JP2018011184A - Receiver, antenna system, reception front end of receiver, radio signal reception method - Google Patents

Abstract

A receiver RX1 is capable of switching reception sensitivity while realizing desired anti-jamming wave performance in a radio signal receiver. A receiver RX1 includes a reception front end 10 for receiving a reception signal RS, A reception demodulator 20 that demodulates the signal RS. The reception front end 10 includes a BPF 12, a directional coupler 13, a delay device 14, and an LNA 16. The directional coupler 13 receives the received signal RS filtered by the BPF 12, and divides the received signal RS into a first received signal that passes through the through path and a second received signal that passes through the combined path. To do. The delay device 14 gives a delay to the first received signal. The LNA 16 amplifies either the first reception signal or the second reception signal input via the delay device 14 and outputs the amplified demodulated signal DS to the reception demodulation unit 20. [Selection] Figure 3

Description

  The present invention relates to a receiver, an antenna system, a reception front end of the receiver, and a radio signal reception method.

  The introduction of MIMO (Multiple-Input and Multiple-Output) in which communication is performed between a receiving side and a transmitting side using a plurality of antennas for communication between a smartphone or a mobile phone and a base station is being studied. In such MIMO, introduction of an active antenna system composed of a plurality of antenna arrays accompanied by beam forming into a base station is being studied. In this case, depending on the traffic requirements of the base station area, the base station operates as a macro device (Wide Area: hereinafter, wide area) and operates as a small cell (small cell) application. (Local Area: hereinafter, a local area) is assumed.

  In the wide area, since the distance between the terminal and the base station is long, a transmission signal is transmitted to one or a small number of terminals using, for example, beam forming. In the local area, the base station transmits and receives simultaneously with a plurality of terminals. Even in this case, it is possible to efficiently transmit a transmission beam to each terminal by utilizing beam forming. In the wide area, since the power of the radio signal received by the base station from the terminal is small, higher reception sensitivity is required than in the local area. On the other hand, since the influence by the jamming wave is smaller than that of the local area, the anti-jamming wave performance can be relaxed compared to the local area. Standards for such reception sensitivity and anti-jamming wave performance are defined in 3GPP (Third Generation Partnership Project) TS (Technical Specification) 36.104.

  In order to cope with both a wide area and a local area with one base station, it is preferable to have a function of switching reception sensitivity and anti-jamming wave performance as described above. For example, a receiver capable of switching the reception sensitivity has already been proposed (Patent Documents 1 to 3).

  Patent Document 1 proposes a receiver that performs gain control so as to satisfy the intermodulation standard. This receiver is provided with a first stage low noise amplifier (hereinafter referred to as LNA) and a second stage LNA, and uses the detection result of the intermodulation in the signal processing unit of the receiver to determine the reception level. The gain of each LNA is switched according to the above and a predetermined appropriate gain is set. Thereby, the LNA gain, that is, the reception sensitivity can be satisfied while satisfying the intermodulation standard.

  In Patent Document 2, a band-pass filter is inserted between a front-stage LNA and a rear-stage LNA, and the front-stage LNA can be bypassed by opening and closing two switches inserted before and after the front-stage LNA. Possible receivers have been proposed. In this receiver, the reception sensitivity can be switched by bypassing the previous stage LNA.

  Patent Document 3 proposes a receiver capable of selecting insertion and removal of a high-frequency attenuator at the front stage of the LNA by switching two switches. According to this, since the reception gain of the LNA is reduced by the insertion of the high frequency attenuator, the reception sensitivity can be switched.

  In addition, there has been proposed a receiver that branches a received signal into two signals having different intensities and inputs the two signals after branching into different LNAs (Patent Document 4).

JP 2000-174650 A JP 2011-211731 A JP 2006-129292 A Japanese Patent Laid-Open No. 2000-137071

  However, the above-described method has the following problems. In Patent Document 1, since the LNA gain is switched, the saturation characteristic of the LNA also changes. In other words, when the LNA gain is reduced in order to cope with the local area, the saturation characteristic of the LNA is also reduced, and there is a problem that the anti-jamming wave performance is lowered.

  In Patent Document 2, since the gain of the latter-stage LNA cannot be switched, the reception noise figure after the bandpass filter cannot be switched. In other words, there is a problem that the anti-jamming wave performance cannot be switched so as to be compatible with both the wide area and the local area.

  In Patent Document 3, although the saturation characteristics of the LNA do not change, a loss occurs due to the two switches in the previous stage of the LNA. Therefore, there is a problem that the reception noise figure and reception sensitivity are greatly deteriorated.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to enable switching of reception sensitivity while achieving desired anti-jamming wave performance in a radio signal receiver. .

  A receiver according to an aspect of the present invention includes a reception front end that receives a radio signal as a reception signal, and a demodulation unit that demodulates the reception signal received by the reception front end. , A band filter to which the reception signal is input, a reception signal filtered by the band filter, and a first reception signal that passes through the through path and a second path that passes through the coupling path. A first directional coupler that divides the received signal, a delay device that delays the first received signal, the first received signal that is input via the delay device, and the second And an amplifier for amplifying one of the received signals and outputting the amplified signal to the demodulator.

  A reception front end of a receiver according to one aspect of the present invention is configured to receive a band filter to which a reception signal is input, a reception signal filtered by the band filter, and pass the reception signal through a through path. Received signal, a second received signal passing through a coupling path, a directional coupler that divides the received signal, a delay unit that delays the first received signal, and the first input through the delay unit. And an amplifier that amplifies one of the first received signal and the second received signal and outputs the amplified signal.

  According to another aspect of the present invention, there is provided a wireless signal reception method, wherein a reception signal is passed through a bandpass filter, and the reception signal filtered by the bandpass filter is passed through a through path by a directional coupler. And a second received signal that passes through the coupling path, and delays the first received signal, and the delayed one of the first received signal and the second received signal And the demodulated signal is demodulated.

  According to the present invention, it is possible to switch reception sensitivity while realizing desired anti-jamming wave performance in a radio signal receiver.

1 is a diagram schematically showing a configuration of an antenna system according to a first exemplary embodiment. 1 is a diagram schematically illustrating a configuration of a receiver according to a first exemplary embodiment. 1 is a diagram schematically illustrating a basic configuration of a receiver according to a first exemplary embodiment. FIG. 2 is a diagram schematically illustrating a configuration of a reception demodulation unit according to the first exemplary embodiment. It is a figure which shows typically communication with a local area base station and a terminal. It is a figure which shows typically communication with a wide area base station and a terminal. It is a figure which shows typically a desired wave, a carrier wave, 1RB modulated wave, and an interference wave. It is a figure which shows typically IIP3 in a wide area and a local area. It is a figure which shows typically the receiver in the case of a wide area. It is a figure which shows typically the receiver in the case of a local area. FIG. 3 is a diagram schematically illustrating a configuration of a receiver according to a second exemplary embodiment. It is a figure which shows typically the receiver in the case of a wide area. It is a figure which shows typically the receiver in the case of a local area.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted as necessary.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a configuration of an antenna system 100 according to the first embodiment. The antenna system 100 includes antennas A1 to An, receivers RX1_1 to RX1_n, a signal processing unit 1, a calibration signal transmitter 2, and a distributor 3. n is an integer of 2 or more.

  Needless to say, the antenna system 100 can transmit not only radio signals but also radio signals. However, in the following description and the drawings to be referred to, in order to pay attention to the reception function of the radio signal in the antenna system 100, the configuration related to the transmission of the radio signal is omitted.

  The antenna system 100 is applicable to, for example, a massive MIMO (Massive MIMO: Massive Multi Input Multi Output) system. In this application, the antenna system 100 can be configured as an active antenna system that performs beam forming of a transmission signal to be transmitted.

  The receivers RX1_1 to RX1_n receive radio signals via the antennas A1 to An, respectively, and output demodulated signals DS1 to DSn obtained by demodulating the received signal RS to the signal processing unit 1.

  The signal processing unit 1 performs predetermined signal processing on the received demodulated signals DS1 to DSn, and extracts information to be received. For example, when the antenna system 100 is applied to massive MIMO, radio signals output from a plurality of terminals (not shown) at the same frequency are received by the antennas A1 to An. Each of the receivers RX1_1 to RX_n demodulates the received radio signal at a predetermined frequency (for example, quadrature demodulation), and outputs demodulated signals DS1 to DSn. The demodulated signals DS1 to DSn are received via different propagation paths between each terminal and each of the antennas A1 to An, and thus have different amplitudes and phases. The signal processing unit 1 adds the amplitude characteristics and phase characteristics of each receiving system by adding the inverse characteristics of the amplitude variation and phase variation of each receiving system acquired by the calibration correctors CC1 to CCn to DS1 to DSn. By removing in the same calibration corrector and then inputting to the demodulator, the amplitude and phase of the propagation path from each terminal to each antenna A1 to An can be extracted by the demodulator. This process is referred to as uplink sounding. Also, the propagation coefficients including the amplitude and phase of the propagation path for each terminal are summarized as a determinant, the inverse matrix of the determinant is calculated, and the inverse matrix is weighted and multiplied to the downlink transmission signal for each terminal. By transmitting and radiating the received signal via the antennas A1 to An, the propagation coefficient from each antenna to each terminal is equivalently canceled. As a result, downlink beam forming is performed on a plurality of terminals.

  The signal processing unit 1 can control the operations of the receivers RX1_1 to RX1_n by supplying control signals to the receivers RX1_1 to RX1_n.

  The antenna system 100 is configured to be able to calibrate the gains of the receivers RX1_1 to RX1_n, for example, in order to equalize the reception characteristics of the receivers RX1_1 to RX1_n. In this case, the signal processing unit 1 may adjust the gains of the receivers RX1_1 to RX1_n by giving the above-described control signals to the receivers RX1_1 to RX1_n.

  Hereinafter, the calibration operation in the antenna system 100 will be described. In calibration, the calibration signal transmitter 2 outputs a calibration signal CAL as a dummy reception signal for calibration. The calibration signal CAL is evenly distributed by the distributor 3 to the receivers RX1_1 to RX1_n. Then, the receivers RX1_1 to RX1_n output a signal obtained by demodulating the received calibration signal CAL to the signal processing unit 1.

  Here, for simplification of description, only the configuration necessary for calibration is displayed as the configuration of the signal processing unit 1. The signal processing unit 1 includes calibration correctors CC1 to CCn that evaluate demodulated signals received from the receivers RX1_1 to RX1_n. The calibration correctors CC1 to CCn analyze the received demodulated signals and determine whether the amplitude and phase of the demodulated signals when passing through the receivers RX1_1 to RX1_n are within a predetermined range. If the amplitude and phase of the demodulated signal when passing through the receivers RX1_1 to RX1_n are not within a predetermined range, the amplitude characteristics and the phase characteristics are reversed in order to equalize the amplitude variations and phase variations of all receivers. A characteristic is generated and added to each of the demodulated signals DS1 to DSn in the calibration correctors CC1 to CCn, so that the amplitudes and phases of the passing signals of all receivers are made uniform.

  Next, the receivers RX1_1 to RX1_n will be described. The receivers RX1_1 to RX1_n are configured as receivers whose reception sensitivity can be switched. Since the receivers RX1_1 to RX1_n have the same configuration, the receiver RX1 having a common configuration will be described. FIG. 2 schematically shows the configuration of the receiver RX1. FIG. 3 schematically shows a basic configuration of the receiver RX1. The receiver RX1 includes a reception front end 10 and a reception demodulation unit 20.

  The reception front end 10 includes a directional coupler 11, a band pass filter (hereinafter referred to as BPF) 12, a directional coupler 13, a delay device 14, a switch 15, and a low noise amplifier (Low Noise). (Amplifier: hereinafter referred to as LNA) 16.

  The directional coupler 11 is inserted between the antenna and the BPF 12, and the received signal RS received via the antenna passes through the through path of the directional coupler 11 and is input to the BPF 12. When performing the above-described calibration operation, the calibration signal CAL from the distributor 3 is input to the BPF 12 through the coupling path of the directional coupler 11. Here, the directional coupler 11 is also referred to as a second directional coupler.

  As a band filter, the BPF 12 filters a predetermined band or less and a predetermined band or more among received radio signals, and outputs a received signal of a desired band to the subsequent stage.

  The directional coupler 13 is provided at the subsequent stage of the BPF 12. The received signal from the BPF 12 is input to the switch 15 via the through path of the directional coupler 13 and the delay device 14 or via the coupling path of the directional coupler 13. Here, the directional coupler 13 is also referred to as a first directional coupler. A reception signal that has passed through the through path of the directional coupler 13 is also referred to as a first reception signal, and a reception signal that has passed through the coupling path of the directional coupler 13 is also referred to as a second reception signal. Needless to say, the power of the first received signal that has passed through the through path of the directional coupler 13 is greater than the power of the second received signal that has passed through the coupled path of the directional coupler 13.

  The delay unit 14 gives a predetermined delay to the received signal input through the through path of the directional coupler 13. The delay amount given to the received signal by the delay device 14 may be set in advance according to the transmission line length provided in the receiver RX1.

  The switch 15 is configured as a two-input one-output switch, one input is connected to the coupling path of the directional coupler 13, and the other input is connected to the delay device 14. Therefore, the switch 15 receives only one of the first reception signal delayed by the delay unit 14 and the second reception signal from the coupling path of the directional coupler 13 that has not been delayed by the delay unit 14. Then, the data is output to the LNA 16 at the subsequent stage.

  The LNA 16 amplifies the reception signal input via the switch 15 and outputs the amplified reception signal to the reception demodulation unit 20.

  The reception demodulator 20 is configured to demodulate the signal from the reception front end 10 and output the demodulated signal DS to the signal processor 1. FIG. 4 schematically illustrates the configuration of the reception demodulation unit 20 according to the first embodiment. The reception demodulator 20 includes an orthogonal demodulator 21, a local oscillator 22, an analog baseband BPF 23, an analog variable gain amplifier 24, an analog-digital converter (hereinafter referred to as an A / D converter) 25, and a digital base. It has a band BPF26. Hereinafter, the reception demodulation unit is also simply referred to as a demodulation unit.

  The quadrature demodulation unit 21 performs quadrature demodulation on the radio signal received from the reception front end 10 using the local oscillation signal output from the local oscillator 22 and outputs an analog baseband signal obtained by demodulation.

  The analog baseband BPF 23 filters a predetermined band or less and a predetermined band or more of the analog baseband signal output from the quadrature demodulator 21, and extracts an analog baseband signal of a desired band.

  The analog variable gain amplifier 24 amplifies the analog baseband signal filtered by the analog baseband BPF 23 with a set gain. In the calibration described above, for example, the signal processing unit 1 may adjust the gain by giving a control signal to the analog variable gain amplification unit 24.

  The A / D converter 25 converts the analog baseband signal amplified by the analog variable gain amplifier 24 into a digital baseband signal.

  The digital baseband BPF 26 filters a predetermined baseband or lower band of the digital baseband signal from the A / D converter 25 and extracts a digital baseband signal of a desired band.

  Next, reception of a radio signal by the antenna system 100 will be described. Hereinafter, a case where the antenna system 100 conforms to the 3GPP-LTE 36.104 standard will be described as an example. The antenna system 100 is used as a system incorporated in a base station of a wireless communication terminal such as a mobile phone or a smartphone. In 3GPP-LTE 36.104, transmission / reception of both a local area base station and a wide area base station is performed. It is required to meet the standards. For this purpose, a local area base station system and a wide area base station system can be provided separately, but this increases the cost of the system. Therefore, in the antenna system 100 according to the present embodiment, it is possible to cope with both a local area and a wide area by configuring the reception sensitivity of the receiver to be switchable according to the application.

  The outline of the communication operation as the local area base station will be described below. FIG. 5 is a diagram schematically illustrating communication between a local area base station and a terminal. When the base station BS functions as a local area base station, radio signals are transmitted and received simultaneously at the same frequency to a plurality of terminals T1 to T3 existing in a narrow area LA compared to the wide area base station. For example, by shaping the beam of the transmission signal output from the antenna of the antenna system 100, signal transmission with high directivity for the terminals T1 to T3 can be performed. Since there is a plurality of terminals while there is one antenna system 100, the transmission output from the antenna system 100 to each terminal takes a value obtained by dividing the total output of the antenna system 100 by the number of terminals. Become. In this case, since the communication distance is relatively short, the terminal distribution is relatively dense. In addition, since reception signals of the same frequency may be received from a plurality of terminals at the same time, the influence of mutual interference of the reception signals becomes large. However, since the communication distance is relatively short as described above, the received signal strength from each terminal is large, so that the required reception sensitivity can be relaxed.

  Next, an outline of communication operation as a wide area base station will be described. FIG. 6 is a diagram schematically illustrating communication between a wide area base station and a terminal. When the base station BS functions as a wide area base station, a plurality of terminals existing in a wide area WA compared to the local area base station, for example, between one terminal or a relatively small number of terminals, Transmit and receive wireless signals. Even in this case, for example, by shaping the beam of the transmission signal output from the antenna of the antenna system 100, signal transmission with high directivity to the terminal can be performed. For example, when a transmission signal is output to only one terminal, the transmission output directs the total output of the antenna system 100 to the terminal. Thereby, it becomes possible to ensure communication quality with a distant terminal. In this case, since the received signal is received only from one or a small number of terminals, the influence of the mutual interference of the received signal is small. However, since the communication distance is relatively long as described above, the strength of the received signal from the terminal is reduced, and thus high reception sensitivity is required.

  5 and 6, the number of terminals has been described as 3, but it goes without saying that the number of terminals may be 1, 2 or 4 or more.

  Next, the reception performance of the receiver when the modulation method of the received signal from the terminal is SC-FDMA / FRC A1-3 (QPSK: Quadrature Phase Shift Keying) will be described in detail. Here, in order to evaluate the intermodulation distortion (Inter Modulation) that should be regarded as the most important in the reception performance, a desired reception noise figure, a reception sensitivity standard, and a third-order input intercept point (hereinafter referred to as the following) in both the wide area and the local area. Pay attention to IIP3).

  In this case, in order to evaluate the intermodulation distortion, in addition to the desired wave C, the conditions are such that the carrier wave I1 and the 1RB modulated wave I2 are input to the receiver as interference waves. FIG. 7 is a diagram schematically showing a desired wave, a carrier wave, a 1 RB modulated wave, and an interference wave. The carrier wave I1 is 345 kHz detuned from the high frequency side end of the desired wave C, and the frequency interval between the carrier wave I1 and the 1RB modulated wave I2 is 1435 kHz. The 1RB modulated wave I2 is a modulated wave in the 180 kHz band, and the frequency at the center of the band is detuned from the high frequency side end of the desired wave C by 1780 (= 345 + 1435) kHz. The input levels of the carrier wave I1 and the 1RB modulated wave I2 are set to -52 dBm in the wide area and -44 dBm in the local area.

  Under this condition, an interference wave IM3 due to third-order intermodulation related to the carrier wave I1 and the 1RB modulated wave I2 appears at a position on the low frequency side by 1090 (= 1435-345) kHz from the edge of the desired wave C. The magnitude of the interference wave, that is, the level of third-order intermodulation distortion, must be within an allowable range defined by the standard in order to ensure communication quality.

  Since the desired wave sensitivity of 95% throughput defined in the standard is -95.5 dBm in the wide area and -87.5 dBm in the local area, if the required C / N (received signal / noise) is -1.15 dB, The allowable input conversion IM3 in the wide area is −95.5-(− 1.15) = − 94.35 dBm, and the allowable input conversion IM3 in the local area is −87.5 − (− 1.15) = − 86. 35 dBm,

The D / U (desired wave / unnecessary wave) of the desired IM3 obtained from the difference between the respective input levels of the carrier wave I1 and the 1RB modulated wave I2 and the allowable input conversion IM3 is the same in the wide area and the local area as follows. 35 dB.
Wide area: −52 − (− 94.35) = 42.35 dB
Local area: −44 − (− 86.35) = 42.35 dB

  Since the input levels of the carrier wave I1 and 1RB modulated wave I2 in the wide area are −52 dBm, a desired third-order input intercept point (hereinafter referred to as IIP3) (IIP_D in FIG. 7) is 42.35 / 2. −52 = −30.8 dBm. Since the input levels of the interference waves of the carrier wave I1 and the 1RB modulated wave I2 in the local area are −44 dBm, the desired IIP3 is 42.35 / 2-44 = −22.8 dBm. That is, in the wide area, since the input levels of the carrier wave I1 and the 1RB modulated wave I2 are 8 dB lower than in the local area, the desired IIP3 is also reduced by 8 dB.

  FIG. 8 is a diagram schematically showing IIP3 in the wide area and the local area. In FIG. 8, the horizontal axis indicates the LNA input level [dBm], and the vertical axis indicates the LNA output level [dBm]. Line D_W indicates a desired wave in the wide area, line IM3_W indicates IM3 in the wide area, line D_L indicates a desired wave in the local area, and line IM3_L indicates IM3 in the local area. In this figure, the intersection of the desired wave and the extension line of IM3 in the non-saturated region indicates IIP3. Here, IIP3 in the wide area is IIP3_W, and IIP3 in the local area is IIP3_L. In this figure, in each of the wide area and the local area, the difference between the desired wave and IM3 indicates D / U_W and D / U_L of IM3.

  As shown in FIG. 8, the output level in the local area is smaller than that in the wide area because the reception gain is reduced by ΔG corresponding to the degree of coupling of the directional coupler 13. In other words, the reception sensitivity in the local area is lower than that in the wide area. However, since the reception sensitivity in the local area can be reduced by 8 dB, for example, as described above, a reduction in reception sensitivity in the local area is allowed.

  On the other hand, since the output saturation characteristics of the LNA are the same in both the local area and the wide area, IIP3 translates by ΔIIP3 in the positive direction of the horizontal axis. Since the slope of the line indicating the desired wave is 1, the fluctuation amount of IIP is the same as the fluctuation amount of the reception sensitivity, which is 8 dB in this example. As a result, although the reception sensitivity in the local area is lower than that in the wide area, the IIP3 can be improved, so that the anti-jamming wave performance is improved.

  Next, the operation of the receiver that realizes the reception sensitivity and anti-jamming wave performance described above will be described. In the antenna system 100, the receiver RX1 can correspond to either the wide area or the local area by controlling the switch 15 of the receiver RX1. FIG. 9 schematically shows the receiver RX1 in the case where it corresponds to the wide area. In the case of a wide area, the through path of the directional coupler 13 is connected to the LNA 16, and the received signal can be input to the LNA 16 with a high strength.

  FIG. 10 schematically shows the receiver RX1 in the case where it corresponds to the local area. In the case of a local area, the coupling path of the directional coupler 13 is connected to the LNA 16. Therefore, although the reception gain is reduced by the degree of coupling, and therefore the reception sensitivity is lowered, the output saturation characteristic of the LNA 16 does not change as described above, so that the IIP3 of the received signal can be improved according to the degree of coupling. .

  As specifically described above, according to the receiver according to the first embodiment, high anti-jamming wave performance is ensured while relaxing the reception sensitivity in the local area, and high reception sensitivity is ensured in the wide area. It can be understood that the anti-jamming wave performance can be relaxed.

  In this configuration, since the reception signal passes through the coupling path of the directional coupler 13 in the local area, the reception signal input to the LNA 16 is delayed compared to the wide area. That is, when the delay is not compensated, a phase difference due to the delay occurs in the received signal in the receiver RX1 between the local area and the wide area, and thus signal processing in consideration of this phase difference is required.

  On the other hand, in this configuration, the received signal that has passed through the through path of the directional coupler 13 in the wide area is delayed by the delay unit 14 for a predetermined time. And by designing the delay amount in the delay unit 14 according to the delay amount of the coupling path of the directional coupler 13, even when switching between the local area setting and the wide area setting, Since the phase difference in the previous stage of the LNA is the same, the state after the phase compensation by the calibration before the switching is maintained without requiring the calibration immediately after the switching. As a result, calibration after switching the setting can be omitted, and a stable phase compensation state can be obtained.

Embodiment 2
Next, a receiver according to the second embodiment will be described. FIG. 11 schematically shows the configuration of the receiver according to the second exemplary embodiment. The receiver RX2 has a configuration in which the reception front end 10 of the receiver RX1 according to the first embodiment is replaced with a reception front end 30. The reception front end 30 has a configuration in which the switch 15 and the LNA 16 of the reception front end 10 are removed, and an LNA 31, an LNA 32, and a combiner 33 are added.

  The LNA 31 and the LNA 32 are configured as amplifiers whose on / off is controlled according to a given control signal. The input of the LNA 31 is connected to a delay device 14 constituted by a delay line. The input of the LNA 32 is connected to the coupling path of the directional coupler 13.

  The synthesizer 33 is inserted between the output of the LNA 31 and the output of the LNA 32 and the reception demodulator 20. The output of the synthesizer 33 is connected to the reception demodulator 20 at the subsequent stage.

  The operation of the receiver according to this embodiment will be described. First, the case of a wide area will be described. FIG. 12 is a diagram schematically illustrating a receiver in the case of a wide area. As shown in FIG. 12, in the case of a wide area, the LNA 31 is turned on and the LNA 32 is turned off. Therefore, only the reception signal output from the LNA 31 passes through the synthesizer 33. As a result, as in the first embodiment, a reception signal that passes through the through path of the directional coupler 13 and is given a predetermined delay is input to the reception demodulation unit 20.

  Next, the case of a local area will be described. FIG. 13 is a diagram schematically illustrating a receiver in the case of a local area. As shown in FIG. 13, in the case of a local area, the LNA 31 is turned off and the LNA 32 is turned on. Therefore, only the reception signal output from the LNA 32 passes through the synthesizer 33. As a result, similarly to the first embodiment, the received signal passes through the coupling path of the directional coupler 13 and is input to the reception demodulator 20.

  As described above, according to this configuration, it is possible to configure a single receiver capable of supporting a wide area as well as the first embodiment.

  Furthermore, according to this configuration, it is not necessary to provide a switch in front of the LNA as compared with the first embodiment, which is advantageous in that it is possible to prevent deterioration of reception gain.

Other Embodiments The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention. For example, in the above-described embodiment, the delay device is provided between the through path of the directional coupler and the LNA, but this is merely an example. For example, a delay device may be further provided between the coupling path of the directional coupler and the LNA, and the two received signals input to the LNA may be synchronized in phase using two delay devices.

  In the second embodiment, the example in which the distributor 33 is provided in the receiver has been described. However, the distributor may be replaced with a switch. In this case, the switch is controlled so as to connect the LNA 31 and the reception demodulator 20 in order to support the wide area, and the LNA 32 and the reception demodulator 20 are connected in order to support the local area. What is necessary is just to control a switch.

DESCRIPTION OF SYMBOLS 1 Signal processing part 2 Calibration signal transmitter 3 Divider 10, 30 Reception front end 11, 13 Directional coupler 12 BPF
14 Delay device 15 Switch 16, 31, 32 LNA
20 reception demodulator 21 quadrature demodulator 22 local oscillator 23 analog baseband BPF
24 Analog Variable Gain Amplifier 25 A / D Converter 26 Digital Baseband BPF
33 Divider 100 Antenna system A1-An Antenna BS Base station CC1-CCn Calibration corrector DM1-DMn Demodulator RX1, RX1_1-RX1_n, RX2 Receiver

Claims (11)

A reception front end for receiving a radio signal as a reception signal;
A demodulator that demodulates the received signal received by the reception front end,
The receiving front end is
A bandpass filter to which the received signal is input;
A first directionality that receives the reception signal filtered by the bandpass filter and divides the reception signal into a first reception signal that passes through a through path and a second reception signal that passes through a coupling path. A coupler;
A delayer for delaying the first received signal;
An amplifier that amplifies one of the first reception signal and the second reception signal that are input via the delay unit and outputs the amplified signal to the demodulation unit;
Receiving machine. The power of the first received signal is greater than the power of the second received signal;
The receiver according to claim 1. The delay device delays the first received signal so that a timing at which the first received signal is input to the amplifier is synchronized with a timing at which the second received signal is input to the amplifier.
The receiver according to claim 1 or 2. A switch that connects only one of the delay unit and the amplifier and the coupling path of the first directional coupler;
The receiver according to any one of claims 1 to 3. A first amplifier and a second amplifier which are the amplifiers;
A switch for connecting one of the output of the first amplifier and the output of the second amplifier to the input of the demodulator;
The first received signal is input to the first amplifier via the delay device,
The second received signal is input to the second amplifier.
The receiver according to any one of claims 1 to 3. A first amplifier and a second amplifier which are the amplifiers;
A synthesizer having an input connected to an output of the first amplifier and an output of the second amplifier, and an output connected to an input of the demodulator;
The first received signal is input to the first amplifier via the delay device,
The second received signal is input to the second amplifier.
The receiver according to any one of claims 1 to 3. Only one of the first amplifier and the second amplifier performs an amplification operation.
The receiver according to claim 5 or 6. A second directional coupler configured to output the received signal input to the through path and the calibration signal input to the coupling path to the bandpass filter;
The receiver according to any one of claims 1 to 7. A plurality of the receivers of claim 8;
A plurality of antennas respectively connected to the plurality of receivers;
A signal processing unit for processing a plurality of demodulated signals demodulated by the plurality of receivers;
A calibration signal transmitter for outputting the calibration signal;
A distributor for distributing the calibration signal to the second directional coupler of each of the plurality of receivers;
The signal processing unit corrects gains of the amplifiers of the plurality of receivers based on a demodulated signal obtained by demodulating the calibration signal distributed to the plurality of receivers.
Antenna system. A bandpass filter to which the received signal is input;
A directional coupler that receives the reception signal filtered by the bandpass filter and divides the reception signal into a first reception signal that passes through a through path and a second reception signal that passes through a coupling path; ,
A delayer for delaying the first received signal;
An amplifier that amplifies one of the first received signal and the second received signal that are input via the delay unit and outputs the amplified signal;
Receiver front end of the receiver. Let the received signal pass through a bandpass filter,
The received signal filtered by the bandpass filter is divided by a directional coupler into a first received signal that passes through the through path and a second received signal that passes through the combined path,
Adding a delay to the first received signal;
Amplifying either the delayed first received signal or the second received signal;
Demodulate the amplified signal,
Radio signal reception method.

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