document (Kondo, "Transmission Diversity Characteristics in TDMA / TDD Communication System" IEICE Autumn Conference B-355). That is, the transmission signal of each branch may be weighted and phase-controlled according to the weight and phase difference of each branch set at the time of reception, and then transmitted. Although the above-mentioned literature examines the application effect by computer simulation, it does not show the detailed configuration of the apparatus.

In order to realize such a base station apparatus having the maximum transmission ratio combining diversity, it is necessary to control the phase and amplitude of a transmission signal for each branch. If these phase and amplitude controls are performed between the output of the final stage power amplifier and the antenna,
The transmission circuit may be a single system similarly to the transmission selection diversity. However, in order to continuously control such phase and amplitude, a configuration using a variable resistor, a reactance element, for example, a PIN diode or the like is used, and power efficiency is reduced. Therefore, in general, at least the final stage power amplifier in the transmission circuit needs to be provided for each branch.
That is, it is necessary to perform the phase / amplitude control in a stage preceding the final stage power amplifier.

As described above, in the conventional radio base station apparatus of the TDD system, the diversity reception and the transmission selection diversity or the transmission maximum ratio combining diversity are performed to improve the transmission quality and expand the communicable area. .

[0008]

However, in the above-described conventional radio base station apparatus, when the maximum ratio combining diversity reception is performed in the uplink, if the downlink is the transmission selection diversity, there is a difference in the diversity gain. High output is required. Therefore, there is a problem that the probability of causing interference to a mobile station connected to another neighboring base station increases, and the frequency utilization efficiency decreases.

Further, even when the maximum transmission ratio combining diversity is performed, at least the last-stage power amplifier in the transmission circuit needs to be provided by the number of branches, which complicates the configuration. Further, the final-stage power amplifier requires good linearity over a wide dynamic range so that the phase characteristics do not change even when the output power changes. For this reason, there is a problem that the circuit must be configured with low power efficiency, and the circuit becomes large due to heat radiation or the like.

Accordingly, an object of the present invention is to solve the above problems and to provide a radio base station apparatus capable of expanding the reach of a downlink control channel without increasing transmission power.

[0011]

SUMMARY OF THE INVENTION The present invention provides a plurality of antennas, a plurality of receiving circuits to which received signals are respectively supplied from the plurality of antennas, and a combining means for combining outputs of the plurality of receiving circuits. Phase difference detecting means for detecting a phase of each received signal in the plurality of receiving circuits, or a phase difference between the respective received signals, a memory for temporarily storing an output of the phase difference detecting means, A modulator that generates the transmission signal, a phase shifter that controls and outputs the phase of the transmission signal, and amplifies the transmission signal that is phase-controlled by the transmission signal and the phase shifter to a required power. And a plurality of power amplifiers each supplying a transmission signal to a plurality of antennas, wherein the phase shifter is controlled according to the contents of the memory.

With this configuration, it is possible to realize a radio base station apparatus capable of expanding the reach of the downlink control channel without increasing the transmission power.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a receiving apparatus according to a first embodiment of the present invention; Means, a phase difference detecting means for detecting a phase of each received signal in the plurality of receiving circuits, or a phase difference between the respective received signals, and a memory for temporarily storing an output of the phase difference detecting means And a modulator that generates a modulated transmission signal, a phase shifter that controls and outputs the phase of the transmission signal, and sets the transmission signal and the transmission signal that is phase-controlled by the phase shifter to required power. A plurality of power amplifiers for amplifying and supplying transmission signals to the plurality of antennas, respectively, wherein the phase shifter is controlled according to the contents of the memory.

With this configuration, since the downlink signal is transmitted with a phase difference corresponding to the phase of each antenna obtained at the time of uplink reception, the phase of the signal transmitted from each antenna is substantially the same at the antenna of the mobile station. It has the effect of strengthening in phase and has the effect that the power amplifier has a constant output.

According to a second aspect of the present invention, there are provided a plurality of antennas, a plurality of receiving circuits to which received signals are respectively supplied from the plurality of antennas, a combining means for combining outputs of the plurality of receiving circuits, A phase difference detecting means for detecting a phase of each received signal in the plurality of receiving circuits, or a phase difference between the received signals, a memory for temporarily storing an output of the phase difference detecting means, A modulator for generating the transmitted signal, a power amplifier for amplifying the transmission signal to a required power, and a phase shifter for controlling and outputting the phase of the power amplifier, wherein the plurality of antennas are connected to the phase shifter. A transmission signal is supplied from each of the phase shifter and the power amplifier, and the phase shifter is controlled according to the contents of the memory.

With this configuration, in addition to the same operation as the first aspect of the invention, the power amplifier has an operation of forming one system.

According to a third aspect of the present invention, in the first or second aspect, the plurality of receiving circuits include a synchronous detector, and the phase difference detecting means includes a synchronous detector in the plurality of receiving units. Detecting the phases of the reproduced carrier waves or the phase differences between the phases of the carrier waves.

According to this configuration, since the reproduced carrier is used as an input to the phase difference detecting means, an effect that the noise component included in the detected phase difference is reduced.

According to a fourth aspect of the present invention, in the first aspect of the present invention, there is provided control means for comparing received signal intensities of the plurality of receiving sections and controlling the operation of the power amplifier. The power amplifier is capable of controlling the output to be stopped individually, and the control unit determines that the difference between the received signal strength of the plurality of receiving units and the largest one is a predetermined threshold value. When there is the antenna corresponding to the receiving unit whose received signal strength is lower than the received signal strength, the output of the power amplifier that supplies a transmission signal to the antenna is controlled to be stopped.

With this configuration, the output of the power amplifier corresponding to the antenna having a poor propagation state is stopped, so that the average power consumption is reduced.

According to a fifth aspect of the present invention, in the first or second aspect of the present invention, the phase shifter can switch and set a discrete value of the phase shift amount, and the resolution of the phase shift amount is 90 degrees. It was configured as follows.

This configuration has the effect of simplifying the configuration of the phase shifter. According to a sixth aspect of the present invention, in the first, second, and fifth aspects, the phase shifter includes a plurality of phase shift circuits having fixed phase shift amounts and different phase shift amounts, and the phase shift circuit. Switching means for switching the phase shift amount, so that the resolution of the phase shift amount is 90 degrees or less.

With this configuration, the phase shift circuit can be constituted by transmission lines, passive components such as inductors and capacitors, and has the effect that a low-loss phase shifter can be constituted.

(Embodiment 1) FIG. 1 is a block diagram of a radio base station apparatus according to Embodiment 1 of the present invention, FIG. 2 is a circuit and a block diagram showing a configuration of a phase difference detector of the radio base station apparatus, FIG. 3 is an explanatory diagram showing the operation of the phase difference detection unit of the wireless base station device, and FIG. 4 is an explanatory diagram showing the phase relationship during operation of the wireless base station device. In the first embodiment, a TD that performs diversity of K branches (K is an integer of 2 or more)
1 shows a wireless base station device using D communication. In addition,
The radio base station apparatuses according to the embodiments described below are all based on TDD communication.

In FIG. 1, reference numeral 1 denotes an antenna, which is generally omnidirectional in a horizontal plane, but may be a directional antenna in the case of, for example, a sectorized cell. Reference numeral 2 denotes an antenna switching device for switching an antenna according to transmission and reception. A receiving circuit 3 converts a received signal obtained by the antenna 1 into a phase baseband signal for each branch, and includes a high-frequency circuit 31, a band-pass filter 32, a limiter amplifier 33, and a detector 34. As with a general digitally modulated signal receiver, a bandpass filter 3
Reference numeral 2 denotes a filter having a narrow band within a range in which intersymbol interference does not occur as much as possible, that is, a matching filter corresponding to a transmission waveform or a ceramic filter having a frequency characteristic approximate thereto.

The limiter amplifier 33 is an amplifier that makes the amplitude of the output signal constant, and has a terminal for outputting the received signal strength (RSSI). The detector 34 detects an input intermediate frequency signal and outputs a signal of a baseband, and uses delay detection, synchronous detection, frequency detection, or the like. Reference numeral 6 denotes a weight calculation unit which calculates a composite weight for performing maximum ratio composition by RSS.
Calculated from I. Reference numeral 71 denotes a multiplier that weights the baseband signal obtained from the receiving circuit 3 with the weight obtained by the weight calculator 6. A combining unit 72 adds the baseband signals weighted by the multiplier 71, determines the data, and outputs demodulated data. The above configuration is the same as that of a conventionally used maximum ratio combining diversity receiver after detection.

Reference numeral 61 denotes a phase difference detection unit for detecting a phase difference with respect to a certain branch in a detector input of the reception unit of each branch, and can obtain K-1 outputs. In the first embodiment, a phase difference with respect to the branch 1 is output. Reference numeral 63 denotes a memory in which the output of the phase difference detection unit 61 obtained during the reception period is written and held until the next transmission period. Numeral 64 denotes a sign inverting unit for inverting the sign of the input. Reference numeral 65 denotes a correction value memory which stores K-1 values for correcting irregularities between the antenna switch 2 and the detector 34 and between branches of the phase characteristic in the transmission circuit. An adder 66 corrects the sign-inverted inter-branch phase difference at the time of reception with the value of the correction value memory 65 and outputs the result.

Reference numeral 8 denotes a modulator that modulates a carrier according to digital data to be transmitted to generate a transmission signal, 9 denotes a frequency converter that converts the transmission signal generated by the modulator 8 into a predetermined communication frequency, and 10 denotes a frequency converter. The phase shifter 11 shifts the phase of the transmission signal obtained from the frequency converter 9 by the phase difference between the branches from the adder 66 for each branch. The phase shifter 11 converts the transmission signals from the phase shifter 10 and the frequency converter 9 into a required power. Is a power amplifier that amplifies the power. With the above configuration, the phase difference detection unit 61 can be configured using, for example, K-1 circuits shown in FIG.

In FIG. 2, 611 and 612 are exclusive OR (EOR) circuits, 613 is a phase shift circuit for delaying the phase of the signal input from the terminal B by π / 2,
A moving average circuit 616 averages the outputs of the EOR circuits 611 and 612. The averaging time is an integral multiple of the period of the intermediate frequency signal input to the phase shift difference detection circuit or is sufficiently longer than the same period.
In addition, a time shorter than the symbol period is set. The values shown in FIG. 3 are output to the terminals C and S in accordance with the phase difference between the input signal of the terminal B and the input signal of the terminal B.
Therefore, in phase conversion section 616, the value of terminal S is １ ／
And the absolute value of the phase difference can be obtained from the value of the terminal C, and a signed phase difference signal can be obtained as an output. Also, the sign inverting section 64 is omitted, and the adder 66 becomes a completely equivalent configuration even when used as a subtractor. Further, the phase difference detection unit 6
1, the processing of the memory 63, the sign inverting section 64, the adder 66, etc., is described in software, and the digital signal processor operates in exactly the same manner. In this case, the detector 34, the weight calculator 6, the multiplier 71, and the synthesizer 7
Similarly, the signal processing in 2 may be described by software and processed by a digital signal processor.

The operation of the radio base station apparatus configured as described above will be described below. Now, assuming that the phase (transmission) characteristic of each unit is the characteristic shown in FIG. 4, the correction value memory 65 stores K-1 values represented by (Equation 1). Note that the phase characteristics of the receiving circuit in FIG. 4 are those from the antenna switch 2 to the input of the detector 34, and the phase characteristics of the transmitting circuit are the antenna characteristics from the output of the frequency converter 9 or the output of the phase shifter 10. Up to the switch 2.

[0031]

(Equation 1)

These correction values are set such that the phase difference between the input phase of the detector 34 and the branch 1 when the signal having the same phase is input to the antenna side terminal of the antenna switch 2 and the phase shifter 10 are all set to 0. This is the difference from the phase difference of the antenna side terminal of the antenna switch 2 with respect to the branch 1. Since the phase characteristics of the receiving circuit and the transmitting circuit do not change over time, the correction value can be measured at the time of installation of the apparatus or during an adjustment process in manufacturing, and can be written in the correction value memory 65.

Next, in the receiving period, the antenna switch 2 is connected to the R side in the figure, and the received signal received by the antenna 1 is converted into a baseband signal by the receiving circuit 3 for each branch and multiplied. The demodulated output is obtained by weighting and adding in the combiner 71 and the combining unit 72. At this time, the receiving circuit 3
Although the input carrier phase of the detector 34, that is, the carrier phase in the antenna 1 is different for each branch, a baseband signal is obtained at the same output irrespective of the carrier phase by the demodulation operation of the detector 34. Therefore, even when the carrier phase differs between the branches by π, the baseband signal of each branch is satisfactorily synthesized by the synthesizing unit 72 without canceling each other. That is, it operates in exactly the same manner as the conventionally used maximum ratio combining diversity receiver after detection. At this time, the phase difference between the input carrier wave phase of the detector 34 of each branch and the branch 1 is detected by the phase difference detection unit 61,
The data is taken into the memory 63.

Next, at the time of transmission, the antenna switch 2
The transmission signal is connected to the transmission side and modulated in accordance with the transmission data. The transmission signal is generated by the modulator 8 and is converted to the communication frequency by the frequency converter 9. The frequency-converted transmission signal is amplified by a power amplifier 11 directly or via a phase shifter 10 and transmitted to a mobile station via an antenna switch 2 and an antenna 1. At this time, the value stored in the memory 63 at the time of reception is read out, and the value K-1 values obtained through the sign inverting unit 64 and the subtractor 66 are set in the phase shifter 10. Therefore, if the phase characteristic of the propagation path during the reception period is as shown in FIG. 4, the value set in the phase shifter 10 is (Equation 2).

[0035]

(Equation 2)

The phase characteristics of the propagation path include the feed line to the antenna 1 and the antenna switch 2. If the moving speed of the mobile station is sufficiently low and the change in the propagation path phase characteristic from the reception period can be ignored, the carrier phase ψ ₁ of the radio wave transmitted from the branch 1 at the mobile station is, as apparent from FIG. Equation 3) is obtained.

[0037]

(Equation 3)

On the other hand, the carrier phases ψ ₂ , ψ ₃ ,. . . ψ _K also becomes as shown in (Equation 4), and becomes in phase with each other.

[0039]

(Equation 4)

Therefore, the mobile station adds the transmission signals from the respective branches in phase, so that the same effect as that of the equal gain combining diversity reception is obtained on the downlink, and the transmission quality when fading occurs is improved. Since equal gain combining diversity has a higher diversity gain than selective combining diversity, even when the transmission power of each branch is set to 1 / K of the transmission power in transmission selection diversity, a diversity gain higher than the transmission selection diversity can be obtained. When used for TDMA communication, the memory 63 may set an address for each time slot or for each mobile station to communicate with and store a value.

(Embodiment 2) FIG. 5 is a block diagram of a radio base station apparatus according to Embodiment 2 of the present invention. FIG.
In the figure, 1 is an antenna, and 2 is an antenna switch, which are the same as those described in the first embodiment. A receiving circuit 4 converts a received signal obtained by the antenna 1 for each branch into a phase baseband signal.
It comprises a bandpass filter 32, a limiter amplifier 33, a synchronous detector 41, and a carrier reproducing unit. Like a general digitally modulated signal receiver, the band-pass filter 32 has a narrow band within a range in which intersymbol interference does not occur as much as possible; Use a ceramic filter or the like.

The limiter amplifier 33 is an amplifier that makes the amplitude of the output signal constant, and has a terminal for outputting the received signal strength (RSSI). The synchronous detector 41 synchronously detects the input intermediate frequency signal and outputs a baseband signal. The carrier reproducing unit 42 reproduces a carrier from a received signal. 6 is a weight calculator, 71 is a multiplier,
Reference numeral 72 denotes a synthesizing unit, the configuration of which is the same as that described in the first embodiment.

Numeral 61 denotes a phase difference detecting section for detecting a phase difference of a reproduced carrier obtained by the carrier reproducing section 42 of each branch with respect to a certain branch, and outputs K-1 outputs. In the second embodiment, the phase difference for the branch 1 is output. 63 is a memory, 64
Is a sign inversion unit, 65 is a correction value memory, 66 is an adder, 8
Is a modulator, 9 is a frequency converter, 10 is a phase shifter, 11 is a power amplifier, and their configurations are the same as those described in the first embodiment.

With the above configuration, the phase difference detecting section 61 can be configured by using, for example, K-1 circuits shown in FIG. 2 as in the first embodiment. Alternatively, the literature (S. Kat
o and others, "A new burst coherent
demodulatorfor microcell
ullar TDMA / TDD systems "IEI
CE Transactions on commun
ications, vol. E77-B, pp. 92
In the case of synchronous detection using a phase signal as described in detail in 7-933), the reproduced carrier is directly obtained as phase information. Therefore, the phase difference detector can be constituted by K-1 subtractors, and is simple. Configuration.

Further, the processing of the phase difference detecting section 61, the memory 63, the sign inverting section 64, the adder 66, and the like is described by software, and the digital signal processor operates in exactly the same manner. In this case, the signal processing in the detector 34, the weight calculating unit 6, the multiplier 71, and the synthesizing unit 72 may be similarly described by software and processed by a digital signal processor.

The operation of the radio base station apparatus configured as described above will be described below. Now, assuming that the phase (transmission) characteristics of the respective units are the characteristics shown in FIG. 4, K-1 values represented by (Equation 1) are stored in the correction value memory 65 as in the first embodiment. Next, during the reception period,
The antenna switch 2 is connected to the R side in the figure, and the received signal received by the antenna 1 is converted into a baseband signal for each branch by the receiving circuit 4 and weighted and added by the multiplier 71 and the combining unit 72. To obtain a demodulated output. That is, the receiving operation is performed in exactly the same manner as in the first embodiment, except for the configuration of the detector. At this time, the phase difference of the reproduced carrier obtained by the carrier reproducing unit 42 of the receiving circuit 4 with respect to the branch 1 is detected by the phase difference detecting unit 61 and is taken into the memory 63.

Next, at the time of transmission, the antenna switch 2
The transmission signal is connected to the transmission side and modulated in accordance with the transmission data. The transmission signal is generated by the modulator 8 and is converted to the communication frequency by the frequency converter 9. The frequency-converted transmission signal is amplified by a power amplifier 11 directly or via a phase shifter 10 and transmitted to a mobile station via an antenna switch 2 and an antenna 1. At this time, the value stored in the memory 63 at the time of reception is read out, and the value K-1 values obtained through the sign inverting unit 64 and the subtractor 66 are set in the phase shifter 10. Since the phase of the reproduced carrier almost follows the true carrier phase at the input of the synchronous detector 41, the value set in the phase shifter 10 is (Equation 2). Therefore, as in Embodiment 1, if the moving speed of the mobile station is sufficiently low and the change in propagation path phase characteristics from the reception period can be ignored, the carrier phase ψ ₁ of the radio wave transmitted from branch 1 in the mobile station and the other Of the radio wave transmitted from each branch of the mobile station at the mobile station ψ ₂ ,
ψ ₃ ,. . . [psi _K each other in phase, the same effect as in the first embodiment can be obtained.

The receiving circuit 3 of the first and second embodiments
Alternatively, the limiter amplifier 33 in 4 may be an automatic gain control (AGC) amplifier circuit. In this case, the average amplitude of the received signal at the output of the circuit is maintained at a constant value, but the amplitude fluctuation due to the modulation is preserved and supplied to the detector. Therefore, the pass band width of the band-pass filter 32 is set to be slightly wide, and A / D conversion is performed at the input of the detector to convert it to a digital signal, and then the signal is detected via a low-pass filter as a matching filter realized by the digital filter. Of the above signal processing. By forming a matched filter by digital signal processing in this way, an optimal transfer function can be formed more accurately,
The receiving sensitivity is improved.

(Embodiment 3) FIG. 6 is a block diagram of a radio base station apparatus according to Embodiment 3 of the present invention. FIG.
In the figure, 1 is an antenna, and 2 is an antenna switch, which are the same as those described in the first embodiment. A receiving circuit 5 converts a received signal obtained by the antenna 1 for each branch into a phase baseband signal.
It comprises a quasi-synchronous detector 52, a low-pass filter 53, a polar coordinate converter 54, and a detector 55. The received signal is amplified to a desired level by the high-frequency circuit 51, quadrature-detected by the quasi-synchronous detector 52 with a local oscillation signal whose frequency is substantially equal to the carrier frequency of the received signal, and converted into a quadrature, in-phase asynchronous baseband signal. . The asynchronous baseband signal is removed by a low-pass filter 53 to remove noise and residual carrier components outside the baseband signal band. Low-pass filter 5
Reference numeral 3 denotes a filter having a narrow band within a range in which intersymbol interference does not occur as much as possible, that is, a filter having a frequency characteristic as a matched filter corresponding to a transmission waveform or similar thereto.

In the polar coordinate converter 54, the in-phase component of the asynchronous baseband signal is taken as a real axis and the quadrature component is taken as an imaginary axis. The amplitude component is output as RSSI. The phase component is detected by the detector 55 and becomes a phase baseband signal. As a configuration of the detector, differential detection that outputs a difference between one symbol and literature (S. Kato et al., “A new burst co.
heren demodulator for mi
crocellular TDMA / TDDsystem
ms ”IEICE Transactions on
communications, vol. E77-
B, pp. 927-933) is used.

Reference numeral 6 denotes a weight calculator, which is the same as that described in the first embodiment. Reference numeral 73 denotes a combining unit, which performs diversity combining according to the configuration disclosed in, for example, Japanese Patent Laid-Open No. 6-268559, makes a determination, and obtains a demodulated output. A phase difference detection unit 610 detects a phase difference of a received signal of each branch with respect to a certain branch, and can obtain K-1 outputs. In the third embodiment, the phase difference for the branch 1 is output. The phase difference detector 610 can be composed of K-1 subtractors, and has a simple configuration.

Reference numeral 620 denotes a low-pass filter which averages the output of the phase difference detector 610 over time to reduce error components such as noise. Reference numeral 63 denotes a memory, 64 denotes a sign inverting unit, 65 denotes a correction value memory, 66 denotes an adder, 8 denotes a modulator, 10 phase shifters, and 11 power amplifiers.
This is the same as that described above. An amplifier 90 amplifies the transmission signal of the modulator 8 to a required level.

With the above configuration, the processing of the phase difference detector 610, the low-pass filter 620, the memory 63, the sign inverting unit 64, the adder 66, and the like is described by software, and the processing is performed by a digital signal processor. Works. In this case, the signal processing in the detector 34, the weight calculating unit 6, the multiplier 71, and the synthesizing unit 72 may be similarly described by software and processed by a digital signal processor.

The operation of the radio base station apparatus configured as described above will be described below. Now, assuming that the phase (transmission) characteristic of each unit is the characteristic shown in FIG. 4, the correction value memory 65 stores K-1 values represented by (Equation 1) as in the first embodiment. Next, during the reception period,
The antenna switch 2 is connected to the R side in the figure, and the received signal received by the antenna 1 is converted into a baseband signal for each branch by the receiving circuit 5, and weighted and added by the multiplier 71 and the combining unit 72. To obtain a demodulated output. That is, the receiving operation is performed in exactly the same manner as in the first embodiment except for the configuration of the receiving circuit. At this time, the phase difference between the received signal and the branch 1 at the input of the quasi-synchronous detector 52 is
Detected at 10 and taken into memory 63. Next, at the time of transmission, the antenna switch 2 is connected to the T side in the figure, and a transmission signal modulated according to transmission data is generated by the modulator 8 and converted to a communication frequency by the frequency converter 9.

The frequency-converted transmission signal is amplified by a power amplifier 11 directly or via a phase shifter 10 and transmitted to a mobile station via an antenna switch 2 and an antenna 1. At this time, the value stored in the memory 63 at the time of reception is read out, and the K obtained through the sign inversion unit 64 and the subtractor 66 is obtained.
One value is set in the phase shifter 10. Therefore, as in the first embodiment, the value set in the phase shifter 10 is (Equation 2). At this time, the phase characteristic of the receiving circuit is determined by the antenna switch 2
7 shows the phase characteristics from the quasi-synchronous detector 52 to. If the moving speed of the mobile station is sufficiently slow and the change in the propagation path phase characteristic from the reception period can be ignored, the carrier phase ψ ₁ of the radio wave transmitted from the branch ₁ and the radio wave transmitted from each of the other branches Carrier phase に お け る₂ ,
ψ ₃ ,. . . [psi _K each other in phase, the same effect as in the first embodiment can be obtained.

In the first, second and third embodiments, the outputs of all the branches, that is, the outputs of the power amplifiers 11 are equal to each other and are constant. It may be configured to monitor and control the transmission power to 0 for the branch whose reception level is equal to or less than the specified value with respect to the maximum reception level branch. As described above, when the reception level is significantly lower than the other branches, that is, when the propagation loss of the branch is large, the reception power at the mobile station hardly changes even if the transmission of the branch is stopped. Therefore, the power consumption required for transmission can be reduced on average, not only contributing to the miniaturization of the device, but also by stopping unnecessary transmission, other communication using the same frequency at a neighboring base station or the like. Can also be suppressed. That is, the repeated use distance of the same frequency can be shortened, and the frequency use efficiency is improved.

(Embodiment 4) Embodiments 1 and 2 above
In 3 and 3, since the phase shifter 10 in the transmission circuit is arranged on the input side of the power amplifier 11, even if the insertion loss of the phase shifter 10 is large, the reduction in the power efficiency of the transmission circuit is small. However, if a phase shifter with a small insertion loss is used,
The configuration shown in FIG. 7 can also be used.

FIG. 7 is a block diagram of a radio base station apparatus according to Embodiment 4 of the present invention. In FIG. 7, 1 is an antenna, 2 is an antenna switch, 3 is a receiving circuit, 6 is a weight calculator, 71 is a multiplier, 72 is a combiner, 61 is a phase difference detector, 63 is a memory, and 64 is a sign inversion. , 65 is a correction value memory, 66 is an adder, 8 is a modulator, and 9 frequency converter. These configurations are the same as those described in the first embodiment.

Reference numeral 110 denotes a power amplifier according to the first or second embodiment.
The output power is K times that of the power amplifier 11 in 2 and 3. A phase shifter 100 has a relatively low loss configuration. For example, a configuration is used in which a plurality of fixed phase shift circuits using a passive circuit such as a coaxial line shown in FIG.

Reference numeral 101 denotes a distributed constant line as a phase shift circuit;
Reference numeral 102 denotes a changeover switch. With such a configuration, the loss of the phase shift circuit can be reduced. Although the settable phase shift amount is a discrete value, the resolution, that is, the phase switching step may be set to π / 2 or less. When the resolution is π / 2, as is clear from FIG. 4 and (Equation 4), the phases of the arriving waves from the branches to the mobile station ψ ₁ , ψ ₂ ,. . . ψ _K
Causes an error of ± π / 4 at the maximum. Therefore, the phase difference between the arriving waves of any two branches is at most π / 2. However, even when signals having phases different from each other by π / 2 are added, the amplitude does not decrease from the original signal, and the amplitude always increases. The amount of deterioration of the amplitude at this time with respect to the amplitude synthesized in phase is 1
/ √2, that is, 3 dB. However, since the error of the phase shift amount is a value uniformly distributed between 0 and ± π / 4, the average deterioration amount is a smaller value.

As described above, by disposing the phase shifter 100 on the output side of the power amplifier 11, one power amplifier is provided,
The configuration is simplified. In FIG. 7, the receiving circuit has the same configuration as that of the first embodiment of FIG. 1. However, the same effects can be obtained by using the same receiving circuits as those of the second and third embodiments of FIGS. be able to.

[0062]

According to the present invention, it is possible to improve downlink transmission quality without increasing the total transmission power of each branch from the transmission power of the conventional transmission selection diversity. That is, the zone expands. Therefore, it is possible to realize a radio base station apparatus suitable for a case where it is desirable to increase the zone radius as much as possible in a low traffic area such as a suburban area. In addition, since the transmission power is always constant, the dynamic range of the transmission power amplifier may be the same as that of a conventional base station apparatus using transmission selection diversity. Moreover, since it is not necessary to consider the phase change characteristic due to the output variation, a transmission power amplifier having a simpler structure and a lower cost than the base station apparatus using the maximum transmission ratio combining diversity can be used, and the apparatus can be reduced in size and cost. . Further, for a branch whose reception level is equal to or less than the specified value with respect to the maximum reception level branch, by controlling the transmission power to 0, the power consumption required for transmission can be reduced on average, and the frequency utilization efficiency is improved. An excellent wireless base station device can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a radio base station apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a circuit and a block diagram illustrating a configuration of a phase difference detection unit of the wireless base station device according to Embodiment 1 of the present invention.

FIG. 3 is an explanatory diagram showing an operation of a phase difference detection unit of the wireless base station device according to Embodiment 1 of the present invention.

FIG. 4 is an explanatory diagram showing a phase relationship during operation of the radio base station apparatus according to Embodiment 1 of the present invention.

FIG. 5 is a block diagram of a radio base station apparatus according to Embodiment 2 of the present invention.

FIG. 6 is a block diagram of a radio base station apparatus according to Embodiment 3 of the present invention.

FIG. 7 is a block diagram of a radio base station apparatus according to Embodiment 4 of the present invention.

FIG. 8 is a block diagram showing a configuration of a phase shifter of a radio base station apparatus according to Embodiment 4 of the present invention.

[Description of Signs] 1 Antenna 2 Antenna Switch 3 Receiving Circuit 4 Receiving Circuit 5 Receiving Circuit 6 Weight Calculation Unit 8 Modulator 9 Frequency Converter 10, 100 Phase Shifter 11, 110 Power Amplifier 61 Phase Difference Detection Unit 63 Memory 64 Sign inversion unit 65 Correction value memory 66 Subtractor 71 Multiplier 72 Synthesis unit 101 Distributed constant line 620 Low-pass filter

Claims (6)

[Claims] A plurality of antennas; a plurality of receiving circuits to which received signals are respectively supplied from the plurality of antennas; synthesizing means for synthesizing outputs of the plurality of receiving circuits; Phase difference detecting means for detecting a phase of a received signal or a phase difference between each of the received signals, a memory for temporarily storing an output of the phase difference detecting means, and a modulation for generating a modulated transmission signal A phase shifter that controls and outputs the phase of the transmission signal, and amplifies the transmission signal and the transmission signal that is phase-controlled by the phase shifter to required power, and transmits the transmission signal to each of the plurality of antennas. And a plurality of power amplifiers to be supplied, wherein the phase shifter is controlled according to the contents of the memory. 2. A plurality of antennas, a plurality of receiving circuits to which received signals are respectively supplied from the plurality of antennas, synthesizing means for synthesizing outputs of the plurality of receiving circuits, and each of the plurality of receiving circuits. Phase difference detecting means for detecting a phase of a received signal or a phase difference between each of the received signals, a memory for temporarily storing an output of the phase difference detecting means, and a modulation for generating a modulated transmission signal A power amplifier for amplifying the transmission signal to a required power, and a phase shifter for controlling and outputting the phase of the power amplifier,
The plurality of antennas are supplied with transmission signals from the phase shifter and the power amplifier, respectively, and the phase shifter is controlled according to the contents of the memory. 3. The plurality of receiving circuits include a synchronous detector,
The said phase difference detection means detects the phase of the carrier reproduced | regenerated by the said synchronous detector in the said several receiving part, respectively, or the phase difference between the phases of the said carrier, The Claims 1 or 2 characterized by the above-mentioned. Wireless base station device. 4. A control means for comparing received signal strengths of the plurality of receiving sections and controlling an operation of the power amplifier, wherein the plurality of power amplifiers can be controlled to individually stop outputs. And wherein the control unit controls the antenna corresponding to the receiving unit to have a difference between a maximum received signal strength of the plurality of receiving units and a received signal strength less than a preset threshold value. 2. The radio base station apparatus according to claim 1, wherein when there is a control, the output of the power amplifier that supplies a transmission signal to the antenna is controlled to be stopped. 5. The phase shifter according to claim 1, wherein the phase shift amount can be set by switching between discrete values, and the resolution of the phase shift amount is 90 degrees or less. Item 3. The wireless base station device according to item 1 or 2. 6. The phase shifter includes a plurality of phase shift circuits having fixed phase shift amounts and different phase shift amounts, and switching means for switching the phase shift circuits, wherein the resolution of the phase shift amount is 90 degrees. 6. The method according to claim 1, wherein the following is configured.
The wireless base station device according to any one of the above.